W50S8X20B0001-0009_Addendum_03_Specifications.pdf

California Air National Guard Fuel Cell Hangar Addendum 3 Moffett Federal Airfield, Mountain View, CA 21 August 2020

SECTION 32 11 34

PORTLAND CEMENT-STABILIZED BASE OR SUBBASE COURSE

08/08

PART 1 GENERAL

1.1 REFERENCES

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 147 (1965; R 2012) Standard Specification for Materials for Aggregate and Soil-Aggregate Subbase, Base, and Surface Courses

AASHTO M 182 (2005; R 2017) Standard Specification for Burlap Cloth Made from Jute or Kenaf and Cotton Mats

AASHTO T 134 (2005; R 2013) Standard Method of Test for Moisture-Density Relations of Soil-Cement Mixtures

AASHTO T 135 (2013) Standard Method of Test for Wetting-and-Drying Test of Compacted Soil-Cement Mixtures

AASHTO T 136 (2013) Standard Method of Test for Freezing-and-Thawing Tests of Compacted Soil-Cement Mixtures

ASTM INTERNATIONAL (ASTM)

ASTM C136/C136M (2014) Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates

ASTM C150/C150M (2018) Standard Specification for Portland Cement

ASTM C171 (2016) Standard Specification for Sheet Materials for Curing Concrete

ASTM D1241 (2015) Materials for Soil-Aggregate Subbase, Base, and Surface Courses

ASTM D1556/D1556M (2015; E 2016) Standard Test Method for Density and Unit Weight of Soil in Place by Sand-Cone Method

ASTM D1557 (2012; E 2015) Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000

SECTION 32 11 34 Page 1 ft-lbf/ft3) (2700 kN-m/m3)

ASTM D1632 (2007) Standard Practice for Making and Curing Soil-Cement Compression and Flexure Test Specimens in the Laboratory

ASTM D1633 (2000; R 2007) Standard Test Methods for Compressive Strength of Molded Soil-Cement Cylinders

ASTM D4318 (2017; E 2018) Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils

ASTM D490 (1992; R 2016) Standard Specification for Road Tar

ASTM D558 (2011) Moisture-Density (Unit Weight) Relations of Soil-Cement Mixtures

ASTM D6938 (2017a) Standard Test Method for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)

ASTM D75/D75M (2019) Standard Practice for Sampling Aggregates

ASTM D977 (2019a) Standard Specification for Emulsified Asphalt

ASTM E11 (2016) Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves

1.2 DEFINITION

Portland cement-stabilized base or subbase course, as used herein, is a mixture of portland cement and in-place, or select borrow, material uniformly blended and thoroughly compacted to produce a pavement course which meets the criteria set forth in the drawings and specifications.

1.3 SUBMITTALS

Government approval is required for submittals with a "G" designation;

submittals not having a "G" designation are for Contractor Quality Control approval. Submittals with an "S" are for inclusion in the Sustainability eNotebook, in conformance to Section 01 33 29 SUSTAINABILITY REPORTING.

Submit the following in accordance with Section 01 33 00 SUBMITTAL

PROCEDURES:

SD-03 Product Data

Mix Design Aggregate Bituminous Material

SD-06 Test Reports

Aggregate

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SD-07 Certificates

Bituminous Material

1.4 ENVIRONMENTAL REQUIREMENTS

Do not apply cement when the atmospheric temperature is less than 40 degrees F or to soils that are frozen or contain frost, or when the underlying material is frozen. If the temperature falls below 35 degrees F, protect completed cement-treated areas against detrimental effects of freezing. Any areas of completed base or subbase that are damaged by freezing, rainfall, or other weather conditions shall be brought to a satisfactory condition in conformance with this specification without additional cost to the Government.

PART 2 PRODUCTS

2.1 EQUIPMENT

Plant, equipment, machines, and tools used in the work is subject to approval and must be maintained in a satisfactory working condition at all times. Provide equipment with the capability of producing the required compaction, meeting grade controls, thickness control and smoothness requirements specified. Place a test section of at least 8 by 100 feet, utilizing the equipment and procedures proposed for use by the Contractor, to demonstrate that soil-cement stabilization conforming to this specification can be produced .

