Investigation of the use of ground basic pumice and silica fume as binders in geopolymer mortars

This thesis study has important implications for reducing the negative impact of traditional Portland cement concrete on our living environment, reducing energy requirements and reusing waste materials in concrete production. The aim of this study is to prepare geopolymer mortar samples using pozzolan based ground basic pumice and silica fume and to determine the physical, mechanical and durability properties of these geopolymer mortars. In this study, geopolymer mortars were produced by determining how much ground basic pumice and silica fume would be used as a result of the trial mixtures. Sodium hydroxide was used as alkali activator solution and the molar concentration/ratio of it were determined by test results. Flexural/compressive strength, capillary water permeability, water absorption, and different binder ratios of cementless mortars produced by using ground basic pumice and silica fume were investigated. The curing process of the mortars was carried out under laboratory conditions at room temperature and in an oven at 60°C. As the polypropylene fiber ratio increased, the fresh unit volume mass decreased. At the same time, a decrease in the spreading diameter was observed with the increase in fiber. Even though this is seen as a negative effect on workability, it is an important feature in terms of cohesion of fresh mortar. Dry and water-saturated dry surface bulk density values of the blends tended to decrease with the increase of added polypropylene fibers. According to the results of the water absorption tests performed on the polypropylene fiber added mortars, the water absorption values increased with the increase in the fiber content. It has been observed that mixtures with high void ratio have high water absorption ability. Although there was an increase in the apparent void ratio, it was concluded that the fibers prevented the opening of capillary voids and the expansion of existing voids. When the mechanical properties of the test results were examined, the use of fiber showed a positive effect. According to the flexural and compressive strength test results on polypropylene fiber added mortars, it was observed that fiber additive increased the strength of the mortars.