Influence of recycled concrete aggregate on volumetric properties of hot mix asphalt

Volumetric properties of hot mix asphalt (HMA) are necessary requirements to ensure good performance for asphalt mixtures. This research is conducted to evaluate the influence of coarse recycled concrete aggregate (CRCA) on the volumetric properties of HMA. Mix design of HMA mixture was performed for CRCA at various percentages 0%, 15%, 30%, and 60%, and the effects of the utilization of CRCA on HMA volumetric properties were evaluated. Additionally, various treatment methods were performed to evaluate the effect of various treatment types of CRCA on the HMA volumetric properties. To achieve this objective, presoaking, heat treatment followed by a short mechanical treatment were conducted. The obtained results showed that the use of the combination approach between different treatments appears to be very successful for enhancing physical properties of CRCA. The natural aggregate (NA) replacement by CRCA leads to increasing the optimum asphalt content (OAC) for the mixtures, whereas the property voids in mineral aggregates (VMA) is decreased. Compared to the mixture with 30% untreated CRCA, a little improvement and a slight increase in VMA and voids filled with asphalt (VFA) properties, respectively, were seen for mixtures with 30% treated CRCA with different treatment techniques. The CRCA addition with different proportions is very successful for both untreated and treated CRCA due to achieving all Ministry of Transportation Ontario (MTO) requirements for volumetric properties of HMA. However, CRCA treated with various treatment methods appears to be more successful than untreated CRCA application.