Scrap plastic is treated for incorporation into asphalt-aggregate compositions by first shredding the plastic, then heating the shredded plastic to harden any pieces of film or flexible plastic and to generally reduce the size of the shreds without decomposing the plastic, and then grinding the heat-treated pieces to a size that can be blended with an aggregate. The blend is then combined with an asphalt binder to produce an asphalt-aggregate composition. No discrimination among, or selection of, specific types or classes of plastic is required.