Performance of slag based Shirasu geopolymer cured under ambient condition

Abstract

A pyroclastic flow deposit called Shirasu was used as aluminosilicate in producing geopolymer incorporating ground granulated blast furnace slag as an admixture for enhancing the performance when cured under ambient conditions. Past research on the use of Shirasu alone showed very low gain in compressive strength and required longer duration of continuous heat curing under oven dry condition. Hence, in this study addition of 10–50% of slag in the place of Shirasu is considered. A mixture of sodium hydroxide and sodium silicate solution with different ratios were used as alkaline activators. Compressive strength, X-ray diffraction, differential thermal analysis and sulfuric acid immersion test were performed to study the behavior of the geopolymer under varied mix proportion and curing conditions. From the test results, it was observed that the initial and long term strength development of Slag-Shirasu geopolymer improved and acid resistance increased with the addition of slag.