USACE / NAVFAC / AFCESA / NASA UFGS-32 11 30 (August 2008)
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Preparing Activity: NAVFAC Superseding
UFGS-32 11 30 (April 2006)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 32 11 30
LIME TREATED SUBGRADE [LIME MODIFIED SOILS]
08/08
NOTE: This guide specification covers the requirements for stabilization of
subgrades by the application of lime.
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).
NOTE: Plant-mix operations and independent importation/placement of new lime
base or sub-base courses are not included. Undefined simplifications of this
guide specification may satisfy a secondary scope of "Lime Modified Soils."
Optional sub-title "Lime Modified Soils" is intended for lime applications for
less critical purposes than lime treated subgrade, such as drying excessively
saturated construction sites during wet seasons. Considerable editing would
be necessary when preparing project specification for this work.
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.
[AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO)AASHTO M 216(2005) Lime for Soil StabilizationAASHTO T 102(1983; R 2004) Spot Test of Asphaltic MaterialsAASHTO T 219(1987; R 2004) Testing Lime for Chemical Constituents and Particle SizesAASHTO T 27(2006) Sieve Analysis of Fine and Coarse Aggregates][ASTM INTERNATIONAL (ASTM)ASTM C 207(2006) Standard Specification for Hydrated Lime for Masonry PurposesASTM C 25(2006) Standard Test Method for Chemical Analysis of Limestone, Quicklime, and Hydrated LimeASTM C 977(2003) Quicklime and Hydrated Lime for Soil StabilizationASTM D 1556(2007) Density and Unit Weight of Soil in Place by the Sand-Cone MethodASTM D 1557(2007) Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3) (2700 kN-m/m3)ASTM D 2397(2005) Standard Specification for Cationic Emulsified AsphaltASTM D 2922(2005) Density of Soil and Soil-Aggregate in Place by Nuclear Methods (Shallow Depth)ASTM D 3017(2005) Water Content of Soil and Rock in Place by Nuclear Methods (Shallow Depth)ASTM D 3551(2008) Laboratory Preparation of Soil-Lime Mixtures Using a Mechanical MixerASTM D 977(2005) Emulsified Asphalt][NATIONAL LIME ASSOCIATION (NLA)NLA BUL 326(2004) Lime-Treated Soil Construction Manual: Lime Stabilization and Lime Modification]1.2 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.][for 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-04 Samples
Cured lime-treated material
Lime
Submit a typical cured sample of on-site material with the required percent of lime content.
SD-05 Design Data
Job-mix formula
Mixing procedures
Analysis of equipment
SD-06 Test Reports
NOTE: Perform site preparation tests dependent upon the criteria required,
the condition of the existing site and the purpose of the stabilization.
NOTE: Allow nuclear testing methods for site preparation testing or final in
place testing on larger projects of over 3300 per square meter 4000 square yards
.
Site preparation test
Final compaction report
[Field application rate test]
SD-07 Certificates
Bituminous curing seal
Lime
Contractor equipment list
Submit a list of construction equipment 7 days prior to bringing equipment on the job.
1.3 DELIVERY AND STORAGE
Deliver lime, bituminous materials in containers showing or including designated trade name, product identification,
specification number, manufacturers name, and source. Store in a manner that will prevent moisture damage, overexposure,
and contamination.
1.4 WEATHER LIMITATIONS
Do not construct subgrade when weather conditions detrimentally affect the quality of the materials. Do not
apply lime unless the air temperature is at least 5 degrees C 40 degrees F in the shade and rising. Do not apply
lime to soils that are frozen or contain frost. If the air temperature falls below 2 degrees C 35 degrees F
in the shade, protect completed lime-treated areas by approved methods against the detrimental effects of freezing.
Remove and replace any damaged portion of the completed soil-lime treated area with new soil-lime material in
accordance with this specification.
[1.4.1 Freeze Protection Method(s)
a. Submit Contractor's plan(s) for freeze protection to Contracting Officer for approval.