2.1.1 Central-Plant

Provide a central plant capable of producing a uniform cement-treated mixture at the required cement and moisture contents. Soil and cement shall be dry-mixed sufficiently to prevent cement balls from forming when water is added.

2.1.2 Straightedge

Furnish and maintain at the site, in good condition, one 12 foot straightedge for each bituminous paver, for use in the testing of the finished surface. Make straightedges available for Government use.

Construct straightedges of aluminum or other lightweight metal with blades of box or box-girder cross section with flat bottom reinforced to insure rigidity and accuracy. Provide handles on straightedges to facilitate movement on pavement.

2.2 MATERIALS

2.2.1 Cement

Provide cement conforming to ASTM C150/C150M, Type II.

2.2.2 Bituminous Material

Submit notification of sources from which bituminous materials are to be obtained, within 15 days after the award of the contract. Submit certified copies of the manufacturer's test reports indicating compliance with applicable specified requirements, not less than 30 days before the material is required in the work. Bituminous material shall conform to

SECTION 32 11 34 Page 3 one of the following:

2.2.2.1 Emulsified Asphalt

ASTM D977, Type RS-2.

2.2.2.2 Tar

ASTM D490, Grade RT-10.

2.2.3 Material to be Stabilized

Stabilize material using select material conforming to AASHTO M 147 or ASTM D1241, Grading B . Remove stones retained on a 2 inch sieve and deleterious substances such as sticks, debris, and organic matter. When the in-place material consists primarily of soil having high plasticity or otherwise undesirable characteristics, construct the course to produce fully hardened soil cement as determined by AASHTO T 135 and AASHTO T 136 ;

not more than 45 percent of the material should be retained on the No. 4 sieve.

2.2.4 Water

Provide water which is clean, fresh, and free from injurious amounts of oil, acid, salt, alkali, organic matter, and other substances deleterious to the hardening of soil-cement, and subject to approval.

2.2.5 Burlap

Burlap shall conform to AASHTO M 182.

2.2.6 Impervious Sheeting

Sheeting shall conform to ASTM C171 and shall be white waterproof paper, white opaque polyethylene film or white burlap-polyethylene sheets.

2.3 MIX DESIGN

Submit proposed mix design, prior to start of stabilization work. Develop the mix using the aggregate or soil-aggregate material to be stabilized.

Mix shall have a minimum compressive strength of 250 psi for subbase, 750 psi for base, a weight loss of 14 percent or less after 12 cycles of the durability test, and "low alkali" cement for alkali reactive aggregate.

2.4 SAMPLING AND TESTING

2.4.1 Testing Facilities

Perform sampling and testing using an approved commercial testing laboratory or by facilities furnished by the Contractor. Work requiring testing will not be permitted until the facilities have been inspected and approved. The first inspection will be at the expense of the Government.

Cost incurred for any subsequent inspection, required because of failure of the facilities to pass the first inspection, will be charged to the Contractor. Perform tests in sufficient numbers, and as specified, to ensure that materials and compaction meet specified requirements. Furnish copies of the test results to the Contracting Officer within 24 hours of completion of tests.

SECTION 32 11 34 Page 4

2.4.2 Test Results

Results shall verify that materials comply with the specification. When a material source is changed, test the new material for compliance . When deficiencies are found, the initial analysis shall be repeated and the material already placed shall be retested to determine the extent of unacceptable material. All in-place unacceptable material shall be replaced or repaired to conform to the contract requirements at no additional cost to the Government.

2.4.3 Aggregate

Submit notification of sources from which aggregates are to be obtained, within 15 days after the award of contract. Tests for determining the suitability of aggregate shall include, but not be limited to: sieve analysis in accordance with ASTM C136/C136M using sieves conforming to ASTM E11, liquid limits and plasticity index in accordance with ASTM D4318.

Take aggregate samples for laboratory tests in accordance with ASTM D75/D75M. Prepare specimens to be used for unconfined compression tests in accordance with ASTM D1632 except that a 4 inch diameter by 8 inch high mold shall be used to prepare specimens when more than 35 percent of the material is retained on the No. 4 sieve. Submit certified copies of aggregate test results, not less than 30 days before the material is required in the work. Provide calibration curves and related test results, prior to using the device or equipment being calibrated.

