Microstructure of geopolymer accounting for associated mechanical characteristics under various stress states

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• 作者：Syuan-Jhih Lyu ; Yu-Hsiang Hsiao ; Tai-Tien Wang ; Ta-Wui Cheng ; Tzuu-Hsing Ueng
• 关键词：Geopolymer ; Failure mode ; Stress&ndash ; strain curve ; Microstructural characteristics
• 刊名：Cement and Concrete Research
• 出版年：December, 2013
• 年：2013
• 卷：54
• 期：Complete
• 页码：199-207
• 全文大小：1753 K

文摘

Geopolymer was prepared with various SiO₂/Na₂O mole ratios and mechanical tests and microstructural analyses are performed to investigate how the constituents affect its mechanical behavior in distinct stress states. Laboratory results reveal that the SiO₂/Na₂O ratio affects the polymerization by influencing the formation of silicon Q⁴(mAl) structures. The proportion of Q⁴(4Al) correlates positively with the mechanical characteristics of geopolymer, and the proportion of Q⁴(2Al) correlates negatively with the mechanical characteristics of geopolymer. The proportions of Q⁴(mAl) affect the stress-strain curve and the failure modes of geopolymer under various confining pressures. Three types of stress-strain curves with different peak strengths and plastic deformations are obtained. Incomplete polymerization generates a geopolymer with an imperfect microstructure, which determines the plastic deformation while unloading. Polymerization of a geopolymer affects its apparent cohesion and friction angle. However, the friction-induced strength declines drastically when the failure mode changes from the split mode to the shear mode.