USACE / NAVFAC / AFCESA / NASA UFGS-03 31 00.00 10 (April 2006)
--------------------------------
Preparing Activity: USACE Replacing without change
UFGS-03300A (January 2006)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 03 31 00.00 10
CAST-IN-PLACE STRUCTURAL CONCRETE
04/06
NOTE: This guide specification covers the requirements for cast-in-place concrete
materials, mixing, placement, and finishes.
Edit this guide specification for project specific requirements by adding, deleting,
or revising text. For bracketed items, choose applicable items(s) or insert
appropriate information.
Remove information and requirements not required in respective project, whether
or not brackets are present.
Comments and suggestions on this guide specification are welcome and should
be directed to the technical proponent of the specification. A listing of technical
proponents, including their organization designation and telephone number, is
on the Internet.
Recommended changes to a UFGS should be submitted as a Criteria Change Request
(CCR).
PART 1 GENERAL
NOTE: This specification covers concrete work primarily for buildings, but
may also be used for other applications such as wharves, docks, drainage structures,
warehouse type slabs, and driveways. The following guide specifications are
relative to this section and will be included to the extent applicable in projects
where this section is used:
Section 03 11 13.00 10 STRUCTURAL CONCRETE FORMWORK
Section 03 20 01.00 10 CONCRETE REINFORCEMENT
Section 03 15 13.00 10 EXPANSION JOINTS, CONTRACTION JOINTS, AND WATERSTOPS
Section 07 92 00 JOINT SEALANTS
Specifications on concrete for bridge construction should be in a separate section
and should be essentially in agreement with concrete construction requirements
in the American Association of State Highway and Transportation Officials, "Standard
Specifications for Highway Bridges." Requirements for deck slabs, curbs, gutters,
and sidewalks forming an integral part of the bridge should be included in the
section concerning concrete for bridge construction.
1.1 REFERENCES
NOTE: This paragraph is used to list the publications cited in the text of
the guide specification. The publications are referred to in the text by basic
designation only and listed in this paragraph by organization, designation,
date, and title.
Use the Reference Wizard's Check Reference feature when you add a RID outside
of the Section's Reference Article to automatically place the reference in the
Reference Article. Also use the Reference Wizard's Check Reference feature
to update the issue dates.
References not used in the text will automatically be deleted from this section
of the project specification when you choose to reconcile references in the
publish print process.
The publications listed below form a part of this specification to the extent referenced. The publications are
referred to within the text by the basic designation only.
[ACI INTERNATIONAL (ACI)ACI 117(2006) Standard Specifications for Tolerances for Concrete Construction and MaterialsACI 211.1(1991; R 2002) Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass ConcreteACI 211.2(1998; R 2004) Standard Practice for Selecting Proportions for Structural Lightweight ConcreteACI 213R(2003) Guide for Structural Lightweight Aggregate ConcreteACI 214R(2002) Recommended Practice for Evaluation of Strength Test Results of ConcreteACI 301(2005; Errata 2008) Specifications for Structural ConcreteACI 303R(2004) Guide to Cast-In-Place Architectural Concrete PracticeACI 305R(1999; Errata 2006) Hot Weather ConcretingACI 318(2008; Errata 2008) Building Code Requirements for Structural Concrete and CommentaryACI 318M(2008) Metric Building Code Requirements for Structural Concrete and Commentary][AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO)AASHTO M 182(2005) Standard Specification for Burlap Cloth Made from Jute or Kenaf and Cotton Mats][ASTM INTERNATIONAL (ASTM)ASTM C 1017/C 1017M(2007) Standard Specification for Chemical Admixtures for Use in Producing Flowing ConcreteASTM C 1059/C 1059M(1999; R 2008) Standard Specification for Latex Agents for Bonding Fresh to Hardened ConcreteASTM C 1064/C 1064M(2008) Standard Test Method for Temperature of Freshly Mixed Hydraulic-Cement ConcreteASTM C 1077(2008) Standard Practice for Laboratories Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Laboratory EvaluationASTM C 1107/C 1107M(2008) Standard Specification for Packaged Dry, Hydraulic-Cement Grout (Nonshrink)ASTM C 1116/C 1116M(2008) Standard Specification for Fiber-Reinforced ConcreteASTM C 1240(2005) Standard Specification for Silica Fume Used in Cementitious MixturesASTM C 1260(2007) Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)ASTM C 131(2006)Standard Test Method for Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles MachineASTM C 136(2006) Standard Test Method for Sieve Analysis of Fine and Coarse AggregatesASTM C 143/C 143M(2008) Standard Test Method for Slump of Hydraulic-Cement ConcreteASTM C 150(2007) Standard Specification for Portland CementASTM C 1567(2008) Standard Test Method for Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar-Bar Method)ASTM C 171(2007) Standard Specification for Sheet Materials for Curing ConcreteASTM C 172(2008) Standard Practice for Sampling Freshly Mixed ConcreteASTM C 173/C 173M(2008) Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric MethodASTM C 192/C 192M(2007) Standard Practice for Making and Curing Concrete Test Specimens in the LaboratoryASTM C 231(2008c) Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure MethodASTM C 260(2006) Standard Specification for Air-Entraining Admixtures for ConcreteASTM C 309(2007) Standard Specification for Liquid Membrane-Forming Compounds for Curing ConcreteASTM C 31/C 31M(2008a) Standard Practice for Making and Curing Concrete Test Specimens in the FieldASTM C 33(2007) Standard Specification for Concrete AggregatesASTM C 330(2005) Standard Specification for Lightweight Aggregates for Structural ConcreteASTM C 39/C 39M(2005e1e2) Standard Test Method for Compressive Strength of Cylindrical Concrete SpecimensASTM C 42/C 42M(2004) Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of ConcreteASTM C 494/C 494M(2008a) Standard Specification for Chemical Admixtures for ConcreteASTM C 496/C 496M(2004e1) Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete SpecimensASTM C 552(2007) Standard Specification for Cellular Glass Thermal InsulationASTM C 567(2005a) Determining Density of Structural Lightweight ConcreteASTM C 578(2008b) Standard Specification for Rigid, Cellular Polystyrene Thermal InsulationASTM C 591(2008) Standard Specification for Unfaced Preformed Rigid Cellular Polyisocyanurate Thermal InsulationASTM C 595(2008) Standard Specification for Blended Hydraulic CementsASTM C 618(2008a) Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in ConcreteASTM C 685/C 685M(2007) Concrete Made by Volumetric Batching and Continuous MixingASTM C 78(2008) Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)ASTM C 881/C 881M(2002) Standard Specification for Epoxy-Resin-Base Bonding Systems for ConcreteASTM C 937(2002) Grout Fluidifier for Preplaced-Aggregate ConcreteASTM C 94/C 94M(2007) Standard Specification for Ready-Mixed ConcreteASTM C 940(1998a; R 2003) Expansion and Bleeding of Freshly Mixed Grouts for Preplaced-Aggregate Concrete in the LaboratoryASTM C 989(2006) Standard Specification for Ground Granulated Blast-Furnace Slag for Use in Concrete and MortarsASTM D 1751(2004; R 2008) Standard Specification for Preformed Expansion Joint Filler for Concrete Paving and Structural Construction (Nonextruding and Resilient Bituminous Types)ASTM D 1752(2004a; R 2008) Standard Specification for Preformed Sponge Rubber Cork and Recycled PVC ExpansionASTM D 75(2003) Standard Practice for Sampling AggregatesASTM E 1155(1996; R 2008) Standard Test Method for Determining Floor Flatness and Floor Levelness NumbersASTM E 1155M(1996; R 2008) Standard Test Method for Determining Floor Flatness and Floor Levelness Numbers (Metric)ASTM E 96/E 96M(2005) Standard Test Methods for Water Vapor Transmission of Materials][NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY (NIST)NIST HB 44(2007) NIST Handbook 44: Specifications, Tolerances, and other Technical Requirements for Weighing and Measuring Devices][NATIONAL READY MIXED CONCRETE ASSOCIATION (NRMCA)NRMCA CPMB 100(2000) Concrete Plant StandardsNRMCA QC 3(2002) Quality Control Manual: Section 3, Plant Certifications Checklist: Certification of Ready Mixed Concrete Production FacilitiesNRMCA TMMB 100(2001) Truck Mixer, Agitator and Front Discharge Concrete Carrier Standards][U.S. ARMY CORPS OF ENGINEERS (USACE)COE CRD-C 104(1980) Method of Calculation of the Fineness Modulus of AggregateCOE CRD-C 400(1963) Requirements for Water for Use in Mixing or Curing ConcreteCOE CRD-C 521(1981) Standard Test Method for Frequency and Amplitude of Vibrators for ConcreteCOE CRD-C 540(2001) Standard Specification for Nonbituminous Inserts for Contraction Joints in Portland Cement Concrete Airfield Pavements, Sawable TypeCOE CRD-C 572(1974) Specifications for Polyvinylchloride WaterstopsCOE CRD-C 94(1995) Specification for Surface Retarders]1.2 UNIT PRICE CONTRACT
NOTE: Remove these paragraphs when lump sum contract is required.
1.2.1 Measurement
Measurement of concrete for payment will be made on the basis of the actual volume within the pay lines of the
structure as indicated on the contract drawings. Measurement for payment of concrete placed against the sides
of any excavation without intervening forms will be made only within the pay lines of the structure as shown
on the contract drawings. No deductions will be made for rounded or beveled edges, for space occupied by metal
work, for conduits, for voids, or for embedded items which are less than 0.15 cubic meters 5 cubic feet in volume
or 0.09 square meters 1 square foot in cross section.
1.2.2 Payment
Unless otherwise specified, payment for concrete will be made at the respective unit prices per cubic meter yard
for the various items of the schedule, measured as specified above, which price shall include the cost of all
labor, materials, and the use of equipment and tools required to complete the concrete work, except for any reinforcement
and embedded parts specified to be paid separately. Unit price payment will not be made for concrete placed
in structures for which payment is made as a lump sum.
1.3 LUMP SUM CONTRACT
NOTE: Remove this paragraph when unit price contract is required.
Under this type of contract concrete items will be paid for by lump sum and will not be measured. The work covered
by these items consists of furnishing all concrete materials, reinforcement, miscellaneous embedded materials,
and equipment, and performing all labor for the forming, manufacture, transporting, placing, finishing, curing,
and protection of concrete in these structures.
1.4 SUBMITTALS
NOTE: Review submittal description (SD) definitions in Section 01 33 00 SUBMITTAL
PROCEDURES and edit the following list to reflect only the submittals required
for the project. Submittals should be kept to the minimum required for adequate
quality control.
A “G” following a submittal item indicates that the submittal requires Government
approval. Some submittals are already marked with a “G”. Only delete an existing
“G” if the submittal item is not complex and can be reviewed through the Contractor’s
Quality Control system. Only add a “G” if the submittal is sufficiently important
or complex in context of the project.
For submittals requiring Government approval on Army projects, a code of up
to three characters within the submittal tags may be used following the "G"
designation to indicate the approving authority. Codes for Army projects using
the Resident Management System (RMS) are: "AE" for Architect-Engineer; "DO"
for District Office (Engineering Division or other organization in the District
Office); "AO" for Area Office; "RO" for Resident Office; and "PO" for Project
Office. Codes following the "G" typically are not used for Navy, Air Force,
and NASA projects.
Choose the first bracketed item for Navy, Air Force and NASA projects, or choose
the second bracketed item for Army projects.
Government approval is required for submittals with a "G" designation; submittals not having a "G" designation
are for [Contractor Quality Control approval.] [information only. When used, a designation following the "G"
designation identifies the office that will review the submittal for the Government.] The following shall be
submitted in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:
SD-03 Product Data
Mixture Proportions[; G][; G, [_____]]
The results of trial mixture design studies along with a statement giving the maximum nominal
coarse aggregate size and the proportions of ingredients that will be used in the manufacture
of each strength or class of concrete, at least 14 days prior to commencing concrete placing
operations. Aggregate weights shall be based on the saturated surface dry condition. The statement
shall be accompanied by test results from an approved independent commercial testing laboratory,
showing that mixture design studies have been made with materials proposed for the project and
that the proportions selected will produce concrete of the qualities indicated. No substitutions
shall be made in the materials used in the mixture design studies without additional tests to
show that the quality of the concrete is satisfactory.
Lightweight Aggregate Concrete
Written recommendations from lightweight aggregate supplier on batching and mixing cycles.
Dry Shake Finish
Manufacturer's written instructions on application of dry shake material 15 days prior to
start of construction.
SD-04 Samples
Surface Retarder
Sample of surface retarder material with manufacturer's instructions for application in conjunction
with air-water cutting.
SD-06 Test Reports
Testing and Inspection for Contractor Quality Control[; G][; G, [_____]]
Certified copies of laboratory test reports, including mill tests and all other test data,
for portland cement, blended cement, pozzolan, ground granulated blast furnace slag, silica
fume, aggregate, admixtures, and curing compound proposed for use on this project.
SD-07 Certificates
Qualifications
Written documentation for Contractor Quality Control personnel.
1.5 QUALIFICATIONS
Contractor Quality Control personnel assigned to concrete construction shall be American Concrete Institute (ACI)
Certified Workmen in one of the following grades or shall have written evidence of having completed similar qualification
programs:
Concrete Field Testing Technician, Grade I
Concrete Laboratory Testing Technician, Grade I or II
Concrete Construction Inspector, Level II
Concrete Transportation Construction Inspector or
Reinforced Concrete Special Inspector, Jointly certified by American Concrete Institute (ACI), Building
Official and Code Administrators International (BOCA), International Code Council (ICC), and Southern Building Code
Congress International (SBCCI).
The foreman or lead journeyman of the flatwork finishing crew shall have similar qualification for ACI Concrete
Flatwork Technician/Finisher or equal, with written documentation.
1.6 FIELD TEST PANELS
NOTE: Edit these paragraphs as appropriate. Specify location for all field
test panels. Add requirements for mock-ups if applicable. Add requirements
for slab panels if exposed aggregate slab finish is required or if superflat
slab finish is required.
Field test panels shall be constructed prior to beginning of work using the materials and procedures proposed
for use on the job, to demonstrate the results to be attained. The quality and appearance of each panel shall
be subject to the approval of the Contracting Officer, and, if not judged satisfactory, additional panels shall
be constructed until approval is attained. Formed or finished surfaces in the completed structure shall match
the quality and appearance of the approved field example.
1.6.1 Sample Wall Panels
One sample panel at least 1220 mm 4 feet by 1525 mm 5 feetand 150 mm 6 inches thick shall be constructed to demonstrate
Class A formed finish and a similar one for Class B formed finish. Panels shall be located [_____]. Each panel
shall include a full length and full width joint line and shall have at least two voids each at least 300 mm
12 inches by 300 mm 12 inches by 75 mm 3 inches deep either impressed in the concrete as placed or chipped in
the hardened concrete. After the concrete is 7 days old, the voids shall be patched to demonstrate the effectiveness
and the appearance of the Contractor's repair procedures.
1.6.2 Slab Panels
A slab panel at least 1220 mm 4 feet by 1525 mm 5 feet and 100 mm 4 inches thick shall be constructed to demonstrate
exposed aggregate slab finish and a similar panel for extra high class slab finish. Panels shall be located
[_____]. Each panel shall have a full length joint line.
1.7 SPECIAL REQUIREMENTS
NOTE: When the construction includes special items such as very high strength
concrete; non-sparking, conductive flooring; acid-resistant concrete; slipforming;
super-flat floors; etc., a pre-installation meeting will be required. In which
case this paragraph will be retained with appropriate editing and identification.
A pre-installation meeting with the Contracting Officer will be required at least 10 days prior to start of construction
on [_____]. The Contractor shall be responsible for calling the meeting; the Project Superintendent and active
installation personnel shall be present.
1.8 GENERAL REQUIREMENTS
NOTE: In addition to specified requirements the following information will
be shown on project drawings:
1. Assumed temperature range when temperature stresses are a factor in design.
2. Details of concrete sections showing dimensions, reinforcement cover, and
required camber.
3. Joint details showing locations and dimensions, including critical construction
joints, indicating waterstop locations and splices, keys, and dowels when required.
4. Locations where structural lightweight concrete will be used.
5. Details which require a depressed structural slab for tile, terrazzo, or
other floor finishes in order to provide finished surfaces at the same elevations.
6. When exposed concrete surfaces are specified, the locations in the finished
structure shall be indicated. If other than cast finish is required, the type
and location shall be indicated.
7. Loading assumptions
8. Material strengths used in design, and f'c.
1.8.1 Tolerances
NOTE: Insert any special tolerance requirements of the project. Select the
method desired for floor finish tolerance and delete the other. Do not use
both as a Contractor's option. An effort should be made to begin to convert
to the F-system for floor slabs. The F-system should always be used where very
flat floors are required, particularly warehouse aisles where high-lift forklift
units or other similar stackers will operate.
Except as otherwise specified herein, tolerances for concrete batching, mixture properties, and construction
as well as definition of terms and application practices shall be in accordance with ACI 117. Level and grade
tolerance measurements of slabs shall be made as soon as possible after finishing; when forms or shoring are
used, the measurements shall be made prior to removal.
1.8.1.1 Floors
For the purpose of this Section the following terminology correlation between ACI 117 and this Section shall
apply:
Floor Profile Quality
Classification From ACI 117 This Section
-------------------------------------- ---------------------
Conventional Bullfloated Same
Conventional Straightedged Same
Flat Float Finish or Trowel Finish
Very Flat Same. Use only with F-system
Levelness tolerance shall not apply where design requires floors to be sloped to drains or sloped for other reasons.
1.8.1.2 Floors by the F-Number System
The flatness and levelness of floors shall be carefully controlled and the tolerances shall be measured by the
F-Number system of Paragraph 4.5.6 and 4.5.6.1 of ACI 117. The Contractor shall furnish an approved floor profilograph
or other equipment capable of measuring the floor flatness (FF) number and the floor levelness (FL) number in
accordance with ASTM E 1155M ASTM E 1155. The Contractor shall perform the tolerance measurements within 72
hours after floor slab construction while being observed by the Contracting Officer. The tolerances of surfaces
beyond the limits of ASTM E 1155M ASTM E 1155 (the areas within 600 mm 24 inches of embedments and construction
joints) shall be acceptable to the Contracting Officer. Tolerances of the following areas shall meet the requirements
for the listed surfaces as specified in paragraphs 4.5.6 and 4.5.6.1 of ACI 117.
Bullfloated- Areas [_____]
Straightedged- Areas [_____]
Float Finish- Areas [_____]
Trowel Finish- Areas [_____]
Very Flat- Areas [_____]
1.8.1.3 Floors by the Straightedge System
The flatness of the floors shall be carefully controlled and the tolerances shall be measured by the straightedge
system as specified in paragraph 4.5.7 of ACI 117, using a 3 m 10 foot straightedge, within 72 hours after floor
slab installation and before shores and/or forms are removed. The listed tolerances shall be met at any and
every location at which the straightedge can be placed.
