Increasing mechanical strength and acid resistance of geopolymers by incorporating different siliceous materials

This study, for the first time, reports using hollow glass microsphere waste (HGMW) and quartz powder (QP) to improve compressive strength and sulphuric acid resistance of fly ash/slag based geopolymers (AAFS), which is aimed for oil-gas well cementing and other uses where acid corrosion medium exists. Due to the lower reactivity of HGMW and QP compared to fly ash and slag, their incorporation needs a high temperature curing process (at 80 °C in this study) to obtain a certain extent of reaction. The resulting product with 5% HGMW and 5% QP exhibits higher compressive strength than the neat AAFS. After sulphuric exposure for 90 days, the high temperature cured samples show less susceptibility to the acid attack in comparison with those samples cured at room temperature and those without HGMW and QP. It is confirmed that better resistance of acid attack of the 80 °C cured mixture with addition of HGMW and QP than the neat AAFS mixture is due to the more crosslinked and compact microstructure. In addition, the volume stability of the geopolymer binders is also assessed and is found to be satisfying under both the ambient and high temperature conditions.