Effect of Low-Quality Recycled Concrete Aggregate on Stabilized Clay Properties

Recycled concrete aggregate (RCA) is the result of the demolition of concrete structures and pavements. Using RCA to replace quarried aggregates in paving projects is one way to utilize the millions of tons of concrete waste that is produced annually and landfilled. However, RCA may have inferior physical properties when compared to virgin aggregates, such as the presence of recycled mortar and preexisting deficiencies. This study evaluated the potential use of RCA from D-cracked pavement for soil stabilization. D-cracking is a type of pavement deterioration that originates in the coarse aggregate particles due to freezing and thawing. The engineering properties of low-plasticity clay with RCA and three common regional stabilizers (i.e., lime, Class C fly ash, and a combination of portland cement and fly ash) were investigated. Clay mixtures with varying proportions of chemical stabilizers and RCA from D-cracked pavements were evaluated by comparing measured unconfined compressive strength, linear shrinkage, and the California bearing ratio. Laboratory test results indicated that RCA, in conjunction with all cementitious materials, except lime, improved clay strength, stiffness, and shrinkage properties. The results from this study highlight that RCA from D-cracked pavements can be used for clay subgrade stabilization.