Synthesis of fly ash based geopolymer mortar considering different concentrations and combinations of alkaline activator solution

Abstract

Geopolymerisation is a process that can transform alumina and silica rich waste materials into valuable binding materials, having excellent mechanical properties. The present experimental study shed a light on the variation in compressive strength of fly ash based geopolymer mortar by varying the molarity of sodium hydroxide as 12M, 14M, 16M and accompanying by sodium silicate (Na2SIO3) in 2:1 (Na2SIO3/ NaOH) with same molarities. All the geopolymer mixes were oven cured at 80°C for 24h and after that kept at room temperature up to the time of testing. The compressive strength was checked subsequently at the ages of 3, 7, 14 and 28 days. The experimental results reveal that the addition of sodium silicate enhances the strength development in geopolymer mortar. The ultimate compressive strength of 40.42MPa was obtained by incorporating sodium silicate along with 16M concentrated sodium hydroxide. Furthermore, increasing trend of the compressive strength was found with increasing molar concentration of sodium hydroxide and curing period.