Laboratory Evaluation of Asphalt Binder Modified with Crumb Rubber and Basalt Fiber

Asphalt pavement subjected to heavy traffic load and harsh environmental conditions can easily build up damage and shorten the service life. In this paper, different dosages of basalt fiber (BF) were introduced into crumb rubber (CR) modified asphalt binder, and a series of laboratory tests were carried out to evaluate the properties and performances. A dynamic shear rheometer (DSR) was employed to evaluate viscosity and rheological properties. Bending beam rheometer (BBR) test and direct tensile test (DTT) were conducted to test the low temperature property. Cone penetration was designed to test shear strength. Results show that the optimum content of BF is 0.3% by the weight of asphalt binder based on the overall performance evaluation. Viscosity, complex modulus, fatigue property, rutting resistance, and shear strength are improved by introducing BF into asphalt binder. Stiffness and elasticity are also increased. BBR indicates that ductility at low temperature is reduced a little by the presence of BF, but DTT shows that both tensile strength and elongation are improved by BF. Considering that DTT is more performance related, DTT is preferred over BBR to evaluate cracking potentials at low temperatures of asphalt binder modified with CR and BF. Finally, it is revealed through microscale scanning that three mechanisms, absorption of asphalt binder, 3-dimensional fiber network, and bridging effects, contribute to the performance improvement of asphalt binder modified with CR and BF.