Preparation of Existing Surface

Posted by Civil Engineering on

Sunday, 2 December 2018

Where local irregularities in the existing surface would otherwise result in an asphaltic layer more than 75 mm thick after compaction, the surface shall be brought to uniform contour by patching with an asphaltic material to be approved by the Engineer and thoroughly tamping or rolling it until it
conforms with the surrounding surface. The mixture used shall be the same as that specified for the next layer, unless the size of the largest aggregate in the mixture precludes this, in which case the Engineer will decide the mixture to be used.
Where the existing pavement is broken or shows instability, the unsuitable material shall be removed and disposed of as directed by the Engineer and replaced with the same asphaltic material as specified for the succeeding pavement layer, compacted to the specified standard and to the elevation of the adjacent surface.
Where the existing surface course is stabilised or constructed of asphaltic materials or Portland cement concrete, and if the edge of the course has become eroded, disintegrated,or broken, the edges shall be trimmed back, the debris removed and disposed of, and the space backfilled with an
asphaltic material or with gravel or similar approved material, and then compacted, as directed by the Engineer.
The surface upon which the asphaltic material is to be placed shall be swept thoroughly and cleaned of all loose dirt and other objectionable material immediately before spreading the asphaltic materials.
Before spreading the asphaltic material upon a Portland cement concrete surface all longitudinal and transverse joints shall be cleaned out and filled with an approved sand asphalt mix. Cracks shall be similarly treated as directed by the Engineer.
Wherever possible the cleaning out shall be to a depth of 40 mm or more and the sand asphalt shall be thoroughly compacted in joints and cracks to a level which will not be more than 5mm below the surface.
If instructed by the Engineer a tack coat shall be applied in accordance with Section 4.3 of these Specifications. If the Engineer considers an additional tack coat is required prior to laying the asphaltic material or between successive layers of the asphaltic material, due to solely to the Contractor’s method of working, then such tack coat shall be at the Contractor’s expense.

Labels: Road Design, Specification

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