Enhancing alkali-activation of metakaolin-based geopolymers using dry water

Abstract

A water-in-air Pickering emulsion, also called dry water, was produced with hydrophobic nanosilica, which was then employed in this study to examine its possible benefit upon the alkali-activation of metakaolin-based geopolymers. The dry water was produced to contain a nanosilica fraction varying from 10 to 20%. The results show that the presence of dry water improves the workability of the fresh alkali-activated paste, and leads to a shorter setting time. It imparts higher compressive strength, both at 7 and at 28 days. XRD and SEM-EDS reveal that dry water effects a greater degree of geopolymerization and a denser micro-structure. The median pore size was 50% smaller and the total porosity dropped by 28%, in the presence of dry water. An optimum nanosilica-to-emulsion ratio of 15% was seen to yield the most satisfactory fresh and hardened properties. This study shows that dry water promotes the alkali-activation of metakaolin and emerges as an expedient agent for sustainable construction practice.