Seal coating is designed to protect asphalt pavements from the damaging effects caused by petroleum products, moisture, and ultraviolet oxidation. Protecting pavements with seal coating has the same basic effect as using sun block on your skin or varnish on wood, it slows down the destructive effects. It also fills surface cracks to prevent water from entering and damaging the base materials.
Seal Coating helps asphalt retain its pliable, oil based nature. Also, it fills surgace cracks to prevent water from entering and causing damage to your subgrade.