Non-thermal activation of geopolymer precursors

Abstract

Three non-thermal pre-treatment methods applied to clay, prior to reaction with alkali silicate, have been investigated. Changes to both their physical and chemical properties are presented with discussion pertaining to kaolinite, metakaolin, halloysite and metahalloysite. Two chemical activation treatments using different reagents - sulphuric acid and hydrogen peroxide — are reported. Both result in removal of aluminium from the clays and an increase in specific surface area. The geopolymer products obtained after using each activator are characterised and reported. In the third pre-treatment, edge-face clay particle interactions have been promoted using simple inorganic flocculants to yield the characteristic "house of cards" structure before reaction with alkali silicate and the subsequent products are discussed.