Analysis of Viscoelastic Response and Creep Properties of Rubberized Asphalt Mixture Containing Nanosilica and Sasobit

ABSTRACT In this work, a triaxial repeated load creep test and a stepwise loading beam bending creep test were performed on different samples of stone mastic asphalt (SMA), including rubberized SMA (AR-SMA), rubberized SMA containing nanosilica (NS) and rubberized SMA containing NS and sasobit (Si/SA-AR-SMA), and SMA modified with styrene-butadiene-styrene to determine their creep behavior under different temperature and stress conditions. In addition, the modified Burgers model and the Zhou model were proposed as viscoelastic prediction models for the asphalt mixtures. The microscopic tests including environmental scanning electron microscopy and fluorescence microscopy were performed to investigate the micromorphology of asphalt rubber (AR) binder and AR binder containing NS and sasobit (Si/Sa-AR). The results show that Si/Sa-AR-SMA has the best high-temperature deformation resistance and showed least sensitivity to stress and temperature changes. NS and sasobit have a positive effect in preventing deformation development, and the low-temperature properties of Si/Sa-AR-SMA are reduced by the presence of sasobit. The predictions of the modified Burgers and Zhou models adequately characterized the evolution of creep damage with loading time for the three asphalt mixtures. The parameter variations of the modified Burgers model can explain the differences in the sensitivity of the different mixtures to stress and temperature, and the parameters based on the Zhou model can further explain the three-stage deformation properties of the three types of mixtures. AR binder show a “dendritic” structure formed by multiple swollen crumb rubber (CR) particles and both AR and Si/Sa-AR show a three-dimensional network structure reinforced by all modifiers, which is partly reflected in the excellent high- and low-temperature performance of asphalt mixtures containing CR particles.