2.4.4 Initial Sampling and Testing

2.4.4.1 Laboratory Density

Conduct moisture-density tests in accordance with the procedure contained in AASHTO T 134 or ASTM D558; however the apparatus and procedures outlined in ASTM D1557 shall be used to compact the soil-cement mixture.

2.4.4.2 Unconfined Compression Testing

Conduct three unconfined compression tests, in accordance with ASTM D1633, for each mix design tested. Cure samples at a constant moisture content and temperature for 7 days.

2.4.4.3 Durability Tests

Conduct wet-dry tests in accordance with AASHTO T 135 . Three tests shall be conducted for each mix design tested.

2.4.5 Sieve Analysis

A minimum of one analysis shall be performed for each 1000 tons of material to be stabilized, with a minimum of 3 analyses for each day's run until the course is completed. When the source of materials is changed and deficiencies are found, the analysis shall be repeated and the material already placed shall be retested to determine the extent of unacceptable material. All in-place unacceptable material shall be replaced at no additional cost to the Government.

2.4.6 Liquid Limit and Plasticity Index

One liquid limit and plasticity index shall be performed for each sieve analysis. Liquid limit and plasticity index shall be in accordance with

SECTION 32 11 34 Page 5

ASTM D4318.

2.4.7 Sampling and Testing During Construction

Perform quality control sampling and testing during construction as required in paragraph FIELD QUALITY CONTROL.

PART 3 EXECUTION

3.1 GENERAL REQUIREMENTS

Do not apply cement if the soil moisture content exceeds optimum moisture content specified for the cement-treated mixture. After mixing is completed, the proportions of the mixture shall be in accordance with the approved mix design. When application of water and mixing are completed, on the basis of dry weight, moisture shall not be below the optimum moisture content of the mixture nor shall it be more than 2 percent above the optimum moisture content. When the stabilized course is constructed in more than 1 layer, clean the previously constructed layer of loose and foreign matter by sweeping with power sweepers or power brooms, except that hand brooms may be used in areas where power cleaning is not practicable. Provide adequate drainage during the entire construction period to prevent water from collecting or standing on the areas to be stabilized or on pulverized, mixed, or partially mixed material. Provide line and grade stakes as necessary for control. Place grade stakes in lines parallel to the centerline of the area under construction and suitably spaced for string lining.

3.2 OPERATION OF BORROW PITS

Obtain borrow material from approved offsite sources.

3.3 STOCKPILING MATERIALS

Stockpile select material, including approved material available from excavation and grading, in the manner and at the locations designated.

Before stockpiling of material, the storage sites shall be cleared, drained, and leveled. Materials obtained from different sources shall be stockpiled separately.

3.4 PREPARATION OF AREA TO BE STABILIZED

Area to be stabilized shall be cleaned of debris; inspected for adequate compaction; and shall be capable of withstanding, without displacement, the compaction specified for the soil-cement mixture. Debris and removed unsatisfactory in-place material shall be disposed of as specified.

3.4.1 In-Place Materials to Receive Stabilized Course

Subgrade shall conform to Section 32 11 13.13 LIME TREATED SUBGRADE.

3.4.2 Select Material

Sufficient select material shall be utilized to provide the required thickness of the soil-cement layer after compaction and shall be processed to meet the requirements specified before cement stabilization is undertaken.

SECTION 32 11 34 Page 6

3.5 INSTALLATION

3.5.1 Edges of Stabilized Course

Placed approved material along the edges of the stabilized course in such quantity as will compact to the thickness of the course being constructed, or to the thickness of each layer in a multiple-layer course, allowing at least a 1 foot width of the shoulder to be rolled and compacted simultaneously with the rolling and compacting of each layer of the stabilized course.

3.5.2 Mixed-in-Place Method

3.5.2.1 Scarifying and Pulverizing of Soil

Prior to the application of cement, scarify and pulverize the soil to the depth shown. Carefully control scarification so that the layer beneath the layer to be stabilized is not disturbed. Do not pulverize to a depth exceeding the depth of scarification. Unless otherwise permitted, do not scarify and pulverize an area greater than can be completed in 2 working days.

3.5.2.2 Application of Cement

Approximately shape pulverized material to the cross section indicated.

Apply cement so that when uniformly mixed with the soil, the specified cement content is obtained, and a sufficient quantity of cement-treated soil is produced to construct a compacted cement-stabilized mixture conforming to the lines, grades, and cross section indicated. Do not pass over the freshly spread cement-stabilized mixture, except for equipment used in spreading and mixing operations.

