A state-of-the-art review on the durability of geopolymer concrete for sustainable structures and infrastructure

The need for sustainable and environmentally friendly concrete for construction has resulted in the development of low carbon concretes such as geopolymer concrete. Geopolymer concrete replaces cement with industrial waste materials i.e., utilizes fly ash and slag for its mixture along with the addition of a small quantity of alkali activator required for the geopolymerization process. There is a large number of articles published on the mix proportion, workability, strength and material properties of geopolymer concrete (GPC) in the last 15-20 years. However, research on the durability of the reinforcing steel in various types of geopolymer concrete is limited and found to be contradictory with ordinary portland cement concrete (OPC) in literature. This paper presents a critical and updated review of the literature on the durability of GPC published between 1990 and 2020. A simple and systematic methodology including Preferred Reporting Items for Systematic Reviews (PRISMA) and Meta-Analyses procedures were adopted with modifications for this review. The review is divided into six key sections after the introductory section to have a holistic understanding of the durability of GPC and to highlight gaps for future research. The first section presents the review of recent articles that purely investigate the development of microstructure of various types of GPC. The second section reviews studies on the repairs of reinforced concrete by GPC. The third section covers articles on the durability of GPC against acids, chlorides, freeze and thaw, and temperature effects. The fourth section reviews studies on the structural performance of GPC specimens when subjected to corrosive environments. The penultimate section reports gaps, opportunities and potential areas of future research on the durability of GPC. Finally, the conclusions summarise the findings of the review. (c) 2021 Elsevier Ltd. All rights reserved.