Effect of Addition of Dry Crumb Rubber on the Performance of Terminal Blend Crumb Rubber Modified Asphalt Mixtures

Abstract

Three major methods are used to produce crumb rubber modified asphalt pavement: the dry process (CRDry), the terminal blend process (CRTB), and the wet process (CRWet). Although the CRDry process replaces the portion of fine aggregate in the asphalt mixture with crumb rubber (CR) particles, the CRWet process incorporates CR particles into hot liquid asphalt before it is mixed with aggregates. CRTB is known as a special type of CRWet process in which the CR is blended with asphalt binder at the asphalt terminal. In general, the CRWet process can integrate 15% to 22% CR by weight of the binder. This amount ranges from 10% to 12% in the CRTB process as a result of the limitations associated with transportation and pumping. This study investigated the feasibility of increasing the CR content of CRTB modified asphalt mixtures. The addition to the mixture of about 0.5% CR (by weight of the mix) through the CRDry process doubled the amount of rubber to be found in a conventional CRTB mix. The relative performances of the CRTB and the CRTB+CRDry processes [i.e., crumb rubber hybrid (CRHY)] were investigated with respect to their linear viscoelastic properties, rutting susceptibility, moisture damage, resistance to fatigue, and low temperature cracking. It was shown that it was possible to increase the amount of CR in the mixture through the use of the CRHY method proposed here, without adverse effect on the performance of the mixture.

Durability Evaluation Study for Crumb Rubber–Asphalt Pavement

“…Crumb rubber-asphalt mixture is a new type of deicing pavement material prepared by replacing some of the aggregates in asphalt mixture with mechanically sheared particles of waste rubber tires and mixing them uniformly with high-performance modified asphalt [1][2][3][4][5][6]. The addition of rubber crumbs changes the original structure of the mixture and the contact state between the materials so that the pavement is more easily loosened than an ordinary asphalt pavement [7]. An investigation has generally shown early damage to the domestic crumb rubber-asphalt pavement test roads for snow-melting [8].…”