Natural pozzolan based geopolymers: A review on mechanical, microstructural and durability characteristics

Natural pozzolans are tremendous source of reactive silica and alumina required for geopolymer synthesis as an alternative binder for ordinary Portland cement. They are available at a comparatively low cost and generate a low ecological footprint through their simple extraction. Following review paper summarizes the mechanical and durability characteristics as well as the microstructural properties of natural pozzolan based geopolymers and their potential as binding material. The microstructural characteristics are based on the advanced analytical techniques used so far to understand geopolymerization, the phase composition, mechanical and durability properties evolution. From this review is obvious that significant analytical techniques have been successfully carried out on fresh and hardened natural pozzolan based geopolymer obtained in alkaline medium, which helped to understand underlying chemical reaction and external factors affecting final properties. These analyses have shown that natural pozzolan based geopolymer has potential to be used as sustainable building materials. But, for its large scale utilisation there is need to upscale the manufacturing process at a pilot-plant in order to address the macroscopic challenges that may arise at that level. (C) 2018 Elsevier Ltd. All rights reserved.