Molecular silicate and aluminate species in anhydrous and hydrated cements.
Molecular silicate and aluminate species in anhydrous and hydrated cements.
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DOI：
10.1021/ja908146m
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发表时间：
2010-05
影响因子：
15
通讯作者：
A. Rawal;Benjamin J Smith;G. Athens;Christopher L. Edwards;L. Roberts;Vijay Gupta;B. Chmelka
中科院分区：
文献类型：
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作者：
A. Rawal;Benjamin J Smith;G. Athens;Christopher L. Edwards;L. Roberts;Vijay Gupta;B. Chmelka
通过使用先进的固态核磁共振 (NMR) 光谱方法建立无水和水合水泥的成分和分子结构，以区分不同的分子种类以及水泥水化和凝固所发生的变化。一维和二维 (2D) 固态 (29)Si 和 (27)Al 魔角旋转 NMR 方法，包括 T(1) 弛豫时间和化学位移各向异性过滤测量以及极高磁场 (19 T) 的使用，可以解析来自不同硅酸盐和铝酸盐部分的共振，并在复杂的光谱中进行分配。单脉冲 (29)Si 和 (27)Al NMR 谱与 X 射线荧光结果相关，以量化无水和水合水泥中不同的结晶和无序硅酸盐和铝酸盐物质。水合水泥的 2D (29)Si{(1)H} 和 (27)Al{(1)H} 异核相关 NMR 谱建立了水和具有不同 (27)Al 和 (29)Si 物种的羟基部分之间的相互作用。使用 (29)Si T(1)-过滤器可以区分与水泥中含铁成分相关的无水和水合硅酸盐物质，表明它们在水合过程中与硅酸钙和铝酸盐成分分离。白色波特兰和灰色油井水泥的不同成分显示出具有与其水化行为相关的不同分子特征。
The compositions and molecular structures of anhydrous and hydrated cements are established by using advanced solid-state nuclear magnetic resonance (NMR) spectroscopy methods to distinguish among different molecular species and changes that occur as a result of cement hydration and setting. One- and two-dimensional (2D) solid-state (29)Si and (27)Al magic-angle spinning NMR methodologies, including T(1)-relaxation-time- and chemical-shift-anisotropy-filtered measurements and the use of very high magnetic fields (19 T), allow resonances from different silicate and aluminate moieties to be resolved and assigned in complicated spectra. Single-pulse (29)Si and (27)Al NMR spectra are correlated with X-ray fluorescence results to quantify the different crystalline and disordered silicate and aluminate species in anhydrous and hydrated cements. 2D (29)Si{(1)H} and (27)Al{(1)H} heteronuclear correlation NMR spectra of hydrated cements establish interactions between water and hydroxyl moieties with distinct (27)Al and (29)Si species. The use of a (29)Si T(1)-filter allows anhydrous and hydrated silicate species associated with iron-containing components in the cements to be distinguished, showing that they segregate from calcium silicate and aluminate components during hydration. The different compositions of white Portland and gray oilwell cements are shown to have distinct molecular characteristics that are correlated with their hydration behaviors.