Paving Procedures
Paving procedures are similar to those used for new maintenance mixes. The existing pavement is swept to clean the surface and a tack coat of diluted emulsion applied for good bonding. RAP maintenance mixes can be placed with a conventional asphalt paver or a motor grader. For motor grader placement, the blade should be straight and sharp and the tires worn or of the turf type to prevent leaving tread marks in the finished mat.

Initial compaction normally is with pneumatic-tired rollers and the final rolling sometimes with a double-drum steel roller. Vibratory compaction can increase density and smooth the surface for better ride quality and usually is completed at low amplitude. Vibration should not be used if damaging the mat with severe checking or slippage or when mix thickness is not at least 1 inch (25 mm). If the mat is tender at placement, it may be possible to re-roll later after losing moisture and/or warmer weather.

Roller drums and tires normally must be kept wetted to prevent picking up of the cold recycled mix.

     

     

     

Surface Treatment
Some type of surface treatment is required for cold central plant recycled maintenance mixes. A fog seal of diluted asphalt emulsion can be applied as a temporary treatment, primarily to prevent raveling. However, a seal coat with a cover aggregate (sand, sand-gravel or chips) is recommended if only to be seal coated. Also, the surface can be an overlay of another type of cold mix or hot mix asphalt (HMA). A fog seal can be applied immediately after placement but other surface treatments typically are not placed until some curing period. This is to allow for moisture loss and mix strength increase.

Information
For additional information on RAP maintenance mixes and reducing your patching costs, contact hallbros@hallrecycling.com