The role of chemistry and fineness of metakaolin on the fresh properties and heat resistance of blended fly ash-based geopolymer

Abstract

Sensible thermal energy storage using concrete as a storage medium is a promising technology that helps minimize energy in power plant. The purpose of this study is to evaluate the potential benefits of metakaolin (MK) as a partial substitute for fly ash-based geopolymer for heat resistance. As a partial substitute (5 and 20 wt.%) for fly ash (FA), nine metakaolins containing different alumina contents were selected. In order to assess their potential for storing high-temperature thermal energy, physical and microstructural analyses were performed before and after heat exposure up to 500 °C. Low packing density limits the workability of some metakaolins and increases water demand in pastes. The mechanical properties of geopolymer weaken as the temperature is raised (< 500 °C). The high alumina content of some metakaolins, however, helps to mitigate strength loss during high temperatures. A higher dosage of metakaolin has also shown to prevent this deterioration of strength. A reduction in strength under heating is caused by both dehydration and dehydroxylation. The higher fineness and alumina content of MK have demonstrated significant potential to enhance the heat resistance of FA-based geopolymers. As a result, the geopolymer paste developed is suitable for being used in heat-resistant applications.Article Highlights Fly ash was the main precursor of as prepared alkali-activated binders. Adding metakaolin enhances the resistance of hardened materials under thermal load. The higher the alumina content inside metakaolin is, the higher the performance is.

Geopolymers: Advanced Materials in Medicine, Energy, Anticorrosion and Environmental Protection

“…For example, Abbass et al indicated that a high content of alumina in metakaolin enhanced the heat resistance of geopolymer materials. Moreover, it was also demonstrated that the higher the fineness of the metakaolin, the better the thermal properties of the geopolymer [81].…”

Effective Stabilization of Cadmium and Copper in Iron-Rich Laterite-Based Geopolymers and Influence on Physical Properties

“…or natural raw materials (clay, lateritic soils, volcanic ash, etc.) [11][12][13][14][15]. The stabilization mechanism in geopolymer materials can differ significantly depending on the type of heavy metals and the nature of the aluminosilicate used.…”