Assessment of Mechanical Performance of Fiber Reinforced Geopolymer Concrete at Different Curing Conditions

The building industry has made extensive use of types of concrete in recent decades. Geopolymer Concrete is one of several common types of concrete and does not require a water spray after casting. The research was limited to the use of industrial waste and waste harmful to disposal in structural technology. This paper investigates the effect of the curing type and hybrid fibers on the properties of reinforced geopolymer concrete. Binder materials for geopolymer mixes consist of 70% fly ash, 20% slag, and 10% cement. Four steel fiber proportions 0%, 0.5 %, 1 % and 1.5%, were studied in addition to mixing reinforced with hybrid steel fiber 0.5% and polyolefin fiber 0.5%. All geopolymer concrete specimens were cured at oven and ambient temperatures for 7, 28, and 56 days. The binder materials were activated with sodium silicate and sodium hydroxide solutions. Trial used the best ratio for an alkaline solution, which is assigned as Alkali Activators/Binder = 0.5, Sodium Silicate/Sodium Hydroxide = 1.5, and 14 Molarity. The mixture containing 1% steel fiber was selected and studied with a hybrid fiber. Hardened properties were tested using compressive strength, flexural strength, splitting tensile strength and modulus of elasticity. The results showed a difference between ambient and oven curing, with oven-cured specimens exhibiting higher compressive strength than ambient-cured specimens at early ages. At the same time, compressive strength was higher at late ages under ambient curing than under oven curing. Also, the other mechanical tests, splitting tensile strength, flexural strength and modulus of elasticity, exhibit the same as compressive strength in both curing conditions. The increase in compressive strength at 0.5%, 1%, and 1.5% steel fiber content at later ages was 20%, 33%, and 49%, respectively. As for the hybrid fiber mixture for Geopolymer Concrete, the increase in compressive strength was 24%. The addition of fibers in Geopolymer Concrete mixes did not affect the modulus of elasticity values. The results concluded that the geopolymer concrete exhibits an efficient performance in both ambient and oven curing. Consequently, it can be the best alternative to Ordinary Portland Cement concrete in site-cast without special curing conditions.