3.5.2.3 Dry Mixing

Immediately after the cement has been distributed, mix with the soil. Do not mix below the required depth. Continue mixing until the cement has been sufficiently blended with the soil to prevent the formation of cement balls when water is applied.

3.5.2.4 Water Application and Moist Mixing

Determine moisture content of the cement stabilized mixture immediately after completion of mixing of the soil and cement. Provide water-supply and pressure distributing equipment that will permit the continuous application within 3 hours of all water required on the section being processed. Incorporate water in the mix so that concentration of water near the surface does not occur. After all the mixing water has been added, continue mixing until the water is uniformly distributed throughout the full depth of the mixture, with no portion of the mixture remaining undisturbed during mixing for more than 30 minutes. Dispose of any portion of the cement stabilized mixture remaining undisturbed more than 30 minutes during mixing.

3.5.3 Central-Plant Method

Haul the mixture to the job in trucks equipped with protective covers.

Thoroughly moisten the underlying course and deposit the material on the prepared area in a quantity that will produce a compacted base of uniform density to the required grade and cross section. Spreading or

SECTION 32 11 34 Page 7

MGIMON

Cloud

MGIMON

Snapshot spreading-trimming equipment shall be constructed and operated to produce a layer of material which is uniform in thickness and surface contour and free from irregularities in density. Use spreading or spreading-trimming equipment in sufficient numbers and in staggered formation to obtain full-width spreading in 1 construction operation. Not more than 60 minutes shall elapse between the start of the moist mixing and the start of compaction of the treated layer. Not more than 30 minutes shall elapse between the placement of the cement-treated soil in adjacent lanes on 2-lane structures at any location.

3.5.4 Layer Thickness

Compacted thickness of the stabilized course shall be as indicated . No layer shall be in excess of 8 inches nor less than 4 inches in compacted thickness.

3.5.5 Compaction

Before compaction operations are started and as a continuation of the mixing operation, the mixture shall be thoroughly loosened to the full depth. At the beginning of compaction, at least 80 percent of the soil shall pass a No. 4 sieve, and 100 percent shall pass the 1 inch sieve.

Start compaction immediately after mixing is completed. Density of compacted soil-cement mixture shall be at least 98 percent of the maximum density obtained from the laboratory prepared samples. Loose mixture shall be uniformly and continuously compacted until the entire depth and width of the area are compacted to the density specified. The moisture content at the surface shall be maintained near optimum at all times through the rolling, but shall be less than that quantity which will cause the soil-cement mixture to become unstable during compaction. Begin rolling at the outside edge of the surface and proceed to the center, overlapping on successive trips at least one-half the width of the roller. Alternate trips of the roller shall be slightly different lengths. Displacement of the mixture shall not occur due to the speed of the roller. Areas inaccessible to rollers shall be compacted with mechanical tampers.

3.6 FINISHING

The surface shall be moistened, if necessary, and shaped to the required lines, grades, and cross section. Lightly scarify the surface, if necessary, to eliminate any imprints made by the compacting or shaping equipment. The surface shall then be thoroughly compacted to the specified density with rubber-tired rollers and smooth-wheel tandem rollers to the extent necessary to provide a smooth, dense, uniform surface that is free of surface checking, ridges, or loose material, and that conforms to the crown, grade, and line indicated. Complete these finishing operations within 2 hours after completion of mixing operations. In places not accessible to finishing and shaping equipment, the mixtures shall be compacted with mechanical tampers to the density specified and shall be shaped and finished by hand methods. Correct, as specified below, any portion of the compacted mix that has density less than that specified, that has not properly hardened, or that is improperly finished.

3.7 CONSTRUCTION JOINTS

At the end of each day's construction, a straight transverse construction joint shall be formed by cutting back into the completed work to form a

SECTION 32 11 34 Page 8 true vertical face free of loose or shattered material. Material along construction joints not properly compacted shall be removed and replaced with soil-cement that is mixed, moistened, and compacted as specified.

3.8 BITUMINOUS MATERIAL APPLICATION

Apply bituminous material uniformly by means of a bituminous distributor within a temperature range of 110 to 160 degrees F, as directed.

