The Bureau uses a Polymer Modified Petroleum based product and slow setting asphalt emulsion product to seal cracks as they develop, thereby avoiding saturation of the sub-base through the infiltration of water and preventing development of a base failure. Repairing potholes and skin patching alligator cracked areas and ruts up to 50 sq. This repair is necessary as an interim measure to extend the roadways serviceability until major maintenance can be scheduled. Skin patching is defined as the manual placement of one inch of asphalt over an alligator cracked or rutted area. Once a street is paved it comes immediately under attack by a variety of man-made and natural forces.
Natural forces break down the asphaltic bond between aggregates by oxidation.
The lack of an asphaltic bond between aggregates causes erosion of the fine aggregate particles away from the larger aggregates. This eventually causes surface erosion and allows for percolation of water into the sub grade causing base failures. Automobiles, large trucks and buses continually flex the asphalt pavement eventually causing cracks permitting larger volumes of water to infiltrate the sub grade causing base failures. Also buses and trucks generally have axle load ratings that exceed the original design limits of a roadway causing pavement failure. Slurry seal is applied to residential streets with good riding and drainage qualities to keep the street perpetually in a good to excellent condition.