A Review on the Effect of Silica to Alumina Ratio, Alkaline Solution to Binder Ratio, Calcium Oxide plus Ferric Oxide, Molar Concentration of Sodium Hydroxide and Sodium Silicate to Sodium Hydroxide Ratio on the Compressive Strength of Geopolymer Concrete

Recently, geopolymer concrete (GPC) has gained substantial consideration and commercial interest in the construction industry owing to the superior mechanical and chemical properties in comparison with the ordinary Portland cement (OPC) that it brings through the use of waste material and reduction in the CO2 emission. Previous research Studies revealed that different ratios of chemical oxide combination of the raw material (fly ash, rice husk ash, meta kaolin, sugarcane bagasse ash, GGBS etc.) strongly affect the mechanical and durability properties of GPC. Nevertheless, findings concerning different ratios of Si/Al, alkaline solution to binder, NaOH to Na2SiO3, combined percentage of Fe2O3 + CaO and molar concentration of NaOH are controversial regarding the compressive strength of GPC. Therefore, in the light of literature, this study presents the investigation of the compressive strength behavior against the different ratios of oxides and alkaline solution (i.e. Si/Al, alkaline solution/binder, NaOH/Na2SiO3, Fe2O3 + CaO and NaOH molar concentration) present in the raw material used for the production of GPC. An extensive data from previous research publications has been collected and trend of compressive strength for 7 and 28 days was developed against different ratios of Si/Al, alkaline solution/binder, NaOH/Na2SiO3, in order to conclude a typical range for the above mention parameters. It was concluded that compressive strength of GPC greatly depends on the variation in ratios of Si/Al, alkaline solution/binder, NaOH/Na2SiO3, Fe2O3 + CaO and NaOH molar concentration. It was also concluded that the compressive strength of GPC has been primarily affected by the ratio of Si/Al, alkaline solution/binder, NaOH/Na2SiO3 and molar concentration of NaOH. Besides, the oxides like CaO and Fe2O3 although smaller in quantity in comparison with the alumina and silicate oxides, have indicated a distinct influence on the compressive strength development.