USACE / NAVFAC / AFCESA / NASA UFGS-03 11 14.00 10 (April 2006)
--------------------------------
Preparing Activity: USACE (CW) Replacing without change
UFGS-03101A (September 2001)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 03 11 14.00 10
FORMWORK FOR CONCRETE
04/06
NOTES: This guide specification covers the requirements for formwork for concrete
structures.
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
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 347(2004) Guide to Formwork for Concrete][APA - THE ENGINEERED WOOD ASSOCIATION (APA)APA PS 1(1995) Voluntary Product Standard for Construction and Industrial Plywood][ASTM INTERNATIONAL (ASTM)ASTM C 1074(2004) Standard Practice for Estimating Concrete Strength by the Maturity MethodASTM C 1077(2008) Standard Practice for Laboratories Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Laboratory EvaluationASTM C 31/C 31M(2008a) Standard Practice for Making and Curing Concrete Test Specimens in the FieldASTM C 39/C 39M(2005e1e2) Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens]1.2 DESIGN REQUIREMENTS
The design, engineering, and construction of the formwork shall be the responsibility of the Contractor. The
formwork shall be designed for anticipated live and dead loads and shall comply with the tolerances specified
in Section [03 31 01.00 10 CAST-IN-PLACE STRUCTURAL CONCRETE][03 70 00 MASS CONCRETE][03 30 53 MISCELLANEOUS
CAST-IN-PLACE CONCRETE], paragraph CONSTRUCTION TOLERANCES. However, for surfaces with an ACI Class A surface
designation, the allowable deflection for facing material between studs, for studs between walers and walers
between bracing shall be limited to 0.0025 times the span. The formwork shall be designed as a complete system
with consideration given to the effects of cementitious materials and mixture additives such as fly ash, cement
type, plasticizers, accelerators, retarders, air entrainment, and others. The adequacy of formwork design and
construction shall be monitored prior to and during concrete placement as part of the Contractor's approved Quality
Control Plan.
1.3 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-02 Shop Drawings
Shop Drawings
Drawings and design computations for all formwork required shall be submitted at least [_____]
days either before fabrication on site or before delivery of prefabricated forms. If reshoring
is permitted, the method, including location, order, and time of erection and removal shall
also be submitted for review.
SD-03 Product Data
Materials
Manufacturer's literature shall be submitted for plywood, concrete form hard board, form accessories,
prefabricated forms,[ and] form coating[, and form-lining materials].
SD-04 Samples
Sample Panels[; G][; G, [_____]]
After shop drawings have been reviewed, sample panels for Class A finish with applied architectural
treatment shall be built on the project site where directed.
SD-06 Test Reports
NOTE: If form removal is not allowed before 24 hours, the submittal, "Formwork
Not Supporting Weight of Concrete; G", and the corresponding bracketed sentences
in paragraph FORMWORK NOT SUPPORTING WEIGHT OF CONCRETE should be deleted.
Inspection
The Contractor shall submit field inspection reports for concrete forms and embedded items.
Formwork Not Supporting Weight of Concrete[; G][; G, [_____]].
If forms are to be removed in less than 24 hours on formwork not supporting the weight of
concrete, the evaluation and results of the control cylinder tests[ or maturity instrumentation]
shall be submitted to and approved before the forms are removed.
1.4 SHOP DRAWINGS
The shop drawings and data submitted shall include the type, size, quantity, and strength of all materials of
which the forms are made, the plan for jointing of facing panels, details affecting the appearance, and the assumed
design values and loading conditions.
1.5 SAMPLE PANELS
Panels shall be of sufficient size to contain joints and shall be not less than 2 meters long and 1.5 meters
wide 6 feet long and 4 feet wide. The panels shall be of typical wall thickness and constructed containing the
full allocation of reinforcing steel that will be used in the structure, with the forming system that duplicates
in every detail the one that will be used in construction of the structure. The same concrete mixture proportion
and materials, the same placement techniques and equipment, and the same finishing techniques and timing shall
be used that are planned for the structure. Construction of Class A finish will not be permitted until sample
panels have been approved. Sample panels shall be protected from construction operations in a manner to protect
approved finish, and are not to be removed until all Class A finish concrete has been accepted.
PART 2 PRODUCTS
2.1 MATERIALS
2.1.1 Forms and Form Liners
NOTE: See the appropriate Concrete Materials Design Memorandum and EM 1110-2-2000
for description of class finishes. See paragraph 5.4.e in EM 1110-2-2000 for
guidance in selecting appropriate finishes.
