Re-cementation of Recycled Concrete Aggregate in Pavement Base or Sub-base

Abstract

Recycled concrete aggregate (RCA) is often used as a pavement base or sub-base material. One unique concern of RCA used for such purposes is re-cementation. Although re-cementation increases the stiffness and bearing capacity of RCA, it may induce cracking if RCA becomes bound or partially bound. Four approaches were used in this study to investigate RCA re-cementation in pavement sub-base, including long-term monitoring of a trial site, test of RCA samples retrieved from the site, performance simulation based on mechanistic-empirical pavement design guide (ME-PDG), and numerical analysis. The trial site reveals that RCA becomes partially bound after 11 years of road use. The bound material exhibits properties similar to those of cement-treated base (CTB). However, due to variations in the content and composition of fines in RCA, the extent of re-cementation is not uniform in sub-base. According to the analysis results generated by ME-PDG, reflective cracking occurs if RCA is assumed to be CTB. Conversely, if bound RCA is non-monolithic, it may not have significantly negative effect on pavement performance. The fine content or composition of fines in RCA may be specified to further reduce the risk of RCA re-cementation.