Thermally-treated asbestos-cement wastes as supplementary precursor for geopolymeric binders: CO emission and properties.

This article explores the impact of thermally treated asbestos-cement waste (ACW) on metakaolin-based geopolymers, using liquid sodium silicate (LSS) and liquid potassium silicate (LKS) as alkali activators. Through statistical mixture design, various formulations were tested for rheological parameters, mineralogical composition, efflorescence mass, electrical conductivity, compressive strength, and CO emissions. Formulations with sodium silicate exhibited higher yield stress compared to those with potassium silicate, while flash setting occurred in LKS-activated mixtures with high ACW content. Alkali activator content significantly affected mechanical strength and leachate electrical conductivity. CO emissions were higher for LKS-activated formulations but lower for those with more ACW. Finally, by incorporating ACW, it was possible to optimize the formulations, resulting in high compressive strength, reduced free ions, and reduced negative environmental impact.