Critical review on fly-ash based geopolymer concrete

Due to enormous growth in industrial development, the consumption of cement is substantially increased in the recent times and the cement manufacturing industry produces annually about 1.35 billion tons of the greenhouse gas emissions which are about 7% of the total greenhouse gas emission by man-made to the atmosphere. At the same time, the thermal power plants have been generating huge quantity of fly-ash, which is not being recycled properly. This creates huge burden on solid waste management. Hence, to minimize the emission of CO2 from cement industry and to increase the utilization of fly-ash, a geopolymer technology is one of the viable solutions. In terms of global warming, the geopolymer technology-based fly-ash activated by an alkaline activators not only have potential to significantly reduce carbon footprint of ordinary portland cement concrete, but also shows considerable promise for applications in concrete industry as an alternative binder to the Portland cement. This paper provides a brief status of fly-ash based geopolymer paste and concrete, encapsulates, and analyses critically the most significant research findings on various properties of geopolymer concrete (GPC) over the past two decades. Also, it identifies the important factors to be considered in improving the performance of GPC at elevated temperatures as well as at ambient temperatures. Collation and analysis of more than 100 research papers in this area may provide a valuable stating document for further research.