Forms and form liners shall be fabricated with facing materials that will produce a finish meeting the specified
irregularities in formed surface requirements as defined in ACI 347. Forms and form liners shall be fabricated
with facing materials as specified below.
2.1.1.1 Class "A" Finish
This class of finish shall apply to [_____]. The form facing material shall be composed of new, well-matched
tongue-and-groove lumber or new plywood panels conforming to APA PS 1, Grade B-B concrete form, Class I. [High
density overlay shall be used in [_____] locations.][ Structural I shall be used in [_____] locations.]
2.1.1.2 Class "B" Finish
This class of finish shall apply to all surfaces except those specified to receive[ Class A][,][ Class C][,][
Class D]. The form facing material shall be composed of tongue-and-groove or shiplap lumber, plywood conforming
to APA PS 1, Grade B-B concrete form, tempered concrete form hard board or steel. Steel lining on wood sheathing
will not be permitted.
2.1.1.3 Class "C" Finish
This class of finish shall apply to [_____]. The form facing may be either tongue-and-groove lumber, plywood,
concrete form hard board or steel. Wood form facing for curved or warped surfaces shall be composed of splines
of lumber which can be bent to the required shape without splitting or cracking.
2.1.1.4 Class "D" Finish
This class of finish shall apply to [_____]. The form facing may be of wood or steel.
2.1.2 Form Coating
Form coating shall be commercial formulation that will not bond with, stain, cause deterioration, or any other
damage to concrete surfaces. The coating shall not impair subsequent treatment of concrete surfaces depending
upon bond or adhesion nor impede the wetting of surfaces to be cured with water or curing compounds. If special
form liners are to be used, the Contractor shall follow the recommendation of the form coating manufacturer.
2.2 ACCESSORIES
NOTE: Removable tie rods are not allowed for structures intended to be a water
barrier. Specify the locations where removable tie rods are not to be used.
Ties and other similar form accessories to be partially or wholly embedded in the concrete shall be of a commercially
manufactured type. After the ends or end fasteners have been removed, the embedded portion of metal ties shall
terminate not less than 50 mm 2 inches from any concrete surface either exposed to view or exposed to water.
[Removable tie rods shall not be allowed in [_____] locations. ]Plastic snap ties may be used in locations where
the surface will not be exposed to view. Form ties shall be constructed so that the ends or end fasteners can
be removed without spalling the concrete.
PART 3 EXECUTION
3.1 INSTALLATION
3.1.1 Form Construction
Forms shall be constructed true to the structural design and required alignment. The form surface and joints
shall be mortar tight and supported to achieve safe performance during construction, concrete placement, and
form removal. The Contractor shall continuously monitor the alignment and stability of the forms during all
phases to assure the finished product will meet the required surface class [or classes] specified in paragraph
FORMS AND FORM LINERS and tolerances specified in paragraph DESIGN REQUIREMENTS. Failure of any supporting surface
either due to surface texture, deflection or form collapse shall be the responsibility of the Contractor as will
the replacement or correction of unsatisfactory surfaces. When forms for continuous surfaces are placed in successive
units, care shall be taken to fit the forms over the completed surface to obtain accurate alignment of the surface
and to prevent leakage of mortar. Forms shall not be re-used if there is any evidence of defects which would
impair the quality of the resulting concrete surface. All surfaces of used forms shall be cleaned of mortar
and any other foreign material before reuse.
3.1.2 Chamfering
All exposed joints, edges and external corners shall be chamfered by molding placed in the forms unless the drawings
specifically state that chamfering is to be omitted or as otherwise specified. Chamfered joints shall not be
permitted where earth or rockfill is placed in contact with concrete surfaces. Chamfered joints shall be terminated
300 mm twelve inches outside the limit of the earth or rockfill so that the end of the chamfers will be clearly
visible.
3.1.3 Coating
Forms for exposed or painted surfaces shall be coated with form oil or a form-release agent before the form or
reinforcement is placed in final position. The coating shall be used as recommended in the manufacturer's instructions.
Forms for unexposed surfaces may be wet with water in lieu of coating immediately before placing concrete, except
that, in cold weather when freezing temperatures are anticipated, coating shall be mandatory. Surplus coating
on form surfaces and coating on reinforcing steel and construction joints shall be removed before placing concrete.
3.2 FORM REMOVAL
NOTES: For unsupported concrete, form removal is based upon a minimum time
requirement of 24 hours. As an option, form removal may be allowed between
18 hours and 24 hours after placement. In this case, form removal is based
upon a minimum time (18 hours), minimum ambient temperature (10 degrees C (50
degrees F)), and minimum compressive strength requirement. For supported concrete,
form removal is based solely upon a minimum compressive strength requirement.
