Sustainable asphalt concrete containing RAP and RCA: volumetrics, mechanical properties, and economic analysis

ABSTRACT The pavement maintenance field produces a large amount of waste materials, primarily composed of reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA), and considering the shortage of natural materials in pavement engineering, the production of sustainable asphalt mixtures to reduce the demand for natural materials become a topical issue. To this end, this study aims to assess the feasibility of utilizing RAP and RCA for the production of sustainable asphalt mixtures. Seven schemes of asphalt mixtures were designed, containing varying proportions of RAP at 20% and 30%, and RCA at 15%, 25%, and 35%, as well as a control scheme with natural materials. A battery of tests, such as Marshall stability, rutting, freeze-thaw splitting, low-temperature bending, and fatigue cracking performance tests, were conducted to evaluate the optimum asphalt content (OAC) and the durability properties of sustainable asphalt mixtures. In addition, the significance of the effect of RAP and RCA was analyzed using the ANOVA method, and the economic benefits of sustainable asphalt mixtures were analyzed. The results show that the OAC of sustainable asphalt mixtures escalates with higher proportions of RAP and RCA. The high-temperature stability, moisture stability, and fatigue performance of sustainable asphalt mixtures can be improved by adding RAP and RCA, albeit with a slight reduction in low-temperature cracking resistance. RCA emerges as a significant factor influencing the mechanical properties of sustainable asphalt mixtures, while RAP primarily impacts low-temperature cracking resistance. The utilization of RAP and RCA yields cost reductions in asphalt mixture production, leading to substantial economic benefits.