Effect of different basalt fibers on the rheological behavior of asphalt mastic

Many research has indicated that fiber content and type have an essential effect on the asphalt mixture performances. However, the impact of fiber properties has not been studied enough. Thus, to evaluate the fiber properties on the rheological behavior of asphalt mastic, this paper adopted four kinds of basalt fibers (three short-cut fibers coated with different infiltration agents and one flocculated basalt fiber, noted as BF-A, BF-B, BF-C, and FBF) and chosen a lignin fiber (noted as LF) as a comparison. First, the hygroscopicity, pH value, and asphalt-adsorption capacity of the five fibers were tested. Then, the rheological behavior of different asphalt mastics was evaluated by viscosity test, Dynamic Shear Rheological (DSR) test, and Bending Beam Rheology (BBR) test. Moreover, microscopic images of the fibers and the asphalt mastics were taken by an Environmental Scanning Electron Microscope (ESEM) to analyze the mechanism of different fiber asphalt mastics. The results show that fibers improve the deformation resistance of the asphalt mastic, but different fibers show different effects on the low-temperature performance. BF-A and LF show the most significant improvements in high-temperature performance and low-temperature performance, respectively, followed by BF-C, FBF, and BF-B. The morphology of the fibers and the type of infiltration agent on the fiber surface affect the rheological properties of fiber asphalt mastic and lead to different mechanisms of fiber asphalt mastic. The role played by flocculent fiber in asphalt mastic is to stabilize asphalt, while the short-cut fibers can also be lapped to form a spatial network to withstand external loads together with asphalt.