Optimum Mix for the Geopolymer Concrete

Geopolymer concrete utilizes an alternate material including fly ash as binding material in place of cement. This fly ash reacts with alkaline solution (e.g., NaOH) and Sodium Silicate (Na₂SiO₃) to form a gel which binds the fine and coarse aggregates. Since Geopolymer concrete is the emerging field, the guidelines from the Bureau of Indian Standards are yet to be formulated. An attempt has been made to find out an optimum mix for the Geopolymer concrete. Concrete cubes of size 150 × 150 × 150 mm were prepared and cured under steam curing for 24 hours. The compressive strength was found out at 7 days and 28 days. The results are compared. The optimum mix is Fly ash: Fine aggregate: Coarse aggregate (1:1.5:3.3) with a solution (NaoH&Na₂SiO₃ combined together) to fly ash ratio of 0.35. High and early strength was obtained in the Geopolymer concrete mix.