Engineering Properties of Fiber Reinforced Cold Asphalt Mixes

A laboratory investigation consisting of Marshall, as well as static and cyclic triaxial tests, was undertaken to study the effect of the addition of randomly distributed synthetic fiber on the mechanical response of a cold-mixed densely graded asphalt mixture. The properties included density, air voids, Marshall stability and flow, elastic, and resilient moduli. The asphalt mixture was treated according to weight with 0.1, 0.25, and 0.50% staple polypropylene fibers 10, 20, and 40 mm long. In the first stage, Marshall tests were carried out in order to determine the optimum length and content of the fiber. The testing data supported that slit film fibers 40 mm long and fiber contents of 0.10 and 0.25% gave the best overall results, from a road engineering perspective. In the second phase, test specimens prepared at the optimum combination were subjected to conventional and cyclic triaxial tests. The results show that the addition of fiber is responsible for a small variation in mixture strength parameters, as well as for substantial drops in the mixture resilient moduli when compared to plain mixtures.