Geopolymers as an alternative to Portland cement: An overview

Portland cement manufacture emits 5-7% CO2, which is responsible for global warming. Geopolymers minimize CO2 emission and may be a partial alternative to Portland cement in the building industry. The geopolymer technology gives solution to the utilization of industrial byproducts (waste) containing aluminosilicate phases with little negative impact on environment. Geopolymer cements are mainly produced by using secondary raw materials such as fly ash, metakaolin, calcined clays, zeolite etc. by the activation of alkali/alkali silicate solutions. Combination of different source materials containing aluminosilicate and alkali solutions with optimization of curing temperature, alkali concentrations, additives, Na2O/SiO2 ratio etc. gives geopolymer cements of high mechanical and durability properties. Due to their high mechanical properties and environmental benefit, geopolymer cement and concrete appear as a future prospective construction material and have applications in different areas. (C) 2019 Elsevier Ltd. All rights reserved.