Slag-based One-part Alkali-Activated Materials for Sustainable Constructions

Abstract

This work deals with the development of innovative cement-free plastering mortars with enhanced thermal properties. To this end, one-part alkali-activated slag-based materials were manufactured, by adding aluminum powder as expanding agent to reduce the density and expanded glass to improve thermal insulation. Different recipes were developed by varying the water content and the alkali-activator. The results show that the admixture containing sodium silicate meets the requirements for a lightweight plastering mortar in terms of mechanical strength (class CSII), despite exhibiting slightly elevated thermal conductivity with respect to that required for a type T2 (0.28 vs. 0.20 W/mK). The admixture with potassium silicate shows instead noteworthy values of both density and thermal conductivity, although its mechanical performance is very limited, due to its higher water content. Nevertheless, this last formulation could potentially serve as a viable starting point for the development of a sustainable cement-free construction material for the insulation of the building envelope. Further studies in this direction are currently underway.