Effect of pH-value of Na2SO4 solution on the structure of C-(A)-S-H gels in Portland cement pastes
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摘要: C-（A）-S-H凝胶的结构不仅受水泥基材料自身组成的影响，更受其所处环境的影响。本文利用固体核磁共振（NMR）并结合去卷积技术，探究硫酸盐侵蚀溶液pH值对硅酸盐水泥浆体中C-（A）-S-H凝胶结构的影响。结果表明：硫酸盐侵蚀过程中，前期进入凝胶中的Al3+后期又会脱出，使凝胶中四配位铝（Al[4]）/Si比值降低。侵蚀溶液pH值的降低促进了凝胶中Al[4]的脱出，使Al[4]的峰位向负值移动；同时也促进了[SiO4]（[AlO4]）四面体间的聚合，使C-（A）-S-H凝胶平均分子链长（MCL）增加。此外，侵蚀溶液pH值的降低，促进了浆体的水化，但抑制了浆体中钙矾石（AFt）的生成。Abstract: C-(A)-S-H gels are not only affected by the composition of cement-based materials, but also affected by the environment. The effect of pH-values of Na2SO4 solution on the structure of C-(A)-S-H gels was studied by solid-state nuclear magnetic resonance (NMR) with deconvolution technique. The results show that the Al[4]/Si value of C-(A)-S-H gels decreases in sulfate attack process, due to Al3+ entering into gel early and coming out later. The decrease of the erosion solution pH value promotes the migration of Al[4] from C-S-H gels, which leads to the peak position of Al[4] shifting to a negative value. It is found that the average molecular chain length (MCL) of C-S-H gel increases due to the polymerization among[SiO4] ([AlO4]) tetrahedra. In addition, the degree of hydration of the pastes is improved with the decrease of the pH-value, which is not favorable to formation of AFt.
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Keywords:
- sulfate attack /
- C-S-H gel /
- pH-value /
- Al[4]/Si /
- average molecular chain length
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期刊类型引用(2)
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2. 王亭亭，李巍，郑婵，陈文哲. 石墨烯纳米片/Si-Pb二元复合凝胶玻璃光限幅性能研究. 红外与激光工程. 2019(11): 23-27 . 百度学术
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