Evaluation of innovative cold mix recycled asphalt concrete as backfill material in pipeline maintenance

Cold mix recycled asphalt (CMRA) concrete was evaluated to be an innovative repair material to improve the pavement quality and environmental impact on pipeline maintenance in this study. The study presented and specifically examined the use of CMRA with 2.5 % foam asphalt content as a replacement for the currently used controlled low-strength material (CLSM) as pipeline backfill material. CMRA's material properties, performance, carbon dioxide emissions, cost, and construction time were analyzed in this study to confirm the advantages and limitations of CMRA. The results concluded that CMRA performed better than CLSM for all the items analyzed. Specifically, according to the performance analysis, CMRA exhibited a better Marshall stability index, California bearing ratio, indirect tensile strength, tensile strength ratio, anti-rutting ability, and penetration than the standards specified. Furthermore, the average carbon emissions of CMRA were 36 % less than CLSM, could save at least 2 h of construction time per cubic meter of construction, and immediately opened traffic. However, CRMA's construction cost in this study was similar to CLSM and was only lower (up to 2.3 %) by considering a similar price of cement, asphalt, and additives. Based on the aforementioned results, this study concluded that the findings may be of particular interest for Taiwanese pipeline maintenance projects as a backfill material and is worthy of further research.