Properties of ground acidic pumice and silica fume based geopolymer mortars

The high cost of cement and the damage it causes to the environment demands the production of economical and environmentally friendly alternative binding materials. The manufacturing of Portland cement requires a significant amount of energy, and it causes high CO2 emissions that cause environmental damage. Additionally, some industries produce wastes like silica fume that cannot be directly released to nature because it has a significant negative effect on the environment. The inclusion of waste materials and by-products in the construction industry contributes to preventing the consumption of natural resources and minimizes environmental damage. This thesis covers the effect of replacing silica fume with ground acidic pumice as a binder on the properties of mortars reinforced with polypropylene fiber. Mortar samples used silica fume substitution rates of 25% and 50% by weight of acidic pumice. Used as alkali activator sodium hydroxide. Polypropylene fiber was added to the produced mortars at the rate of 0, 0.5 and 1% by volume. Two curing regimens were applied, curing for 6 hours at 60 ⁰C under laboratory conditions and in a high temperature oven. Spreading diameter test was carried out. Physical properties such as apparent void ratio, bulk density and water absorption were investigated. It was observed that there was an increase in water absorption percentage values and apparent void ratio with the increase in fiber content. It was noticed that the effect of thermal curing on the samples increased with the increase in the acidic pumice content of the mortars. Bending and compressive strength were determined after 7 and 28 days of curing. It shows that the strength increases with the increase of polypropylene fiber. The mixture containing 75% ground acidic pumice series showed the lowest compressive and flexural strengths while curing at high temperatures. In addition, the durability of the geopolymer was determined by using the capillary water permeability coefficient. Obtained results show that the coefficient of fibrous mortars is lower than non-fiber mortars.