Effect of liquid ASAs on the rheological properties of crumb rubber modified asphalt

Abstract

Effect of three liquid anti-stripping agents (ASAs) (M5000, M1 and LOF-6500) on the rheological properties of crumb rubber modified asphalt (CRMA) was investigated. ASAs with three dosages (0.25%, 0.50%, and 0.75%) were interfused in CRMA using melt blending method. All binders were aged employing rolling thin film oven (RTFO) and pressure aging vessel (PAV). Fourier transform infrared spectroscopy (FTIR) was employed to characterize chemical functional groups of ASAs and CRMA. The high temperature rheological properties were evaluated by rotational viscosity, G*, δ, G*/sin δ, failure temperature, Jnr and R, while the low temperature rheological properties were assessed by S and m-value. FTIR result indicates that the chemical reaction between amine in ASA and anhydride in CRMA can happen, and usually form organogels which have exceptional thermal and mechanical stability compared with the amine substances and anhydrides. Rheological tests results show that, with adding various ASAs, the rotational viscosity, G*, G*/sin δ, failure temperature, R and S are enhanced, while the δ and m-value are reduced. It suggests that ASAs improve the high temperature stability of CRMA whereas weaken the low temperature performance of CRMA. Amplitude sweep test results suggest that adding various ASAs does not change the linear viscoelasticity of CRMA before aging when the shear strain range is from 0.01 to 0.1. However, after RTFO, adding M1 and LOF-6500 (aside from 0.75% dosage) greatly reduces the linear viscoelastic range of CRMA. Performance grade (PG) analysis illustrates that M5000 and M1 (except for 0.50% dosage) have no influence on the PG of CRMA, while LOF-6500 decreases one low temperature grade of CRMA.