Özet:

Cement production continues to increase year by year, bringing many economic and environmental problems. The search for alternative binders to cement is among the most popular research topics of the 21st century. In the studies conducted, "geopolymer" binders, also called alkali activated binders, stand out. Geopolymers are the new generation three-dimensional binders obtained by activating natural and waste pozzolans with high silica and alumina content in high alkaline environments. Geopolymer binders have quite important advantages in terms of strength, durability and economy when compared to normal Portland cement binders. However, the most important obstacle to the widespread use of geopolymer concretes is the thermal curing process required in its production. There is no study in the literature on the effect of fiber length and content on acid resistance of fiber reinforced geopolymer concretes. In this study, the effect of fiber length and fiber content on acid resistance of geopolymer concretes produced without heat curing was revealed. For this purpose, 6 and 12 mm length polypropylene (PP) fiber was added at the rate of 0.5%, 1.0% and 1.5% by volume. Blast furnace slag (BFS) was used as an aluminosilicate source. Geopolymer concrete samples cured for 28 days in laboratory conditions were then exposed to 5% HCl solution for 14 and 28 days. The changes in the physical and mechanical properties of geopolymer concrete such as compressive strength, weight, ultrasonic pulse velocity (UPV), visual appearance after acid effect were investigated. In addition, microstructures were examined with SEM analyzes. As a result of the experimental studies, it has been determined that the PP fiber additive significantly improves the acid resistance of geopolymer concretes as it prevents the formation of cracks with the bridging effect.

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