Properties of fresh and hardened fly ash/slag based geopolymer concrete: A review

Geopolymers are recognized as a potentially viable alternative binder to ordinary Portland cement (OPC), for reducing carbon dioxide emissions and achieving efficient waste recycling. Among the raw materials of geopolymers, fly ash (FA) and ground-granulated blast-furnace slag (GGBFS) have been preferentially applied to geopolymer concrete (GPC) owing to their availability and high silica and alumina contents. The FA/GGBFS-based GPC provides a clean technology option for sustainable development. Therefore, the specific review of FA/GGBFS-based GPC used to replace traditional concrete has become extremely imperative because the related study results on the FA/GGBFS-based GPC can promote the further study and application of this green construction material. In the present review, the reaction mechanism of geopolymers, as well as the properties and durability of fresh and hardened FA/GGBFS-based GPC, are discussed. In addition, the latest data on the FA/GGBFS-based GPC are presented. The GPC has excellent properties and a wide range of application prospects. However, there are obstacles to its large-scale applications in engineering and industry. Consequently, scholars and engineers must perform further research to provide a complete set of theory and engineering applications of FA/GGBFS-based GPC system. (C) 2020 Elsevier Ltd. All rights reserved.