ITEM 206 – CHEMICALLY STABILIZED ROAD MIX SUB-BASE/BASE COURSE

206.1 Description

This item shall consist of polymer-based chemical soil additive to improve the strength and other properties of ordinary soil for use as sub-base/surfacing materials in roads in accordance with this Specification and in conformity with the requirements shown on the Plans or as directed by the Engineer.

206.2 Material Requirements

206.2.1 Polymer-Based Chemical Soil Additive

It shall be a polymer-based chemical soil additive that is non-hazardous, environmentally safe, and easy to use.

206.2.2 Soil Aggregate

It shall consist of any combination of gravel, sand, silt and clay or other approved combination of materials free from vegetable or other objectionable matter. It may be materials encountered in the construction site or materials obtained from approved sources. It is the intent of this Specification to utilize soils existing on the roadbed if the quality is satisfactory. If the quantity is deficient, the soil aggregate shall be obtained wholly or partly from approved outside sources.

206.2.3 Salvaged Soil Aggregate

Where soil-aggregate required is already in place, the Contractor shall not be responsible for its grading or quality except for removal of oversized materials as directed by the Engineer. In general, salvaged soil-aggregate to be used for soil stabilization shall consist of material meeting the requirements given in Subsection 206.2.2, Soil Aggregate.

206.2.4 Water

It shall conform to the requirements of Item 714, Water.

206.2.5 Proportioning of Mixture

Polymer-based chemical soil additive shall be less than 2% by weight of soil.

206.2.6 Strength of Mixture

The unsoaked CBR value treated soil material with Polymer based chemical soil additive shall be greater than the unsoaked CBR value untreated same oil material as determined AASHTO T 193.

206.3 Construction Requirements

206.3.1 Weather Limitations

Polymer-based chemical soil additive and water shall not be mixed and applied during rainy or impending bad weather condition. In the event rain occurs during operations, the work shall be promptly stopped and the entire section shall be reconstructed in accordance with this Specification.

206.3.2 Construction Equipment

Equipment and tools necessary for handling the material and performing all parts of the works shall be approved by the Engineer as to design, capacity and mechanical condition. The equipment shall be at the jobsite sufficiently ahead of the start of application operation.

206.3.3 Sub-base/Base Preparation

Existing road sub-base/base materials shall be scarified by use of grader depth of 150mm o 200mm and shall be stockpiled on both sides of the road. Rolling of sub-base/base shall follow until the desire compaction is attained.

If further needed, polymer-based chemical soil additive shall be applied on the sub-base/base after it was exposed for 24 hours, provided that after applying the said chemical additive, the firs layer of road sub-base/base materials which is thoroughly mixed shall be spread immediately. The dilution rate for sub-base/base shall be 1 part polymer-based chemical soil additive and 5 to 9 parts of water depending on the type of soil and application method.

206.3.4 Application, Compacting and Finish of Polymer-Based Chemical Soil Additive on Road Sub-base/Base

After the preparation of sub-base/base, a windrow procedure on stockpiled sub-base/base course materials shall be carried out in the application of polymer-based chemical soil additive. It shall be mixed thoroughly and spread by a grader in approximately two (2) equal layers. The rate of dilution in each layer shall be 1:5 to 1:9 or one part Polymer-Based Chemical Soil Additive and 5 to 9 parts of water.

Compaction shall be done using steel roller on the first layer, and steel and rubber rollers on the second layer. Steel roller shall be used to crush aggregates larger than half inch on the surface of the laid/treated sub-base/base course while rubber roller shall follow to smoothen the surface. Compaction shall continue until the surface has formed a bond and little or no moisture is present. If further needed, after compaction of the second layer, as final application of polymer-based chemical soil additive shall be sprayed on the second layer to ensure that the sub-base/base was totally saturated while compaction is in process. After 48 hours of curing, polymer-based chemical soil additive shall be sprayed on the compacted road sub-base/base with dilution rate of 1 part polymer-based chemical soil additive and 9 parts water as sealant for coating for the new road sub-base/base pavement.

206.3.5 Trial Sections

Trial sections of the stabilized sub-base/base shall be constructed by the contractor at least 2 weeks before actual sub-base/base construction. These shall conform to the applicable requirements of Subsection 200.3.4, Trial Sections.

206.3.6 Tolerances

The stabilized sub-base/base course shall be laid to the designed level and transverse slopes on the Plans. The allowable tolerances shall be in accordance with Subsection 201.3.5, Tolerance.

206.3.7 Traffic

The Contractor shall not be permitted to drive heavy equipment over completed portions prior to the end of 24 hours curing period except pneumatic-tired equipment required for constructing adjoining sections.

206.4 Certification

The manufacturer or authorized distributor/dealer shall file with the purchaser a certificate stating the chemical composition and other pertinent information that may be needed for application and use. The manufacturer or authorized distributor/dealer shall include in the certificate of guarantee stating that the polymer-based chemical soil additive meets the requirements of the specification. The certificate shall be attested to by a person having legal authority to bind the company.

 206.5 Quality Control

The manufacturer or authorized distributor/dealer shall be responsible for establishing and maintaining a quality control program so as to assure compliance with the requirements of this specification.

206.6 Method of Measurement

The polymer-based chemical soil additive shall be measured by the liter. The quantity to be paid for shall be the design volume applied in place as shown on the Plans, and accepted in the completed course.

206.7 Basis of Payment

The accepted quantities, determined as provided above shall be paid for at the contract unit price for polymer-based chemical soil additive incorporated into the soil material.

Payment will be made under:

Pay  Item Number	Description	Unit of Measurement
206	Polymer-Based Chemical Soil Additive	Liter