]1.5 QUALITY ASSURANCE
1.5.1 Required Data
[Ten] [_____] days prior to the commencement of the work, a job-mix formula showing the amount of lime and water
required per cubic meter cubic yard, and procedures for blending the lime/subgrade mixture for each type of existing
soil. Include process type and number of: Lime applications, stages of mixing, slurry injection depths, mixing
depths and depths of compaction lifts. Also, a list of equipment to be used and their relation to method of
mixing proportioning, spreading, pulverizing and compacting subgrade, slurry injection, jet slurry mixing and
other related work. The formula shall also contain amount of lime, either in sacks or kg per cubic meter pounds
per cubic yard and the amount of water to be used, if slurry method is used. Use the following laboratory test
method when applicable: ASTM D 3551.
PART 2 PRODUCTS
2.1 LIME TREATMENT REQUIREMENTS
NOTE: Allow the use of Type III lime for non-critical subgrade applications
such as standard roads and parking areas. For primary roads and airfields consider
the use of Type I or II first. Take into consideration availability of the lime
chosen (including shipping/hauling charges). Type IV should be considered when
Types I, II, III and quicklime are not available or not cost effective for project
use.
NOTE: Add the A/E design criteria choice and percent of lime according to the
chemical composition of the soil, (including the liability of excessive sand
content) purpose of the lime stabilization and local site and climatic conditions.
The percent of lime will also vary according to the type of lime chosen (hydrated
or quicklime). The disadvantages of quicklime must be considered: (1) Dry
quicklime produces a coarser material with poorer distribution in soil mass
because field hydration is less effective than commercial hydrators. (2) Dry
quicklime requires more water than hydrate for stabilization which may be a
problem for dry areas. (3) Dry quicklime or quicklime slurry requires careful
handling due to greater susceptibility to skin and eye burns.
Perform lime treatment of subgrade. Scarify subgrade soil and mix uniformly with lime and water, spread, shape,
compact and cure in accordance with these specifications and the following requirements:
a. Lime requirement: The percent of [hydrated lime] [quicklime] by weight of dry soil material:
[_____] percent.
2.1.1 Hydrated Lime
NOTE: For projects in Texas specify only AASHTO M 216, Type I, Grade A.
2.1.1.1 Type I
NOTE: Specifying a grade is optional, however, when no grade is specified the
requirements of Grade A shall govern and when Grade B and C are used plan quantities
for Grade A will be increased according to the "Basis of Purchase" paragraph
within AASHTO M 216.
AASHTO M 216 [Grade A], [Grade B], [Grade C].
2.1.1.2 Type II
NOTE: Specifying a grade is optional, however, when no grade is specified the
requirements of Grade A shall govern and when Grade B and C are used plan quantities
for Grade A will be increased according to the "Basis of Purchase" paragraph
within AASHTO M 216.
AASHTO M 216, [Grade A], [Grade B], [Grade C].
2.1.1.3 Type III
Magnesium or dolomitic lime containing magnesium, calculated as magnesium oxide no more than 41 percent by weight
and in compliance with ASTM C 977.
[2.1.1.4 Type IV
By-Product, Waste, Salvaged or Specially Formulated Lime. ASTM C 207, Type N with the following modifications:
NOTE: For surface applications such as the drying of excessively wet ground
surfaces at construction sites, allow a minimum of 50 percent total calcium
and magnesium oxide (nonvolatile basis).
a. Total calcium and magnesium oxides (nonvolatile basis) equal 60 percent [_____] minimum.
b. Available calcium hydroxide (rapid sugar test), ASTM C 25 plus total MgO content calculated
to be an equivalent Ca (OH)2 equal 30 percent minimum.
c. Loss on ignition (carbon dioxide plus moisture, combined and free) as-received basis equal
35 percent maximum sampled at place of manufacture or 40 percent maximum, if sampled other than
at place of manufacture.
d. Free water (as received basis) equal 4 percent maximum.
e. Residue: Sieve analysis of lime as follows:
Sieve Maximum Percent Retained
4.75 mm 0
600 micrometers 5.0
150 micrometers 20.0
Sieve Maximum Percent Retained
No. 4 0
No. 30 5.0
No. 100 20.0
f. No requirements for plasticity, pops or pits, or water retention.
]2.1.2 Quicklime
2.1.2.1 Type V
High calcium quicklime containing at least 113 percent calcium hydroxide determined by AASHTO T 27 and AASHTO T 219
testing procedures.
Sieve Maximum Percent Retained
9.5 mm 100
150 micrometers 15 max.
Sieve Maximum Percent Retained
3/8 inch 100
No. 100 15 max.
