Influence of pre-treatment methods for recycled concrete aggregate on the performance of recycled concrete: A review

Natural aggregate (NA) can be replaced by recycled concrete aggregate (RCA) in the construction industry, which can solve the problem of construction waste disposal and reduce the gap between demand and supply. Various methods that were used to pretreat the RCA from the published research can be divided into the removal of adhered mortar, polymer impregnation, pozzolanic slurry immersion, carbonation or CO2 curing and bio-deposition method. This paper compared the pretreatment efficiency of these methods and their effects on mechanical properties, shrinkage, and durability of recycled aggregate concrete (RAC) based on statistical analyses. The pretreatment method is a highly attractive candidate for enhancing the mechanical strength and durability and decreasing the drying shrinkage. The effects of pretreatment methods with different parameters, testing age, mixture proportion, and measurement parameters on RAC are analyzed in detail. The findings of this paper can improve the development of eco-friendly concrete incorporating pretreated-RCAs in construction and civil engineering in the future.