A review on deterioration Mechanisms, durability prediction and enhancement techniques for recycled aggregate concrete

Abstract

The expanding global construction industry is driven by the need to develop sustainable alternatives to replace natural resources in concrete manufacturing. Reusing construction materials and increasing reuse effectiveness have emerged as popular study areas. Recently, the durability of recycled aggregate concrete (RAC) has drawn attention of numerous researchers worldwide. This review paper discusses the different approaches used to predict the durability of RAC (deterministic, probabilistic, and artificial intelligence). In addition, a critical review of the parameters more influential on the RAC durability performance is presented, including replacement ratio, particle size, chemical admixtures and additives, mixing technique, and curing conditions. Several contradictory results concerning the chloride ingress, carbonation, air and water permeability in the RAC are reported and discussed. The methods used to enhance the characteristics coarse recycled aggregate (CRA) are also categorised and summarised. We have found that complex, non-linear, and multivariable mechanisms control chloride ingress, carbonation, and permeability, rendering conventional modelling techniques inadequate. It is therefore advised to use artificial intelligence methods supported by comprehensive databases to provide precise durability predictions. The performance of RAC is greatly impacted by the adhered mortar (AM) in CRA; its increased porosity and water absorption result in weaker interfacial transition zones (ITZs), decreasing impermeability, and weakening resistance to carbonation and chloride ingress. Therefore, we have also reported that strengthening the microstructure or altering AM characteristics are the main treatment strategies used to increase RAC durability performance. By enhancing RAC performance and lowering the ecological footprint of construction and demolition waste, CRA carbonation stands out among these techniques as a potential technology that offers both technical and environmental benefits.