Revolutionizing roads: Exploring crumble rubber and sisal fibers for sustainable asphalt solutions

This research aims to investigate the stability of asphalt mixtures using crumble rubber and sisal fiber mixes. Common laboratory tests were performed on the modified bitumen asphalt mix using various proportions of CR-SF and thus analyzed. The Marshal Mix design procedure was used to determine the Optimum Bitumen Content (OBC) and test the modified mixture properties. Hot Mix Asphalt (HMA) is a particulate composite material consisting of mineral aggregates, asphalt binder, and air voids. Asphalt binder is considered the most expensive and economically variable material. The increase in energy cost, the need for improvement of pavement quality, and Environmental concerns force the researcher to find alternative materials to modify the properties of ASPHALT binder. For this research, 16 samples were used to determine the OBC, and the remaining were used to investigate the effects of adding different CR- SF percentages to the asphalt mix. The OBC was 5.5 % by weight of the asphalt mix. Seven proportions of CR: SF by weight of OBC were tested (0%:1%, 3%:0.9%, 5%:0.7%, 7%:0.5%, 10%:0.3%, 12%:0.1%, and 15%:0%) besides testing of ordinary asphalt mix. Tests include the determination of stability, bulk density, flow, and air voids. Results indicated that CR: SF can be conveniently used as a modifier for asphalt mixes for sustainable management of crumble rubber waste and for improved performance of asphalt mix. CR: SF content of 5 %:0.7% by weight of OBC is recommended as the optimum CR: SF content for improving the performance of the asphalt mix. Asphalt mix modified with 5.5%:0.7% CR: SF by OBC weight has approximately 40% higher stability value compared to the conventional asphalt mix. Asphalt mix modified with higher percentages of CR: SF exhibits lower bulk density, higher flow, and higher air voids.