Mechanistic Characterization and Performance Evaluation of Recycled Aggregate Systems

This paper provides a mechanistic procedure for performance characterization of recycled aggregate systems for use as aggregate base layers. Twelve recycled aggregate systems with different lithologies and known field performance histories were selected for this study. The aggregate sources were selected from seven different states with different climatic conditions to account for the environmental impacts on the performance of the pavements constructed with recycled materials. A comprehensive material testing protocol was followed to characterize the mechanical and physio-chemical properties of the recycled aggregate systems. A shear strength test at different confinement levels and the Canadian freeze-thaw test, Micro-Deval test, and tube suction test were performed on the samples. Analysis of the laboratory tests showed that several recycled systems performed equally or better compared to control systems consisting of virgin aggregates in terms of higher shear strength and higher hardening index. Laboratory test results also showed that recycled concrete (RC) materials typically had superior mechanical properties such as a higher resilient modulus and hardening index compared to recycled asphalt (RA) systems; however, RC systems showed higher frost susceptibility. The laboratory analysis and numerical simulation results presented in this study underscore the significance of climatic conditions and subgrade soil type when a RA system is considered as a viable option