New Approach to Recycling Asphalt Shingles in Hot-Mix Asphalt

The objective of this study is to introduce a new approach to recycling asphalt shingles in asphalt paving construction in which recycled asphalt shingles (RAS) are ground to ultrafine particle sizes and blended with asphalt binder through a wet process. In the proposed wet process, the ground recycled material is blended with the binder at a high temperature prior to mixing with the aggregates. Two unmodified binders that are classified as PG 64-22 and PG 52-28 were blended with two contrasting sources of RAS at a modification content ranging from 10–40% by weight of the binder. The use of RAS modification through the proposed wet process was successful in the laboratory. Based on the results of the experimental program, the use of RAS modification through the proposed wet process would generally improve or not influence the high temperature grade of the binder, but it may reduce the low temperature grade of the binder. As demonstrated in this study, an optimum shingle content may be identified t...