Base is critical to the life of asphalt work. It determines the solidity, shape and drainage of the project. The sub-base should be shaped and compacted while removing all vegetation. Base material is then added using the proper amount of moisture for optimum compaction and rolled to compact. The same process is used on an existing project that has some base material already in place to consolidate the surface and provide the proper thickness of base for the application. It is necessary to let it dry before applying prime oil for a bonding surface for asphalt. The drying process could be overnight or several days depending on the weather conditions at the time. Essentially the same base work should be performed for both a hot mix surface and a chip and seal surface.
The mix is produced at our plant on Highway 248 and delivered to the jobsite by dump truck at approximately 320 degrees. The mix is dumped into the laydown machine, which spreads and partially compacts the material over the prepared base. Areas that can’t be reached by machine are done by hand and all seams are raked and consolidated by hand. As the mix cools it is rolled for final compaction. Thickness may vary but a minimum of 2″ is required for light duty applications.
Chip and Seal:
This type of surface consists of applying hot asphalt oil to the prepared surface and spreading chips (gravel) on the oil before it cools. The roller follows this process to compact the chips into the oil so that it will hold them in place. A double seal adds another layer of oil and chips over the first one. A double seal will amount to about 5/8″ of thickness.
This requires that any failure areas be repaired and the surface to be broomed or cleaned to provide a good bonding surface. Next a tack oil is applied to enhance the bonding characteristics of the surface. The hot mix is delivered as above and laid over the existing surface and compacted.