Laboratory investigation on effects of organic montmorillonite on performance of crumb rubber modified asphalt

In this paper, organic montmorillonite (OMMT) was added into crumb rubber modified asphalt (CRMA) to improve its high temperature performance, anti-aging performance and storage stability. The effects of different OMMT content on properties of CRMA were studied. The rutting factor obtained by dynamic shear rheological (DSR) test was adopted to evaluate the high-temperature performance. The creep stiffness and m value determined by the bending beam rheometer (BBR) test were employed to evaluate the low-temperature performance. The softening point, ductility, rutting factor before and after rolling thin film ovens test (RTFOT) and pressure aging vessel test (PAV) were compared to characterize the aging properties. Moreover, the segregation test after being reserved for 48 h and 7 d was conducted, and the softening point and rutting factor of upper and lower layers of segregation pipe were adopted to evaluate the storage stability. The results indicated that the high-temperature performance and anti-aging performance were developed with the increasing content of OMMT, while the low-temperature performance deteriorated. The storage stability was improved with the increasing content of OMMT before the content exceeded 4%, after which the storage stability declined. Taking account of all factors, it is suggested that the optimum content of OMMT is 3%–4%.