Laboratory investigation on the synthesis and mechanical characterization of fiber reinforced geopolymer concrete

Abstract

Geopolymer concrete was invented as an eco-friendly alternative of conventional concrete. The work reported in this paper is based on laboratory investigation on geopolymer concrete synthesized using locally available materials. The Class F – fly ash was used in the synthesis along with a mix of 25 mm long crimped steel and 12 mm long glass fibers as hybrid fibers. A total of 24 mix designs were investigated to obtain an optimal constituent mixes corresponding to high mechanical strength. In order to study the effect of molarity of alkaline solution on the fresh and hardened geopolymer concrete; Compressive Strength, indirect tensile and flexural strength tests were conducted on the mixes. The maximum compressive strength was explored by varying concentration of NaOH, ratio of alkaline solution to fly ash and ratio of Na2SiO3 to NaOH solution. The hybrid fiber (0.15% glass and 0.85% steel fiber) gives the maximum mechanical strength at 1% by volume. The observed strength of geopolymer concrete without and with fiber was found to be equivalent to M40 and M50 conventional cement concrete.