Effect of Alkaline Activator Rest Time on the Compressive Strength of Geopolymer Mortar: A Taguchi-Based Study

The cement industry is a major contributor to global CO۲ emissions, prompting the development of sustainable alternatives such as geopolymer binders. This study investigates the compressive strength behavior of geopolymer mortar synthesized using Taftan pozzolan and activated with a combination of sodium silicate and sodium hydroxide. The primary focus is on evaluating the influence of rest time of the alkaline activating solution―۱ hour versus ۲۴ hours prior to mixing on the compressive strength of the resulting mortar. Sixteen mix designs were generated using the Taguchi method to systematically vary three parameters: water-to-solids ratio, silica- to-sodium oxide molar ratio, and cement replacement percentage. All specimens were cured for ۲۸ days under ambient conditions before testing. The results show that extending the rest time of the activating solution generally enhances compressive strength, though the degree of improvement varies depending on the mix composition. These findings highlight the importance of considering rest time in conjunction with mix design parameters when optimizing the mechanical performance of geopolymer mortars.

کلیدواژه ها:

Geopolymer mortar ، Compressive strength ، Rest time ، Taguchi design