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					BOS – BOSTON, MA RTR E/G REPLACEMENT                                                            MARCH 2007

                                          SECTION 02500 - AGGREGATE BASE COURSE


1.1     General - The work specified herein consists of the construction of aggregate base course. The work shall be
        performed in accordance with this specification and shall conform to the lines, grades and notes shown on the plans.
        Sources of all materials shall be selected well in advance of the time that materials will be required in the work.

        A.       Testing Laboratory - Qualifications of the commercial testing laboratory who will be performing all testing
                 specified herein.

        B.       Test Reports - Copies of all laboratory and field test reports within 24 hours of the completion of each test.
                 Certified copies of test results, on aggregate base to be used, for approval not less than 30 days before
                 material is required for the work.

1.2     Applicable Documents - The following publications, of the issues currently in force, form a part of this specification
        and are applicable to the extent specified herein.

        A.       American Society for Testing and Materials (ASTM):
                 D 422      Particle-Size Analysis of Soils
                 D 1556     Density of Soil in Place by the Sand Cone Method
                 D 1557     Moisture-Density Relations of Soils and Soil-Aggregate Mixtures Using 10-lb. Rammer and
                                 18-in. Drop

        B.       Commonwealth of Massachusetts, Massachusetts Highway Department (MHD)
                 Standard Specifications for Highways and Bridges (Latest Edition)


2.1     Materials

        A.       Aggregate Base - Aggregate conforming to the requirements of Section 400 of MHD.

        B.       Aggregate Subbase – Aggregate Subbase conforming to the requirements of Section 400 of MHD.

2.2     Installation

        A.       General Requirements - The aggregate base shall be constructed to the lines and grades indicated on the
                 drawings. When the base is constructed in more than one layer, the previously constructed layer shall be
                 cleaned 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. Adequate drainage shall be provided
                 during the entire period of construction to prevent water from collecting or standing on the area to receive
                 aggregate base. Line and grade stakes shall be provided as necessary for control. Grade stakes shall be in
                 lines parallel to the centerline of the area under construction and suitably spaced for string lining.

        B.       Weather limitations - Base shall not be constructed when the atmospheric temperature is less than 35F.
                 Base shall not be constructed on subgrades that are frozen or contain frost. If the temperature falls below 35
                  F, completed areas shall be protected against any detrimental effects of freezing.

        C.       Compaction - Each layer of aggregate base course shall be compacted. Water content shall be maintained
                 at optimum. Density of compacted mixture shall be at least 95 percent of laboratory maximum density.

Aggregate Base Course                                                                                                 02500-1
BOS – BOSTON, MA RTR E/G REPLACEMENT                                                               MARCH 2007

                 Rolling shall begin 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.
                 Speed of the roller shall be such that displacement of the aggregate does not occur. Areas inaccessible to
                 the rollers shall be compacted with a hand tamper.

        D.       Finishing - The surface of the top layer shall be finished to grade and cross section shown. Finished surface
                 shall be of uniform texture. Light blading during compaction may be necessary for the finished surface to
                 conform to the lines, grades, and cross sections. Should the surface for any reason become rough,
                 corrugated, uneven in texture, or traffic marked prior to completion, such unsatisfactory portion shall be
                 scarified, reworked, recompacted, or replaced as directed.

2.3     Quality Assurance

        A.       General - The Contractor shall establish and maintain quality control for operations under this section to
                 assure compliance with contract requirements and maintain records of his quality control for all materials,
                 equipment, and construction operations.

        B.       Testing - The Contractor shall arrange and pay for the services of a commercial laboratory for material and
                 compaction testing. The Contractor shall coordinate and cooperate with the testing lab to insure timely
                 completion of the required tests. The testing laboratory shall be approved by the Contracting Officer’s
                 Representative and all required testing shall be performed by this laboratory.

2.4     Laboratory Testing

        A.       Laboratory Maximum Density - Tests shall be made in accordance with ASTM D 1557 for each type of
                 material to be used on the project to determine the optimum moisture content and laboratory maximum
                 density values. One representative test shall be made per 500 cubic yards of material or when any change in
                 material occurs which may affect the optimum moisture content or laboratory maximum density.

        B.       Materials Analysis - Aggregate base material shall be tested per ASTM D 422.

2.5     Field Testing

        A.       In-Place Density - Field in-place density shall be determined in accordance with ASTM D 1556. Areas not
                 meeting specified compaction requirements shall be reworked as recommended by the testing lab and
                 retested until the specified compaction is obtained.

                 Tests shall be performed as follows:                     Aggregate Base - Two (2) tests per lift

        B.       Samples - Samples of all materials imported to the site for use on the project shall be submitted to or taken
                 by the testing lab for testing as specified herein. Copies of the test reports shall be approved by the
                 Contracting Officer's Representative prior to importing any materials to the site.

        C.       Defects - Settlement is considered to be among defects to be corrected. The Contractor shall repair all
                 defects and replace any permanent construction items disturbed by the corrective measures at no additional
                 cost to the Government.

        D.       Smoothness - Surface of each layer shall show no deviations in excess of 3/8 inch when tested with the 10-
                 foot straightedge. Deviations exceeding this amount shall be corrected by removing material and replacing
                 with new material, or by reworking existing material and compacting, as directed.

Aggregate Base Course                                                                                                      02500-2
BOS – BOSTON, MA RTR E/G REPLACEMENT                                                            MARCH 2007

        E.       Thickness - Thickness of the stabilized course shall be measured at intervals in such a manner as to ensure
                 one measurement for each 500 square yards of aggregate base course. Measurements shall be made in
                 3-inch diameter test holes penetrating the aggregate base course.

                 Compacted thickness of the aggregate base course shall be within l/2 inch of the thickness indicated. Where
                 the measured thickness is more than l/2 inch deficient, such areas shall be corrected by scarifying, adding
                 new material of proper gradation, reblading, and recompacting as directed. Where the measured thickness is
                 more than l/2 inch thicker than indicated, the course shall be considered as conforming to the specified
                 thickness requirements. Average job thickness shall be the average of all thickness measurements taken for
                 the job, but shall be within l/4 inch of the thickness indicated.

        F.       Traffic - Completed portions of the area may be opened to traffic, provided there is no marring or distorting of
                 the surface by the traffic. Heavy equipment shall not be permitted except when necessary to construction,
                 and then the area shall be protected against marring or damage to the completed work.

        G.       Protection - The aggregate base course shall be maintained in a satisfactory condition until accepted.
                 Maintenance shall include immediate repairs to any defects and shall be repeated as often as necessary to
                 keep the area intact.

                                                       END OF SECTION 02500

Aggregate Base Course                                                                                                 02500-3

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