Evaluation of reclaimed asphalt pavement as base/subbase material in Egypt

Abstract

The application of reclaimed asphalt pavement (RAP) has become a common practice in road construction as a substitute to natural aggregate. The significance of RAP amount on the resilient modulus behavior, shear strength and hydraulic conductivity characteristics of unbound granular base materials were investigated in this research. RAP was blended with crushed aggregate by different percentages ranging from 0% to 100% by the blend weight. The laboratory testing program includes modified compaction, California Bearing Ratio (CBR), permeability, and repeated and static triaxial tests. A descriptive statistical analysis was conducted on all testing results. Furthermore, the X-ray computed tomography (CT) scanning technique was applied to investigate the internal (micro) structure of specimens. It was noted that with the addition of more RAP to the blend the resilient modulus increased and the coefficient of permeability decreased. The apparent cohesion of the RAP blends increased almost linearly and the friction angle decreased as the RAP replacement level increased. The CT scanning results indicated that the virgin crushed aggregate has a higher void ratio than the RAP blends, which interpreted the lower permeability and higher resilient modulus of RAP blends. In conclusion, blending RAP with virgin aggregate produces superior quality material for road bases.