Paper Title
Effect of Silica Modulus on Compressive Strength of Volcanic Tuff based Geopolymer Concrete

Abstract
The aim of this present research is to examine effect of silica modulus (Ms), curing temperature and liquid/binder ratio (l/b) on the compressive strength of geopolymer concrete samples produced from volcanic tuff. Volcanic tuff used as raw material was activated with NaOH+ Na2SiO3 according to 0.8 and 0.6 of Ms meaning mass molar ratio of Na2O to SiO2. During the production phase of the sample, three different cure temperatures (90, 105 and 120 °C) and two different alkali liquid/binder (l/ b) ratio (0.5 and 0.6) were used. To each sample produced using this paremeters, changes in compressive strength values of 3, 7, 28 and 90 day sample were determined. The optimum values were determined as 0.8 for silica modulus, 105 °C for curing temperature and 0.6 for l/b ratio. Test results demonstrated that curing temperature and l/b ratio have a significant effect on geopolymerization reaction. Also, the majority of the ultimate compressive strengths of geopolymer concrete samples were obtained as a result of heat curing process. Keywords - Geopolymer Concrete, Volcanic Tuff, Compressive Strength, Silica Modulus