INVESTIGATION OF THE EFFECTS OF VARIOUS OPERATING PARAMETERS ON GEOPOLYMER MORTARS MADE FROM NATURAL MINERALS AND INDUSTRIAL WASTE MATERIALS

In this study, fly ash (FA) from Sivas/Kangal thermal power plant and blast furnace slag (BFS) from Bolu cement industry were used as the main binder materials. Based on both the literature and preliminary tests, samples were prepared with 85% blast furnace slag and 15% fly ash (85BFS15FA) as the main binder. In addition, the effect of geopolymer main binders and different additives such as mine waste, marble powder, and titanium dioxide were evaluated under various working conditions. The aim was to observe the effect of three different levels and 6 different parameters on the geopolymer samples using the Taguchi optimization method. Accordingly, the L27 orthogonal matrix was created. Three different molar ratios (8M, 10M, 12M) of sodium hydroxide (NaOH) solution and sodium silicate (Na2SiO3) solution were used as alkaline activators. Physical and some mechanical tests such as flexural strength, compressive strength, water absorption, and void ratio were performed on the 7, 28, 56, and 90-day samples, and Taguchi and ANOVA statistical analyses were performed on the 90-day samples. The highest compressive strength observed among 108 samples reached 65.75 MPa in the S20 samples (90-day). Taguchi and ANOVA statistical analyses identified curing temperature as the most significant parameter influencing the geopolymer samples. Additionally, the Signal to Noise ratio data indicated that the optimal curing temperature, determined to be the most effective based on the 'Larger is better' criterion, was found to be 75 ̊C.