Analysis of Water Erosion on Asphalt Binder Using Multi-scale Experimental Methods

Asphalt binder plays a vital role in the entire resistance to moisture damage for asphalt mixture. Comparing with static water immersion and freeze–thaw, the water environment of dynamic pore water pressure induced by moving vehicle loads exhibits a different damage mechanism on asphalt pavement. This study evaluated moisture sensitivity of a base asphalt binder using multi-scale experimental methods, which included bending beam rheometer (BBR) test, surface free energy (SFE) method, and Fourier transform infrared spectroscopy (FTIR) test. The results showed that both the BBR retained stiffness ratio and the water stability indexes calculated by SFE parameters declined with the conditioning duration in dynamic water environment. The water erosion effect of long-term conditioning in dynamic water environment on asphalt binder was harsher than static water immersion and almost equal to and even harsher than freeze–thaw. The FTIR spectrums showed that all water conditioning environments could cause fluctuations of transmission rate in several wavenumber ranges, while dynamic water environment showed more significant influences. The erosion effects induced by water environments of static water immersion, freeze–thaw, and dynamic pore water pressure on asphalt binder showed basically consistent ranking and regulars. However, apparent differences of the influential extents induced by water environments on functional groups and chemical bonds of asphalt binder emerged around wavenumbers of 3425, 1460, and 1376 cm−1in the FTIR spectrums.