Investigation of the dynamic and fatigue properties of fiber-modified asphalt mixtures

The dynamic response and fatigue properties of fiber-modified asphalt mixtures were investigated in this paper. Three types of fibers including cellulose fiber, polyester fiber and mineral fiber were used as modifiers for asphalt mixture with the dosage of 0.3%, 0.3% and 0.4% by the total weight of asphalt mixture, respectively. Dynamic modulus tests using Superpave simple performance tester (SPIT) were conducted to determine the dynamic modulus and phase angle of asphalt mixtures at various temperatures and frequencies. The fatigue properties of asphalt mixtures were studied by the indirect tension fatigue test (ITFT) at different stress ratios. Test results showed that asphalt mixtures containing different fibers tended to have lower dynamic modulus (vertical bar E*vertical bar) and phase angle (delta). It indicated that the stiffness of fiber-modified asphalt mixtures could be reduced and the flexibility of mixtures was improved, which also resulted in the change of viscoelastic properties of asphalt mixtures. Fatigue parameter (vertical bar E*vertical bar . sin delta) derived from the dynamic response measurements was employed to estimate the fatigue resistance of asphalt mixtures. The results showed that the fatigue parameters of asphalt mixtures with fibers were decreased, which indicated that the fatigue property could be improved by fiber modifiers. The fatigue test results further demonstrated that fiber-modified asphalt mixtures showed better fatigue resistance when compared with the control mixture. (C) 2009 Elsevier Ltd. All rights reserved.