Improvement the Properties of High Strength Fly Ash Based Geopolymer Concrete by Using Cement

Geopolymer concrete was introduced to decrease the consumption of Portland cement, reduce the emission of CO₂ and produce alternative binders by applying by-products materials such as fly ash. This study the effect of steel fiber on the fresh and hardened properties of geopolymer concrete and also aimed to improve the properties of this type of concrete by replacing the fly ash by Portland cement by 5, 10, 15, 20 and 25% by weight. The results demonstrated that the use of steel fiber leads to improve compressive, splitting tensile and flexural strengths and reduce the flowability and drying shrinkage. The results also showed that the compressive strength of geopolymer concrete increased with increasing the replacement level up to 25%, the increase reached to 40.24 and 34.66% at 7 and 28 days respectively. Splitting tensile strength and flexural strength also increased with the replacement level of fly ash by cement. The results also revealed that the drying shrinkage of fly ash geopolymer concrete increased with cement replacement level.