Bullfloated [_____]
Straightedged [_____]
Float Finish [_____]
Trowel Finish [_____]
1.8.2 Strength Requirements and w/c Ratio
1.8.2.1 Strength Requirements
NOTE: The designer will list the strengths of concrete for the job and the
uses for each. A 28-day compressive strength of 20 MPa (3000 psi) will be required
for most building work. Concrete of 27.5 MPa (4000 psi) should be used in containers
for liquids, and in other structures where loading, durability, or wear requirements
dictate. Higher compressive strengths will be used if required by structural
design. A 28-day flexural strength of 4.5 MPa (650 psi) will normally be specified
for slabs on grade subject to vehicular traffic; however, since cylinders are
easier to cast and test than beams, 27.5 MPa (4000 psi) compressive strength
concrete may be specified if past experience has shown this to be appropriate.
Concrete for hangar floors will be designed according to airfield pavement criteria
and will be specified in Section 32 13 13.03 AIRFIELDS AND HEAVY-DUTY CONCRETE
PAVEMENT LESS THAN 10000 CUBIC YARDS.
When the designer considers it appropriate, 90-day compressive or flexural strength
may be specified in lieu of 28-day, but not both.
Specified compressive strength (f'c) shall be as follows:
COMPRESSIVE STRENGTH STRUCTURE OR PORTION OF STRUCTURE
[35 MPa 5000 psi at 28 days [_____]]
[27.5 MPa 4000 psi at 28 days [_____]]
[20 MPa 3000 psi at 28 days [_____]]
[[_____] MPa psi at [_____] days [_____]]
Concrete slabs on-grade shall have a 28-day flexural strength of [4.5] [_____] MPa [650] [_____] psi. Concrete
made with high-early strength cement shall have a 7-day strength equal to the specified 28-day strength for concrete
made with Type I or II portland cement. Compressive strength shall be determined in accordance with ASTM C 39/C 39M
. Flexural strength shall be determined in accordance with ASTM C 78.
a. Evaluation of Concrete Compressive Strength. Compressive strength specimens (152 by 305
mm 6 by 12 inch cylinders) shall be fabricated by the Contractor and laboratory cured in accordance
with ASTM C 31/C 31M and tested in accordance with ASTM C 39/C 39M. The strength of the concrete
will be considered satisfactory so long as the average of all sets of three consecutive test
results equals or exceeds the specified compressive strength f'c and no individual test result
falls below the specified strength f'c by more than 3.5 MPa 500 psi. A "test" is defined as
the average of two companion cylinders, or if only one cylinder is tested, the results of the
single cylinder test. Additional analysis or testing, including taking cores and/or load tests
may be required at the Contractor's expense when the strength of the concrete in the structure
is considered potentially deficient.
b. Investigation of Low-Strength Compressive Test Results. When any strength test of standard-cured
test cylinders falls below the specified strength requirement by more than 3.5 MPa 500 psi or
if tests of field-cured cylinders indicate deficiencies in protection and curing, steps shall
be taken to assure that the load-carrying capacity of the structure is not jeopardized. When
the strength of concrete in place is considered potentially deficient, cores shall be obtained
and tested in accordance with ASTM C 42/C 42M. At least three representative cores shall be
taken from each member or area of concrete in place that is considered potentially deficient.
The location of cores will be determined by the Contracting Officer to least impair the strength
of the structure. Concrete in the area represented by the core testing will be considered adequate
if the average strength of the cores is equal to at least 85 percent of the specified strength
requirement and if no single core is less than 75 percent of the specified strength requirement.
Non-destructive tests (tests other than test cylinders or cores) shall not be used as a basis
for acceptance or rejection. The Contractor shall perform the coring and repair the holes.
Cores will be tested by the Government.
c. Load Tests. If the core tests are inconclusive or impractical to obtain or if structural
analysis does not confirm the safety of the structure, load tests may be directed by the Contracting
Officer in accordance with the requirements of ACI 318M ACI 318. Concrete work evaluated by
structural analysis or by results of a load test as being understrength shall be corrected in
a manner satisfactory to the Contracting Officer. All investigations, testing, load tests,
and correction of deficiencies shall be performed by and at the expense of the Contractor and
must be approved by the Contracting Officer, except that if all concrete is found to be in compliance
with the drawings and specifications, the cost of investigations, testing, and load tests will
be at the expense of the Government.
d. Evaluation of Concrete Flexural Strength. Flexural strength specimens (beams) shall be
fabricated by the Contractor and laboratory cured in accordance with ASTM C 31/C 31M and tested
in accordance with ASTM C 78. The strength of the concrete will be considered satisfactory
so long as the average of all sets of three consecutive test results equals or exceeds the specified
flexural strength and no individual test result falls below the specified flexural strength
by more than 350 kPa 50 psi. A "test" is defined as the average of two companion beams. Additional
analysis or testing, including taking cores and/or load tests may be required at the Contractor's
expense when the strength of the concrete in the slab is considered potentially deficient.
1.8.2.2 Water-Cement Ratio
NOTE: Where durability or other factors are a major consideration, retain this
paragraph limiting w/c; coordinate this subparagraph with paragraph MIXTURE
PROPORTIONS and its subparagraphs before deleting any of the contents, otherwise
delete. When cementitious materials other than portland cement are used, retain
the last two sentences. Consult EM 1110-2-2000 to fill in the blanks and to
select the appropriate w/c.
Maximum water-cement ratio (w/c) for normal weight concrete shall be as follows:
WATER-CEMENT RATIO, BY WEIGHT STRUCTURE OR PORTION OF STRUCTURE
[0.40] [_____]
[0.45] [_____]
[0.50] [_____]
[0.55] [_____]
[_____] [_____]
These w/c's may cause higher strengths than that required above for compressive or flexural strength. The maximum
w/c required will be the equivalent w/c as determined by conversion from the weight ratio of water to cement
plus pozzolan, silica fume, and ground granulated blast furnace slag (GGBF slag) by the weight equivalency method
as described in ACI 211.1. In the case where silica fume or GGBF slag is used, the weight of the silica fume
and GGBF slag shall be included in the equations of ACI 211.1 for the term P which is used to denote the weight
of pozzolan.
1.8.3 Air Entrainment
NOTE: Remove last two sentences when lightweight concrete is not required.
Except as otherwise specified for lightweight concrete, all normal weight concrete shall be air entrained to
contain between 4 and 7 percent total air, except that when the nominal maximum size coarse aggregate is 19 mm
3/4 inch or smaller it shall be between 4.5 and 7.5 percent. Concrete with specified strength over 35 MPa 5000
psi may have 1.0 percent less air than specified above. Specified air content shall be attained at point of
placement into the forms. Air content for normal weight concrete shall be determined in accordance with ASTM C 231
. Lightweight concrete in the [_____] parts of the structure shall be air-entrained with a total air content
of 4.5 to 7.5 percent, except that if the nominal maximum size coarse aggregate is 9.5 mm 3/8 inch or less, the
air content shall be 5.5 to 8.5 percent. Air content for lightweight concrete shall be determined in accordance
with ASTM C 173/C 173M.
1.8.4 Slump
NOTE: Use the sentence in the first set of brackets when those admixtures are
permitted by the specifications. Add special slump requirements for Class 8
and 9 floor slabs from ACI 302, when such floors are to be constructed. Edit
for lightweight concrete as required.
Slump of the concrete, as delivered to the point of placement into the forms, shall be within the following limits.
Slump shall be determined in accordance with ASTM C 143/C 143M.
Slump
Structural Element Minimum Maximum
_________________________ _______ _______
Walls, columns and beams 50 mm 2 in. 100 mm 4 in.
Foundation walls, substructure
walls, footings, slabs 25 mm 1 in. 75 mm 3 in.
Any structural concrete approved
for placement by pumping:
At pump 50 mm 2 in. 150 mm 6 in.
At discharge of line 25 mm 1 in. 100 mm 4 in.
[When use of a plasticizing admixture conforming to ASTM C 1017/C 1017M or when a Type F or G high range water
reducing admixture conforming to ASTM C 494/C 494M is permitted to increase the slump of concrete, concrete shall
have a slump of 50 to 100 mm 2 to 4 inches before the admixture is added and a maximum slump of 200 mm 8 inches
at the point of delivery after the admixture is added.] [For troweled floors, slump of structural lightweight
concrete with normal weight sand placed by pump shall not exceed 125 mm 5 inches at the point of placement.
For other slabs, slump of lightweight concrete shall not exceed 100 mm 4 inches at point of placement.]
1.8.5 Concrete Temperature
The temperature of the concrete as delivered shall not exceed 32 degrees C 90 degrees F. When the ambient temperature
during placing is 5 degrees C 40 degrees F or less, or is expected to be at any time within 6 hours after placing,
the temperature of the concrete as delivered shall be between 12 and 25 degrees C 55 and 75 degrees F.
1.8.6 Size of Coarse Aggregate
The largest feasible nominal maximum size aggregate (NMSA) specified in paragraph AGGREGATES shall be used in
each placement. However, nominal maximum size of aggregate shall not exceed any of the following: three-fourths
of the minimum cover for reinforcing bars, three-fourths of the minimum clear spacing between reinforcing bars,
one-fifth of the narrowest dimension between sides of forms, or one-third of the thickness of slabs or toppings.
1.8.7 Special Properties and Products
NOTE: If the use of a particular type of admixture is required for certain
parts of the structure, this paragraph should be revised accordingly.
Concrete may contain admixtures other than air entraining agents, such as water reducers, superplasticizers,
or set retarding agents to provide special properties to the concrete, if specified or approved. Any of these
materials to be used on the project shall be used in the mix design studies.
1.8.8 Lightweight Aggregate Structural Concrete
NOTE: Retain this paragraph when lightweight aggregate structural concrete
is required. Use bracketed alternate strength inserts (compressive or splitting
tensile strength) as appropriate. Correlate strength versus unit weight requirements
as determined from table in ASTM C 330, and as determined by consultation with
local producers. Remove last sentence when floor fill is not required.
Lightweight aggregate structural concrete shall conform to the requirements specified for normal weight concrete
except as specified herein. [Specified compressive strength shall be at least [_____] at 28 days,] [Specified
splitting tensile strength determined in accordance with ASTM C 496/C 496M shall be at least [_____] at 28 days,]
as determined by test specimens that have been air dried at 50 percent relative humidity for the last 21 days.
Air-dry unit weight shall be not over [_____] at 28 days as determined by ASTM C 567. However, fresh unit weight
shall be used for acceptance during concreting, using a correlation factor between the two types of unit weight
as determined during mixture design studies. Lightweight aggregate structural concrete floor fill shall have
a 28-day compressive strength of at least 17.3 MPa 2500 psi and an air-dry unit weight not exceeding 1850 kg/cubic
meter 115 pcf.
1.8.9 Technical Service for Specialized Concrete
NOTE: Use this paragraph when lightweight aggregate structural concrete is
specified or for other specialized concretes like those containing silica fume.
The services of a factory trained technical representative shall be obtained to oversee proportioning, batching,
mixing, placing, consolidating, and finishing of specialized structural concrete, such as [_____]. The technical
representative shall be on the job full time until the Contracting Officer is satisfied that field controls indicate
concrete of specified quality is furnished and that the Contractor's crews are capable of continued satisfactory
work. The technical representative shall be available for consultation with, and advice to, Government forces.
1.9 MIXTURE PROPORTIONS
NOTE: This paragraph places the responsibility for mixture proportioning on
the Contractor. Where Government mix design is required, the entire paragraph
will be revised accordingly. Do not delete 15 percent minimum for pozzolan,
unless pozzolan is prohibited.
Concrete shall be composed of portland cement, other cementitious and pozzolanic materials as specified, aggregates,
water and admixtures as specified.
1.9.1 Proportioning Studies for Normal Weight Concrete
Trial design batches, mixture proportioning studies, and testing requirements for various classes and types of
concrete specified shall be the responsibility of the Contractor. Except as specified for flexural strength
concrete, mixture proportions shall be based on compressive strength as determined by test specimens fabricated
in accordance with ASTM C 192/C 192M and tested in accordance with ASTM C 39/C 39M. Samples of all materials
used in mixture proportioning studies shall be representative of those proposed for use in the project and shall
be accompanied by the manufacturer's or producer's test reports indicating compliance with these specifications.
Trial mixtures having proportions, consistencies, and air content suitable for the work shall be made based on
methodology described in ACI 211.1, using at least three different water-cement ratios for each type of mixture,
which will produce a range of strength encompassing those required for each class and type of concrete required
on the project. The maximum water-cement ratios required in subparagraph Water-Cement Ratio will be the equivalent
water-cement ratio as determined by conversion from the weight ratio of water to cement plus pozzolan, silica
fume, and ground granulated blast furnace slag (GGBF slag) by the weight equivalency method as described in ACI 211.1
. In the case where silica fume or GGBF slag is used, the weight of the silica fume and GGBF slag shall be included
in the equations in ACI 211.1 for the term P, which is used to denote the weight of pozzolan. If pozzolan is
used in the concrete mixture, the minimum pozzolan content shall be 15 percent by weight of the total cementitious
material, and the maximum shall be 35 percent. Laboratory trial mixtures shall be designed for maximum permitted
slump and air content. Separate sets of trial mixture studies shall be made for each combination of cementitious
materials and each combination of admixtures proposed for use. No combination of either shall be used until
proven by such studies, except that, if approved in writing and otherwise permitted by these specifications,
an accelerator or a retarder may be used without separate trial mixture study. Separate trial mixture studies
shall also be made for concrete for any conveying or placing method proposed which requires special properties
and for concrete to be placed in unusually difficult placing locations. The temperature of concrete in each
trial batch shall be reported. For each water-cement ratio, at least three test cylinders for each test age
shall be made and cured in accordance withASTM C 192/C 192M. They shall be tested at 7 and 28 days in accordance
with ASTM C 39/C 39M. From these test results, a curve shall be plotted showing the relationship between water-cement
ratio and strength for each set of trial mix studies. In addition, a curve shall be plotted showing the relationship
between 7 day and 28 day strengths. Each mixture shall be designed to promote easy and suitable concrete placement,
consolidation and finishing, and to prevent segregation and excessive bleeding.
1.9.2 Proportioning Studies for Flexural Strength Concrete
NOTE: Retain this paragraph only when the design requires flexural strength
concrete.
Trial design batches, mixture proportioning studies, and testing requirements shall conform to the requirements
specified in paragraph Proportioning Studies for Normal Weight Concrete, except that proportions shall be based
on flexural strength as determined by test specimens (beams) fabricated in accordance with ASTM C 192/C 192M
and tested in accordance with ASTM C 78. Procedures given in ACI 211.1 shall be modified as necessary to accommodate
flexural strength.
1.9.3 Proportioning Studies for Lightweight Aggregate Structural Concrete
Trial design batches, mixture proportioning studies, and testing requirements shall conform to the requirements
specified in paragraph Proportioning Studies for Normal Weight Concrete, except as follows. Trial mixtures having
proportions, consistencies and air content suitable for the work shall be made based on methodology described
in ACI 211.2, using at least three different cement contents. Trial mixes shall be proportioned to produce air
dry unit weight and concrete strengths specified in paragraph GENERAL REQUIREMENTS. Trial mixtures shall be
proportioned for maximum permitted slump and air content. Test specimens and testing shall be as specified for
normal weight concrete except that [28-day compressive strength] [splitting tensile strength in accordance with
ASTM C 496/C 496M] shall be determined from test cylinders that have been air dried at 50 percent relative humidity
for the last 21 days. Air dry unit weight shall be determined in accordance with ASTM C 567 and shall be designed
to be at least 32 kg/cubic meter 2.0 pcf less than the maximum specified air dry unit weight in paragraph GENERAL
REQUIREMENTS. Curves shall be plotted using these results showing the relationship between cement factor and
strength and air dry unit weight. Normal weight fine aggregate may be substituted for part or all of the lightweight
fine aggregate, provided the concrete meets the strength and unit weight. A correlation shall also be developed
showing the ratio between air dry unit weight and fresh concrete unit weight for each mix.
1.9.4 Average Compressive Strength Required for Mixtures
The mixture proportions selected during mixture design studies shall produce a required average compressive strength
(f'cr) exceeding the specified compressive strength (f'c) by the amount indicated below. This required average
compressive strength, f'cr, will not be a required acceptance criteria during concrete production. However,
whenever the daily average compressive strength at 28 days drops below f'cr during concrete production, or daily
average 7-day strength drops below a strength correlated with the 28-day f'cr, the mixture shall be adjusted,
as approved, to bring the daily average back up to f'cr. During production, the required f'cr shall be adjusted,
as appropriate, based on the standard deviation being attained on the job.
1.9.4.1 Computations from Test Records
Where a concrete production facility has test records, a standard deviation shall be established in accordance
with the applicable provisions of ACI 214R. Test records from which a standard deviation is calculated shall
represent materials, quality control procedures, and conditions similar to those expected; shall represent concrete
produced to meet a specified strength or strengths (f'c) within 7 MPa 1,000 psi of that specified for proposed
work; and shall consist of at least 30 consecutive tests. A strength test shall be the average of the strengths
of two cylinders made from the same sample of concrete and tested at 28 days. Required average compressive strength
f'cr used as the basis for selection of concrete proportions shall be the larger of the equations that follow
using the standard deviation as determined above:
f'cr = f'c + 1.34S where units are in MPa f'cr = f'c + 1.34S where units are in psi
f'cr = f'c + 2.33S - 3.45 where units are in MPa f'cr = f'c + 2.33S - 500 where units are in psi
Where S = standard deviation
Where a concrete production facility does not have test records meeting the requirements above but does have
a record based on 15 to 29 consecutive tests, a standard deviation shall be established as the product of the
calculated standard deviation and a modification factor from the following table:
MODIFICATION FACTOR
NUMBER OF TESTS FOR STANDARD DEVIATION
15 1.16
20 1.08
25 1.03
30 or more 1.00
1.9.4.2 Computations without Previous Test Records
When a concrete production facility does not have sufficient field strength test records for calculation of the
standard deviation, the required average strength f'cr shall be determined as follows:
a. If the specified compressive strength f'c is less than 20 MPa 3,000 psi,
f'cr = f'c + 6.9 MPa f'cr = f'c + 1000 psi
b. If the specified compressive strength f'c is 20 to 35 MPa 3,000 to 5,000 psi,
f'cr = f'c + 8.3 MPa f'cr = f'c + 1,200 psi
c. If the specified compressive strength f'c is over 35 MPa 5,000 psi,
f'cr = f'c + 9.7 MPa f'cr = f'c + 1,400 psi
1.9.5 Average Flexural Strength Required for Mixtures
NOTE: Retain this paragraph when flexural strength mixtures are used.
The mixture proportions selected during mixture design studies for flexural strength mixtures and the mixture
used during concrete production shall be designed and adjusted during concrete production as approved, except
that the overdesign for average flexural strength shall simply be 15 percent greater than the specified flexural
strength at all times.
1.9.6 Mix Design for Bonded Topping for Heavy Duty Floors
NOTE: Retain this paragraph when design requires heavy duty floors.
The concrete mix design for bonded topping for heavy duty floors shall contain the greatest practical proportion
of coarse aggregate within the specified proportion limits. The mix shall be designed to produce concrete having
a 28-day strength of at least 34.5 MPa 5000 psi. Concrete for the topping shall consist of the following proportions,
by weight:
1.00 part portland cement
1.15 to 1.25 parts fine aggregate
1.80 to 2.00 parts coarse aggregate
Maximum w/c shall be 0.33. The topping concrete shall not be air-entrained. The concrete shall be mixed so
as to produce a mixture of the driest consistency possible to work with a sawing motion of the strike-off and
which can be floated and compacted as specified without producing water or excess cement at the surface. In
no case shall slump exceed 25 mm 1 inch as determined by ASTM C 143/C 143M.
