Methods for improving the microstructure of recycled concrete aggregate: A review
Abstract Recycled concrete aggregate (RCA) differ from natural aggregate as the former contains attached mortar. Given the recycling process of RCA, that is, by crushing, the microstructure presents several disadvantages, such as porosity, micro cracks, as well as weak interface transition zones (ITZs) which will also damage the mechanical properties and durability of recycled aggregate concrete (RAC) According to current literature, the microstructure of RAC is mainly affected by ITZs and the porosity of RCA. This paper summarises the principles, advantages and disadvantages of the methods for improving the microstructure of RCA from four aspects, such as removal of attached mortar in the RCA, surface coating on RCA, different mixing methods and CaCO3 precipitation. Methods are also discussed from the aspects of environment, RCA particle size and application, which provide readers with a reference for improving the microstructure of RCA.