Some properties and microstructure of fibre reinforced lightweight geopolymer concrete

The purpose of this investigation is to study the effect of inclusion steel fiber on microstructure and some properties of lightweight geopolymer concrete. Lightweight geopolymer concrete containing, Fly Ash, alkaline liquids (mixture of sodium hydroxide and sodium silicate solutions) and steel fibers were produced. Mixtures were prepared with, alkaline liquid to fly ash ratio of 0.4, sodium silicate: sodium hydroxide solutions of 2.5, using artificial local lightweight aggregate and steel fiber in volume fractions of 0.25%, and 0.5% with aspect ratio of 60. Reference lightweight geopolymer concrete not containing steel fiber was also prepared. Properties studied including, density, compressive strength, ultrasonic pulse velocity, splitting tensile strength, and flexural strength; also the microstructure of lightweight geopolymer concrete was investigated. Steel fibers increase the splitting and flexural tensile strength. Specimens with steel fiber volume fraction of 0.5% achieved increase in flexural strength of 6.3% relative to specimens without steel fiber at 28 day age.