Study on the multi-phase aging mechanism of crumb rubber modified asphalt binder
Meng Guo, Xiaofeng Xie, Xiuli Du, Chenlu Sun, Yu Sun
Abstract
The aims of this study is to prospectively study the aging evolution of CRMA from the perspective of a multi-phase composite system. In this study, the multi-phase separation of CRMA was carried out by physical filtration and chemical extraction, and the multi-phase aging evolution of CRMA was investigated. The results showed a general increase in the density of the remaining sub-phases of CRMA during aging, except the liquid asphalt binder phase (LABP). The volume of the adsorbed asphalt binder phase (AABP) increased by 17.91% after TFOT aging and decreased after PAV aging, reflecting the demonstrating a change in the multi-phase structure of CRMA. The complex shear modulus of each phase of CRMA increased after aging, but the amplitude of the change was smaller than that of 70# asphalt binder. Adsorbed phase (AP) and AABP inhibited the susceptibility of CRMA high and low temperature properties to aging, respectively. The adsorption protection provided by crumb rubber inhibited the volatilisation and oxidation of the aromatics within the adsorbed asphalt binder phase. Both CRMA and its sub-phases contain polymer phases. Polymer dispersion was more evenly in AABP, and polymer agglomeration was present in AP. The swelling effect caused the polymer to disperse more unevenly.