CEMENT-TREATED BASE COURSE

308.01 Description

Construct one or more courses of a mixture of portland cement or blended hydraulic cement, soil or soil-aggregate, and water on a prepared foundation. Use with non-sulfate containing soils and water only.

308.02 Material

Provide materials as specified in:

Portland Cement Subsection 701.02

Blended Hydraulic Cement Subsection 701.03

Cutback Asphalt Subsection 702.01(B)

Emulsified Asphalt Subsection 702.01(C)

Asphalt Concrete Aggregates Subsection 703.04

Fly Ash Subsection 713.03(C)(1)

Ground Granulated Blast Furnace Slag Subsection 713.03(C)(2)

Water Subsection 714.01(A)

308.03 Construction

A. Proportioning. Obtain approval from the Engineer to substitute fly ash or ground granulated blast furnace slag for cement at cement replacement percentages by weight (mass) not to exceed 35 and 50 percent, respectively.

B. Construction Methods and Equipment. Use either the travel plant or central plant method.

1. Travel Plant Method. Scarify the existing roadway or other designated material source, and pulverize the scarified material until a minimum of [80] percent passes a No. 4 (4.75-mm) sieve. Remove all material retained on a 3-in. (75-mm) sieve.

Remove unsuitable soil and organic material. Blend designated borrow with the scarified material to obtain a uniform mixture. Clean butt joints at existing pavements or structures before mixing.

Correct soft or yielding subgrade areas. Place and spread pulverized aggregate

Such payment is full compensation for furnishing all materials, equipment, labor, and incidentals to complete the work as specified.

The Agency will base payment for quicklime upon a 90 percent available lime index calculated as percent calcium oxide (CaO) by weight.

The Agency will base payment for hydrated lime upon a 90 percent available lime index calculated as percent calcium hydroxide (Ca(OH)2) by weight.

SECTION 308

CEMENT-TREATED BASE COURSE

308.01 Description

Construct one or more courses of a mixture of portland cement or blended hydraulic cement, soil or soil-aggregate, and water on a prepared foundation. Use with non-sulfate containing soils and water only.

308.02 Material

Provide materials as specified in:

Portland Cement Subsection 701.02

Blended Hydraulic Cement Subsection 701.03

Cutback Asphalt Subsection 702.01(B)

Emulsified Asphalt Subsection 702.01(C)

Asphalt Concrete Aggregates Subsection 703.04

Fly Ash Subsection 713.03(C)(1)

Ground Granulated Blast Furnace Slag Subsection 713.03(C)(2)

Water Subsection 714.01(A)

308.03 Construction

A. Proportioning. Obtain approval from the Engineer to substitute fly ash or ground granulated blast furnace slag for cement at cement replacement percentages by weight (mass) not to exceed 35 and 50 percent, respectively.

B. Construction Methods and Equipment. Use either the travel plant or central plant method.

1. Travel Plant Method. Scarify the existing roadway or other designated material source, and pulverize the scarified material until a minimum of [80] percent passes a No. 4 (4.75-mm) sieve. Remove all material retained on a 3-in. (75-mm) sieve.

Remove unsuitable soil and organic material. Blend designated borrow with the scarified material to obtain a uniform mixture. Clean butt joints at existing pavements or structures before mixing.

Correct soft or yielding subgrade areas. Place and spread pulverized aggregate uniformly to required thickness and width.

Apply the specified quantity of cement uniformly throughout the material to be stabilized. Replace cement lost before mixing at no cost to the Agency. Ensure the quantity of cement applied is within ±[5] percent of the requirement.

Blend the materials in a traveling plant mixer. Introduce water uniformly during the mixing cycle. Blend the materials thoroughly to prevent formation of cement balls as water is applied.

Complete wet mixing, lay down, and finishing operations within 2 hours after adding cement. Suspend work when windy conditions cause a cement loss.

2. Central Plant Method. Proportion and mix the aggregate, cement, and water in a central mixing plant. Equip the plant to feed and meter design batch quantities. Mix until material is uniformly blended.

Ensure the quantity of cement incorporated is within±[5] percent of the requirement.

Reject materials outside of this tolerance.

Use a mechanical spreader to distribute in a uniform layer. Moisten the subgrade or base before lay down. Begin compaction within 60 minutes of introducing mix water.

C. Compacting and Finishing. Compact the mixture to a minimum of [95] percent of the maximum density as determined from a field sample, taken as compaction begins, according to AASHTO T 134. The Engineer will determine in-place field density according to AASHTO T 191 or T 310, correcting for oversized particles according to AASHTO T 224 as necessary. Ensure that moisture in the completed mixture remains within±2 percent of the optimum moisture content as determined according to AASHTO T 134. Complete compacting and finishing within 2 hours after adding water to the mixture. Install a construction joint at the point of removal for any material needing removal.

D. Surface Tolerance. Finish the surface so that deviations do not exceed to ¹/2 in. (15 mm), longitudinal or transverse, when tested according to Subsection 401.03(K)(1).

E. Protecting and Curing. Apply a curing seal of cutback or emulsified asphalt immediately after final rolling. Keep the surface moist until the seal is applied.

Apply the curing seal as specified in Section 405.

Protect and maintain the subgrade surface until covered. Construct at least one course of base or subbase on the treated subgrade before using it for hauling operations.

Protect the base course from freezing for [5] days after placement.

F. Weather Limitations. Place cement-treated base only when the air temperature is above 40°F (5°C) or if forecast temperatures will remain above 35°F (2°C) for 24 hours. Place cement-treated material only on unfrozen subgrade, incorporate only unfrozen aggregate, and do not place during rainy conditions.

308.04 Measurement

The Engineer will measure work acceptably completed as specified in Subsection 109.01 and as follows:

A. The Engineer will measure cement-treated base course by the yd² (m²) or by the individual components for material and processing, as established in the contract.

308.05 Payment

The Agency will pay for accepted quantities at the contract unit price as follows:

Pay Item Pay Unit

(A) Cement-treated course yd² (m²)

(B) Hydraulic or blended hydraulic cement ton (Mg)

(C) Aggregate ton (Mg)

(D) Processing cement-treated base course station, mi (km), yd² (m²)

Such payment is full compensation for furnishing all materials, equipment, labor, and incidentals to complete the work as specified.

SECTION 309