DETERMINATION OF GEOPOLYMER MORTAR CHARACTERIZATION USING FLY ASH AND PUMICE SAND

Abstract

The cement-making process is one of the highest contributors to atmospheric CO₂ levels, leading to wide consideration and analysis of alternative cement substitutes. One of the materials widely used as a substitute is fly ash, whose properties are similar to cement. It is also abundant in nature, due to the combustion of coal furnaces at the Rum Steam Power Plant. Therefore, this study aims to determine the effect of heating in the geopolymer mortar treatment process. The test object was a cube mortar containing a mixture of cement, fly ash, water, and an activator, with dimensions of 5 x 5 x 5 cm³. The utilized Class-C fly ash also had a calcium content above 10%. In this process, the specimens produced were then heated in an oven for 24 h at temperatures of 20°C, 40°C, 60°C, 80°C, and 100°C. This heating process emphasized the determination of the best temperature responsible for the production of maximum compressive strength in geopolymer mortar. Based on the results, higher heating temperatures led to better compressive strength. This indicated that the 8M and 10M geopolymer mortar produced compressive strength of 17.60 and 18.60 MPa at 100°C heating, respectively. In addition, higher molarity provided better compressive strength in geopolymer mortar.