Copyright 2013 © A.S.A.P. Asphalt Maintenance
Properties of Asphalt
Benefits of Sealcoating
10 years of
The asphalt you see is only the “skin” of the entire pavement. This “skin” covers a bed of graded stone aggregates of varying depths according to ground conditions as well as traffic requirements. This base of aggregate is what really carries the load of traffic. The same theory applies to parking lots or driveways. A firm, resilient surface that provides a healthy skin of the stone base will keep the pavement bed dry. Like your own skin, it is important to have an elastic characteristic so it can expand and contract and still remain intact.
Asphalt is a very complex mixture of thousands of chemicals that are “open” in molecular structure, which leaves them susceptible to damaging properties of water chemicals and salt.
The first sign that the asphalt molecules have begun disintegrating is a change in color from rich black to brown, to gray.
Roads, having the advantage of continuously rolling traffic, do not need sealcoating protection as the traffic steadily brings the lower layers, rich in asphalt, to the surface and kneads the oxidized surface layers back into the pavement. However, eventually, all the asphalt binder is exhausted and the aggregates will unravel.
The rate of pavement deterioration depends upon traffic volume as well as climatic conditions. Once pavement has turned gray, it will develop cracks that will widen and deepen over time. If the cracks are not repaired, water will seep into the base courses and damage the pavement’s load bearing capacity. This is evidenced by rutting, shifting and serious alligatoring, which results in the necessary and costly replacement, that could have been prevented by sealcoating and crackfilling.
Today’s asphalt pavement is a mixture of stone aggregate and mineral filler combined with 4.5% to 12% asphaltic binder. The strength of an asphalt pavement is directly related to the pavement design from the ground up.