2114.01 DESCRIPTION.
Class A subbase shall consist of the construction of a 100,000 ESAL, 3/4 inch (19 mm) HMA base course, or a slip formed PCC base, at the option of the Contractor, according to the contract documents.

2114.02 CONSTRUCTION.
Class A subbase shall be constructed as follows:

A. Hot Mix Asphalt Base.
HMA base shall be constructed in accordance with the contract documents and requirements of Section 2203, with the following modification:

Tack coats will be required between lifts but will not be measured for payment.

B. Slip Formed Portland Cement Concrete Base.
Slip formed PCC base shall be constructed in accordance with the contract documents and requirements of Section 2301 with the following modifications:

1. Aggregates shall meet the requirements of Section 4127 or shall be the aggregates to be used in the pavement course and may be used in any ratio permitted in pavement.

2. The cement content of the base shall be a minimum of 350 pounds per cubic yard (210 kg/m³), unless otherwise specified. Class C fly ash may be substituted for up to 30% of the cement required.

3. The entrained air content of the fresh, unvibrated, concrete base, as determined by Materials I.M. 318 shall be 7.0% with a maximum variation of ± 2.0%.

4. An approved, water reducing admixture shall be required.

5. It is not intended that any hand finishing or texturing of the base be performed.

6. The surface tolerance prescribed in Article 2301.16, B, shall not apply. The tolerances prescribed in Article 2114.03 shall apply.

7. The curing compound shall be applied at a rate not less than 0.067 gallon per square yard (0.3 L/m²).

8. It is intended that the base be constructed without longitudinal or transverse joints, except day's work joints.

9. The base shall be placed on a natural subgrade in accordance with Article 2109.04.

10. When load transfer devices (CD joints) are required at transverse joints in the pavement to be placed over the subbase, a joint shall be sawn 1/2 inch (15 mm) in depth at the assembly location and within the limitations of Article 2301.22. At the Contractor's option, an equivalent weakened plane may be created in the fresh concrete with a trowel against a straightedge.

The load transfer devices may be placed before or after the base has hardened. Devices incorrectly placed in the unhardened base shall be removed and replaced at the Contractor's expense.

11. The Contractor shall maintain the completed base free from damage.

12. No subsequent construction shall be permitted on the completed base until at least the following day. No hauling equipment shall be permitted on the completed base.

13. Water cement ratio limitations for pavement concrete shown in Section 2301 do not apply to this construction.

2114.03 TOLERANCES.
The surface of the finished subbase shall not be higher or be more than 0.05 foot (15 mm) lower than the design elevation of the bottom of the concrete pavement. For HMA, areas which are lower shall be tacked and corrected to this tolerance by adding fresh, hot, base mixture or other hot or cold asphalt mixtures approved by the Engineer. This material shall be thoroughly compacted. For slip formed PCC base, areas which are lower may be corrected by adding an asphalt mixture as described above, or by thickening the concrete pavement to be subsequently placed thereon.

For any of the base materials, the Contractor may construct the subbase to a greater width than that shown in the contract documents, utilizing base materials or other materials of a quality not less than that of the normal subgrade materials, in order to facilitate construction operations. Furnishing and placing these materials shall be considered incidental to the work and not measured for payment. If areas of subbase constructed outside the minimum width are damaged by subsequent construction operations, the damaged areas shall be incorporated in the finished structure in a condition comparable to that of the shoulder area.

2114.04 METHOD OF MEASUREMENT.
Class A Subbase will be measured as follows:

The thickness of the completed subbase will be determined by measurement of cores, measurement of hole depth, or as determined by the Engineer.

A. Hot Mix Asphalt Base.
HMA base will be measured in square yards (square meters) in accordance with the contract documents and Article 2303.05.

B. Slip Formed Portland Cement Concrete Base.
Slip formed PCC base will be measured in square yards (square meters) in accordance with the contract documents and Article 2301.34.

2114.05 BASIS OF PAYMENT.
For the number of square yards (square meters) of Class A Subbase constructed, measured as provided above, the Contractor will be paid the respective contract unit price per square yard (square meter).

A. Hot Mix Asphalt Base.
HMA base will be paid for in accordance with Article 2303.06.

B. Slip Formed Portland Cement Concrete Base.
Slip formed PCC base will be paid for in accordance with Article 230l.35.