Rheological and fatigue performance of asphalt binder in chloride salt environment considering ageing effect

Chloride salt erosion is one of the common adverse working conditions of asphalt pavement, and its effect on the basic properties of asphalt binder has attracted wide attention, but there is limited research on the rheological and fatigue performance of asphalt binders in chloride salt environments. Besides, the ageing effect of asphalt binder in salt erosion process is usually neglected. This study aims to evaluate the high-temperature rheological and fatigue performance of matrix and SBS-modified asphalt binders in NaCl environments while considering the ageing effect. Firstly, different ageing of the two asphalt binders was simulated using the rolling thin film oven test and pressure ageing vessel test. Secondly, the asphalt binders in each ageing state were immersed in a NaCl solution of the corresponding concentration for distinct cycles. Temperature sweep and frequency sweep tests were conducted on the eroded asphalt binder using a dynamic shear rheometer, and the viscoelastic rheological performance was analysed on the basis of the complex modulus (G*), phase angle (δ), rutting factor (G*/sin δ) and G* master curves combined with the Christensen–Anderson–Marasteanu (CAM) model. Based on the viscoelastic continuum damage (VECD) theory, linear amplitude sweep (LAS) tests were performed to evaluate the fatigue performance of salt-eroded asphalt binders using the damage curve and fatigue life (Nf). The results indicate that the NaCl environment accelerates the fatigue damage of the asphalt binder and that the ageing effect correlates with the influence of NaCl concentration on its Nf. More severe ageing, the occurrence of fatigue damage corresponded to higher NaCl concentrations. Ageing and low-concentration (