Production and strength of pre-formed foamed fly ash-based geopolymer concrete

A study has been undertaken to investigate the possibility of producing foamed fly ash based geopolymer concrete by adopting the pre-formed foam method. Mixes with a density of 1000 kg/m3 were designed and produced. Molarity value, sand fineness, fly ash type, sodium silicate solution (SS)/ sodium hydroxide(SH) ratio and viscosity of sodium silicate solution (SS) were investigated as factors affecting the production of foamed geopolymer concrete. From the experimental work, among these several investigated factors; it was found that the viscosity of sodium silicate solution (SS) is the crucial factor affecting the production process i.e. producing mixes without the issue of solid materials segregation. In addition, it was noticed that the mix made with only sodium hydroxide(SH) as an activator was produced successfully without segregation issue. However, its strength was less than that of mix made with the combination of the sodium silicate solution (SS) and sodium hydroxide solution (SH) as activator by about 60%. The compressive strength of foamed geopolymer-based fly ash type F was greater than that of foamed geopolymer-based fly ash type C by about 118%.