Parent Concrete Strength Effects on the Quality of Recycled Aggregate Concrete: A Review

Abstract

Previous studies in the literature have illustrated that the strength properties of the parent concrete (PC), that might come from an assortment of origins, may considerably affect the characteristics of Recycled Concrete Aggregates (RCAs) and Recycled Aggregate Concrete (RAC). The effects of PC strength on physical, mechanical, long-term, and microstructural properties of RCAs and RACs have been extensively studied. These properties include water absorption, specific gravity, compressive strength, elastic modulus, splitting tensile strength, flexural strength, durability, and microstructure. These studies examining the influence of source concrete grade on the characteristics of RCA as well as RAC have been comprehensively reviewed in this paper. Upon reviewing the literature, it was found that the porosity of the source concrete and the crushing procedure of the source concrete aggregates were the two main causes of variability in the results of the RCA characteristics. Contrary to the widespread perception that, quote, “RACs in general have lower quality than virgin aggregate concrete”, studies on the effects of parent concrete on RAC characteristics have shown that RACs produced with aggregates obtained from recycling high-strength concrete (not less than 80 MPa) can have equivalent or better characteristics than conventional natural aggregate concrete. Therefore, by carefully considering the quality of the RCAs, it is possible to produce high-performance RAC without the need for additional natural aggregates. The limitations of previous studies have been identified in this work, and recommendations for further research have been provided.