Resilient Modulus of Recycled Asphalt Pavement and Recycled Concrete Aggregate

Abstract

The most common recycled construction materials used as unbound base course in pavement construction are recycled concrete aggregate (RCA) and recycled asphalt pavement (RAP). This study investigated the mechanical properties of RCA and RAP as unbound base, including the relationships between resilient modulus (Mr) and composition (e.g., particle shape, binder type, aggregate mineralogy, and contamination). The recycled materials were collected from a wide geographical area, covering eight states in the U.S. The Mr tests were conducted following National Cooperative Highway Research Program (NCHRP) protocol, which measures specimen deflections externally and internally. Power function and NCHRP models were applied to estimate Mr. The NCHRP model was more reliable in capturing Mr dependency on stress state in RCA and RAP. A multiple linear regression model was developed to predict the Mr of RCA (R2=0.96) and RAP (R2=0.97). There was a high degree of correlation between the predicted Mr and the physical properties of RCA (R2=0.89) and RAP (R2=0.99).