2.1.2.2 Type VI
ASTM C 977.
2.2 SOIL
The inorganic natural material in the area to be stabilized[ unless imported material, relocated material, or
preliminary earthwork is required: See Section 31 00 00 EARTHWORK]. Remove stones retained on a 75 mm 3 inch
sieve and deleterious substances such as sticks, debris, and vegetable matter.
2.3 WATER
Potable
2.4 BITUMINOUS CURING SEAL
2.4.1 Emulsified Asphalt
Conform to [ASTM D 977, Type SS-1] [or] [ASTM D 977 Type SS-1h]; [ASTM D 2397, Type CSS-1] [or] [ASTM D 2397
Type CSS-1h] [_____]. The base asphalt used to manufacture the emulsion shall show a negative spot when tested
in accordance with AASHTO T 102 using standard naphtha.
PART 3 EXECUTION
3.1 SITE PREPARATION
Clean debris from area to be stabilized. Perform clearing and grubbing [to a depth of [_____] mm inches] [as
specified in Section [31 11 00 CLEARING AND GRUBBING] [31 00 00 EARTHWORK]] [as required]. Remove rocks larger
than 75 mm 3 inches. Inspect original ground for adequacy for the forthcoming compactive effort of lime treatment
work. [Rough grade and shape the area to be stabilized to conform to the lines, grades, and cross sections indicated.]
[Comply with subgrade requirements of Section 31 00 00 EARTHWORK].
3.1.1 Grade Control
When stabilized course is to be constructed to meet a fixed grade, provide adequate line and grade stakes for
control. Finished and completed stabilized areas shall conform to the lines, grades, cross section, and dimensions
indicated. Locate grade stakes in lanes parallel to center line of areas under construction, and suitably placed
for string lining. Maintain line and grade.
3.1.2 Soil Testing
NOTE: Perform site preparation tests dependent upon the criteria required,
the condition of the existing site and the purpose of the stabilization.
Test original ground prior to scarification in accordance with ASTM D 1557.
3.2 LIME TREATMENT AND SEQUENCE OF CONSTRUCTION OPERATIONS
Comply with NLA BUL 326 and sequence of construction operations, unless specified otherwise hereinafter.
3.2.1 Application Requirements
NOTE: Specify double application of lime or two stage pulverization and mixing
when the site contains extremely plastic or heavy clays.
After site preparation, scarify subgrade and spread lime. Blend lime into subgrade to required depth as indicated.
Apply lime and water only to those areas where mixing operations can be completed during the same working day.
Accomplish application and mixing of lime by either the dry placing method or the slurry method. Use same method
during any single days operation. [Double application of lime is required; percentage of lime for the initial
application shall be between 2 and 3 percent. Apply curing seal as specified hereinafter and allow 6 to 7 days
curing.]
3.2.2 Scarification
After obtaining required line and grade, scarify and partially pulverize the subgrade. Remove organic materials
such as stumps and roots. Remove rocks larger than 75 mm 3 inches.
3.2.3 Dry Placing
Spread and distribute lime at a uniform rate with protection from wind as an important distribution and timing
criteria. Prevent dry lime from blowing by adding water to lime or by other suitable means. Do not apply lime
when wind conditions, in the opinion of the Contracting Officer, are objectionable.
3.2.4 Slurry Method
Apply or inject mixture of lime and water into the existing soil. Maintain the water content at 5 percent above
optimum during application to lime/soil mixture. Prepare hydrate slurry either in a central mixing tank or tank
trucks, with agitation provided for mixing or using a jet slurry maker. Prepare quicklime slurry using a portable
batch slaking unit. Accurately weigh or meter lime and water. Standard water or asphalt trucks, properly cleaned,
with or without pressure distributors, may be used to apply lime treatment. Spread or inject lime slurry evenly
to yield uniform distribution of lime throughout soil. Distribute lime in successive passes over subgrade materials
until proper amount of lime has been spread or injected to proper depth. Continually agitate slurry to keep
mixture uniform. Keep pumps, distribution spray bars, slurry injection equipment and other equipment clean of
excessive lime slurry. The Contractor's laboratory shall verify the specified amount and rate of application
of lime for the various materials encountered.
