In spite of its excellent adhesive and waterproofing properties, asphalt is subject to traffic, wear and tear, exposure to the climactic conditions and corrosive chemicals. Seal coating provides a protective barrier from those natural enemies.
Fading and minor cracks, if not repaired, will increase the porosity, damaging the lower layers—those that are load bearing and ultimately require full replacement.
First: the sunlight and oxidation weakens the asphalt binder that hold the blacktop surface together. Second: the surface becomes brittle, tiny hairline cracks appear. Aggregate raveling creates rough patches on the surface. Third: the cracks deepen into the subsurface, further damaging the integrity of the asphalt. Water penetration and the freeze/thaw cycle widen the cracks. Sealcoating is a protective film that will wear away over time so the process must be repeated every 3 years to provide a consistently high level of protection.
Depending upon the amount of wear, the sealcoating process typically involves---