1.10 STORAGE OF MATERIALS
Cement and other cementitious materials shall be stored in weathertight buildings, bins, or silos which will
exclude moisture and contaminants and keep each material completely separated. Aggregate stockpiles shall be
arranged and used in a manner to avoid excessive segregation and to prevent contamination with other materials
or with other sizes of aggregates. Aggregate shall not be stored directly on ground unless a sacrificial layer
is left undisturbed. Reinforcing bars and accessories shall be stored above the ground on platforms, skids or
other supports. Other materials shall be stored in such a manner as to avoid contamination and deterioration.
Admixtures which have been in storage at the project site for longer than 6 months or which have been subjected
to freezing shall not be used unless retested and proven to meet the specified requirements. Materials shall
be capable of being accurately identified after bundles or containers are opened.
1.11 GOVERNMENT ASSURANCE INSPECTION AND TESTING
Day-to day inspection and testing shall be the responsibility of the Contractor Quality Control (CQC) staff.
However, representatives of the Contracting Officer can and will inspect construction as considered appropriate
and will monitor operations of the Contractor's CQC staff. Government inspection or testing will not relieve
the Contractor of any of his CQC responsibilities.
1.11.1 Materials
The Government will sample and test aggregates, cementitious materials, other materials, and concrete to determine
compliance with the specifications as considered appropriate. The Contractor shall provide facilities and labor
as may be necessary for procurement of representative test samples. Samples of aggregates will be obtained at
the point of batching in accordance with ASTM D 75. Other materials will be sampled from storage at the jobsite
or from other locations as considered appropriate. Samples may be placed in storage for later testing when appropriate.
1.11.2 Fresh Concrete
Fresh concrete will be sampled as delivered in accordance with ASTM C 172 and tested in accordance with these
specifications, as considered necessary.
1.11.3 Hardened Concrete
Tests on hardened concrete will be performed by the Government when such tests are considered necessary.
1.11.4 Inspection
Concrete operations may be tested and inspected by the Government as the project progresses. Failure to detect
defective work or material will not prevent rejection later when a defect is discovered nor will it obligate
the Government for final acceptance.
PART 2 PRODUCTS
NOTE: Edit this PART to include only those products which are locally available,
are required by the project, and are acceptable to the designer.
2.1 CEMENTITIOUS MATERIALS
NOTE: EPA recommends that procuring agencies use flowable fill containing coal
fly ash (pozzolan) and/or ferrous foundry sands for backfill and other fill
applications. EPA further recommends that procuring agencies include provisions
in all construction contracts involving backfill or other fill applications,
to allow for the use of flowable fill containing coal fly ash and/or ferrous
foundry sands, where appropriate.
Include the limits on soluble alkalies for portland cement and for pozzolan
whenever there is a possibility of alkali-aggregate reactive aggregates being
furnished.
Where alkali-bearing soil or groundwater is encountered, or where the concrete
will be exposed to seawater, brackish water, or sewage, see ACI 201.2 R for
guidance on selecting cementitious material. See EM 1110-2-2000 for guidance
when proposing to use any type of portland-pozzolan or portland-furnace-slag
cement.
Edit bracketed items as required.
Cementitious Materials shall be portland cement, [portland-pozzolan cement,] [portland blast-furnace slag cement,]
or portland cement in combination with [pozzolan] [or ground granulated blast furnace slag] [or silica fume]
and shall conform to appropriate specifications listed below. Use of cementitious materials in concrete which
will have surfaces exposed in the completed structure shall be restricted so there is no change in color, source,
or type of cementitious material.
2.1.1 Portland Cement
ASTM C 150, Type I [low alkali] with a maximum 15 percent amount of tricalcium aluminate, or Type II [low alkali]
[including false set requirements] or [Type V]. White portland cement shall meet the above requirements except
that it may be Type I, Type II or Type III [low alkali]. White Type III shall be used only in specific areas
of the structure, when approved in writing.
2.1.2 High-Early-Strength Portland Cement
ASTM C 150, Type III with tricalcium aluminate limited to [5][8] percent, [low alkali]. Type III cement shall
be used only in isolated instances and only when approved in writing.
2.1.3 Blended Cements
NOTE: Never specify I(PM) or I(SM) cement.
ASTM C 595, Type [IP][IP (MS)][IP (MH)][IS][IS (MS)][IS (MH)].
2.1.4 Pozzolan (Fly Ash)
Pozzolan shall conform to ASTM C 618, Class C or F, including low alkali [multiple factor,] [drying shrinkage,]
[uniformity,] [,and [moderate][severe] sulfate resistance] requirements in Table 3 of ASTM C 618. [Requirement
for maximum alkalies from Table 1A of ASTM C 618 shall apply]. If pozzolan is used, it shall never be less than
15 percent nor more than 35 percent by weight of the total cementitious material. The Contractor shall comply
with EPA requirements in accordance with Section 01 62 35 RECYCLED / RECOVERED MATERIALS.
2.1.5 Ground Granulated Blast-Furnace (GGBF) Slag
ASTM C 989, Grade 120.
2.1.6 Silica Fume
NOTE: Silica Fume Concrete should be used where low permeability and enhanced
durability are necessary and justified by additional cost, such as marine structures,
other places where low permeability is needed, and severe abrasion resistance.
Finishing is more difficult than conventional concrete. Proper curing is essential
because there is a strong tendency for severe plastic shrinkage cracking.
Supervision by manufacturer's representative should be required during batching,
finishing, and curing at start-up of the job. A HRWR recommended by the manufacturer
of the silica fume should be used.
Silica fume shall conform to ASTM C 1240. Available alkalies shall conform to the optimal limit given in Table
2 of ASTM C 1240. Silica fume may be furnished as a dry, densified material or as a slurry. In accordance with
paragraph Technical Service for Specialized Concrete, the Contractor shall provide at no cost to the Government
the services of a manufacturer's technical representative experienced in mixing, proportioning, placement procedures,
and curing of concrete containing silica fume.
2.2 AGGREGATES
NOTE: Edit and fill in the blanks as appropriate. Consideration should always
be given to the local aggregate supply situation, quality, and availability.
This note may be disregarded for regions where Alkali-Silica Reactivity (ASR)
is not a concern. Some aggregate sources may exhibit an ASR potential. ASR
is a potentially deleterious reaction between alkalis present in concrete and
some siliceous aggregates, reference EM 1110-2-2000 paragraph 2-3b(6) and appendix
D. Where ASR is known or suspected to pose a concern for concrete durability,
it is recommended that aggregates proposed for use in concrete be evaluated
to determine ASR potential and an effective mitigation. EM 1110-2-2000, provides
recommendations for evaluating and mitigating ASR in concrete mixtures. Aggregate
evaluations may not be practical for projects requiring small quantities of
concrete (less than 250 cubic yards).
UFGS Section 32 13 11 CONCRETE PAVEMENT FOR AIRFIELDS AND OTHER HEAVY-DUTY PAVEMENTS
MORE THAN 10,000 CUBIC YARDS, paragraph 2.2.1.2 Alkali-Silica Reactivity, provides
a specification method for the Contractor to evaluate and mitigate ASR in concrete
mixtures. The expansion limits specified in UFGS Section 32 13 11 are requirements
for pavements and exterior slab construction. For structural concrete applications
the measured expansion shall be less than 0.10 percent. It may not be economical
or practical to specify different test limit requirements for use on the same
project. In which case the lower limit required by the application should be used.
The designer may use the specification method in UFGS Section 32 13 11 by incorporating
the relevant paragraphs into this specification, or may use the following requirements
(retain either the 0.10 or the 0.08 percent expansion limits as appropriate)
included in the set of brackets highlighted thus "[.]".
Fine and coarse aggregates shall "[be tested and evaluated for alkali-aggregate reactivity in accordance with
ASTM C 1260. The fine and coarse aggregates shall be evaluated separately and in combination, which matches
the Contractor's proposed mix design proportioning. All results of the separate and combination testing shall
have a measured expansion less than 0.10 (0.08) percent at 16 days after casting. Should the test data indicate
an expansion of 0.10 (0.08) percent or greater, the aggregate(s) shall be rejected or additional testing using
ASTM C 1260 and ASTM C 1567 shall be performed. The additional testing using ASTM C 1260 and ASTM C 1567 shall
be performed using the low alkali portland cement in combination with ground granulated blast furnace (GGBF)
slag, or Class F fly ash. GGBF slag shall be used in the range of 40 to 50 percent of the total cementitious
material by mass. Class F fly ash shall be used in the range of 25 to 40 percent of the total cementitious material
by mass.]" [conform to the following.]
2.2.1 Fine Aggregate
Fine aggregate shall conform to the quality and gradation requirements of ASTM C 33.
2.2.2 Coarse Aggregate
Coarse aggregate shall conform to ASTM C 33, Class 5S, size designation [_____].
2.2.3 Lightweight Aggregate
Lightweight fine and coarse aggregate shall conform to the quality and gradation requirements of ASTM C 330,
size [_____] for coarse aggregate. Lightweight aggregate shall be prewetted in accordance with the Manufacturer's
instructions unless otherwise specified. For pumped concrete, prewetting shall be sufficient to ensure that
slump loss through the pump line does not exceed 100 mm 4 inches.
2.2.4 Materials for Bonded Topping for Heavy Duty Floors
In addition to the requirements specified above, coarse aggregate used for this purpose shall be a well graded,
hard, sound diabase, trap rock, emery, granite or other natural or manufactured aggregate having equivalent hardness
and wearing qualities and shall have a percentage of loss not to exceed 30 after 500 revolutions when tested
in accordance with ASTM C 131. Gradation of the aggregates when tested in accordance with ASTM C 136 shall be
as follows:
Coarse Aggregate
Cumulative Percent
Sieve Size By Weight Passing
__________ _________________
19 mm 3/4 in. 100
12.5 mm 1/2 in. 50-100
9.5 mm 3/8 in. 25-50
4.75 mm No. 4 0-15
2.36 mm No. 8 0-8
Fine Aggregate
Cumulative Percent
Sieve Size By Weight Passing
__________ __________________
9.5 mm 3/8 in. 100
4.75 mm No. 4 95-100
2.36 mm No. 8 65-80
1.18 mm No. 16 45-65
0.600 mm No. 30 25-45
0.300 mm No. 50 5-15
0.150 mm No. 100 0-5
2.3 CHEMICAL ADMIXTURES
NOTE: Edit as appropriate for the project. Do not permit the use of calcium
chloride.
Chemical admixtures, when required or permitted, shall conform to the appropriate specification listed. Admixtures
shall be furnished in liquid form and of suitable concentration for easy, accurate control of dispensing.
2.3.1 Air-Entraining Admixture
ASTM C 260 and shall consistently entrain the air content in the specified ranges under field conditions.
2.3.2 Accelerating Admixture
ASTM C 494/C 494M, Type C or E, except that calcium chloride or admixtures containing calcium chloride shall
not be used.
2.3.3 Water-Reducing or Retarding Admixture
ASTM C 494/C 494M, Type A, B, or D, except that the 6-month and 1-year compressive and flexural strength tests
are waived.
2.3.4 High-Range Water Reducer
NOTE: Use this paragraph only when high-range water reducing admixture is allowed
in paragraph SLUMP in PART 1.
ASTM C 494/C 494M, Type F or G, except that the 6-month and 1-year strength requirements are waived. The admixture
shall be used only when approved in writing, such approval being contingent upon particular mixture control as
described in the Contractor's Quality Control Plan and upon performance of separate mixture design studies.
2.3.5 Surface Retarder
COE CRD-C 94.
2.3.6 Expanding Admixture
Aluminum powder type expanding admixture conforming to ASTM C 937.
2.3.7 Other Chemical Admixtures
NOTE: Use this paragraph only when a plasticizing admixture is allowed in paragraph
SLUMP in PART 1.
Chemical admixtures for use in producing flowing concrete shall comply with ASTM C 1017/C 1017M, Type I or II.
These admixtures shall be used only when approved in writing, such approval being contingent upon particular
mixture control as described in the Contractor's Quality Control Plan and upon performance of separate mixture
design studies.
2.4 CURING MATERIALS
2.4.1 Impervious-Sheet
Impervious-sheet materials shall conform to ASTM C 171, type optional, except, that polyethylene sheet shall
not be used.
2.4.2 Membrane-Forming Compound
Membrane-Forming curing compound shall conform to ASTM C 309, Type 1-D or 2, except that only a styrene acrylate
or chlorinated rubber compound meeting Class B requirements shall be used for surfaces that are to be painted
or are to receive bituminous roofing, or waterproofing, or floors that are to receive adhesive applications of
resilient flooring. The curing compound selected shall be compatible with any subsequent paint, roofing, waterproofing,
or flooring specified. Nonpigmented compound shall contain a fugitive dye, and shall have the reflective requirements
in ASTM C 309 waived.
2.4.3 Burlap and Cotton Mat
Burlap and cotton mat used for curing shall conform to AASHTO M 182.
2.5 WATER
Water for mixing and curing shall be fresh, clean, potable, and free of injurious amounts of oil, acid, salt,
or alkali, except that non-potable water may be used if it meets the requirements of COE CRD-C 400.
2.6 NONSHRINK GROUT
Nonshrink grout shall conform to ASTM C 1107/C 1107M, Grade [A] [B] [C], and shall be a commercial formulation
suitable for the proposed application.
2.7 NONSLIP SURFACING MATERIAL
Nonslip surfacing material shall consist of 55 percent, minimum, aluminum oxide or silicon-dioxide abrasive ceramically
bonded together to form a homogeneous material sufficiently porous to provide a good bond with portland cement
paste; or factory-graded emery aggregate consisting of not less than 45 percent aluminum oxide and 25 percent
ferric oxide. The aggregate shall be well graded from particles retained on the 0.6 mm No. 30 sieve to particles
passing the 2.36 mm No. 8 sieve.
2.8 LATEX BONDING AGENT
Latex agents for bonding fresh to hardened concrete shall conform to ASTM C 1059/C 1059M.
2.9 EPOXY RESIN
Epoxy resins for use in repairs shall conform to ASTM C 881/C 881M, Type V, Grade 2. Class as appropriate to
the existing ambient and surface temperatures.
2.10 EMBEDDED ITEMS
Embedded items shall be of the size and type indicated or as needed for the application. Dovetail slots shall
be galvanized steel. Hangers for suspended ceilings shall be as specified in Section 09 51 00 ACOUSTICAL CEILINGS.
Inserts for shelf angles and bolt hangers shall be of malleable iron or cast or wrought steel.
2.11 FLOOR HARDENER
NOTE: Floor hardener should only be specified on specialized indoor floors
where dusting of concrete would present an unusual problem or where specially
requested by the Using Service.
Floor hardener shall be a colorless aqueous solution containing zinc silicofluoride, magnesium silicofluoride,
or sodium silicofluoride. These silicofluorides can be used individually or in combination. Proprietary hardeners
may be used if approved in writing by the Contracting Officer.
2.12 PERIMETER INSULATION
NOTE: Show required K-value on the drawings.
Perimeter insulation shall be polystyrene conforming to ASTM C 578, Type II; polyurethane conforming to ASTM C 591
, Type II; or cellular glass conforming to ASTM C 552, Type I or IV. The Contractor shall comply with EPA requirements
in accordance with Section 01 62 35 RECYCLED / RECOVERED MATERIALS.
2.13 VAPOR BARRIER
Vapor barrier shall be polyethylene sheeting with a minimum thickness of 0.15 mm 6 mils or other equivalent material
having a vapor permeance rating not exceeding 30 nanograms per Pascal per second per square meter 0.5 perms as
determined in accordance with ASTM E 96/E 96M.
2.14 JOINT MATERIALS
2.14.1 Joint Fillers, Sealers, and Waterstops
NOTE: Do not use bituminous filler with non-bituminous sealer. Designer will
edit bracketed items for joint sealing.
Expansion joint fillers shall be preformed materials conforming to [ASTM D 1751] [ASTM D 1752]. Materials for
waterstops shall be in accordance with Section 03 15 13.00 10 EXPANSION JOINTS, CONTRACTION JOINTS, AND WATERSTOPS.
Materials for and sealing of joints shall conform to the requirements of Section [07 92 00 JOINT SEALANTS] [
32 01 19 FIELD MOLDED SEALANTS FOR SEALING JOINTS IN RIGID PAVEMENTS] [32 13 73 COMPRESSION JOINT SEALS FOR CONCRETE
PAVEMENTS].
2.14.2 Contraction Joints in Slabs
Sawable type contraction joint inserts shall conform to COE CRD-C 540. Nonsawable joint inserts shall have sufficient
stiffness to permit placement in plastic concrete without undue deviation from a straight line and shall conform
to the physical requirements of COE CRD-C 540, with the exception of Section 3.4 "Resistance to Sawing". Plastic
inserts shall be polyvinyl chloride conforming to the materials requirements of COE CRD-C 572.
2.15 SYNTHETIC FIBERS FOR REINFORCING
NOTE: Use fiber reinforcement only when approved by the designer; in that case
retain this paragraph. Drawings should indicate where fiber reinforced concrete
is located. Fiber reinforcing is used to help control cracking due to drying
shrinkage and thermal expansion/contraction; reduce permeability; and increase
impact capacity, shatter and abrasion resistance, and toughness. Fiber reinforcing
will not: control cracking due to structural stresses, significantly increase
strength, control curling or creeping, justify reducing structural members,
eliminate control joints, or replace any moment or structural steel reinforcement.
Include flexural toughness tests when synthetic reinforcement fibers are used
to increase toughness and when justified by size and importance of the job,
but not when fibers are used only to control shrinkage cracking. Include technical
representative requirement when warranted by size and importance of the job.
Synthetic fibers shall conform to ASTM C 1116/C 1116M, Type III, Synthetic Fiber, and as follows. Fibers shall
be 100 percent virgin polypropylene fibrillated fibers containing no reprocessed olefin materials. Fibers shall
have a specific gravity of 0.9, a minimum tensile strength of 480 MPa 70 ksi graded in accordance with manufacturer,
and specifically manufactured to an optimum gradation for use as concrete secondary reinforcement.
2.16 DRY SHAKE FLOOR TOPPING MATERIAL
NOTE: Edit and supplement this paragraph for light reflective, spark resistant,
static disseminating floors as applicable to the project.
Dry shake floor topping material shall be a premixed ready-to-use dry shake. It shall be proportioned, mixed
and packaged at the factory, and delivered to the jobsite in sealed, moisture resistant bags, ready to apply,
finish and cure. The manufacturer of the dry shake material shall have at least 10 years experience in the manufacture
of such material. Any material from a manufacturer who makes any disclaimer of the materials performance shall
not be used.
PART 3 EXECUTION
3.1 PREPARATION FOR PLACING
Before commencing concrete placement, the following shall be performed. Surfaces to receive concrete shall be
clean and free from frost, ice, mud, and water. Forms shall be in place, cleaned, coated, and adequately supported,
in accordance with Section 03 11 13.00 10 STRUCTURAL CONCRETE FORMWORK. Reinforcing steel shall be in place,
cleaned, tied, and adequately supported, in accordance with Section 03 20 01.00 10 CONCRETE REINFORCEMENT. Transporting
and conveying equipment shall be in-place, ready for use, clean, and free of hardened concrete and foreign material.
