Effects of bamboo fiber on the mechanical properties of asphalt mixtures

Fiber addition could enhance the permanent deformation and crack resistance of the asphalt mixture. Previous research has found the effect of fibers on asphalt mixtures, while bamboo fibers have been overlooked. Bamboo fibers involve strength and toughness properties, and the addition of bamboo fibers is significant for studying the improvement of the mechanical performance in asphalt mixtures. In this paper, the reinforcing effects of bamboo fiber on the mechanical properties of asphalt binders and mixtures are investigated under various loading and temperature conditions. Bending beam rheometer tests and frequency sweep tests using dynamic shear rheometer were conducted in this study to characterize the relevant properties of asphalt binder with different fiber contents. A Superpave gyratory compactor was used to produce asphalt mixture specimens with 0.3% bamboo fiber. In addition, dynamic modulus, stress sweep rutting, and cyclic fatigue tests were conducted to investigate the mechanical properties of the test specimens. The results indicate that the high-temperature shear strength and low-temperature flexibility of the asphalt binders were improved by the inclusion of bamboo fiber. The inclusion of only 0.3% bamboo fiber improved the rutting resistance and fatigue life of the asphalt mixtures. In general, the dynamic modulus values of the asphalt mixtures increased and the phase angles decreased with the addition of bamboo fiber. The performance test results show that the inclusion of bamboo fiber enhances the stiffness and cracking performance of asphalt mixture at the intermediate temperature, but the improvements are not significant at high temperature. The research could evaluate the mechanical properties of bamboo fiber asphalt mixtures, and provide a reference for the engineering application of bamboo fiber in asphalt mixtures.