Expansion and Strength Evolution Mechanism of Granite-Based Geopolymer Based on the Reactivity of Calcium Expansive Agents

Abstract

In this article, the role of the reactivity of different heat-treated calcium oxides on the properties of a granite-based geopolymer was investigated for low-temperature application to attain high linear expansion and its strength as well as understanding the probable underlying mechanism. The reactivity of the calcium oxide was investigated using the combination of isocalorimetry and BET. The heat-treated calcium oxides were classified as low reactive, medium reactive, and highly reactive with respect to their heat release in water. In addition to this, the resultant effect of the heat-treated calcium oxide was explored in terms of the exothermic behavior, linear expansions, compressive strength, and the pore volume distribution at a dosage of 0.1 wt% of the solid phase of the geopolymer mix. The results indicate that the different reactivities of the calcium oxide impact the linear expansion as well as the compressive strength. The different reactive calcium oxides improved the linear expansion by at least 100%. However, the low reactive calcium tends to decrease the compressive strength by 35% as a result of overexpansion. Therefore, this calls for the optimization of the reactivity of CaO for its application geopolymer for the best properties.