Preparation and characterization of high-strength calcium silicate boards from coal-fired industrial solid wastes

• Published in: International journal of minerals, metallurgy and materials metallurgy and materials, 2015-08, Vol.22 (8), p.892-900
• Main Authors: Cao, Zhao, Cao, Yong-dan, Zhang, Jin-shan, Sun, Chun-bao, Li, Xian-long
• Format: Article
• Language: English
• Subjects: Air pollution control; Calcium; Calcium silicate hydrate; Calcium silicates; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Ettringite; Flexural strength; Flue gas; Flue gas desulfurization; Fly ash; Fourier transforms; Glass; Gypsum; High strength; Hydration; Industrial wastes; Infrared spectroscopy; manufacture; calcium; Materials Science; Metallic Materials; Natural Materials; Pollution control equipment; Quartz; recycling; board; Slag; solid; Solid wastes; Surfaces and Interfaces; Thin Films; Tribology; waste; X-ray diffraction
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-015-1147-2

To realize the comprehensive utilization of coal-fired industrial solid wastes, a novel high-strength board was prepared from calcium silicate slag, fly ash, and flue gas desulfurization(FGD) gypsum. The changes in mineral phases, chemical structure, and morphology during hydration were investigated by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), and scanning electron microscopy(SEM). A traditional board made from quartz and lime was prepared as a reference. The novel board not only consumes a lot of solid wastes, but also meets the strength requirement of the class-five calcium silicate board according to the Chinese Standard JC/T 564.2—2008. Microanalysis showed that hydrated calcium silicate gel(C-S-H(I)), ettringite, tobermorite, and xonotlite were successively generated in the novel board by synergistic hydration of the mixed solid wastes. The board strength was improved by the formation of tobermorite and xonotlite but decreased by unhydrated quartz. It was demonstrated that quartz was not completely hydrated in the traditional board. As a result, the flexural strength of the traditional board was much lower than that of the novel board.