Effects of RCA Replacement Level on Concrete Mechanical Properties

Abstract

Recycled concrete aggregate (RCA) has the potential to replace virgin coarse aggregate in new concrete pavements to increase their sustainability. However, the effects of RCA replacement on concrete properties can vary widely, depending on the RCA properties and the concrete in which it is being incorporated. This study investigated the effects of coarse RCA on concrete mechanical properties based on a large number of studies available in the literature. A property ratio was used to normalize the results of each study to its own control group, thereby allowing studies with different mix designs to be compared. By comparing the change in concrete properties observed in each study as the RCA replacement percentage increased, the wide range of possible effects on mechanical properties is illustrated. This wide range of effects should be considered when developing policy related to RCA use because no single study can capture the possible effects of RCA use. The applicability of standard correlations for predicting elastic modulus, split tensile, and flexural strength from compressive strength for concrete made with RCA was also investigated. The flexural strength correlation was found to have a similar level of validity for mixes containing RCA versus virgin aggregate, but correlations for elastic modulus and tensile strength were less accurate for mixes containing RCA, especially at high replacement levels.