A succinct review on the durability of treated recycled concrete aggregates

Building materials constitute a considerable portion of all the materials we use and about half the waste (in solid form) generated worldwide. Construction and demolishment (C&D) aggregates can be an invaluable source of construction material. If we measure the quantity of C&D waste in India, it will exceed the amount of all other types of hard solid wastes put together. Therefore, the use of recycled concrete aggregates (RCA) in new construction is being encouraged worldwide. But due to the inferior compressive, mechanical strengths and poor durability performance, it cannot be qualified for structural usage. Hence, there is a need to treat these aggregates and produce better quality aggregates suitable for good structural grade concrete. The present work focuses on the study and comparison of the effects on durability performance due to different treatment techniques of recycled aggregates. Effective treatment techniques can potentially separate or strengthen the weaker portions of the recycled aggregates like the old adhered mortar and the ITZs formed due to them. Effects of different RCA treatment methods along with their combinations such as immersing aggregate in acid solution and silicate solution impregnation, multistage-mixing techniques, biologically induced carbonate precipitation, modifier solution impregnation, ultrasonic cleaning, crushing aggregates at multiple levels, and mechanical grinding are considered for analyzing their effectiveness in improving RCA durability. The durability performance of treated RCA is evaluated based on the improvement in the parameters such as water absorption and resistance to acid attack, permeability, chloride attack, and carbonation.