Equipment for consolidating concrete shall be at the placing site and in proper working order. Equipment and
material for curing and for protecting concrete from weather or mechanical damage shall be at the placing site,
in proper working condition and in sufficient amount for the entire placement. When hot, windy conditions during
concreting appear probable, equipment and material shall be at the placing site to provide windbreaks, shading,
fogging, or other action to prevent plastic shrinkage cracking or other damaging drying of the concrete.
3.1.1 Foundations
3.1.1.1 Concrete on Earth Foundations
Earth (subgrade, base, or subbase courses) surfaces upon which concrete is to be placed shall be clean, damp,
and free from debris, frost, ice, and standing or running water. Prior to placement of concrete, the foundation
shall be well drained and shall be satisfactorily graded and uniformly compacted.
3.1.1.2 Preparation of Rock
Rock surfaces upon which concrete is to be placed shall be free from oil, standing or running water, ice, mud,
drummy rock, coating, debris, and loose, semidetached or unsound fragments. Joints in rock shall be cleaned
to a satisfactory depth, as determined by the Contracting Officer, and to firm rock on the sides. Immediately
before the concrete is placed, rock surfaces shall be cleaned thoroughly by the use of air-water jets or sandblasting
as specified below for Previously Placed Concrete. Rock surfaces shall be kept continuously moist for at least
24 hours immediately prior to placing concrete thereon. All horizontal and approximately horizontal surfaces
shall be covered, immediately before the concrete is placed, with a layer of mortar proportioned similar to that
in the concrete mixture. Concrete shall be placed before the mortar stiffens.
3.1.1.3 Excavated Surfaces in Lieu of Forms
NOTE: Delete this paragraph when forms are required.
Concrete for [footings] [and] [walls] may be placed directly against the soil provided the earth or rock has
been carefully trimmed, is uniform and stable, and meets the compaction requirements of Section 31 00 00 EARTHWORK.
The concrete shall be placed without becoming contaminated by loose material, and the outline of the concrete
shall be within the specified tolerances.
3.1.2 Previously Placed Concrete
NOTE: If structure has few construction joints to be bonded, none of them critical,
remove the following requirements except for subparagraph Preparation of Previously
Placed Concrete. Otherwise, use the following requirements and remove subparagraph
Preparation of Previously Placed Concrete.
Concrete surfaces to which additional concrete is to be bonded shall be prepared for receiving the next horizontal
lift by cleaning the construction joint surface with either air-water cutting, sandblasting, high-pressure water
jet, or other approved method. Concrete at the side of vertical construction joints shall be prepared as approved
by the Contracting Officer. Air-water cutting shall not be used on formed surfaces or surfaces congested with
reinforcing steel. Regardless of the method used, the resulting surfaces shall be free from all laitance and
inferior concrete so that clean surfaces of well bonded coarse aggregate are exposed and make up at least 10-percent
of the surface area, distributed uniformly throughout the surface. The edges of the coarse aggregate shall not
be undercut. The surface of horizontal construction joints shall be kept continuously wet for the first 12 hours
during the 24-hour period prior to placing fresh concrete. The surface shall be washed completely clean as the
last operation prior to placing the next lift. For heavy duty floors and two-course floors a thin coat of neat
cement grout of about the consistency of thick cream shall be thoroughly scrubbed into the existing surface immediately
ahead of the topping placing. The grout shall be a 1:1 mixture of portland cement and sand passing the 2.36
mm No. 8 sieve. The topping concrete shall be deposited before the grout coat has had time to stiffen.
3.1.2.1 Air-Water Cutting
Air-water cutting of a fresh concrete surface shall be performed at the proper time and only on horizontal construction
joints. The air pressure used in the jet shall be 700 kPa 100 psi plus or minus, 70 kPa 10 psi, and the water
pressure shall be just sufficient to bring the water into effective influence of the air pressure. When approved
by the Contracting Officer, a surface retarder complying with the requirements of COE CRD-C 94 may be applied
to the surface of the lift in order to prolong the period of time during which air-water cutting is effective.
After cutting, the surface shall be washed and rinsed as long as there is any trace of cloudiness of the wash
water. Where necessary to remove accumulated laitance, coatings, stains, debris, and other foreign material,
high-pressure waterjet or sandblasting shall be used as the last operation before placing the next lift.
3.1.2.2 High-Pressure Water Jet
A stream of water under a pressure of not less than 20 MPa 3,000 psi shall be used for cutting and cleaning.
Its use shall be delayed until the concrete is sufficiently hard so that only the surface skin or mortar is removed
and there is no undercutting of coarse-aggregate particles. If the waterjet is incapable of a satisfactory cleaning,
the surface shall be cleaned by sandblasting.
3.1.2.3 Wet Sandblasting
Wet sandblasting shall be used after the concrete has reached sufficient strength to prevent undercutting of
the coarse aggregate particles. After wet sandblasting, the surface of the concrete shall then be washed thoroughly
to remove all loose materials.
3.1.2.4 Waste Disposal
The method used in disposing of waste water employed in cutting, washing, and rinsing of concrete surfaces shall
be such that the waste water does not stain, discolor, or affect exposed surfaces of the structures, or damage
the environment of the project area. The method of disposal shall be subject to approval.
3.1.2.5 Preparation of Previously Placed Concrete
NOTE: When the structure has few construction joints to be bonded, none of
them critical, use this subparagraph and delete requirements of above subparagraphs
and of paragraph Previously Placed Concrete. Renumber this specification accordingly.
Concrete surfaces to which other concrete is to be bonded shall be abraded in an approved manner that will expose
sound aggregate uniformly without damaging the concrete. Laitance and loose particles shall be removed. Surfaces
shall be thoroughly washed and shall be moist but without free water when concrete is placed.
3.1.3 Vapor Barrier
NOTE: When this paragraph is used, coordinate drawings and specifications ensuring
that drawings indicate vapor barrier beneath slabs. Retain the penultimate
sentence unless experience in the area has shown it to be unnecessary.
Vapor barrier shall be provided beneath the interior on-grade concrete floor slabs. The greatest widths and
lengths practicable shall be used to eliminate joints wherever possible. Joints shall be lapped a minimum of
300 mm 12 inches. Torn, punctured, or damaged vapor barrier material shall be removed and new vapor barrier
shall be provided prior to placing concrete. For minor repairs, patches may be made using laps of at least 300
mm 12 inches. Lapped joints shall be sealed and edges patched with pressure-sensitive adhesive or tape not less
than 50 mm 2 inches wide and compatible with the membrane. Vapor barrier shall be placed directly on underlying
subgrade, base course, or capillary water barrier, unless it consists of crushed material or large granular material
which could puncture the vapor barrier. In this case, a thin layer of approximately 13 mm 1/2 inch of fine graded
material should be rolled or compacted over the fill before installation of the vapor barrier to reduce the possibility
of puncture. Concrete placement shall be controlled so as to prevent damage to the vapor barrier.
3.1.4 Perimeter Insulation
NOTE: When this paragraph is used, ensure that drawings indicate location and
extent of perimeter insulation.
Perimeter insulation shall be installed at locations indicated. Adhesive shall be used where insulation is applied
to the interior surface of foundation walls and may be used for exterior application.
3.1.5 Embedded Items
Before placement of concrete, care shall be taken to determine that all embedded items are firmly and securely
fastened in place as indicated on the drawings, or required. Conduit and other embedded items shall be clean
and free of oil and other foreign matter such as loose coatings or rust, paint, and scale. The embedding of
wood in concrete will be permitted only when specifically authorized or directed. Voids in sleeves, inserts,
and anchor slots shall be filled temporarily with readily removable materials to prevent the entry of concrete
into voids. Welding shall not be performed on embedded metals within 300 mm 12 inches of the surface of the
concrete. Tack welding shall not be performed on or to embedded items.
3.2 CONCRETE PRODUCTION
NOTE: Use this paragraph and its subparagraphs for all projects except where
designer chooses to use the following optional paragraph CONCRETE PRODUCTION,
SMALL PROJECTS, provided it meets the criteria described therein, in which case
delete these. Do not specify both options.
3.2.1 General Requirements
NOTE: The designer must choose one of the two bracketed requirements and delete
the other. Do not use the first bracketed requirement if ready-mixed concrete
is not wanted.
[Concrete shall either be batched and mixed onsite or shall be furnished from a ready-mixed concrete plant.
Ready-mixed concrete shall be batched, mixed, and transported in accordance with ASTM C 94/C 94M, except as otherwise
specified. Truck mixers, agitators, and nonagitating transporting units shall comply with NRMCA TMMB 100. Ready-mix
plant equipment and facilities shall be certified in accordance with NRMCA QC 3. Approved batch tickets shall
be furnished for each load of ready-mixed concrete. Site-mixed concrete shall conform to the following subparagraphs.]
[Concrete shall be batched and mixed onsite, or close to onsite, and shall conform to the following subparagraphs.]
3.2.2 Batching Plant
NOTE: Choose the desired bracketed options for plant locations. Insert desired
minimum capacity of plant, it should be sufficient to accommodate the largest
placement within a reasonable time.
The batching plant shall be located [on site in the general area indicated on the drawings] [or] [off site close
to the project]. The batching, mixing and placing system shall have a capacity of at least [_____] cubic meters
yards per hour. The batching plant shall conform to the requirements of NRMCA CPMB 100 and as specified; however,
rating plates attached to batch plant equipment are not required.
3.2.3 Batching Equipment
NOTE: Retain the bracketed sentence concerning truck mixers unless it is desired
to prohibit truck mixers. Always retain bracketed item about silica fume when
its use is allowed, otherwise delete.
The batching controls shall be semiautomatic or automatic, as defined in NRMCA CPMB 100. A semiautomatic batching
system shall be provided with interlocks such that the discharge device cannot be actuated until the indicated
material is within the applicable tolerance. The batching system shall be equipped with accurate recorder or
recorders that meet the requirements of NRMCA CPMB 100. The weight of water and admixtures shall be recorded
if batched by weight. Separate bins or compartments shall be provided for each size group of aggregate and type
of cementitious material, to prevent intermingling at any time. Aggregates shall be weighed either in separate
weigh batchers with individual scales or, provided the smallest size is batched first, cumulatively in one weigh
batcher on one scale. Aggregate shall not be weighed in the same batcher with cementitious material. If both
portland cement and other cementitious material are used, they may be batched cumulatively, provided that the
portland cement is batched first, [except that silica fume shall always be batched separately]. Water may be
measured by weight or volume. Water shall not be weighed or measured cumulatively with another ingredient.
Filling and discharging valves for the water metering or batching system shall be so interlocked that the discharge
valve cannot be opened before the filling valve is fully closed. Piping for water and for admixtures shall be
free from leaks and shall be properly valved to prevent backflow or siphoning. Admixtures shall be furnished
as a liquid of suitable concentration for easy control of dispensing. An adjustable, accurate, mechanical device
for measuring and dispensing each admixture shall be provided. Each admixture dispenser shall be interlocked
with the batching and discharging operation of the water so that each admixture is separately batched and individually
discharged automatically in a manner to obtain uniform distribution throughout the water as it is added to the
batch in the specified mixing period. [When use of truck mixers makes this requirement impractical, the admixture
dispensers shall be interlocked with the sand batchers]. Different admixtures shall not be combined prior to
introduction in water and shall not be allowed to intermingle until in contact with the cement. Admixture dispensers
shall have suitable devices to detect and indicate flow during dispensing or have a means for visual observation.
The plant shall be arranged so as to facilitate the inspection of all operations at all times. Suitable facilities
shall be provided for obtaining representative samples of aggregates from each bin or compartment, and for sampling
and calibrating the dispensing of cementitious material, water, and admixtures. Filling ports for cementitious
materials bins or silos shall be clearly marked with a permanent sign stating the contents.
3.2.4 Scales
The weighing equipment shall conform to the applicable requirements of CPMB Concrete Plant Standard, and of NIST HB 44
, except that the accuracy shall be plus or minus 0.2 percent of scale capacity. The Contractor shall provide
standard test weights and any other auxiliary equipment required for checking the operating performance of each
scale or other measuring devices. The tests shall be made at the specified frequency in the presence of a Government
inspector. The weighing equipment shall be arranged so that the plant operator can conveniently observe all
dials or indicators.
3.2.5 Batching Tolerances
(A) Tolerances with Weighing Equipment
PERCENT OF REQUIRED
MATERIAL WEIGHT
Cementitious materials 0 to plus 2
Aggregate plus or minus 2
Water plus or minus 1
Chemical admixture 0 to plus 6
(B) Tolerances with Volumetric Equipment
For volumetric batching equipment used for water and admixtures, the following tolerances shall apply to the
required volume of material being batched:
PERCENT OF REQUIRED
MATERIAL MATERIAL
Water: plus or minus 1 percent
Chemical admixtures: 0 to plus 6 percent
3.2.6 Moisture Control
The plant shall be capable of ready adjustment to compensate for the varying moisture content of the aggregates
and to change the weights of the materials being batched.
3.2.7 Concrete Mixers
NOTE: Retain bracketed phrase unless it is desired to prohibit truck mixers,
in which case delete.
Mixers shall be stationary mixers [or truck mixers]. Mixers shall be capable of combining the materials into
a uniform mixture and of discharging this mixture without segregation. The mixers shall not be charged in excess
of the capacity recommended by the manufacturer. The mixers shall be operated at the drum or mixing blade speed
designated by the manufacturer. The mixers shall be maintained in satisfactory operating condition, and the
mixer drums shall be kept free of hardened concrete. Should any mixer at any time produce unsatisfactory results,
its use shall be promptly discontinued until it is repaired.
3.2.8 Stationary Mixers
Concrete plant mixers shall be drum-type mixers of tilting, nontilting, horizontal-shaft, or vertical-shaft type,
or shall be pug mill type and shall be provided with an acceptable device to lock the discharge mechanism until
the required mixing time has elapsed. The mixing time and uniformity shall conform to all the requirements in
ASTM C 94/C 94M applicable to central-mixed concrete.
3.2.9 Truck Mixers
NOTE: Delete this subparagraph if truck mixers have been previously prohibited,
otherwise retain. Use bracketed item only for small jobs.
Truck mixers, the mixing of concrete therein, and concrete uniformity shall conform to the requirements of ASTM C 94/C 94M
. A truck mixer may be used either for complete mixing (transit-mixed) or to finish the partial mixing done
in a stationary mixer (shrink-mixed). Each truck shall be equipped with two counters from which it is possible
to determine the number of revolutions at mixing speed and the number of revolutions at agitating speed. [Or,
if approved in lieu of this, the number of revolutions shall be marked on the batch tickets.] Water shall not
be added at the placing site unless specifically approved; and in no case shall it exceed the specified w/c.
Any such water shall be injected at the base of the mixer, not at the discharge end.
3.3 CONCRETE PRODUCTION, SMALL PROJECTS
NOTE: Use this paragraph at the designer's option in lieu of the previous paragraph
CONCRETE PRODUCTION and its subparagraphs, which must then be deleted, but only
when all the following conditions exist:
(a) There are no particularly critical structural items.
(b) There are no items of particularly critical appearance.
(c) No concrete is required with a specified compressive strength greater than
24.2 MPa (3500 psi).
(d) Not over 1150 cubic meters (1500 cubic yards) of concrete are required.
Otherwise, use the above listed previous paragraph and subparagraphs only.
Do not specify both options.
Batch-type equipment shall be used for producing concrete. Ready-mixed concrete shall be batched, mixed, and
transported in accordance with ASTM C 94/C 94M, except as otherwise specified. Truck mixers, agitators, and
nonagitating transporting units shall comply with NRMCA TMMB 100. Ready-mix plant equipment and facilities shall
be certified in accordance with NRMCA QC 3. Approved batch tickets shall be furnished for each load of ready-mixed
concrete. Site-mixed concrete shall be produced in accordance with ACI 301, and plant shall conform to NRMCA CPMB 100
. [In lieu of batch-type equipment, concrete may be produced by volumetric batching and continuous mixing, which
shall conform to ASTM C 685/C 685M.]
3.4 LIGHTWEIGHT AGGREGATE CONCRETE
In addition to the requirements specified for normal weight concrete, lightweight aggregate concrete shall conform
to the following. The batching and mixing cycle shall be as directed based on written recommendations from the
aggregate supplier which the Contractor shall furnish. Unless otherwise directed, the mixer shall be charged
with approximately 2/3 of the total mixing water and all of the aggregate. This shall be mixed for at least
1.5 minutes in a stationary mixer or 15 revolutions at mixing speed in a truck mixer. The remaining ingredients
shall then be added and mixing continued as specified for normal weight concrete. Lightweight aggregate concrete
shall not be vibrated to the extent that large particles of aggregate float to the surface. During finishing,
lightweight aggregate concrete shall not be worked to the extent that mortar is driven down and lightweight coarse
aggregate appears at the surface. Lightweight aggregate concrete to be pumped shall have a cement content of
at least 335 kg/cubic meter 564 lb/cu. yd. [A field trial run of lightweight aggregate concrete placement and
finishing shall be made in accordance with ACI 213R.]
3.5 FIBER REINFORCED CONCRETE
NOTE: Only use fiber reinforcing when approved by the structural designer.
Drawings should indicate where fiber reinforced concrete is located. Fiber
reinforcing is used (1) to help control cracking due to drying shrinkage and
thermal expansion and contraction, (2) to reduce permeability, (3) to increase
impact capability, shatter resistance, abrasion resistance, and toughness.
Fiber reinforcing will not: control cracking due to structural stresses, significantly
increase strength, control curling or creeping, justify reducing structural
members, eliminate control joints, or replace any moment or structural steel
reinforcement. Include flexural toughness tests when synthetic reinforcement
fibers are used to increase toughness and when justified by size and importance
of job, but not when fibers are used only to control shrinkage cracking. Include
technical representative when warranted by size and importance of job.
Fiber reinforced concrete shall conform to ASTM C 1116/C 1116M and as follows, using the fibers specified in
PART 2. A minimum of 0.9 kg of fibers per cubic m 1.5 pounds of fibers per cubic yard of concrete shall be used.
Fibers shall be added at the batch plant. [Toughness indices shall meet requirements for performance level I
of ASTM C 1116/C 1116M.] The services of a qualified technical representative shall be provided to instruct
the concrete supplier in proper batching and mixing of materials to be provided.
3.6 TRANSPORTING CONCRETE TO PROJECT SITE
Concrete shall be transported to the placing site in [truck mixers,] [agitators,] [nonagitating transporting
equipment conforming to NRMCA TMMB 100] or by approved [pumping equipment] [conveyors]. Nonagitating equipment,
other than pumps, shall not be used for transporting lightweight aggregate concrete.
3.7 CONVEYING CONCRETE ON SITE
NOTE: Delete conveying equipment not wanted on the project.
Concrete shall be conveyed from mixer or transporting unit to forms as rapidly as possible and within the time
interval specified by methods which will prevent segregation or loss of ingredients using following equipment.
Conveying equipment shall be cleaned before each placement.
3.7.1 Buckets
The interior hopper slope shall be not less than 58 degrees from the horizontal, the minimum dimension of the
clear gate opening shall be at least 5 times the nominal maximum-size aggregate, and the area of the gate opening
shall not be less than 0.2 square meters 2 square feet. The maximum dimension of the gate opening shall not
be greater than twice the minimum dimension. The bucket gates shall be essentially grout tight when closed and
may be manually, pneumatically, or hydraulically operated except that buckets larger than 1.5 cubic meters 2
cubic yards shall not be manually operated. The design of the bucket shall provide means for positive regulation
of the amount and rate of deposit of concrete in each dumping position.
