Mechanical performance of asphalt mixtures modified with rubber granules and recycled concrete aggregates

The use of recycled-concrete-aggregate (RCA) in asphalt mixtures is considered a viable technique from a technical standpoint to provide a solution to the environmental problem of final waste disposal. Likewise, the use of crumb-rubber-modified asphalts (CRMA) could contribute to this end. This article evaluated the physical-mechanical behaviour of a hot-mix asphalt (HMA) manufactured with CRMA and partially replacing the coarse fraction of the coarse aggregate of natural (NA) with RCA. For this purpose, four HMA mix designs were conducted by Marshall test, considering NA and RCA, and using as binders an asphalt cement AC 60-70 and CRMA. The mechanical performance was measured by performing Marshall, Indirect-Tensile-Strength (ITS), resilient modulus (RM), and permanent deformation. Resistance to moisture damage was also measured by calculating the Tensile Strength Ratio (TSR). The results show that mixtures with RCA require higher asphalt content. When replacing NA with RCA, HMA decreases its mechanical strength under monotonic and cyclic loading. Likewise, its resistance to moisture damage decreases. Contrary to the above, CRMA tends to increase the mechanical performance of the mixtures. However, the CRMA content used in this study was insufficient to adequately cover and adhere to the RCA, generating a mix that undergo the worst performance.