Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
J Am Chem Soc. 2010 Jun 2;132(21):7321-37. doi: 10.1021/ja908146m.
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.
采用先进的固态核磁共振（NMR）光谱方法来确定无水和水合水泥的组成和分子结构，以区分不同的分子种类以及水泥水化和凝固过程中发生的变化。一维和二维（2D）固态（29）Si 和（27）Al 魔角旋转 NMR 方法，包括 T1-弛豫时间和化学位移各向异性过滤测量以及使用超高磁场（19 T），可以分辨和分配复杂光谱中不同的硅酸盐和铝酸盐部分的共振。单脉冲（29）Si 和（27）Al NMR 光谱与 X 射线荧光结果相关联，以定量无水和水合水泥中不同的结晶和无定形硅酸盐和铝酸盐种类。水合水泥的 2D（29）Si{(1)H}和（27）Al{(1)H}异核相关 NMR 光谱确定了水和羟基与不同的（27）Al 和（29）Si 物种之间的相互作用。使用（29）Si T1-过滤器可以区分与水泥中铁含量成分相关的无水和水合硅酸盐物种，表明它们在水化过程中与硅酸钙和铝酸钙成分分离。白波特兰水泥和灰色油井水泥的不同组成具有与其水化行为相关的独特分子特征。
