Ultraviolet rays in sunlight dry out the oil in the asphalt causing fine sand to shed out of the pavement. Sand and gravel is blown in by the wind, tracked in by tires, or washed in by rain. Any sand, mud or gravel on the surface of your pavement becomes abrasives that wear out your pavement.

How does loose gravel wear out your pavement?

When tires drive over the dirty surface, the abrasives are ground into your asphalt like sandpaper causing it to erode and shed more sand and rock onto the surface. This is called "raveling" and can lead to cracks, "aligatoring" and potholes in your parking lot.

Landscaping that sheds lots of leaves and vegetation which accumulates on the pavement can destroy asphalt.

When leaves are moistened by rain or sprinklers, they decompose and release acids that break down the oils in the asphalt and deteriorate it.