In Situ Time-Resolved X-Ray Diffraction of Tobermorite Formation Process Under Autoclave Condition
In Situ Time-Resolved X-Ray Diffraction of Tobermorite Formation Process Under Autoclave Condition
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DOI：
10.1111/j.1551-2916.2010.03815.x
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发表时间：
2010-09-01
影响因子：
3.9
通讯作者：
Sato, Masugu
中科院分区：
文献类型：
--
作者：
Kikuma, Jun;Tsunashima, Masamichi;Sato, Masugu
利用同步辐射高能X射线，结合新研制的高压釜和光子计数像元阵列探测器，研究了托贝莫来石的水热形成反应。在饱和蒸汽压力下，在100℃-190℃的温度范围内进行了7.5h的反应时间，时间间隔为4.25min。比较了使用不同类型水泥的两种试件：高早强硅酸盐水泥和普通硅酸盐水泥。在这两种情况下，都清楚地观察到非晶态硅酸钙(C-S-H)、羟基硅灰石(HE)和钙钛矿作为中间物质。提出了非晶态C-S-H和HE作为托贝莫来石前驱体的消耗顺序发生而不是同时发生的可能机制。在同一时间开始检测到对应于不同反射的四个托勃莫来石峰，这表明托勃莫来石在开始时没有任何对特定晶轴的偏好。在反应过程中观察到基面反射的布拉格间距减小，这意味着沿c轴的周期性增加。
Hydrothermal formation reaction of tobermorite has been investigated by in situ X-ray diffraction (XRD) using high-energy X-rays from a synchrotron radiation source in combination with a newly developed autoclave cell and a photon-counting pixel array detector. XRD measurements were conducted in a temperature range of 100 degrees-190 degrees C throughout 7.5 h of reaction time with a time interval of 4.25 min under a saturated steam pressure. Two samples using different types of cements were compared: high early strength Portland cement and ordinary Portland cement. In both cases, noncrystalline calcium silicate hydrate (C-S-H), hydroxylellestadite (HE), and katoite were clearly observed as intermediate materials. A possible mechanism that the consumption of noncrystalline C-S-H and HE as precursors of tobermorite occurs sequentially rather than simultaneously has been suggested. Four tobermorite peaks corresponding to different reflections started to be detected at the same timing, suggesting tobermorite is formed without any preference for a particular crystal axis at the beginning. A decrease in the Bragg spacing of the basal reflection during the reaction was observed, implying the increase of periodicity along the c-axis.