The surface course is the topmost structural layer in asphalt pavement. In most cases it is the top layer of the pavement and also acts as a wear course. Since it is exposed to direct traffic and environmental forces, it must be produced with the highest quality materials.

Characteristics of Surface Course

The surface course for asphalt pavement must provide the following characteristics.

Sufficient wet weather abrasion for protection
High resistance to load-induced rooting, shoveling and surface cracking
High resistance to thermally induced cracking
Low permeability to reduce surface-water infiltration
High durability to resist disintegration due to the combined effects of aging, traffic loading and freeze-thaw effects.
Suitable surface texture for noise control, safety and aesthetics
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