The effect of nano-CaCO_3/styrene-butadiene rubber (SBR) on fundamental characteristic of hot mix asphalt

摘要

This study investigates the performance characteristics of nano-CaCO3/SBR-modified asphalt mixture. SBR-modified asphalt was mixed with nano-CaCO3 particles at a concentration of 3%, 4%, 5%, 6% and 7% by weight of asphalt binder. Wheel track test was used to determine the proper dosage of nano-compound modifiers which are comparable to SBS-modified asphalt mixture in terms of deformation performance at high temperature. Asphalt mixture performance tests such as static creep test, overlay test and three-point beam bending test were conducted for nano-modified asphalt mixture and SBS-modified asphalt mixture. The micro topography and micromechanical property of modified bitumen are evaluated by atomic force microscopy (AFM) to study the modification mechanism of nano modifiers. Results show that 5%CaCO3/4%SBR-modified asphalt mixture has superior rutting resistance and creep characteristics at high temperature in terms of wheel track test and static creep test. However, reflection cracking resistance and flexural deformation stability of 5%CaCO3/SBR-modified asphalt mixture at low temperature are slightly worse than SBS-modified asphalt mixture. Despite this, ANOVA result indicates that the difference between the two kinds of asphalt mixture is not significant. AFM test result reveals that 5%CaCO3/SBR modifier can well be dispersed in bitumen and evidently increase the micromechanical properties of bitumen such as adhesion and dissipated energy while it has a negative effect on Derjaguin-Muller-Toporov (DMT) modulus. In general, 5%nano-CaCO3/4%SBR modifier has the desirable potential to comprehensively improve the performance of hot mix asphalt and is promised to be applied in the warm area.