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制备了具有宽范围Ca/(Si+Al)比和Al/Si比的铝掺杂水化硅酸钙(C-A-S-H)系列样品,采用~(27)Al魔角旋转固体核磁共振技术(~(27)Al MAS NMR)半定量研究了Al在C-A-S-H结构中的配位状态。结果表明:Al在C-A-S-H结构的配位形式和位置主要取决于其初始Ca/(Si+Al)比和Al/Si比。当初始Ca/(Si+Al)比低时(0.6和0.8),Al只能取代硅酸盐链硅氧四面体结构中四配位的Si,以Al[4]的形式存在;随着Ca/(Si+Al)比的增加,部分Al开始形成Al[5]和Al[6],且随着Al/Si比的增加,Al[4]的含量减小,Al[5]和Al[6]的总量增加,但Al[4]还是占主要比例,Al[5]的量非常少。Al[4]既可取代桥四面体中的Si也可取代配对四面体中的Si,但优先取代的是桥四面体中的Si,两者取代比并非恒定,而是随着初始Ca/(Si+Al)比和Al/Si比的变化而变化。
A series of aluminum doped calcium silicate (CASH) samples with a wide range of Ca / (Si + Al) ratio and Al / Si ratio were prepared and characterized by ~ (27) Al magic angle rotation solid state nuclear magnetic resonance ) Al MAS NMR) The coordination state of Al in CASH structure was semi-quantitatively studied. The results show that the coordination form and position of Al in C-A-S-H structure mainly depend on its initial Ca / (Si + Al) ratio and Al / Si ratio. When the initial Ca / (Si + Al) ratio is low (0.6 and 0.8), Al can only replace the tetrahedral Si in the silicate tetrahedral structure of silicate chains and exists in the form of Al [4] Al and Al [6]. Al [5] and Al [6] decrease with the increase of Al / Si ratio. Al [5] and Al [ 6], but Al [4] still accounts for the major proportion, and the amount of Al [5] is very small. Al [4] can replace both Si in the bridge tetrahedron and Si in the pairing tetrahedron, but preferentially replace Si in the bridge tetrahedron. The substitution ratio of Al [4] is not constant, but with the initial Ca / ( Si + Al) ratio and Al / Si ratio changes.