3.2.5 Preliminary Mixing and Watering
Distribute lime uniformly by mixing and pulverizing subgrade. During mixing, add water to subgrade to provide
a moisture content of 5 percent above optimum moisture content of material and to insure chemical action of lime
and subgrade materials. Mixer shall continue making passes until it has produced a homogeneous, uniform mixture
of lime, soil, and water. Continue mixing or remixing operations, until material is free of streaks or pockets
of lime and mixture is uniform as indicated by testing. After initial mixing, shape and roll subgrade lightly
to seal surface in order to reduce evaporation of moisture and lime carbonation.
3.2.6 Preliminary Curing
Moisture cure lime-soil mixture up to 48 hours until adhesive quality of clay is reduced to almost normal soil
consistency. Allow 7 days or more for curing heavy clays.
3.2.7 Mixing, Uniformity Testing and Compaction
After dry lime or lime slurry is uniformly applied to soil and mixture is pulverized and cured, continue mixing
until individual agglomerates of soil do not exceed 25 mm one inch in maximum dimension (soil particles will
pass a 25 mm one inch sieve with at least 60 percent passing the 4.75 mm No. 4 sieve). Continue mixing and re-mixing
until material is uniformly mixed. Moisture shall be at approximately 2 percent over optimum for material other
than rock. Compact lime-treated material immediately after final mixing and testing. Aerate or sprinkle as
necessary to provide optimum moisture content during compaction. Compact lime-treated material in specified
lifts to 95 percent of maximum density at optimum moisture content in accordance with ASTM D 1557, Method D.
Base density value on a representative soil sample obtained from site and treated with required proportion of
lime. As compaction progresses, maintain the shape of the lifts by blading. Surface upon completion shall be
smooth and conform to indicated section and established lines and grades. Perform initial compaction with sheepsfoot
roller or other suitable roller. Perform final rolling by means of sheepsfoot, steel-tired, or pneumatic rollers.
[3.2.8 Two-Stage Pulverization and Mixing
NOTE: Specify double application of lime or two stage pulverization and mixing
when the site contains extremely plastic or heavy clays.
After curing, pulverize lime treated material until soil particles pass a 25 mm one inch sieve and 60 percent
pass the 4.75 mm No. 4sieve. If resultant mixture contains clods, reduce their size by scarifying, remixing,
or pulverization to meet specified gradation.
]3.2.9 Finishing
Surface of finished lime-treated material after compaction shall be the established graded plane. At any point
the surface shall not vary more than 15 mm 0.05 foot [_____] above or below established grade. Finish completed
section by rolling with a pneumatic or suitable roller sufficiently light to prevent hairline cracking. Keep
surface of each compacted layer of lime-treated material moist until covered by a subsequent layer of lime-treated
material or curing seal.
3.2.10 Limit of Daily Operations (Temporary Joints)
At the end of each working day, prepare a temporary joint in fully compacted material normal to paved surface
centerline. Construct a longitudinal temporary joint for partial width sections against which future material
is to be placed. Remove temporary joints during next work period by trimming 75 mm 3 inches into treated material
for continuity. Trimmed material may be incorporated in subsequent work. Temporary joints shall not coincide
with any longitudinal or transverse temporary joint location of previous or subsequent construction. Remixing
100 mm 4 inches into the previous day's work may be substituted for joints providing the method and equipment
is acceptable to the Contracting Officer.
3.2.11 Final Curing
3.2.11.1 Curing
Cure lime-treated material for 72 hours. During curing period, add [water] [bituminous curing seal] to surface
to maintain moisture content of mixture at five percent above optimum water content. Lime that has been overexposed
to open air shall be removed and disposed of off-station.
a. Moist curing (water only): Keep surface damp by sprinkling and use light rollers to keep
surface knitted together (preventing surface cracks) until following course of material is placed.
b. Asphalt emulsion curing seal: Apply at least two applications uniformly to top (final)
layer of lime-treated material at a rate of 0.68 to 0.9 liters per square meter 0.15 to 0.20
gallons per square yard of surface. Apply curing seal same day as soon as possible after completion
of final rolling, before temperature falls below 5 degrees C 40 degrees F.
3.3 TRAFFIC CONTROL, CURING MAINTENANCE AND DRAINAGE PROTECTION
Keep traffic off surfaces freshly treated with bituminous material. Provide warning signs and barricades so
that traffic will not travel over freshly treated surfaces. Do not permit equipment or traffic on lime-treated
material until subgrade stability is assured. Maintain finished surface until work has been completed. Provide
drainage during entire period of construction to prevent water from collecting or standing on area to be stabilized.
