Investigation of structural material production with geopolymerization method using alumina silicate resources

Recently different types of aluminosilicates have been used as a replacement for metekaolin and fumed silica in synthesis of geopolymeric materials. This study investigates the suitability of pumice from the Turkish origin as a replacement for metakaolin in synthesis of geopolymeric structural materials. Considering that the starting material affects the resultant geopolimer, as-received pumice was characterized by XRF, XRD and NMR analysis. As-received and metakaolin added pumices were dissolved in a NaOH and sodium silicate solutions. Thus, a series of geopolymer pastes were obtained by introducing the different proportions of usual metakaolin and fumed silica. The slurries were casted into a poliasetal mold to obtain geopolymer samples for mechanical tests and cured in a constant 50 °C temperature/humidity oven for 24 h, and then left one week for additional curing at ambient temperature. The microstructural and mechanical characterizations of final geopolymer samples were based on XRD, SEM, 3-point bending and compressive tests. The mechanical tests were made according to ASTM standards and measured values were further analyzed by Weibull statistics. By the assessment of the results showed that the pumice can be used as an alternative aluminosilicate source by improving its reactivity with small amount of metakaolin and fumed silica additions in a structural materials production.