An experienced concrete materials engineer or [_____] should be consulted before
allowing the use of the maturity concept instead of compressive strength test
on field cured cylinders.
Forms shall not be removed without approval. The minimal time required for concrete to reach a strength adequate
for removal of formwork without risking the safety of workers or the quality of the concrete depends on a number
of factors including, but not limited to, ambient temperature, concrete lift heights, type and amount of concrete
admixture, and type and amount of cementitious material in the concrete. It is the responsibility of the Contractor
to consider all applicable factors and leave the forms in place until it is safe to remove them. In any case
forms shall not be removed unless the [minimum time][, ][ or ][minimum compressive strength][, ][ or ][minimum
time, minimum ambient temperature, and minimum compressive strength] requirements below are met, except as otherwise
directed or specifically authorized. When conditions are such as to justify the requirement, forms will be required
to remain in place for a longer period. All removal shall be accomplished in a manner which will prevent damage
to the concrete and ensure the complete safety of the structure. Where forms support more than one element,
the forms shall not be removed until the form removal criteria are met by all supported elements. Form removal
shall be scheduled so that all necessary repairs can be performed as specified in Section [[_____]] [_____],
paragraph [_____]. Evidence that concrete has gained sufficient strength to permit removal of forms shall be
determined by tests on control cylinders. All control cylinders shall be stored in the structure or as near
the structure as possible so they receive the same curing conditions and protection methods as given those portions
of the structure they represent. Control cylinders shall be removed from the molds at an age of no more than
24 hours. All control cylinders shall be prepared and tested in accordance with ASTM C 31/C 31M and ASTM C 39/C 39M
at the expense of the Contractor by an independent laboratory that complies with ASTM C 1077 and shall be tested
within 4 hours after removal from the site.[ After obtaining approval, the Contractor may use maturity instrumentation
instead of control cylinders to determine the compressive strength of the concrete. ASTM C 1074 procedures shall
be used for estimating concrete strength by means of the maturity method. All expenses associated with instrumenting
the concrete and evaluating the strength using maturity relationships shall be the responsibility of the Contractor.]
3.2.1 Formwork Not Supporting Weight of Concrete
NOTES: If form removal is to be allowed before 24 hours, the concrete must
have sufficient strength to resist damage from the removal operation. A minimum
of 3.5 MPa (500 psi) is recommended.
If the bracketed sentences below are deleted from the project specification,
the corresponding submittal requirements for the evaluation and results of control
cylinder tests [or maturity instrumentation] should also be deleted from paragraph
SUBMITTALS.
Formwork for walls, columns, sides of beams, gravity structures, and other vertical type formwork not supporting
the weight of concrete shall not be removed in less than 24 hours after concrete placement is completed.[ Form
removal before 24 hours will be allowed for simple floor slab, sidewalks, and driveways provided the ambient
temperature during this period has not fallen below 10 degrees C 50 degrees F at any time since placement and
evidence from compressive tests on field-cured concrete control cylinders [or maturity instrumentation ]indicate[s]
that the concrete has attained a compressive strength of at least [_____] MPa psi. Control cylinders shall be
prepared for each set of forms to be removed before 24 hours. The stability of the concrete shall be evaluated
by a structural engineer prior to removal of the forms.]
3.2.2 Formwork Supporting Weight of Concrete
NOTE: ACI 347 suggests that at least 70 percent of the design strength should
be achieved before removal of formwork support from horizontal members, unless
otherwise approved by the Contracting Officer. (ACI 347, paragraph 3.7.2.1)
When specifications are being prepared, a structural engineer should determine
the actual minimum percentage of design strength that should be achieved for
the specific conditions on each structure.
Formwork supporting weight of concrete and shoring shall not be removed until structural members have acquired
sufficient strength to safely support their own weight and any construction or other superimposed loads to which
the supported concrete may be subjected. As a minimum, forms shall be left in place until control concrete test
cylinders [or maturity instrumentation] indicate evidence the concrete has attained at least [_____] percent
of the compressive strength required for the structure in accordance with the quality and location requirements
of Section [[_____]] [_____], paragraph [_____].
3.2.3 Tunnel Forms
Tunnel lining bulkhead forms shall not be removed in less than 12 hours and tunnel lining forms in not less than
16 hours.
3.3 INSPECTION
Forms and embedded items shall be inspected in sufficient time prior to each concrete placement by the Contractor
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.