3.7.2 Transfer Hoppers
Concrete may be charged into nonagitating hoppers for transfer to other conveying devices. Transfer hoppers
shall be capable of receiving concrete directly from delivery vehicles and shall have conical-shaped discharge
features. The transfer hopper shall be equipped with a hydraulically operated gate and with a means of external
vibration to effect complete discharge. Concrete shall not be held in nonagitating transfer hoppers more than
30 minutes.
3.7.3 Trucks
Truck mixers operating at agitating speed or truck agitators used for transporting plant-mixed concrete shall
conform to the requirements of ASTM C 94/C 94M. Nonagitating equipment shall be used only for transporting plant-mixed
concrete over a smooth road and when the hauling time is less than 15 minutes. Bodies of nonagitating equipment
shall be smooth, watertight, metal containers specifically designed to transport concrete, shaped with rounded
corners to minimize segregation, and equipped with gates that will permit positive control of the discharge of
the concrete.
3.7.4 Chutes
When concrete can be placed directly from a truck mixer, agitator, or nonagitating equipment, the chutes normally
attached to this equipment by the manufacturer may be used. A discharge deflector shall be used when required
by the Contracting Officer. Separate chutes and other similar equipment will not be permitted for conveying
concrete.
3.7.5 Belt Conveyors
Belt conveyors shall be designed and operated to assure a uniform flow of concrete from mixer to final place
of deposit without segregation of ingredients or loss of mortar and shall be provided with positive means, such
as discharge baffle or hopper , for preventing segregation of the concrete at the transfer points and the point
of placing. Belt conveyors shall be constructed such that the idler spacing shall not exceed 900 mm 36 inches
. The belt speed shall be a minimum of 90 meters 300 feet per minute and a maximum of 225 meters 750 feet per
minute. If concrete is to be placed through installed horizontal or sloping reinforcing bars, the conveyor shall
discharge concrete into a pipe or elephant truck that is long enough to extend through the reinforcing bars.
3.7.6 Concrete Pumps
Concrete may be conveyed by positive displacement pump when approved. The pumping equipment shall be piston
or squeeze pressure type; pneumatic placing equipment shall not be used. The pipeline shall be rigid steel pipe
or heavy-duty flexible hose. The inside diameter of the pipe shall be at least 3 times the nominal maximum-size
coarse aggregate in the concrete mixture to be pumped but not less than 100 mm 4 inches. Aluminum pipe shall
not be used.
3.8 PLACING CONCRETE
Mixed concrete shall be discharged within 1-1/2 hours or before the mixer drum has revolved 300 revolutions,
whichever comes first after the introduction of the mixing water to the cement and aggregates. When the concrete
temperature exceeds 30 degrees C 85 degrees F, the time shall be reduced to 45 minutes. Concrete shall be placed
within 15 minutes after it has been discharged from the transporting unit. Concrete shall be handled from mixer
or transporting unit to forms in a continuous manner until the approved unit of operation is completed. Adequate
scaffolding, ramps and walkways shall be provided so that personnel and equipment are not supported by in-place
reinforcement. Placing will not be permitted when the sun, heat, wind, or limitations of facilities furnished
by the Contractor prevent proper consolidation, finishing and curing. Sufficient placing capacity shall be provided
so that concrete can be kept free of cold joints.
3.8.1 Depositing Concrete
Concrete shall be deposited as close as possible to its final position in the forms, and there shall be no vertical
drop greater than 1.5 meters 5 feet except where suitable equipment is provided to prevent segregation and where
specifically authorized. Depositing of the concrete shall be so regulated that it will be effectively consolidated
in horizontal layers not more than 300 mm 12 inches thick, except that all slabs shall be placed in a single
lift. Concrete to receive other construction shall be screeded to the proper level. Concrete shall be deposited
continuously in one layer or in layers so that fresh concrete is deposited on in-place concrete that is still
plastic. Fresh concrete shall not be deposited on concrete that has hardened sufficiently to cause formation
of seams or planes of weakness within the section. Concrete that has surface dried, partially hardened, or contains
foreign material shall not be used. When temporary spreaders are used in the forms, the spreaders shall be removed
as their service becomes unnecessary. Concrete shall not be placed in slabs over columns and walls until concrete
in columns and walls has been in-place at least two hours or until the concrete begins to lose its plasticity.
Concrete for beams, girders, brackets, column capitals, haunches, and drop panels shall be placed at the same
time as concrete for adjoining slabs.
3.8.2 Consolidation
NOTE: For large jobs, this paragraph may be expanded. Consolidation equipment
and procedures are described in detail in ACI 309.
Immediately after placing, each layer of concrete shall be consolidated by internal vibrators, except for slabs
100 mm 4 inches thick or less. The vibrators shall at all times be adequate in effectiveness and number to
properly consolidate the concrete; a spare vibrator shall be kept at the jobsite during all concrete placing
operations. The vibrators shall have a frequency of not less than 10,000 vibrations per minute, an amplitude
of at least 0.6 mm 0.025 inch, and the head diameter shall be appropriate for the structural member and the concrete
mixture being placed. Vibrators shall be inserted vertically at uniform spacing over the area of placement.
The distance between insertions shall be approximately 1.5 times the radius of action of the vibrator so that
the area being vibrated will overlap the adjacent just-vibrated area by a reasonable amount. The vibrator shall
penetrate rapidly to the bottom of the layer and at least 150 mm 6 inches into the preceding layer if there is
such. Vibrator shall be held stationary until the concrete is consolidated and then vertically withdrawn slowly
while operating. Form vibrators shall not be used unless specifically approved and unless forms are constructed
to withstand their use. Vibrators shall not be used to move concrete within the forms. Slabs 100 mm 4 inches
and less in thickness shall be consolidated by properly designed vibrating screeds or other approved technique.
Excessive vibration of lightweight concrete resulting in segration or flotation of coarse aggregate shall be
prevented. Frequency and amplitude of vibrators shall be determined in accordance with COE CRD-C 521. Grate
tampers ("jitterbugs") shall not be used.
3.8.3 Cold Weather Requirements
NOTE: When the designer is especially concerned about corrosion of reinforcing
steel or embedded items, or possibility of sulfate attack, (particularly to
prestressing steel) the percentage of chloride ion in the mixture should be
limited. See ACI Committee 201 report "Guide to Durable Concrete" and ACI Committee
222 report "Corrosion of Metals in Concrete" for guidance on control of chloride
ion.
Special protection measures, approved by the Contracting Officer, shall be used if freezing temperatures are
anticipated before the expiration of the specified curing period. The ambient temperature of the air where concrete
is to be placed and the temperature of surfaces to receive concrete shall be not less than 5 degrees C 40 degrees
F. The temperature of the concrete when placed shall be not less than 10 degrees C 50 degrees F nor more than
25 degrees C 75 degrees F. Heating of the mixing water or aggregates will be required to regulate the concrete
placing temperature. Materials entering the mixer shall be free from ice, snow, or frozen lumps. Salt, chemicals
or other materials shall not be incorporated in the concrete to prevent freezing. Upon written approval, an
accelerating admixture conforming to ASTM C 494/C 494M, Type C or E may be used, provided it contains no calcium
chloride. Calcium chloride shall not be used.
3.8.4 Hot Weather Requirements
NOTE: If desired, placement of floor slabs may be specified to be delayed until
a roof is in place. Additional information concerning hot weather concreting
may be obtained from ACI 305R.
When the ambient temperature during concrete placing is expected to exceed 30 degrees C 85 degrees F, the concrete
shall be placed and finished with procedures previously submitted and as specified herein. The concrete temperature
at time of delivery to the forms shall not exceed the temperature shown in the table below when measured in accordance
with ASTM C 1064/C 1064M. Cooling of the mixing water or aggregates or placing concrete in the cooler part of
the day may be required to obtain an adequate placing temperature. A retarder may be used, as approved, to facilitate
placing and finishing. Steel forms and reinforcements shall be cooled as approved prior to concrete placement
when steel temperatures are greater than 49 degrees C 120 degrees F. Conveying and placing equipment shall be
cooled if necessary to maintain proper concrete-placing temperature.
Maximum Allowable Concrete Placing Temperature
Relative Humidity, Percent, Maximum Allowable Concrete
During Time of Temperature
Concrete Placement Degrees
Greater than 60 33 C 90 F
40-60 30 C 85 F
Less than 40 27 C 80 F
3.8.5 Prevention of Plastic Shrinkage Cracking
During hot weather with low humidity, and particularly with appreciable wind, as well as interior placements
when space heaters produce low humidity, the Contractor shall be alert to the tendency for plastic shrinkage
cracks to develop and shall institute measures to prevent this. Particular care shall be taken if plastic shrinkage
cracking is potentially imminent and especially if it has developed during a previous placement. Periods of
high potential for plastic shrinkage cracking can be anticipated by use of Fig. 2.1.5 of ACI 305R. In addition
the concrete placement shall be further protected by erecting shades and windbreaks and by applying fog sprays
of water, sprinkling, ponding or wet covering. Plastic shrinkage cracks that occur shall be filled by injection
of epoxy resin as directed, after the concrete hardens. Plastic shrinkage cracks shall never be troweled over
or filled with slurry.
3.8.6 Placing Concrete Underwater
NOTE: Delete this paragraph when not applicable. If major underwater concrete
placement is required, supplement this paragraph using guidance from ACI 304R.
If appropriate, add special requirements for underwater concrete to paragraphs
Concrete Proportioning Studies, Normal Weight Concrete and General Requirements
both in PART 1. If considered necessary, require a special technical representative
in paragraph Technical Service for Specialized Concrete in PART 1. Contractor
will be required to submit proposed procedures.
Concrete shall be deposited in water by a tremie or concrete pump. The methods and equipment used shall be subject
to approval. Concrete buckets shall not be used for underwater placement of concrete except to deliver concrete
to the tremie. The tremie shall be watertight and sufficiently large to permit a free flow of concrete. The
concrete shall be deposited so that it enters the mass of the previously placed concrete from within, displacing
water with a minimum disturbance to the surface of the concrete. The discharge end of the pump line or tremie
shaft shall be kept continuously submerged in the concrete. The underwater seal at start of placing shall not
produce undue turbulence in the water. The tremie shaft shall be kept full of concrete to a point well above
the water surface. Placement shall proceed without interruption until the concrete has been brought to the required
height. The tremie shall not be moved horizontally during a placing operation, and a sufficient number of tremies
shall be provided so that the maximum horizontal flow of concrete will be limited to 5 m 15 feet. Concrete shall
not be deposited in running water or in water with a temperature below 2 degrees C 35 degrees F.
3.8.7 Placing Concrete in Congested Areas
NOTE: Delete the last sentence when not applicable.
Special care shall be used to ensure complete filling of the forms, elimination of all voids, and complete consolidation
of the concrete when placing concrete in areas congested with reinforcing bars, embedded items, waterstops and
other tight spacing. An appropriate concrete mixture shall be used, and the nominal maximum size of aggregate
(NMSA) shall meet the specified criteria when evaluated for the congested area. Vibrators with heads of a size
appropriate for the clearances available shall be used, and the consolidation operation shall be closely supervised
to ensure complete and thorough consolidation at all points. Where necessary, splices of reinforcing bars shall
be alternated to reduce congestion. Where two mats of closely spaced reinforcing are required, the bars in each
mat shall be placed in matching alignment to reduce congestion. Reinforcing bars may be temporarily crowded
to one side during concrete placement provided they are returned to exact required location before concrete placement
and consolidation are completed.
3.8.8 Placing Flowable Concrete
NOTE: Delete this paragraph when flowable concrete is not permitted.
If a plasticizing admixture conforming to ASTM C 1017/C 1017M is used or if a Type F or G high range water reducing
admixture is permitted to increase the slump, the concrete shall meet all requirements of paragraph GENERAL REQUIREMENTS
in PART 1. Extreme care shall be used in conveying and placing the concrete to avoid segregation. Consolidation
and finishing shall meet all requirements of paragraphs Placing Concrete, Finishing Formed Surfaces, and Finishing
Unformed Surfaces. No relaxation of requirements to accommodate flowable concrete will be permitted.
3.9 JOINTS
NOTE: All joints should be indicated on the drawings. When some of the joints
are not shown, the Designer must edit this paragraph for conformance with job
requirements.
Joints shall be located and constructed as indicated or approved. Joints not indicated on the drawings shall
be located and constructed to minimize the impact on the strength of the structure. In general, such joints
shall be located near the middle of the spans of supported slabs, beams, and girders unless a beam intersects
a girder at this point, in which case the joint in the girder shall be offset a distance equal to twice the width
of the beam. Joints in walls and columns shall be at the underside of floors, slabs, beams, or girders and at
the tops of footings or floor slabs, unless otherwise approved. Joints shall be perpendicular to the main reinforcement.
All reinforcement shall be continued across joints; except that reinforcement or other fixed metal items shall
not be continuous through expansion joints, or through construction or contraction joints in slabs on grade.
Reinforcement shall be 50 mm 2 inches clear from each joint. Except where otherwise indicated, construction
joints between interior slabs on grade and vertical surfaces shall consist of 1.5 kg per square meter 30 pound
asphalt-saturated felt, extending for the full depth of the slab. The perimeters of the slabs shall be free
of fins, rough edges, spalling, or other unsightly appearance. Reservoir for sealant for construction and contraction
joints in slabs shall be formed to the dimensions shown on the drawings by removing snap-out joint-forming inserts,
by sawing sawable inserts, or by sawing to widen the top portion of sawed joints. Joints to be sealed shall
be cleaned and sealed as indicated and in accordance with Section 07 92 00 JOINT SEALANTS.
3.9.1 Construction Joints
NOTE: Drawings must show details for construction joints, including any required
dowels or keyways. Drawings must indicate whether dowels are conventional smooth
"paving" dowels or "structural" type deformed dowels (tie-bars).
For concrete other than slabs on grade, construction joints shall be located so that the unit of operation does
not exceed [_____] meters feet. Concrete shall be placed continuously so that each unit is monolithic in construction.
Fresh concrete shall not be placed against adjacent hardened concrete until it is at least 24 hours old. Construction
joints shall be located as indicated or approved. Where concrete work is interrupted by weather, end of work
shift or other similar type of delay, location and type of construction joint shall be subject to approval of
the Contracting Officer. Unless otherwise indicated and except for slabs on grade, reinforcing steel shall extend
through construction joints. Construction joints in slabs on grade shall be keyed or doweled as shown. Concrete
columns, walls, or piers shall be in place at least 2 hours, or until the concrete begins to lose its plasticity,
before placing concrete for beams, girders, or slabs thereon. In walls having door or window openings, lifts
shall terminate at the top and bottom of the opening. Other lifts shall terminate at such levels as to conform
to structural requirements or architectural details. Where horizontal construction joints in walls or columns
are required, a strip of 25 mm 1 inch square-edge lumber, bevelled and oiled to facilitate removal, shall be
tacked to the inside of the forms at the construction joint. Concrete shall be placed to a point 25 mm 1 inch
above the underside of the strip. The strip shall be removed 1 hour after the concrete has been placed, and
any irregularities in the joint line shall be leveled off with a wood float, and all laitance shall be removed.
Prior to placing additional concrete, horizontal construction joints shall be prepared as specified in paragraph
Previously Placed Concrete.
3.9.2 Contraction Joints in Slabs on Grade
NOTE: Drawings must indicate desired location and detail for contraction joints.
Contraction joints shall be located and detailed as shown on the drawings. Contraction Joints shall be produced
by forming a weakened plane in the concrete slab by [use of rigid inserts impressed in the concrete during placing
operations] [use of snap-out plastic joint forming inserts] [or] [sawing a continuous slot with a concrete saw].
Regardless of method used to produce the weakened plane, it shall be 1/4 the depth of the slab thickness and
between 3 and 5 mm 1/8 and 3/16 inch wide. For saw-cut joints, cutting shall be timed properly with the set
of the concrete. Cutting shall be started as soon as the concrete has hardened sufficiently to prevent ravelling
of the edges of the saw cut. Cutting shall be completed before shrinkage stresses become sufficient to produce
cracking. Reservoir for joint sealant shall be formed as previously specified.
3.9.3 Expansion Joints
Installation of expansion joints and sealing of these joints shall conform to the requirements of Section
03 15 13.00 10 EXPANSION JOINTS, CONTRACTION JOINTS, AND WATERSTOPS and Section 07 92 00 JOINT SEALANTS.
3.9.4 Waterstops
Waterstops shall be installed in conformance with the locations and details shown on the drawings using materials
and procedures specified in Section 03 15 13.00 10 EXPANSION JOINTS, CONTRACTION JOINTS, AND WATERSTOPS.
3.9.5 Dowels and Tie Bars
Dowels and tie bars shall be installed at the locations shown on the drawings and to the details shown, using
materials and procedures specified in Section 03 20 01.00 10 CONCRETE REINFORCEMENT and herein. Conventional
smooth "paving" dowels shall be installed in slabs using approved methods to hold the dowel in place during concreting
within a maximum alignment tolerance of 1 mm in 100 mm 1/8 inch in 12 inches. "Structural" type deformed bar
dowels, or tie bars, shall be installed to meet the specified tolerances. Care shall be taken during placing
adjacent to and around dowels and tie bars to ensure there is no displacement of the dowel or tie bar and that
the concrete completely embeds the dowel or tie bar and is thoroughly consolidated.
3.10 FINISHING FORMED SURFACES
NOTE: Formwork, form materials and form construction are specified in Section
03 11 13.00 10 STRUCTURAL CONCRETE FORMWORK. Classes of finish to be used for
various formed surfaces of the structure must be indicated on the drawings or
clearly specified herein. Criteria to use in choosing class of finish are as
follows:
Class A Finish. This finish is for surfaces permanently exposed to public view
that require excellent appearance at close range. Examples: Exterior walls
of office and residential buildings, of warehouse/industrial type buildings
where frequent public access occurs, and of other similar exposed structures;
and interior walls, columns or beams of these same structures where no other
finish treatment is to be added.
Class B Finish. This finish is for surfaces exposed to public view that do
not require the excellent appearance of Class A. Exterior walls of warehouse/
industrial buildings where public access is infrequent, structures on combat
training ranges, and other similar exposed structures; interior exposed surfaces
of such structures, and interior surfaces of liquid containers.
Class C Finish. This finish is for concealed surfaces not exposed to view and
for all surfaces not covered by Class A, B, or D finish. Examples: Interior
surfaces that will be covered by dry wall or other applied surfaces, surfaces
of mechanical rooms and elevator shafts.
Class D Finish. This finish is for surfaces where roughness and irregularities
are not objectionable. Examples: Walls and foundation surfaces against which
backfill will be placed, exterior surfaces permanently submerged in water where
no coating is to be applied.
When a Class A or B Finish is specified, add to paragraph FIELD TEST PANELS
in PART 1 requirements for the Contractor to construct a sample panel for approval
before start of construction. Finishes for surfaces to be exposed to high velocity
flow of water (above 40 ft per sec) will be designed and constructed in accordance
with Civil Works criteria.
Forms, form materials, and form construction are specified in Section 03 11 13.00 10 STRUCTURAL CONCRETE FORMWORK.
