Sustainable Asphalt Concrete Containing RAP and Coal Gangue Aggregate: Performance, Costs, and Environmental Impact

Abstract

The shortage of natural aggregates is becoming a severe problem in the pavement industry globally. To address this issue, in this study, an effort was made to use reclaimed asphalt pavement (RAP) and coal gangue (CG) as coarse and fine aggregate, respectively for producing the hot mix asphalt (HMA). As the replacement of natural aggregate, there were seven types of HMA containing 20% and 40% RAP coarse aggregate content, and 10% and 25% CG fine aggregate content were designed and prepared. In addition, Marshall Stability test, rutting resistance test, immersion Marshall test, freezing-thaw splitting test, moisture-induced sensitivity test, and low-temperature semicircle bending test were conducted. The results show that the properties of the asphalt mixture containing both RAP and CG meet the Chinese specification through it is slightly lower than the virgin asphalt mixture. Furthermore, the addition of 40% RAP coarse aggregate and 25% CG fine aggregate to asphalt mixes can signifi- cantly reduce manufacturing costs, energy consumption, and CO2 emissions by 29.4%, 19.8%, and 21.9%, respectively, compared to the virgin asphalt mixture. The finding of this study contributes to current knowledge by investigating the feasibility of jointly using the RAP and CG in asphalt mixture, which could be interested by both industry and academic society.