Nano-engineered, Fly Ash-Based Geopolymer Composites: An Overview

Fly ash-based geopolymer composites (FA-GPCs) are an innovative type of cementitious materials that show great potential in replacing ordinary Portland cement composites. The production of FA-GPCs has a lower carbon footprint and consumes less energy than their Portland cement counterpart. The adoption of fly ash-based geopolymer as an alternative cementitious binder can also facilitate value-added utilization of coal fly ashes that remain an underutilized type of industrial byproduct collected from coal fired power plants. Recent advances in nanotechnology further improve the engineering properties of FA-GPCs and enable their broadened applications, often through the use of nano-materials as admixtures. This review focuses on the state of knowledge relevant to nano-engineered FA-GPCs, especially progresses made during the last decade (from 2010 to 2020). The influences of admixed nanomaterials on the features of both fresh and hardened FA-GPCs, including workability, in-service performance, and durability, are reviewed and discussed in this work. This work also presents a retrospective statistical analysis of mechanical performance of nano-engineered FA-GPCs, and concludes with a discussion of knowledge gaps and remaining challenges for future work.