Method Statement for ABC Construction

Aggregate Base Coarse

Materials

• Aggregate Base Course. (0-40mm)
• Water

Equipment

The major equipment used for the laying of ABC works and compaction, but are not limited to the following.

• JCB, and/or Backhoes
• Bob Cat
• Dump Trucks
• Rollers
• Motor Grader
• Rammers / Plate Compactors
• Water Bowser
• Sampling & Testing Equipment
• Auto Level, Straight Edge & Wedge
• Other minor tools

Man Power

Man Power used for the Aggregate Base course works includes, but are not limited to the following.

• Site Engineer
• Technical Officers
• Supervisors
• Labours

Safety & Traffic controllers

Safety Management and Traffic Control

All workers will be advised to wear helmets, boots, and gloves while working. There will be a stand by vehicle near site always if needed in a case of accident. The safety officer inspects several times to inspect safety matters.

Method and Procedures

ABC Indication in drawing

General

Once the Sub base is completed ABC 1^st layer will be spread over the widening part and on the existing pavement of the total width of 9.0 m.

Aggregate Base Course construction will be done half of the road way at a time and other side permits to go vehicles with out any disturbance.

Before starting the ABC construction both side shoulder preparation will be done for some extend to avoid the wasting of ABC and to shift away of aggregates at the edge compacting.

Where (0-40 mm) ABC material has to be spread on a sub-base, the surface of sub-Base should be cleared from any extraneous matter and where the ABC is laid over an existing bituminous pavement, the surface will be lightly scarified and scarified material will be cleaned before laying the base course.

ABC will be spread by using of JCB or Motor grader for 1^st layer and the final layer will be spread by motor grader.

The ABC material will be spread after checking all necessary testing, which will be given in specifications and the material will be mix with water at the yard and well saturated material will be transported to the site.

After checking the underlying layer for damages or deficiencies, ABC will be spread in layers not exceeding 200 mm & the length of spreading will be 500m or less at a time and compaction will be done by 17 Tons roller.

Before starting the compaction, required water content will be added and mixed ABC with the help of a water bowser, motor grader and compaction will be started using suitable roller depending on the layer thickness. Any areas of segregated course and fine material will be corrected by re-mixing, removing or replacing with well graded material.

Rolling will be carries out by a series of overlapping longitudinal passes working from the edge towards the center, in the super elevated section where the rolling will be proceed from the lower edge to the higher edge. After that inspect the compacted surface.

The compacted layer will be tested for degree of compaction not less than 98%. After getting required compaction next layer will be started and repeat as mention above up to required levels in the drawings or as instructed by the Engineer.

In cases where an existing ABC layer is to be improved by adding a layer of material less than 100mm thick, the existing surface will be scarified to a certain depth and mixed with the imported material. After that re-compaction will be started as per the specification requirement or as directed by the Engineer.

After compaction of ABC layer final finish level will be taken jointly and check for undulation to ensure the surface is within the allowable tolerance.

Traffic will not be allowed to go on the finished ABC layer until the layer covered by prime coat.