Evaluating an Eco-Olivine Nanosilica as an Alternative Silica Source in Alkali-Activated Composites

Abstract

In this study, an eco-olivine nanosilica is produced from natural olivine, and then used as an alternative silicate source in synthesizing the silicate-based alkali activator. The effects of silicate origin and dosage on activator characteristics, fresh behaviors, gel structure, strength, porosity, and shrinkage are investigated. The results indicate that the soluble silica content in the alternative activators is above 98%; compared with the traditional waterglass-based mixes, the nanosilica-derived ones exhibit similar behaviors in the early age reaction, gel structure, and mechanical properties. As some important engineering properties, nanosilica-based mixtures also exhibit increased workability, prolonged setting time, slightly increased porosity, and shrinkage. Thus, by using this alternative silica source in alkali-activated materials, a more sustainable product with less cost and carbon emission can be achieved, and with comparable key performances.