Design of Cold-Mix Asphalt Mixture Using Tire Crumb Rubber and Coconut Fiber as Additives

The utilization of waste materials in bituminous construction has gained significant traction due to environmental and economic considerations. Tire Crumb rubber (TCR) and coconut fiber (CF) are two promising waste materials that can be incorporated into cold-mix asphalt to enhance their performance. TCR can improve the flexibility and fatigue resistance of cold mix asphalt, while CF can enhance their tensile strength and reduce their susceptibility to moisture damage. Using cold-mix asphalt was put in consideration for the reason that hot mix asphalt is made to be ordered on a batching plant with limited selection of volumes and could be costly, considering that the study was only for repairing or patching potholes. With these ideas in mind, the researchers came up with the study of combining both materials with cold-mix asphalt which supplies an affective alternative for asphalt laying. This study includes different testing to assess the effectiveness of the mixtures. The tests that were done are compression test, bulk specific gravity, and index retained strength using 100% of cold-mix asphalt (CMA) with tire crumb rubbers and coconut fiber as additives (percentage varies on different mixture) that was included in the production of the prototypes and with data that were analyzed and interpreted by MEGASTESTING CENTER INC. in Quezon City. Throughout the study, the results and methodologies complied with the requirements, set by the standard specification of ASTM C136, ASTM D1074, ASTM D1075, ASTN D7229, and Standard Specification of Department of Public Works and Highway (2013). Analysis of a product's properties is essential, along with its fabrication cost and price when released in the market. With that said, the cost analysis procedure aligned with the overall cost of the product when produced and all expected expenditures that came along with the process. The total cost of the production of all individual materials of the total prototype for standard cold mix asphalt mixture is PHP 540.000 while the most effective mixture costs PHP 135.00 which is similar to the price of the traditional cold-mix asphalt. The study proved that the mixture of 100% cold-mix asphalt with 1% tire crumb rubber and 0.7% coconut fiber as additives proved the most efficacious with compressive strength of 343.9 PSI and index of retained strength of 79.63%. with the results presented, the researchers concluded that the mixture was effective for repairing and pothole laying.