Bituminous material for curing shall be uniformly applied at the rate of

0.2 to 0.25 gallon/square yard. Areas inaccessible to or missed by the distributor shall be properly treated using the manually operated hose attachment. Bituminous material shall be applied only to the top layer.

At the time the bituminous material is applied, the surface shall be free of loose or foreign matter and shall contain sufficient moisture to prevent excessive penetration of the bituminous material. When necessary, water in sufficient quantity to fill the surface voids shall be applied immediately before the bituminous material is applied. Treated surface shall be sanded or dusted to prevent the bituminous material from being picked up by traffic.

3.9 FIELD QUALITY CONTROL

3.9.1 Grade Control

Underlying material shall be excavated to sufficient depth for the required stabilized-course thickness. The finished stabilized course with the subsequent surface course shall meet the fixed grade. Finished and completed stabilized area shall conform to the lines, grades, cross section, and dimensions indicated.

3.9.2 Smoothness Test

The surface of a stabilized layer shall show no deviations in excess of 3/8 inch when tested with the straightedge. Deviations exceeding this amount shall be corrected by removing material and replacing new material, or by reworking existing material and compacting, as directed.

Measurements for deviation from grade and cross section shown shall be taken in successive positions parallel to the road centerline with a straightedge. Measurements shall also be taken perpendicular to the road centerline at 50 foot intervals.

3.9.3 Thickness Control

The completed thickness of the stabilized course shall be within 1/2 inch of the thickness indicated. Where the measured thickness is more than 1/2 inch deficient, such areas shall be corrected by scarifying, adding mixture of proper gradation, reblading, and recompacting as directed.

Where the measured thickness is more than 1/2 inch thicker than indicated, the course shall be considered as conforming with the specified thickness requirements. Average job thickness shall be the average of all thickness measurements taken for the job, but shall be within 1/4 inch of the thickness indicated. The thickness of the stabilized course shall be measured at intervals which ensure one measurement for each 500 square yards of stabilized course. Measurements shall be made in 3 inch diameter test holes penetrating the stabilized course.

3.9.4 Testing

Perform field tests in sufficient numbers to assure that the

SECTION 32 11 34 Page 9 specifications are being met. Testing is be the responsibility of the Contractor and shall be performed by an approved commercial laboratory.

3.9.5 Field Density

Field density tests shall be performed in accordance with ASTM D1556/D1556M or ASTM D6938. ASTM D6938 results in a wet unit weight of soil and ASTM D6938 shall be used to determine the moisture content of the soil.

Calibration curves furnished along with the density gauge shall be checked as described in ASTM D6938. Calibration checks of the density gauge shall be made at the beginning of a job on each type of material encountered.

If ASTM D6938 is used, in-place densities shall be checked by ASTM D1556/D1556M at least once per lift for each 2500 square yard of stabilized material. Calibration curves and calibration test results shall be furnished within 24 hours of conclusion of the tests. At least 1 field density test shall be performed for each 250 square yards of each layer of base material.

3.9.6 Samples of Bituminous Materials

Obtain under the supervision of the Contracting Officer a sample of the bituminous material used. The sample will be retained by the Government.

3.9.7 Maintenance

Maintain the stabilized area in a satisfactory condition until the completed work is accepted. Maintenance shall include immediate repairs to any defects and shall be repeated as often as necessary to keep the area intact. Defects shall be remedied as specified.

3.9.8 Traffic

Completed portions of the cement-treated soil area may be opened immediately to light traffic provided the curing is not impaired. After the curing period has elapsed, completed areas may be opened to all traffic provided that the cement-stabilized course has hardened sufficiently to prevent marring or distorting of the surface by equipment or traffic. Heavy equipment will not be permitted on the area during the curing period. Cement and water may be hauled over the area with pneumatic-tired equipment as approved. Finished portions of cement-stabilized soil that are traveled on by equipment used in constructing an adjoining section shall be protected in a manner that prevents equipment from marring or damaging the completed work.

3.10 DISPOSAL OF UNSATISFACTORY MATERIALS

Dispose of removed in-place materials, that are unsuitable for stabilization, material that is removed for the required correction of defective areas, waste material, and debris as directed .

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SECTION 32 11 34 Page 10

3.10 DISPOSAL OF UNSATISFACTORY MATERIALS