Finishing of formed surfaces shall be as specified herein. Unless another type of architectural or special finish
is specified, surfaces shall be left with the texture imparted by the forms except that defective surfaces shall
be repaired. Unless painting of surfaces is required, uniform color of the concrete shall be maintained by use
of only one mixture without changes in materials or proportions for any structure or portion of structure that
requires a Class A or B finish. Except for major defects, as defined hereinafter, surface defects shall be repaired
as specified herein within 24 hours after forms are removed. Repairs of the so-called "plaster-type" will not
be permitted in any location. Tolerances of formed surfaces shall conform to the requirements of ACI 117. These
tolerances apply to the finished concrete surface, not to the forms themselves; forms shall be set true to line
and grade. Form tie holes requiring repair and other defects whose depth is at least as great as their surface
diameter shall be repaired as specified in paragraph Damp-Pack Mortar Repair. Defects whose surface diameter
is greater than their depth shall be repaired as specified in paragraph Repair of Major Defects. Repairs shall
be finished flush with adjacent surfaces and with the same surface texture. The cement used for all repairs
shall be a blend of job cement with white cement proportioned so that the final color after curing and aging
will be the same as the adjacent concrete. Concrete with excessive honeycomb, or other defects which affect
the strength of the member, will be rejected. Repairs shall be demonstrated to be acceptable and free from cracks
or loose or drummy areas at the completion of the contract and, for Class A and B Finishes, shall be inconspicuous.
Repairs not meeting these requirements will be rejected and shall be replaced.
3.10.1 Class A Finish and Class B Finish
Class A finish is required [where indicated on the drawings.] [in the following areas, [_____].] Class B finish
is required [where indicated on the drawings] [in the following areas, [_____].] Fins, ravelings, and loose
material shall be removed, all surface defects over 12 mm 1/2 inch in diameter or more than 12 mm 1/2 inch deep,
shall be repaired and, except as otherwise indicated or as specified in Section 03 11 13.00 10 STRUCTURAL CONCRETE
FORMWORK, holes left by removal of form ties shall be reamed and filled. Defects more than 12 mm 1/2 inch in
diameter shall be cut back to sound concrete, but in all cases at least 25 mm 1 inch deep. The Contractor shall
prepare a sample panel for approval (as specified in PART 1) before commencing repair, showing that the surface
texture and color match will be attained. Metal tools shall not be used to finish repairs in Class A surfaces.
3.10.2 Class C and Class D Finish
Class C finish is required [where indicated on the drawings.] [in the following areas, [_____].] Class D finish
is required [where indicated on the drawings.] [in the following areas, [_____].] Fins, ravelings, and loose
material shall be removed, and, except as otherwise indicated or as specified in Section 03 11 13.00 10 STRUCTURAL
CONCRETE FORMWORK, holes left by removal of form ties shall be reamed and filled. Honeycomb and other defects
more than 12 mm 1/2 inch deep or more than 50 mm 2 inches in diameter shall be repaired. Defects more than 50
mm 2 inches in diameter shall be cut back to sound concrete, but in all cases at least 25 mm 1 inch deep.
3.10.3 Architectural and Special Finishes
NOTE: The specification writer must ensure that any areas to receive architectural
and special finishes are indicated on the drawings or specified in Section 03
33 00 CAST-IN-PLACE ARCHITECTURAL CONCRETE or herein. Where these paragraphs
require a finish to match a sample panel on display during the bidding period,
the specification writer must ensure that such panel is fabricated and displayed.
When considered appropriate, require a test panel to be fabricated for approval
before start of construction.
Architectural concrete finishes are specified in Section 03 33 00 CAST-IN-PLACE ARCHITECTURAL CONCRETE. Special
finishes shall conform to the requirements specified herein.
3.10.3.1 Smooth Finish
After other concrete construction is complete in each overall separate contiguous area of the structure, smooth
finish shall be applied to [the areas indicated on the drawings] [the following areas, [_____]]. A mortar mix
consisting of one part portland cement and two parts well-graded sand passing a 0.6 mm No. 30 sieve, with water
added to give the consistency of thick paint, shall be used. Where the finished surface will not receive other
applied surface, white cement shall be used to replace part of the job cement to produce an approved color, which
shall be uniform throughout the surfaces of the structure. After the surface has been thoroughly wetted and
allowed to approach surface dryness, the mortar shall be vigorously applied to the area by clean burlap pads
or by cork or wood-floating, to completely fill all surface voids. Excess grout shall be scraped off with a
trowel. As soon as it can be accomplished without pulling the mortar from the voids, the area shall be rubbed
with burlap pads having on their surface the same sand-cement mix specified above but without any mixing water,
until all of the visible grout film is removed. The burlap pads used for this operation shall be stretched tightly
around a board to prevent dishing the mortar in the voids. The finish of any area shall be completed in the
same day, and the limits of a finished area shall be made at natural breaks in the surface. The surface shall
be continuously moist cured for 48 hours commencing immediately after finishing operations in each area. The
temperature of the air adjacent to the surface shall be not less than 10 degrees C 50 degrees F for 24 hours
prior to, and 48 hours after, the application. In hot, dry weather the smooth finish shall be applied in shaded
areas or at night, and shall never be applied when there is significant hot, dry wind.
3.10.3.2 Exposed Coarse-Aggregate Finish
Coarse aggregate shall consist of [_____] material, shall meet the specified quality requirements, and shall
have a grading as follows: [_____]. Coarse aggregate shall be exposed by an approved method. The finish shall
be similar to and shall closely match the finish on the sample panel put on display during the bidding period,
and the finish on the approved preconstruction test panel fabricated by the Contractor.
3.10.3.3 Sandblast Finish
The concrete surface shall be blasted at an approved age with approved wet sandblasting procedures to obtain
a [brush] [light] [medium] [heavy] finish which will match the descriptive photographs in ACI 303R. The finish
shall be similar to and shall closely match the finish on the approved preconstruction test panel fabricated
by the Contractor.
3.10.3.4 Tooled Finish
The thoroughly cured concrete shall be dressed at an approved age with approved electric, air, or hand tools
to a uniform texture with a [hand-tooled] [rough] [fine-pointed] [crandalled] [or] [bush-hammered] surface texture.
The finish shall be similar to and shall closely match the finish on the approved preconstruction test panel
fabricated by the Contractor.
3.11 REPAIRS
3.11.1 Damp-Pack Mortar Repair
Form tie holes requiring repair and other defects whose depth is at least as great as their surface diameter
but not over 100 mm 4 inchesshall be repaired by the damp-pack mortar method. Form tie holes shall be reamed
and other similar defects shall be cut out to sound concrete. The void shall then be thoroughly cleaned, thoroughly
wetted, brush-coated with a thin coat of neat cement grout and filled with mortar. Mortar shall be a stiff mix
of 1 part portland cement to 2 parts fine aggregate passing the 1.18 mm No. 16 mesh sieve, and minimum amount
of water. Only sufficient water shall be used to produce a mortar which, when used, will stick together on being
molded into a ball by a slight pressure of the hands and will not exude water but will leave the hands damp.
Mortar shall be mixed and allowed to stand for 30 to 45 minutes before use with remixing performed immediately
prior to use. Mortar shall be thoroughly tamped in place in thin layers using a hammer and hardwood block.
Holes passing entirely through walls shall be completely filled from the inside face by forcing mortar through
to the outside face. All holes shall be packed full. Damp-pack repairs shall be moist cured for at least 48
hours.
3.11.2 Repair of Major Defects
Major defects will be considered to be those more than 12 mm 1/2 inch deep or, for Class A and B finishes, more
than 12 mm 1/2 inch in diameter and, for Class C and D finishes, more than 50 mm 2 inches in diameter. Also
included are any defects of any kind whose depth is over 100 mm 4 inches or whose surface diameter is greater
than their depth. Major defects shall be repaired as specified below.
3.11.2.1 Surface Application of Mortar Repair
Defective concrete shall be removed, and removal shall extend into completely sound concrete. Approved equipment
and procedures which will not cause cracking or microcracking of the sound concrete shall be used. If reinforcement
is encountered, concrete shall be removed so as to expose the reinforcement for at least 50 mm 2 inches on all
sides. All such defective areas greater than 7800 square mm 12 square inches shall be outlined by saw cuts at
least 25 mm 1 inch deep. Defective areas less than 7800 square mm 12 square inches shall be outlined by a 25
mm 1 inch deep cut with a core drill in lieu of sawing. All saw cuts shall be straight lines in a rectangular
pattern in line with the formwork panels. After concrete removal, the surface shall be thoroughly cleaned by
high pressure washing to remove all loose material. Surfaces shall be kept continually saturated for the first
12 of the 24 hours immediately before placing mortar and shall be damp but not wet at the time of commencing
mortar placement. The Contractor, at his option, may use either hand-placed mortar or mortar placed with a mortar
gun. If hand-placed mortar is used, the edges of the cut shall be perpendicular to the surface of the concrete.
The prepared area shall be brush-coated with a thin coat of neat cement grout. The repair shall then be made
using a stiff mortar, preshrunk by allowing the mixed mortar to stand for 30 to 45 minutes and then remixed,
thoroughly tamped into place in thin layers. If hand-placed mortar is used, the Contractor shall test each repair
area for drumminess by firm tapping with a hammer and shall inspect for cracks, both in the presence of the Contracting
Officer's representative, immediately before completion of the contract, and shall replace any showing drumminess
or cracking. If mortar placed with a mortar gun is used, the gun shall be a small compressed air-operated gun
to which the mortar is slowly hand fed and which applies the mortar to the surface as a high-pressure stream,
as approved. Repairs made using shotcrete equipment will not be accepted. The mortar used shall be the same
mortar as specified for damp-pack mortar repair. If gun-placed mortar is used, the edges of the cut shall be
beveled toward the center at a slope of 1:1. All surface applied mortar repairs shall be continuously moist
cured for at least 7 days. Moist curing shall consist of several layers of saturated burlap applied to the surface
immediately after placement is complete and covered with polyethylene sheeting, all held closely in place by
a sheet of plywood or similar material rigidly braced against it. Burlap shall be kept continually wet.
3.11.2.2 Repair of Deep and Large Defects
NOTE: Use this paragraph only for areas where the designer considers this degree
of repair acceptable; otherwise require removal and replacement of concrete
containing these types of defects.
Deep and large defects will be those that are more than 150 mm 6 inches deep and also have an average diameter
at the surface more than 450 mm 18 inches or that are otherwise so identified by the Project Office. Such defects
shall be repaired as specified herein or directed, except that defects which affect the strength of the structure
shall not be repaired and that portion of the structure shall be completely removed and replaced. Deep and large
defects shall be repaired by procedures approved in advance including forming and placing special concrete using
applied pressure during hardening. Preparation of the repair area shall be as specified for surface application
of mortar. In addition, the top edge (surface) of the repair area shall be sloped at approximately 20 degrees
from the horizontal, upward toward the side from which concrete will be placed. The special concrete shall be
a concrete mixture with low water content and low slump, and shall be allowed to age 30 to 60 minutes before
use. Concrete containing a specified expanding admixture may be used in lieu of the above mixture; the paste
portion of such concrete mixture shall be designed to have an expansion between 2.0 and 4.0 percent when tested
in accordance with ASTM C 940. A full width "chimney" shall be provided at the top of the form on the placing
side to ensure filling to the top of the opening. A pressure cap shall be used on the concrete in the chimney
with simultaneous tightening and revibrating the form during hardening to ensure a tight fit for the repair.
The form shall be removed after 24 hours and immediately the chimney shall be carefully chipped away to avoid
breaking concrete out of the repair; the surface of the repair concrete shall be dressed as required.
3.11.3 Resinous and Latex Material Repair
NOTE: The portland cement type repairs specified above are considered appropriate
for usual repairs. The designer should use the materials specified herein only
if there is a record of previous successful use or if the use has been discussed
in detail with the Waterways Experiment Station (CEWES-SL-EP). Additional requirements
for their use must be added. Color match may be a problem with this type of
repair.
In lieu of the portland cement [bonding coats specified above, an epoxy resin or a latex bonding agent may be
used.] [based mortars specified above, an epoxy resin mortar based on epoxy resin or a mortar based on latex
bonding agent may be used in the following specific locations [_____].] The following additional requirements
shall be met in the use of these materials [_____].
3.12 FINISHING UNFORMED SURFACES
NOTE: Type of finish of unformed surfaces should be indicated on the drawings.
If not on the drawings, it must be specified here. Correlate this paragraph
with paragraph Tolerances in PART 1 and ACI 117.
The finish of all unformed surfaces shall meet the requirements of paragraph Tolerances in PART 1, when tested
as specified herein.
3.12.1 General
The ambient temperature of spaces adjacent to unformed surfaces being finished and of the base on which concrete
will be placed shall be not less than 10 degrees C 50 degrees F. In hot weather all requirements of paragraphs
Hot Weather Requirements and Prevention of Plastic Shrinkage Cracking shall be met. Unformed surfaces that are
not to be covered by additional concrete or backfill shall have a float finish, with additional finishing as
specified below, and shall be true to the elevation shown on the drawings. Surfaces to receive additional concrete
or backfill shall be brought to the elevation shown on the drawings, properly consolidated, and left true and
regular. Unless otherwise shown on the drawings, exterior surfaces shall be sloped for drainage, as directed.
Where drains are provided, interior floors shall be evenly sloped to the drains. Joints shall be carefully made
with a jointing or edging tool. The finished surfaces shall be protected from stains or abrasions. Grate tampers
or "jitterbugs" shall not be used for any surfaces. The dusting of surfaces with dry cement or other materials
or the addition of any water during finishing shall not be permitted. If bleedwater is present prior to finishing,
the excess water shall be carefully dragged off or removed by absorption with porous materials such as burlap.
During finishing operations, extreme care shall be taken to prevent over finishing or working water into the
surface; this can cause "crazing" (surface shrinkage cracks which appear after hardening) of the surface. Any
slabs with surfaces which exhibit significant crazing shall be removed and replaced. During finishing operations,
surfaces shall be checked with a 10 foot straightedge, applied in both directions at regular intervals while
the concrete is still plastic, to detect high or low areas.
3.12.2 Rough Slab Finish
NOTE: Rough-slab finish alone is used when a bonded surface course for heavy
use industrial floor is specified, or where roof fill or thick mortar setting
bed is used. If the drawings do not indicate the slabs to receive only a rough
slab finish, they must be specified here. Rough slab finish must be retained
as the first operation for all subsequent finishing.
As a first finishing operation for unformed surfaces and as final finish for slabs to receive mortar setting
beds, the surface shall receive a rough slab finish prepared as follows. [Areas indicated on the drawings] [The
following areas [_____]] shall receive only a rough slab finish. The concrete shall be uniformly placed across
the slab area, consolidated as previously specified, and then screeded with straightedge strikeoffs immediately
after consolidation to bring the surface to the required finish level with no coarse aggregate visible. Side
forms and screed rails shall be provided, rigidly supported, and set to exact line and grade. Allowable tolerances
for finished surfaces apply only to the hardened concrete, not to forms or screed rails. Forms and screed rails
shall be set true to line and grade. "Wet screeds" shall not be used.
3.12.3 Floated Finish
NOTE: If the drawings do not indicate the areas to receive a floated finish,
they must be specified here.
Slabs to receive more than a rough slab finish shall next be given a wood float finish. [Areas as indicated
on the drawings] [The following areas [_____]] shall be given only a float finish. The screeding shall be followed
immediately by darbying or bull floating before bleeding water is present, to bring the surface to a true, even
plane. Then, after the concrete has stiffened so that it will withstand a man's weight without imprint of more
than 6 mm 1/4 inch and the water sheen has disappeared, it shall be floated to a true and even plane free of
ridges. Floating shall be performed by use of suitable hand floats or power driven equipment. Sufficient pressure
shall be used on the floats to bring a film of moisture to the surface. Hand floats shall be made of wood, magnesium,
or aluminum. Lightweight concrete or concrete that exhibits stickiness shall be floated with a magnesium float.
Care shall be taken to prevent over-finishing or incorporating water into the surface.
3.12.4 Troweled Finish
NOTE: If the drawings do not indicate the areas to receive a trowel finish,
they must be specified here. Edit accordingly. A troweled finish will be specified
for most wearing surfaces and where a smooth dense surface finish is required.
Edit bracketed items as desired by designer. Delete this paragraph when no
troweled finish or subsequent finish is required.
[Areas as indicated on the drawings] [The following areas [_____]] shall be given a trowel finish. After floating
is complete and after the surface moisture has disappeared, unformed surfaces shall be steel-troweled to a smooth,
even, dense finish, free from blemishes including trowel marks. In lieu of hand finishing, an approved power
finishing machine may be used in accordance with the directions of the machine manufacturer. Additional trowelings
shall be performed, either by hand or machine until the surface has been troweled [2] [3] [4] times, with waiting
period between each. Care shall be taken to prevent blistering and if such occurs, troweling shall immediately
be stopped and operations and surfaces corrected. A final hard steel troweling shall be done by hand, with the
trowel tipped, and using hard pressure, when the surface is at a point that the trowel will produce a ringing
sound. The finished surface shall be thoroughly consolidated and shall be essentially free of trowel marks and
be uniform in texture and appearance. The concrete mixture used for troweled finished areas shall be adjusted,
if necessary, in order to provide sufficient fines (cementitious material and fine sand) to finish properly.
3.12.5 Superflat Finish
NOTE: If the drawings do not indicate the areas to receive a superflat surface,
they must be specified here. Correlate this paragraph with the "Tolerances"
paragraph in PART 1. Primary locations where superflat floors are required
are warehouse aisles where very high lift forklifts and other type stackers
operate. Delete this paragraph when superflat finish is not required.
[Areas as indicated on the drawings] [The following areas [_____]] shall be constructed as superflat floors.
Extreme care shall be taken to meet specified tolerances. If necessary, special heavy duty, laser guided machines
built especially for this work shall be used and shall have experienced, factory-trained operators. Finishing
operations shall include use of long-handled 3 meter 10 foot "highway type" cutting straightedges plus any other
tools necessary to meet the surface tolerance requirements. Surface finish shall conform to paragraph [Troweled
Finish] [_____].
3.12.6 Non-Slip Finish
NOTE: If drawings do not indicate the areas to receive non-slip finish, they
must be specified here. Broom finish is usually used for exterior slabs and
abrasive aggregate for interior slabs, but such policy is not definite. Edit
bracketed items as appropriate. Delete these paragraphs when Non-Slip Finish
is not required.
Non-slip floors shall be constructed in accordance with the following subparagraphs.
3.12.6.1 Broomed
[Areas as indicated on the drawings] [The following areas [_____]] shall be given a broomed finish. After floating,
the surface shall be lightly steel troweled, and then carefully scored by pulling a [hair] [coarse fiber] push-type
broom across the surface. Brooming shall be transverse to traffic or at right angles to the slope of the slab.
After the end of the curing period, the surface shall be vigorously broomed with a coarse fiber broom to remove
all loose or semi-detached particles.
3.12.6.2 Abrasive Aggregate
[Areas as indicated on the drawings] [The following areas [_____]] shall be given an abrasive aggregate finish.
