Effect of solid-to-liquid ratios on the properties of waste catalyst-metakaolin based geopolymers

摘要

In this study, the changes caused by adding a waste catalyst on the properties of the final product were investigated by applying curing on samples of waste catalyst metakaolin-based geopolymers (WCMBGs) prepared with different solid-to-liquid (S/L) ratios (0.66-0.81) and at different waste catalyst replacement levels (0-40 wt.%). The mechanical properties of WCMBG samples, such as compressive strength and porosity, were determined after the curing process. Thermogravimetric and differential thermal analysis (TG/DTA), Si-29 magic-angle spinning nuclear magnetic resonance (Si-29 MAS NMR), and scanning electron microscopy (SEM) were also used to determine their microstructural properties. When the S/L ratio was 0.76, WCMBG samples contained 10% waste catalyst exhibited greater compressive strength and lower porosity which were comparable with pure metakaolin samples. The TG/DTA results indicated that WCMBG samples contained 10 wt.% waste catalyst had more structural water and geopolymer gels. The results of Si-29 NMR spectroscopy of the samples showed that the major structures of the Si and Al are Q(4)(3Al) and Q(4)(2Al), and strong resonances were between -85 and -95 ppm, respectively. Furthermore, the waste catalyst was the compromising resource material in preparing geopolymers. (C) 2015 Published by Elsevier Ltd.