Laboratory Performance of Asphalt Mixtures Containing Recycled Asphalt Shingles, Reclaimed Asphalt Pavement, and Recycling Agents

Abstract

As the price of liquid asphalt continuously climbs, methods are being sought to decrease material costs without compromising material or pavement performance while having a positive influence on sustainability. One potential method is the use of recycled materials, such as recycled asphalt shingles (RAS) and reclaimed asphalt pavements (RAP). The objective of this study was to characterize the laboratory performance of conventional asphalt mixtures and mixtures containing RAP and/or RAS, with and without recycling agents (RAs). The RAS type utilized in this study was postconsumer waste shingles. Six 12.5-mm asphalt mixtures were designed to meet certain criteria with four of the six mixtures containing no RAs and two mixtures containing RAs [Hydrogreen and soft asphalt binder (Asphalt & Wax Innovations, Pass Christian, Mississippi)]. A suite of laboratory tests was used to ascertain the mechanistic behavior of the mixtures evaluated against major distresses. Laboratory testing evaluated the high-, intermediate-, and low-temperature properties of laboratory produced mixtures using the Hamburg loaded-wheel tester, the semicircular bending test, and the thermal stress restrained specimen test in addition to the dynamic modulus test. Results indicated that the use of RAs improved the blending between aged and virgin binders, which adversely affected the intermediate- and low-temperature performance of the mixture. With the increase in availability of aged binder in the mix, the inclusion of RAP and/or RAS with and without RAs showed an improvement in rutting performance.