2115.01 DESCRIPTION.
Modified subbase shall consist of a uniform mixture of uniformly moistened granular materials, placed on a subgrade, shaped, and compacted in accordance with the contract documents.

2115.02 MATERIAL.
Section 4123 shall apply.

2115.03 EQUIPMENT.
Article 2001.05, Paragraphs B, C, D, and F shall apply except rollers shall have a minimum compactive effort of 300 pounds per inch (5.25 kg/mm) width. Other types of equipment may be used provided it is demonstrated that they will consistently produce the required compaction without excessive aggregate breakdown.

All other equipment used shall meet the other requirements of Section 2001.

2115.04 CONSTRUCTION.

A. Preparation of Subgrade.
The requirements of Section 2109 shall apply. In addition, the subgrade shall be disked to a depth of 6 inches (150 mm), aerated, and recompacted. Recompaction shall meet requirements of Article 2107.05 on Primary projects and Article 2107.06 on Secondary projects. Preparation of subgrade shall be followed by proof rolling.

B. Proof Rolling of Subgrade.
Proof rolling shall be performed with a truck loaded to the maximum single legal axle gross weight (mass) of 20,000 pounds (9.1 Mg) or the maximum tandem axle gross weight of 34,000 pounds (15.4 Mg). The truck shall be operated at a speed less than 10 mph (16 km/h). One pass shall be made on every lane. The subgrade will be considered to be unstable if, under the operation of the loaded truck, the surface shows yielding or rutting of more than 2.0 inches (50 mm) measured from the top to the bottom of the rut at the outside edges. Correction of the unstable subgrade shall be done according to Section 2109.

C. Delivery of Materials.
A clean aggregate interface shall be maintained between the granular subbase material and the porous backfill of all longitudinal subdrains.

D. Construction of Modified Subbase.
Modified subbase material shall be uniformly moist prior to and during compaction.

Modified subbase shall be placed in uniform lifts of not more than 6 inches (150 mm) in thickness.

Modified subbase shall be compacted with a minimum of six roller passes.

2115.05 METHOD OF MEASUREMENT.
The quantity of Modified Subbase for which payment will be made, will be the quantity shown in the contract documents.

2115.06 BASIS OF PAYMENT.
Modified Subbase will be paid for at the contract price per cubic yard (cubic meter). This payment shall be full compensation for furnishing all materials, water, preparation of subgrade, and for all work necessary to complete the modified subbase in compliance with contract documents. The contract will have a separate item for Modified Subbase, Place Only, in cubic yards (m³), when the Contracting Authority is providing the material or if the material is available from mandatory crushing on the contract. The cost of crushing should be included in the Contractor's price for modified subbase if recycling is not required but the Contractor chooses to crush the pavement removed for modified subbase.

Excavation or filling in excess of 3 inches (75 mm) for preparation of subgrade at locations other than structures or existing pavements will be paid for according to Article 2102.14; or if no contract unit price is provided it will be paid as extra work in accordance with Article 1109.03, B, except where grading is a part of the contract.

Correction of subgrade after proof rolling will be paid as extra work in accordance with Article 1109.03, B, except where grading is a part of the contract.