3.4 EQUIPMENT LIMITATIONS
3.4.1 General
The type of equipment to be used for each category of work shall conform to the NLA BUL 326 unless specified
otherwise. Maintain equipment in satisfactory and safe operating condition.
3.4.2 Spreading Equipment
At windy locations use an approved screw type spreader box, mixer, or other semi-enclosed equipment which will
offer protection from wind. Spreading hydrated lime by aggregate spreaders, dump trucks or agricultural spreaders
is not allowed. Spreading by end-dumping, or tailgate control methods are not allowed. Change or alter equipment
to be used in the event of non-uniform spreading of lime.
3.4.3 Additional Mixing Equipment Limitations
a. Motor graders will not be allowed to mix lime with clays.
b. Deep-lift rotary mixers may be used and may facilitate changes in specified depths of operation,
providing equipment and method of operation sustains uniform distribution of lime with required
compacted density throughout the deeper layer, with approval of Contracting Officer.
3.4.4 Additional Compaction Equipment Limitations
Unauthorized equipment, hauling or transportation vehicles will not be allowed for compaction purposes.
3.5 SAFETY REQUIREMENTS
In addition to the Contract Clause entitled "Accident Prevention", prevent employee eye or skin contact with
quicklime during transport or application. Provide and require employees use the following:
a. Protective clothing, high top boots, gauntlet-type gloves and protective headwear
b. Splash-proof safety goggles and face shields
c. Protective cream.
3.6 TESTS
3.6.1 General
Perform sampling and testing using a laboratory which has been inspected by the Cement and Concrete Reference
Laboratory (of ASTM/CCRL) within the past 3 years or by a Government approved independent commercial testing
laboratory. Frequency of sampling and testing of materials for conformance and quality control shall be as specified
herein and shall be performed at such other times as necessary to document contract compliance. Test reports
and results shall be certified by the laboratory and submitted together with Contractor's daily certification.
3.6.2 Optimum Moisture, Maximum Density
Perform optimum moisture, maximum density test on lime-treated material sampled after final mixing and prior
to final compaction. Soil mixture shall be laboratory compacted within 3 hours of sampling and then moist-cured
for 24 hours prior to optimum moisture-maximum density determination. Test in accordance with ASTM D 1557, Method
D and the Job-Mix Formula.
3.6.3 Uniformity Tests
After placement and mixing of each lift perform a series of uniformity tests. Excavate a hole 250 mm 10 inches
in diameter through full depth of lift and impregnate sides of hole with a standard phenolphthalein alcohol
indicator. Non-conformity of color reaction, when material is treated as above, will be considered evidence
of inadequate mixing.
3.6.4 Compaction
NOTE: Allow nuclear testing methods for site preparation testing or final in-place
testing on larger projects of over 3300 square meters 4000 square yards. The
required frequency of ASTM D 1556 check testing should vary according to the
critical nature and purpose of the project.
Perform in-place density test to determine degree of compaction between 24 and 72 hours after final compaction
and 24 hour moist cure period. Test in accordance with ASTM D 1556. [Subject to approval of the Contracting
Officer the following test methods may be included: ASTM D 2922, ASTM D 3017 and compatible meter methods providing
one ASTM D 1556 check test is made after every [four] [_____] nuclear tests.]
3.6.5 Thickness and Smoothness
Thickness of final lime treated subgrade shall be not less than thickness shown. Final grade smoothness shall
not deviate by more than 10 mm 3/8 inch, when tested with a 3 m 10 foot straightedge.
[3.6.6 Field Application Rate Test
Test for checking initial lime spreading rate.
]3.6.7 Frequency of Tests
The minimum number and type of quality control tests shall be as follows:
a. Optimum moisture, maximum density. [Two] [_____] of each type or change of material with
in-place density requirements.
b. Thickness, smoothness and uniformity. [Two] [_____] tests each day for every 850 square
meters 1000 square yards [_____] or less mixed and placed.
c. Field density. One set of [3] [_____] tests for each lift for every 1650 square meters
[2000] square yards [_____] or less.
[d. Field application rate test. One test for each lime spreading vehicle to be used on site.]