| 摘要: |
| 利用X射线衍射技术（XRD）和29Si固体核磁共振（29Si SSNMR）技术，对不同镁硅摩尔比下氧化镁/硅灰（MgO/SF）试样的水化产物进行了微观结构和形成机理研究.结果表明：生成的水化硅酸镁凝胶（M-S-H）聚合度较高，结构复杂，M-S-H的形成离不开氢氧化镁（MH）的形成和解离，二者在Mg2+的争夺方面存在竞争关系；MgO/SF试样水化反应早期主要生成MH，后期主要生成M-S-H凝胶，龄期的延长有助于M-S-H的聚合，长龄期养护有利于Q1向Q2、Q2向Q3的转化；富镁条件促进了M-S-H的生成，长龄期下Mg2+起拆网作用，支链硅氧四面体含量增多；贫镁条件下试样中剩余大量SF未参与反应，长龄期下Mg2+起补网作用，用于构建层状硅酸盐骨架；M-S-H凝胶是以层状硅氧四面体为主体、包含端链和支链硅氧四面体的复杂非晶相无序结构. |
| 关键词: 镁硅摩尔比 水化硅酸镁凝胶 微观结构 形成机理 |
| DOI：10.3969/j.issn.1007-9629.2021.06.002 |
| 分类号:TQ172.79 |
| 基金项目:陕西省自然科学基金基础研究计划项目（2021JQ-500）；国家重点研发计划课题（2017YFB0309903-03）；陕西省教育厅重点科学研究计划（20JS079）；陕西省教育厅一般专项科学研究计划（20JK0727） |
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| Microstructure of Magnesium Silicate Hydrates in Different Mg/Si Molar Ratios |
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XIAO Jianmin, HU Yaru
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College of Materials Science and Engineering， Xi’an University of Architecture and Technology， Xi’an 710055， China
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| Abstract: |
| The microstructure and formation mechanism of hydration products of magnesia/silica fume（MgO/SF） pastes in different Mg/Si molar ratios were investigated by X-ray diffraction（XRD） and 29Si solid state nuclear magnetic resonance（29Si SSNMR） respectively. The results reveals that the formed magnesium silicate hydrates（M-S-H） is a complex structure with a high degree of polymerization，and the formation of M-S-H is related to the formation and decomposition of magnesium hydroxide （MH）. It is inevitable that M-S-H and MH competes for the acquisition of Mg2+. MH is mainly formed in the early hydration age of MgO/SF pastes while M-S-H is mainly formed in the late hydration age. The prolongation of hydration time is conductive to polymerization of M-S-H， and the long curing age is good for the conversion of Q1 to Q2 and Q2 to Q3. The MgO/SF paste with higher Mg/Si molar ratio promotes the formation of M-S-H， and Mg2+ plays the role of dismantling network in long curing age， as the result， the content of chain tetrahedra increases. A large amount of unreacted SF remains in the MgO/SF pastes with lower Mg/Si molar ratio， and Mg2+ plays the role of network supplementation in long curing age， which is used to construct layered silicate skeleton of M-S-H. M-S-H is a complex amorphous structure with mainly layered tetrahedra and chain tetrahedra and branching chain tetrahedra. |
| Key words: Mg/Si molar ratio magnesium silicate hydrates（M-S-H） microstructure formation mechanism |
