Mechanical Properties and Crack Resistance of Cement-Stabilized Macadam Modified by Crumb Rubber and Polypropylene Fiber

This study tempts to investigate the effect of crumb rubber and polypropylene fiber on the mechanical properties and crack resistance of cement-stabilized macadam (CSM). Firstly, orthogonal test was conducted to determine the optimum mix proportion considering 7-day unconfined compressive strength and dry shrinkage coefficient. Under the optimum mix proportion, unconfined compressive strength test, splitting strength test, compressive resilient modulus test, and dry shrinkage test were performed. The results indicated that the crumb rubber content had the most significant influence on the strength and crack resistance of CSM, followed by the fiber content, while fiber length and rubber particle size had little effect. The optimum mix proportion was 40 mesh rubber and 6 mm fiber substituting 1% and 0.8‰ of mixture, respectively. The incorporation of crumb rubber and polypropylene fiber effectively reduced the resilience modulus of CSM and improved the compressive strength, splitting strength, and dry shrinkage resistance.