Mechanical and durability assessment of unconfined recycled concrete aggregates and natural aggregates used in road constructions

In the past few decades, recycling crushed concrete pieces and producing recycled concrete aggregate (RCA) has emerged as an effective way for controlling and managing construction and demolition wastes. Among all construction applications of RCA, its consumption in road facilities has increased significantly over the last few years. In this paper, the feasibility of utilising RCAs as an unconfined aggregate in road structure courses was evaluated. For this purpose, six types of natural aggregates (NAs) and three types of RCAs were selected. Then, various physical, mechanical, and durability tests including water absorption, specific weight, proctor test, impact test, crushing test, Los Angles abrasion test, California bearing ratio (CBR) test, sulfate soundness test and different frost soundness tests such as CSA A23.2-24A and AASHTO T103 were conducted on the specimens. The results indicated that all RCAs were acceptable for general applications in road construction. Although the sulfate soundness test suggested that RCAs were durable, they failed in both frost soundness tests. CSA frost soundness tests had the best correlation with the physical and mechanical properties of the aggregates compared to the other durability tests. Also, the AASHTO test method with its defined time-temperature cycles was not satisfactorily applicable to RCAs.