Investigation of microstructure and mechanical properties of geopolymer mortars containing different percentage of nano titanium

In the study carried out within the scope of this thesis, 50% fly ash, 50% blast furnace slag were used as binders, sodium silicate and sodium hydroxide were used for alkali activation. The sodium silicate and sodium hydroxide ratio was selected as 2.5, sodium hydroxide molarity was selected as 14M, and the C (control) microstructures and mechanical properties of geopolymer samples formed by adding nano titanium to the binder ratio at 1% and 2% and samples without nano additives were investigated. UPV (ultrasound transmission rate), water absorption capacity, bending strength, compressive strength tests and SEM (Scanning electron Microscope), EDS (Energy Dispersive Spectroscopy) and 3D computerized tomography images of the samples, which were completed with 28, 56 and 90 days of freeze-thaw curing periods, were examined. As a result, it was determined that geopolymer samples containing 2% nano titanium additive had the highest ultrasound transmission speed, lowest water absorption rate and highest compressive strength values. In terms of flexural strength, both 1% and 2% nano additive samples showed high performance, and since the difference between them was low, it is recommended to prefer 1% nano additive samples from an economic perspective. Microstructure analyses show that nano particles fill the pores, densify the internal structure and contribute to the formation of C-S-H and N-A-S-H gels. While the highest strength loss after freeze-thaw cycles was observed in the control sample, this loss was significantly reduced in nano additive samples. In addition, 3D tomography analyses revealed that nano additives thinned the void structure, reduced the macro void ratio and provided a more durable structure. In general, it was concluded that nano titanium additive improved the mechanical and physical properties of geopolymer structures and increased their resistance to environmental effects.