Influence of the incorporation of recycled coarse aggregate on water absorption and chloride penetration into concrete

Abstract

Knowledge of the transport properties for recycled aggregate concrete (RAC) exposed to chloride environment plays a critical role in assessing its durability and predicting the service life. In this study, the effect of the incorporation of coarse recycled concrete aggregates (RCAs) on the durability of cement-based cementitious materials was experimentally investigated. Two types of RCAs were obtained to produce the RAC with water-to-binder ratio of 0.33 and 0.39, and different substitutions of RCAs ranging from 0%, 30%, 50% and 100% by weight were selected. A series of experiments including compressive strength, water and salt absorption test, and rapid chloride migration (RCM) test for RAC with various replacement ratios of RCAs were conducted. The results indicate that the incorporation of RCAs generally decreases the compressive strength, and inversely increases water and chloride transport coefficient compared to those of the control concrete. An increasing trend can be found in the influence of RCAs replacement ratio on the initial coefficient of capillary water absorption, but it inversely decreases as the quality of RCAs is improved. The chloride content and penetration depth in RAC were remarkably increased as RCA content increases and its quality decreases. The linear changing behavior for the penetration depth between water and chloride ion in RAC with different replacement ratios was well exhibited. This finding reveals the retardation effect that the chloride transport process lags behind water migration for the absorption tests of RAC.