Alkali activated clay mortars with different activators: Fid-Bau Portal

Alkali activated clay mortars with different activators

Karozou, A. / Konopisi, S. / Paulidou, E. / Stefanidou, M.

Highlights • Develop alkali activated earthen materials with enhanced physical and mechanical properties. • The role of pH has been proven critical for the influence of the alkali activators on the properties of clay mortars. • Water-glass addition (WGS) is as unadvisable activator for clay materials. • Sodium carbonate(SC) is a promising alkali activator even at lower pH values. • Water-glass with the NaOH solution (WGN), is a promising activator in terms of mechanical characteristics and structural cohesiveness of the mortar. • Clay mortars activated with potassium metasilicate (PO) and water-glass with the NaOH solution (WGN), with pH = 12–14, presented the highest compressive strength.

Abstract The purpose of this study was to develop alkali activated earthen materials with enhanced physical and mechanical properties. Specifically, clay mortars were produced, by using various alkaline activators of different pH (values 11–14). The specimens were cured in certain conditions. The physical and mechanical properties of the mortars manufactured were measured at the age of 28 days. Specifically, capillary absorption, shrinkage, Karsten tube penetration, porosity, as well as compressive and flexural strength tests were performed. Additionally, microscopic analysis was also conducted. The results of the experiments indicated the positive effect of potassium metasilicate and the combination of sodium metasilicate with sodium hydroxide solution on mechanical characteristics. The influence of sodium carbonate as an alkali activator was also proven beneficial on the physical properties of the specimens. In conclusion, the alkaline activators with pH > 12, lacked in enhancing physical properties, yet allowed the development of mechanical strength, while the alkaline activators with lower pH values showed reversed results.