Mechanical performance evaluation of crumb rubber enriched rejuvenator modified RAP mixtures

Abstract

The asphalt mixtures containing Reclaimed Asphalt Pavement (RAP) materials are commonly stiffer than the conventional mixtures, and a rejuvenating agent may be used to maintain their flexibility. However, the use of rejuvenators could decrease the rutting resistance. In this study, to overcome this issue, crumb rubber (CR) was used as a modifier to rectify the effect of rejuvenators on rutting resistance in recycled mixtures. In this manner, two types of waste oils (waste cooking and engine oils) were mixed with CR separately, and the final manufactured materials were used as CR-modified rejuvenators. Then, the CR modified rejuvenators and pure rejuvenators (i.e., waste cooking oil and engine oil) were added to the asphalt mixture containing 25, 50, and 75% RAP materials. The cracking resistance at intermediate temperature, the rutting resistance, and the moisture sensitivity of different samples was evaluated by performing the semi-circular bending, dynamic creep, and moisture sensitivity tests. The results showed that CR-modified rejuvenators remarkably increase the rutting resistance of rejuvenated mixtures without compromising the cracking resistance and moisture sensitivity. Additionally, the statistical analysis indicated that the type of rejuvenators and RAP content are significant variablesfor cracking resistance, rutting resistance, and moisture sensitivity.