Precoated Aggregate

Aggregates may be precoated with asphalt binder to address the following issues:
  • To maximize adhesion of the aggregate to asphalt cement binders
  • To reduce or minimize the accumulation of dust on the surface of the aggregate
  • To address the aggregate absorption quality of the aggregate
  • To improve color contrast between striping and roadway surface.
Asphalt binders for precoating aggregates can be emulsions or asphalt cements. The target value of precoating material typically varies from 0.5 to 1.5 percent (0.5 to 3.0 percent for lightweight aggregate), by weight, of residual binder on the aggregate.
When the seal coat binder is to be an asphalt cement, precoating of the aggregate is recommended to maximize adhesion and reduce the adverse effect of dust. In general, precoated aggregate is not recommended when asphalt emulsions are used.