Some mechanical and durability properties of basalt fiber and carbon fiber reinforced blast furnace slag based geopolymer mortars

The use of an alternative material to reduce cement production, which accounts for 8% of the world's annual CO2 emissions, is important for creating a sustainable environment. Geopolymer concretes allow waste materials to be incorporated into production, resulting in less energy consumption and low CO2 emissions. In addition, research is being conducted on the use of fibers to improve the brittleness, low flexural strength and some durability properties of geopolymers. In this study, the effect of basalt fiber and carbon fiber addition to mortars using blast furnace slag as precursor on some strength and durability properties was investigated. Geopolymer mortars were produced at two different dosages (300 kg/m3 and 320 kg/m3) and basalt fiber and carbon fiber were added at 0%, 0.5% and 1%. Sodium hydroxide and sodium silicate were used as alkali activators. Compressive and flexural strengths, ultrasonic pulse velocity, water absorption, capillarity coefficients, abrasion losses, impact strengths and mechanical properties and mass losses after exposure of 200℃, 400℃, 600℃ and 800℃ temperatures were determined. The addition of basalt fiber and carbon fiber to blast furnace slag based geopolymer mortars increased the compressive and flexural strengths, decreased the water absorption and capillarity coefficients, increased the impact strength, and reduced the abrasion loss of high dosage mortars. Compressive strength increased at 200oC, and losses in mechanical properties at 600oC and 800oC were at the same level as mortars without fibers. The effect of fiber type varied according to the properties and the most positive impact was generally observed in mortars with 1% fiber addition.