A thermo-mechano-chemical activation technique to use quartz rich marine clay for one-part geopolymer preparation

Abstract

This research aims to prepare one-part geopolymer by using the quartz rich marine clay available in Singapore. The higher quartz and lower kaolinite mineral (∼29%) in marine clay is not ideal for a precursor material in geopolymerization. Hence, a novel thermo-mechano-chemical activation process is employed. The process of thermal activation (calcination at 850 C) transforms kaolinite into reactive metakaolin form. The mechanical activation by ball milling alters the surface group of quartz by forming non-bridging oxygen. The chemical activation process is promoted by adding alkali materials, such as NaOH, Na2CO3, and Ca(OH)2. XPS results inform the presence of higher non-bridging oxygen content in Na2CO3 and NaOH based mixtures than Ca(OH)2 based mixture. However, more reactive Q0(0Al) and Q1(1Al) states of 29Si are observed in Ca(OH)2 based mixture from NMR spectra. This resulted in higher compressive strength of Ca(OH)2 based one-part mixture. A temperature curing (at 80 C) is required to facilitate the geopolymerization process.