The concrete surface shall be given a float finish. Abrasive aggregate shall then immediately be uniformly sprinkled
over the floated surface at a total rate of not less than 1.25 kg per square meter 0.25 psf spread in two applications
at right angles to each other. The surface shall then be troweled to a smooth, even finish that is uniform in
texture and appearance and free from blemishes including trowels marks. Immediately after curing, cement paste
and laitance covering the abrasive aggregate shall be removed by steel brushing, rubbing with abrasive stone,
or sandblasting to expose the abrasive particles.
3.12.7 Dry Shake Finish
NOTE: If the drawings do not indicate the areas to receive a dry shake finish,
they must be specified here. When dry shake finish is required, add to paragraph
Technical Service for Specialized Concrete a requirement that a manufacturer's
representative be present during use of dry shake finish.
[Areas as indicated on the drawings] [The following areas [_____]] shall be constructed with a dry shake finish.
[Dry shake floor armoring topping] [Dry shake conductive and spark resistant floor topping] [Dry shake non-metallic,
light reflective floor topping] shall be used to surface the floor. The base slab shall be constructed and the
dry shake material applied in accordance with the manufacturer's written instructions, which shall be furnished
by the Contractor. The dry shake material shall be applied in a two-stage application. Total application shall
be at the rate recommended by the manufacturer but at a rate not less than 7.5 kg per square meter 1.5 psf.
The first application shall be at the rate of two-thirds of the total and shall be applied immediately following
floating of total area. The dry shake material shall first be applied to the floated concrete adjacent to forms,
entryways, columns, and walls where moisture will be lost first. Dry shake material shall be distributed evenly
using an approved mechanical spreader. The material shall not be hand thrown on the surface. Finishing machines
with float shoes shall be used as soon as dry shake has absorbed moisture (indicated by darkening of surface);
floating shall be done just sufficiently to bring moisture from base slab through the shake. Immediately following
floating of the first shake, the remaining one-third of the total specified shake shall be applied in the same
manner and machine floated. Surface shall be further compacted by a third mechanical floating if time and setting
characteristics will allow. At no time shall water be added to the surface. As surface further stiffens, indicated
by loss of sheen, it shall be hand or mechanically troweled with blades relatively flat. All marks and pinholes
shall be removed in the final raised trowel operation. Floors finished with dry shake material shall be cured
using a curing compound recommended by the manufacturer of the dry shake material. Membrane curing compound
shall be applied immediately after the floor surface has hardened sufficiently so surface will not be marred
by the application. Compound shall be applied uniformly over the entire surface at a coverage which will provide
moisture retention in excess of the requirements of ASTM C 309. When dry, the coating shall be protected from
droppings of plaster, paint, dirt, and other debris by a covering of scuffproof, non-staining building paper.
Floor shall remain covered and be kept free of traffic and loads for at least 10 days after completion. Adequate
provision shall be made for maintaining the concrete temperature at 10 degrees C 50 degrees F or above during
the curing period. The curing compound shall remain in place for not less than 30 days. The curing compound
shall be removed by a manufacturer recommended method prior to turning the facility over to the Government.
3.12.8 Heavy Duty Floors
NOTE: Heavy duty floors are to be used only for floors that will receive major
traffic of tracked vehicles or steel wheeled equipment when the designer is
concerned about wear. Moderate amounts of such traffic can be accommodated
by ordinary concrete floors. If drawings do not indicate areas to receive heavy
duty finish, they must be specified here. Delete this subparagraph if not required.
Edit bracketed items. Add to and strengthen this subparagraph as needed but
do not delete any of the listed requirements.
[Areas as indicated on the drawings] [The following areas [_____]] shall have heavy duty floors constructed as
follows:
3.12.8.1 General
Heavy duty floor shall be constructed by placing a heavy duty bonded topping on a base slab which has had a rough
slab finish left 50 mm 2 inches below final grade. Concrete in the base slab shall be thoroughly hardened but
not more than 30 hours old. The temperature of the fresh concrete topping shall not vary more than 5 degrees
C 10 degrees F plus or minus from the temperature of the base slab. The ambient temperature of the space adjacent
to the concrete placement and of the base slab shall be between 10 and 30 degrees C 50 and 90 degrees F.
3.12.8.2 Preparation of Base Slab
The base slab shall be kept continuously damp until topping is placed. The surface of the base slab shall be
thoroughly cleaned with an air-water jet immediately before placing the topping. A thin coat of neat cement
grout of about the consistency of thick cream shall be thoroughly scrubbed into the existing surface immediately
ahead of the overlay placing. At the time the neat cement grout is placed, the existing concrete surface shall
be damp but shall have no free water present. The overlay concrete shall be deposited before the grout coat
has had time to stiffen.
3.12.8.3 Placing and Finishing
Concrete shall be placed, as nearly as practicable in final position, in a uniform layer. The overlay shall
be placed and screeded slightly above the required finished grade, compacted by rolling with rollers weighing
not less than 4.5 kg/linear 25 mm 10 pounds/linear inch of roller width or by approved tamping equipment and
finish screeded to established grade. Grid type tampers shall not be used. The concrete, while still green
but sufficiently hardened to bear a person's weight without deep imprint, shall be floated to a true even plane
with no coarse aggregate visible. Floating shall be performed with an approved disc-type mechanical float which
has integral impact mechanism. The surface of the overlay shall then be left undisturbed until the concrete
has hardened enough to prevent excess fines from being worked to the top. Joints shall be formed to match those
in the base slab.
3.12.8.4 Curing and Protection
Concrete shall be maintained in a moist condition and shall be protected against rapid temperature change, mechanical
injury, and injury from rain or flowing water, for a curing period of not less than 10 days. Concrete shall
be maintained in a moist condition at temperatures above 10 and below 30 degrees C 50 and below 90 degrees F
throughout the specified curing period. Concrete shall be protected from a temperature change greater than 3
degrees C 5 degrees F per hour and from rapid drying for the first 24 hours following the removal of temperature
protection. Curing activities shall begin as soon as free water has disappeared from the concrete surface after
placing and finishing. Curing shall be moist curing accomplished by the following method. Surfaces shall be
covered with a double layer of burlap, wetted before placing, and overlapped at least 150 mm 6 inches. Burlap
shall be kept continually wet and in intimate contact with the surface. Burlap shall be kept covered with a
polyethylene sheeting at least 0.1 mm 4 mils thick. All traffic shall be kept from the floor during the curing
period and heavy traffic shall be kept off till 28-day age.
3.12.9 Two-Course Floor Construction
NOTE: Where it is anticipated that the surface of a floor slab may be damaged
during construction operations, a two-course floor may be specified with the
second course applied late in the contract. If the drawings do not indicate
areas to receive two-course floor construction, they must be specified here.
Delete this subparagraph when two-course floor is not required. Edit bracketed
items.
[Areas as indicated on the drawings] [The following areas [_____]] shall have floors constructed with two-course
construction. Two-course floor shall be constructed by placing a bonded topping on the thoroughly hardened concrete
base slab which has been left with a rough slab finish left 50 mm 2 inches below final grade as shown on the
drawings. Topping shall be applied at an approved time late in the contract period. The floor topping mixture
shall have a specified compressive strength of 34.5 MPa 5000 psi at 28 days, a 50 mm 2 inch maximum slump, 12.5
mm 1/2 inch maximum size coarse aggregate, and shall be proportioned to obtain required finishability. The surface
of the base slab shall be thoroughly cleaned by sandblasting or high-pressure waterjet immediately before placing
topping. The temperature of the fresh concrete topping shall not vary more than 5 degrees C 10 degrees F plus
or minus from the temperature of the base slab. The ambient temperature of the space adjacent to the concrete
placement and of the base slab shall be between 10 and 30 degrees C 50 and 90 degrees F. The base slab shall
be kept continuously wet for the first 12 hours during the 24 hour period immediately prior to placing the finished
floor. After all free water has evaporated or has been removed from the surface, a grout shall be scrubbed in.
The grout shall be a 1:1 mixture of portland cement and sand passing the 2.36 mm No. 8 sieve mixed to a creamlike
consistency. The grout shall be scrubbed into the surface just ahead of the concrete topping placing operation.
While the grout is still damp, the top course shall be spread and screeded and darbied or bull floated. When
the surface moisture has disappeared, the surface shall then be floated with disc-type power float with integral
impact mechanism followed by a minimum of two power trowelings. Trowel marks left by the machine shall be removed
by a final, hard steel troweling by hand. Joints shall be formed to match those in the base slab. Concrete
shall be maintained in a moist condition and shall be protected against rapid temperature change, mechanical
injury, and injury from rain or water, for a curing period of not less than 10 days. Concrete shall be maintained
in a moist condition at temperatures above 10 and below 30 degrees F 50 and below 90 degrees F throughout the
specified curing period. Concrete shall be protected from a temperature change greater than 3 degrees C 5 degrees
F per hour and from rapid drying for the first 24 hours following the removal of temperature protection. Curing
activities shall be started immediately as soon as free water has disappeared from the surface of the concrete
after placing and finishing. Curing shall be moist curing accomplished by the following method. Surfaces shall
be covered with a double layer of burlap, wetted before placing, and overlapped at least 150 mm 6 inches. Burlap
shall be kept continually wet and in intimate contact with the surface. Burlap shall be kept covered with a
polyethylene sheeting at least 0.1 mm 4 mils thick. All traffic shall be kept from the topping during the curing
period.
3.13 FLOOR HARDENER
NOTE: If the drawings do not indicate the areas to receive floor hardener,
they must be specified here. Normally, floor hardener is not needed. Use only
where extreme dust-free area is required or where requested by using service.
[Areas as indicated on the drawings] [The following areas [_____]] shall be treated with floor hardener. Floor
hardener shall be applied after the concrete has been cured and then air dried for [14] [28] days. Three coats
shall be applied, each the day after the preceding coat was applied. For the first application, 0.5 kg one pound
of the silocofluoride shall be dissolved in 4 liters one gallon of water. For subsequent applications, the
solution shall be 1.0 kg two pounds of silicofluoride to each 4 liters gallon of water. Floor should be mopped
with clear water shortly after the preceding application has dried to remove encrusted salts. Proprietary hardeners
shall be applied in accordance with the manufacturer's instructions. During application, area should be well
ventilated. Precautions shall be taken when applying silicofluorides due to the toxicity of the salts. Any
compound that contacts glass or aluminum should be immediately removed with clear water.
3.14 EXTERIOR SLAB AND RELATED ITEMS
NOTE: Edit bracketed statements and use these paragraphs only when minor amounts
of specified items are required in the project. Remove affected paragraph when
pertinent Section (Ex: 32 13 13.03 AIRFIELDS AND HEAVY-DUTY CONCRETE PAVEMENT
LESS THAN 10000 CUBIC YARDS, 32 16 13 CONCRETE SIDEWALKS AND CURBS AND GUTTERS)
is included in the contract.
3.14.1 Pavements
Pavements shall be constructed where shown on the drawings. After forms are set and underlying material prepared
as specified, the concrete shall be placed uniformly throughout the area and thoroughly vibrated. As soon as
placed and vibrated, the concrete shall be struck off and screeded to the crown and cross section and to such
elevation above grade that when consolidated and finished, the surface of the pavement will be at the required
elevation. The entire surface shall be tamped with the strike off, or consolidated with a vibrating screed,
and this operation continued until the required compaction and reduction of internal and surface voids are accomplished.
Care shall be taken to prevent bringing excess paste to the surface. Immediately following the final consolidation
of the surface, the pavement shall be floated longitudinally from bridges resting on the side forms and spanning
but not touching the concrete. If necessary, additional concrete shall be placed and screeded, and the float
operated until a satisfactory surface has been produced. The floating operation shall be advanced not more than
half the length of the float and then continued over the new and previously floated surfaces. After finishing
is completed but while the concrete is still plastic, minor irregularities and score marks in the pavement surface
shall be eliminated by means of long-handled cutting straightedges. Straightedges shall be 3.75 m 12 feet in
length and shall be operated from the sides of the pavement and from bridges. A straightedge operated from the
side of the pavement shall be equipped with a handle 1 m 3 feet longer than one-half the width of the pavement.
The surface shall then be tested for trueness with a 3.75 12 foot straightedge held in successive positions parallel
and at right angles to the center line of the pavement, and the whole area covered as necessary to detect variations.
The straightedge shall be advanced along the pavement in successive stages of not more than one-half the length
of the straightedge. Depressions shall be immediately filled with freshly mixed concrete, struck off, consolidated,
and refinished. Projections above the required elevation shall also be struck off and refinished. The straightedge
testing and finishing shall continue until the entire surface of the concrete is true. Before the surface sheen
has disappeared and well before the concrete becomes nonplastic, the surface of the pavement shall be given a
nonslip sandy surface texture by [belting with approved "belt" and procedures] [use of a burlap drag. A strip
of clean, wet burlap from 1.0 to 1.5 m 3 to 5 feet wide and 0.7 m 2 feet longer than the pavement width shall
be carefully pulled across the surface]. Edges and joints shall be rounded with an edger having a radius of
3 mm 1/8 inch. Curing shall be as specified.
3.14.2 Sidewalks
Concrete shall be 100 mm 4 inches minimum thickness. Contraction joints shall be provided at 1.75 m 5 feet spaces
unless otherwise indicated. Contraction joints shall be cut 25 mm 1 inch deep with a jointing tool after the
surface has been finished. Transverse expansion joints 12 mm 1/2 inch thick shall be provided at changes in
direction and where sidewalk abuts curbs, steps, rigid pavement, or other similar structures. Sidewalks shall
be given a lightly broomed finish. A transverse slope of 1 mm per 50 mm 1/4 inch per foot shall be provided,
unless otherwise indicated. Variations in cross section shall be limited to 1 mm per 250 mm 1/4 inch in 5 feet
.
3.14.3 Curbs and Gutters
Concrete shall be formed, placed, and finished by hand using a properly shaped "mule" or constructed using a
slipform machine specially designed for this work. Contraction joints shall be cut 75 mm 3 inches deep with
a jointing tool after the surface has been finished. Expansion joints (12 mm 1/2 inch wide) shall be provided
at 35 m 100 feet maximum spacing unless otherwise indicated. Exposed surfaces shall be finished using a stiff
bristled brush.
3.14.4 Pits and Trenches
Pits and trenches shall be constructed as indicated on the drawings. Bottoms and walls shall be placed monolithically
or waterstops and keys, shall be provided as approved.
3.15 CURING AND PROTECTION
3.15.1 General
NOTE: Do not allow membrane curing compound on surfaces where appearance is
critical or that are maintained at curing temperature with free steam. Moist
curing should almost always be permitted.
Concrete shall be cured by an approved method for the period of time given below:
Concrete with Type III cement 3 days
All other concrete 7 days
Immediately after placement, concrete shall be protected from premature drying, extremes in temperatures, rapid
temperature change, mechanical injury and damage from rain and flowing water for the duration of the curing period.
Air and forms in contact with concrete shall be maintained at a temperature above 10 degrees C 50 degrees F for
the first 3 days and at a temperature above 0 degrees C 32 degrees F for the remainder of the specified curing
period. Exhaust fumes from combustion heating units shall be vented to the outside of the enclosure, and heaters
and ducts shall be placed and directed so as not to cause areas of overheating and drying of concrete surfaces
or to create fire hazards. Materials and equipment needed for adequate curing and protection shall be available
and at the site prior to placing concrete. No fire or excessive heat, including welding, shall be permitted
near or in direct contact with the concrete at any time. Except as otherwise permitted by paragraph Membrane
Forming Curing Compounds, moist curing shall be provided for any areas to receive floor hardener, any paint or
other applied coating, or to which other concrete is to be bonded. Concrete containing silica fume shall be
initially cured by fog misting during finishing, followed immediately by continuous moist curing. Except for
plastic coated burlap, impervious sheeting alone shall not be used for curing.
3.15.2 Moist Curing
Concrete to be moist-cured shall be maintained continuously wet for the entire curing period, commencing immediately
after finishing. If water or curing materials used stain or discolor concrete surfaces which are to be permanently
exposed, the concrete surfaces shall be cleaned as approved. When wooden forms are left in place during curing,
they shall be kept wet at all times. If steel forms are used in hot weather, nonsupporting vertical forms shall
be broken loose from the concrete soon after the concrete hardens and curing water continually applied in this
void. If the forms are removed before the end of the curing period, curing shall be carried out as on unformed
surfaces, using suitable materials. Surfaces shall be cured by ponding, by continuous sprinkling, by continuously
saturated burlap or cotton mats, or by continuously saturated plastic coated burlap. Burlap and mats shall be
clean and free from any contamination and shall be completely saturated before being placed on the concrete.
The Contractor shall have an approved work system to ensure that moist curing is continuous 24 hours per day.
3.15.3 Membrane Forming Curing Compounds
Membrane forming curing compounds shall be used only on surfaces in the following areas, [_____]. Concrete in
the following areas [may be cured with a pigmented curing compound in lieu of moist curing.] [may be cured with
a nonpigmented curing compound containing a fugitive dye in lieu of moist curing.] Membrane curing shall not
be used on surfaces that are to receive any subsequent treatment depending on adhesion or bonding to the concrete,
including surfaces to which a smooth finish is to be applied or other concrete to be bonded. However, a styrene
acrylate or chlorinated rubber compound meeting ASTM C 309, Class B requirements, may be used for surfaces which
are to be painted or are to receive bituminous roofing or waterproofing, or floors that are to receive adhesive
applications of resilient flooring. The curing compound selected shall be compatible with any subsequent paint,
roofing, waterproofing or flooring specified. Membrane curing compound shall not be used on surfaces that are
maintained at curing temperatures with free steam. Curing compound shall be applied to formed surfaces immediately
after the forms are removed and prior to any patching or other surface treatment except the cleaning of loose
sand, mortar, and debris from the surface. All surfaces shall be thoroughly moistened with water. Curing compound
shall be applied to slab surfaces as soon as the bleeding water has disappeared, with the tops of joints being
temporarily sealed to prevent entry of the compound and to prevent moisture loss during the curing period. The
curing compound shall be applied in a two-coat continuous operation by approved motorized power-spraying equipment
operating at a minimum pressure of 500 kPa 75 psi, at a uniform coverage of not more than 10 cubic meters/L 400
square feet/gallon for each coat, and the second coat shall be applied perpendicular to the first coat. Concrete
surfaces which have been subjected to rainfall within 3 hours after curing compound has been applied shall be
resprayed by the method and at the coverage specified. Surfaces on which clear compound is used shall be shaded
from direct rays of the sun for the first 3 days. Surfaces coated with curing compound shall be kept free of
foot and vehicular traffic, and from other sources of abrasion and contamination during the curing period.
3.15.4 Impervious Sheeting
NOTE: Use impervious sheeting only for surfaces that are horizontal or near
horizontal. Do not use on slab surfaces where appearance is critical.
The following concrete surfaces may be cured using impervious sheets: [_____]. However, except for plastic coated
burlap, impervious sheeting alone shall not be used for curing. Impervious-sheet curing shall only be used on
horizontal or nearly horizontal surfaces. Surfaces shall be thoroughly wetted and be completely covered with
the sheeting. Sheeting shall be at least 450 mm 18 inches wider than the concrete surface to be covered. Covering
shall be laid with light-colored side up. Covering shall be lapped not less than 300 mm 12 inches and securely
weighted down or shall be lapped not less than 100 mm 4 inches and taped to form a continuous cover with completely
closed joints. The sheet shall be weighted to prevent displacement so that it remains in contact with the concrete
during the specified length of curing. Coverings shall be folded down over exposed edges of slabs and secured
by approved means. Sheets shall be immediately repaired or replaced if tears or holes appear during the curing
period.
