Modifiaction of limestone alkali-activation by addition of grinded glass

Abstract

The development of alkali-activated materials for construction has grown over the past 20 years due to the reduction of environmental impact compared to cementitious materials. In case of materials with high calcium content (limestone) activated by soda solution (without silicate), it is possible, with an optimized formulation, to obtain mortars with compressive strength of 20MPa. The activation products are pirssonite and portlandite. However, due to their solubility, these materials lose much of their mechanical strength in high humidity environments. In order to resolve this problem, finely grinded glass, from recycling bottles, was added at different amounts. The impact of this addition was studied in terms of reaction process, fresh and hardened properties. The addition of grinded glass led to formation of new products, probably hydrated, which are responsible of a significant reduction of mortar porosity but the compressive strength, at 28 days, decreased overall 23% compared to mortars without grinded glass. However, the behavior in humidity environments was significantly improved and the compressive strength was maintained after a leaching test.