3.15.5 Ponding or Immersion
Concrete shall be continually immersed throughout the curing period. Water shall not be more than 10 degrees
C 20 degrees F less than the temperature of the concrete.
3.15.6 Cold Weather Curing and Protection
When the daily ambient low temperature is less than 0 degrees C 32 degrees F the temperature of the concrete
shall be maintained above 5 degrees C 40 degrees F for the first seven days after placing. During the period
of protection removal, the air temperature adjacent to the concrete surfaces shall be controlled so that concrete
near the surface will not be subjected to a temperature differential of more than 13 degrees C 25 degrees F as
determined by suitable temperature measuring devices furnished by [the Government][the Contractor], as required,
and installed adjacent to the concrete surface and 50 mm 2 inches inside the surface of the concrete. The installation
of the thermometers shall be made by the Contractor as directed.
3.16 SETTING BASE PLATES AND BEARING PLATES
NOTE: Damp-pack bedding mortar will be specified for setting base and bearing
plates, except that nonshrink grout will be specified for heavy machinery bases
or where design requires precision setting of plates or requires that bedding
material have high resistance to shear, impact, or vibration, and where good
damp packing is difficult or impossible. When using nonshrink grout on important
structures, such as large machinery bases, the grout should be required to meet
ASTM C 1107/C 1107M, Grade A, B, or C, grade or grades as selected by the designer.
This nonshrink grout must not be used for embedding post-tensioned tendons or
rock bolts. Edit bracketed item as appropriate, and delete entire paragraph
if not needed.
After being properly positioned, column base plates, bearing plates for beams and similar structural members,
and machinery and equipment base plates shall be set to the proper line and elevation with damp-pack bedding
mortar, except where nonshrink grout is indicated. The thickness of the mortar or grout shall be approximately
1/24 the width of the plate, but not less than 19 mm 3/4 inch. Concrete and metal surfaces in contact with grout
shall be clean and free of oil and grease, and concrete surfaces in contact with grout shall be damp and free
of laitance when grout is placed. Nonshrink grout shall be used for [_____].
3.16.1 Damp-Pack Bedding Mortar
Damp-pack bedding mortar shall consist of 1 part cement and 2-1/2 parts fine aggregate having water content such
that a mass of mortar tightly squeezed in the hand will retain its shape but will crumble when disturbed. The
space between the top of the concrete and bottom of the bearing plate or base shall be packed with the bedding
mortar by tamping or ramming with a bar or rod until it is completely filled.
3.16.2 Nonshrink Grout
Nonshrink grout shall be a ready-mixed material requiring only the addition of water. Water content shall be
the minimum that will provide a flowable mixture and completely fill the space to be grouted without segregation,
bleeding, or reduction of strength.
3.16.2.1 Mixing and Placing of Nonshrink Grout
Mixing and placing shall be in conformance with the material manufacturer's instructions and as specified therein.
Ingredients shall be thoroughly dry-mixed before adding water. After adding water, the batch shall be mixed
for 3 minutes. Batches shall be of size to allow continuous placement of freshly mixed grout. Grout not used
within 30 minutes after mixing shall be discarded. The space between the top of the concrete or machinery-bearing
surface and the plate shall be filled solid with the grout. Forms shall be of wood or other equally suitable
material for completely retaining the grout on all sides and on top and shall be removed after the grout has
set. The placed grout shall be carefully worked by rodding or other means to eliminate voids; however, overworking
and breakdown of the initial set shall be avoided. Grout shall not be retempered or subjected to vibration from
any source. Where clearances are unusually small, placement shall be under pressure with a grout pump. Temperature
of the grout, and of surfaces receiving the grout, shall be maintained at 18 to 30 degrees C 65 to 85 degrees
F until after setting.
3.16.2.2 Treatment of Exposed Surfaces
For metal-oxidizing nonshrink grout, exposed surfaces shall be cut back 25 mm 1 inch and immediately covered
with a parge coat of mortar consisting of 1 part portland cement and 2-1/2 parts fine aggregate by weight, with
sufficient water to make a plastic mixture. The parge coat shall have a smooth finish. For other mortars or
grouts, exposed surfaces shall have a smooth-dense finish and be left untreated. Curing shall comply with paragraph
CURING AND PROTECTION.
3.17 TESTING AND INSPECTION FOR CONTRACTOR QUALITY CONTROL
NOTE: For non-critical small projects, less than 1200 cubic meters (1500 cu.
yd.) of concrete, the designer may reduce, but not eliminate, the requirements
of this paragraph, and edit it appropriately for the project specifications.
Otherwise, retain complete.
The Contractor shall perform the inspection and tests described below and, based upon the results of these inspections
and tests, shall take the action required and shall submit specified reports. When, in the opinion of the Contracting
Officer, the concreting operation is out of control, concrete placement shall cease and the operation shall be
corrected. The laboratory performing the tests shall be onsite and shall conform with ASTM C 1077. Materials
may be subjected to check testing by the Government from samples obtained at the manufacturer, at transfer points,
or at the project site. The Government will inspect the laboratory, equipment, and test procedures prior to
start of concreting operations and at least once per [_____] thereafter for conformance with ASTM C 1077.
3.17.1 Grading and Corrective Action
3.17.1.1 Fine Aggregate
At least once during each shift when the concrete plant is operating, there shall be one sieve analysis and fineness
modulus determination in accordance with ASTM C 136 and COE CRD-C 104 for the fine aggregate or for each fine
aggregate if it is batched in more than one size or classification. The location at which samples are taken
may be selected by the Contractor as the most advantageous for control. However, the Contractor is responsible
for delivering fine aggregate to the mixer within specification limits. When the amount passing on any sieve
is outside the specification limits, the fine aggregate shall be immediately resampled and retested. If there
is another failure on any sieve, the fact shall immediately reported to the Contracting Officer, concreting shall
be stopped, and immediate steps taken to correct the grading.
3.17.1.2 Coarse Aggregate
At least once during each shift in which the concrete plant is operating, there shall be a sieve analysis in
accordance with ASTM C 136 for each size of coarse aggregate. The location at which samples are taken may be
selected by the Contractor as the most advantageous for production control. However, the Contractor shall be
responsible for delivering the aggregate to the mixer within specification limits. A test record of samples
of aggregate taken at the same locations shall show the results of the current test as well as the average results
of the five most recent tests including the current test. The Contractor may adopt limits for control coarser
than the specification limits for samples taken other than as delivered to the mixer to allow for degradation
during handling. When the amount passing any sieve is outside the specification limits, the coarse aggregate
shall be immediately resampled and retested. If the second sample fails on any sieve, that fact shall be reported
to the Contracting Officer. Where two consecutive averages of 5 tests are outside specification limits, the
operation shall be considered out of control and shall be reported to the Contracting Officer. Concreting shall
be stopped and immediate steps shall be taken to correct the grading.
3.17.2 Quality of Aggregates
Thirty days prior to the start of concrete placement, the Contractor shall perform all tests for aggregate quality
required by ASTM C 33. In addition, after the start of concrete placement, the Contractor shall perform tests
for aggregate quality at least every three months, and when the source of aggregate or aggregate quality changes.
Samples tested after the start of concrete placement shall be taken immediately prior to entering the concrete
mixer.
3.17.3 Scales, Batching and Recording
The accuracy of the scales shall be checked by test weights prior to start of concrete operations and at least
once every three months. Such tests shall also be made as directed whenever there are variations in properties
of the fresh concrete that could result from batching errors. Once a week the accuracy of each batching and
recording device shall be checked during a weighing operation by noting and recording the required weight, recorded
weight, and the actual weight batched. At the same time, the Contractor shall test and ensure that the devices
for dispensing admixtures are operating properly and accurately. When either the weighing accuracy or batching
accuracy does not comply with specification requirements, the plant shall not be operated until necessary adjustments
or repairs have been made. Discrepancies in recording accuracies shall be corrected immediately.
3.17.4 Batch-Plant Control
The measurement of concrete materials including cementitious materials, each size of aggregate, water, and admixtures
shall be continuously controlled. The aggregate weights and amount of added water shall be adjusted as necessary
to compensate for free moisture in the aggregates. The amount of air-entraining agent shall be adjusted to control
air content within specified limits. A report shall be prepared indicating type and source of cement used, type
and source of pozzolan or slag used, amount and source of admixtures used, aggregate source, the required aggregate
and water weights per cubic meter yard amount of water as free moisture in each size of aggregate, and the batch
aggregate and water weights per cubic meter yard for each class of concrete batched during each day's plant operation.
3.17.5 Concrete Mixture
a. Air Content Testing. Air content tests shall be made when test specimens are fabricated.
In addition, at least two tests for air content shall be made on randomly selected batches of
each separate concrete mixture produced during each 8-hour period of concrete production. Additional
tests shall be made when excessive variation in workability is reported by the placing foreman
or Government inspector. Tests shall be made in accordance with ASTM C 231 for normal weight
concrete and ASTM C 173/C 173M for lightweight concrete. Test results shall be plotted on control
charts which shall at all times be readily available to the Government and shall be submitted
weekly. Copies of the current control charts shall be kept in the field by testing crews and
results plotted as tests are made. When a single test result reaches either the upper or lower
action limit, a second test shall immediately be made. The results of the two tests shall be
averaged and this average used as the air content of the batch to plot on both the air content
and the control chart for range, and for determining need for any remedial action. The result
of each test, or average as noted in the previous sentence, shall be plotted on a separate control
chart for each mixture on which an "average line" is set at the midpoint of the specified air
content range from paragraph Air Entrainment. An upper warning limit and a lower warning limit
line shall be set 1.0 percentage point above and below the average line, respectively. An upper
action limit and a lower action limit line shall be set 1.5 percentage points above and below
the average line, respectively. The range between each two consecutive tests shall be plotted
on a secondary control chart for range where an upper warning limit is set at 2.0 percentage
points and an upper action limit is set at 3.0 percentage points. Samples for air content may
be taken at the mixer, however, the Contractor is responsible for delivering the concrete to
the placement site at the stipulated air content. If the Contractor's materials or transportation
methods cause air content loss between the mixer and the placement, correlation samples shall
be taken at the placement site as required by the Contracting Officer, and the air content at
the mixer controlled as directed.
b. Air Content Corrective Action. Whenever points on the control chart for percent air reach
either warning limit, an adjustment shall immediately be made in the amount of air-entraining
admixture batched. As soon as practical after each adjustment, another test shall be made to
verify the result of the adjustment. Whenever a point on the secondary control chart for range
reaches the warning limit, the admixture dispenser shall be recalibrated to ensure that it is
operating accurately and with good reproducibility. Whenever a point on either control chart
reaches an action limit line, the air content shall be considered out of control and the concreting
operation shall immediately be halted until the air content is under control. Additional air
content tests shall be made when concreting is restarted.
c. Slump Testing. In addition to slump tests which shall be made when test specimens are fabricated,
at least four slump tests shall be made on randomly selected batches in accordance with ASTM C 143/C 143M
for each separate concrete mixture produced during each 8-hour or less period of concrete production
each day. Also, additional tests shall be made when excessive variation in workability is reported
by the placing foreman or Government inspector. Test results shall be plotted on control charts
which shall at all times be readily available to the Government and shall be submitted weekly.
Copies of the current control charts shall be kept in the field by testing crews and results
plotted as tests are made. When a single slump test reaches or goes beyond either the upper
or lower action limit, a second test shall immediately be made. The results of the two tests
shall be averaged and this average used as the slump of the batch to plot on both the control
charts for slump and the chart for range, and for determining need for any remedial action.
Limits shall be set on separate control charts for slump for each type of mixture. The upper
warning limit shall be set at 12.5 mm 1/2 inch below the maximum allowable slump specified in
paragraph Slump in PART 1 for each type of concrete and an upper action limit line and lower
action limit line shall be set at the maximum and minimum allowable slumps, respectively, as
specified in the same paragraph. The range between each consecutive slump test for each type
of mixture shall be plotted on a single control chart for range on which an upper action limit
is set at 50 mm 2 inches. Samples for slump shall be taken at the mixer. However, the Contractor
is responsible for delivering the concrete to the placement site at the stipulated slump. If
the Contractor's materials or transportation methods cause slump loss between the mixer and
the placement, correlation samples shall be taken at the placement site as required by the Contracting
Officer, and the slump at the mixer controlled as directed.
d. Slump Corrective Action. Whenever points on the control charts for slump reach the upper
warning limit, an adjustment shall immediately be made in the batch weights of water and fine
aggregate. The adjustments are to be made so that the total water content does not exceed that
amount allowed by the maximum w/c ratio specified, based on aggregates which are in a saturated
surface dry condition. When a single slump reaches the upper or lower action limit, no further
concrete shall be delivered to the placing site until proper adjustments have been made. Immediately
after each adjustment, another test shall be made to verify the correctness of the adjustment.
Whenever two consecutive individual slump tests, made during a period when there was no adjustment
of batch weights, produce a point on the control chart for range at or above the upper action
limit, the concreting operation shall immediately be halted, and the Contractor shall take appropriate
steps to bring the slump under control. Additional slump tests shall be made as directed.
e. Temperature. The temperature of the concrete shall be measured when compressive strength
specimens are fabricated. Measurement shall be in accordance with ASTM C 1064/C 1064M. The
temperature shall be reported along with the compressive strength data.
f. Strength Specimens. At least one set of test specimens shall be made, for compressive or
flexural strength as appropriate, on each different concrete mixture placed during the day for
each 380 cubic meters 500 cubic yards or portion thereof of that concrete mixture placed each
day. Additional sets of test specimens shall be made, as directed by the Contracting Officer,
when the mixture proportions are changed or when low strengths have been detected. A truly
random (not haphazard) sampling plan shall be developed by the Contractor and approved by the
Contracting Officer prior to the start of construction. The plan shall assure that sampling
is done in a completely random and unbiased manner. A set of test specimens for concrete with
a 28-day specified strength in accordance with paragraph Strength Requirements in PART 1 shall
consist of four specimens, two to be tested at 7 days and two at 28 days. [A set of test specimens
for concrete with a 90-day strength in accordance with the same paragraph shall consist of six
specimens, two tested at 7 days, two at 28 days, and two at 90 days.] Test specimens shall
be molded and cured in accordance with ASTM C 31/C 31M and tested in accordance with ASTM C 39/C 39M
for test cylinders and ASTM C 78 for test beams. Results of all strength tests shall be reported
immediately to the Contracting Officer. Quality control charts shall be kept for individual
strength "tests", ("test" as defined in paragraph Strength Requirements in PART 1) moving average
of last 3 "tests" for strength, and moving average for range for the last 3 "tests" for each
mixture. The charts shall be similar to those found in ACI 214R.
3.17.6 Inspection Before Placing
Foundations, construction joints, forms, and embedded items shall be inspected by the Contractor in sufficient
time prior to each concrete placement in order to certify to the Contracting Officer that they are ready to receive
concrete. The results of each inspection shall be reported in writing.
3.17.7 Placing
The placing foreman shall supervise placing operations, shall determine that the correct quality of concrete
or grout is placed in each location as specified and as directed by the Contracting Officer, and shall be responsible
for measuring and recording concrete temperatures and ambient temperature hourly during placing operations, weather
conditions, time of placement, volume placed, and method of placement. The placing foreman shall not permit
batching and placing to begin until it has been verified that an adequate number of vibrators in working order
and with competent operators are available. Placing shall not be continued if any pile of concrete is inadequately
consolidated. If any batch of concrete fails to meet the temperature requirements, immediate steps shall be
taken to improve temperature controls.
3.17.8 Vibrators
The frequency and amplitude of each vibrator shall be determined in accordance with COE CRD-C 521 prior to initial
use and at least once a month when concrete is being placed. Additional tests shall be made as directed when
a vibrator does not appear to be adequately consolidating the concrete. The frequency shall be determined while
the vibrator is operating in concrete with the tachometer being held against the upper end of the vibrator head
while almost submerged and just before the vibrator is withdrawn from the concrete. The amplitude shall be determined
with the head vibrating in air. Two measurements shall be taken, one near the tip and another near the upper
end of the vibrator head, and these results averaged. The make, model, type, and size of the vibrator and frequency
and amplitude results shall be reported in writing. Any vibrator not meeting the requirements of paragraph Consolidation,
shall be immediately removed from service and repaired or replaced.
3.17.9 Curing Inspection
a. Moist Curing Inspections. At least once each shift, and not less than twice per day on
both work and non-work days, an inspection shall be made of all areas subject to moist curing.
The surface moisture condition shall be noted and recorded.
b. Moist Curing Corrective Action. When a daily inspection report lists an area of inadequate
curing, immediate corrective action shall be taken, and the required curing period for those
areas shall be extended by 1 day.
c. Membrane Curing Inspection. No curing compound shall be applied until the Contractor has
verified that the compound is properly mixed and ready for spraying. At the end of each operation,
the Contractor shall estimate the quantity of compound used by measurement of the container
and the area of concrete surface covered, shall compute the rate of coverage in square meters/L
square feet/gallon, and shall note whether or not coverage is uniform.
d. Membrane Curing Corrective Action. When the coverage rate of the curing compound is less
than that specified or when the coverage is not uniform, the entire surface shall be sprayed
again.
e. Sheet Curing Inspection. At least once each shift and once per day on non-work days, an
inspection shall be made of all areas being cured using impervious sheets. The condition of
the covering and the tightness of the laps and tapes shall be noted and recorded.
f. Sheet Curing Corrective Action. When a daily inspection report lists any tears, holes,
or laps or joints that are not completely closed, the tears and holes shall promptly be repaired
or the sheets replaced, the joints closed, and the required curing period for those areas shall
be extended by 1 day.
3.17.10 Cold-Weather Protection
At least once each shift and once per day on non-work days, an inspection shall be made of all areas subject
to cold-weather protection. Any deficiencies shall be noted, corrected, and reported.
3.17.11 Mixer Uniformity
a. Stationary Mixers. Prior to the start of concrete placing and once every 6 months when
concrete is being placed, or once for every 60,000 cubic meters 75,000 cubic yards of concrete
placed, whichever results in the shortest time interval, uniformity of concrete mixing shall
be determined in accordance with ASTM C 94/C 94M.
b. Truck Mixers. Prior to the start of concrete placing and at least once every 6 months when
concrete is being placed, uniformity of concrete mixing shall be determined in accordance with
ASTM C 94/C 94M. The truck mixers shall be selected randomly for testing. When satisfactory
performance is found in one truck mixer, the performance of mixers of substantially the same
design and condition of the blades may be regarded as satisfactory.
c. Mixer Uniformity Corrective Action. When a mixer fails to meet mixer uniformity requirements,
either the mixing time shall be increased, batching sequence changed, batch size reduced, or
adjustments shall be made to the mixer until compliance is achieved.
3.17.12 Reports
All results of tests or inspections conducted shall be reported informally as they are completed and in writing
daily. A weekly report shall be prepared for the updating of control charts covering the entire period from
the start of the construction season through the current week. During periods of cold-weather protection, reports
of pertinent temperatures shall be made daily. These requirements do not relieve the Contractor of the obligation
to report certain failures immediately as required in preceding paragraphs. Such reports of failures and the
action taken shall be confirmed in writing in the routine reports. The Contracting Officer has the right to
examine all contractor quality control records.