The influence of inorganic admixtures on early cement hydration from the point of view of thermodynamics
The influence of inorganic admixtures on early cement hydration from the point of view of thermodynamics
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从热力学角度探讨无机外加剂对水泥早期水化的影响
DOI：
10.1016/j.conbuildmat.2020.119777
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发表时间：
2020-10-30
影响因子：
7.4
通讯作者：
Cheng, Xin
中科院分区：
文献类型：
--
作者：
Chen, Heng;Feng, Pan;Cheng, Xin
钙盐等无机化学物质作为水泥水化的促进剂已被广泛应用，但其作用机理尚不清楚。在这方面的贡献，水泥系统与氯化钙（0.06 M和0.12 M），氢氧化钾（0.28 M和0.56 M）和盐酸（0.09 M和0.18 M）的热力学分析结合定量分析这些系统的量热曲线。量热试验表明，氯化钙和盐酸可提高水化速率，而氢氧化钾用量较低则会降低水化速率。热力学分析表明，在所有体系中，C3 S溶解的化学驱动力不断增大，而水化硅酸钙（C-S-H）析出的化学驱动力不断减小，表明C3 S的溶解可能是水泥水化的限制步骤。硅酸三钙（C3 S）溶解的化学驱动力与硅酸盐峰的强度和硅酸盐峰出现的时间均呈正相关，而与诱导期的长短呈负相关。此外，孔隙溶液中钙离子浓度与C3 S溶解的化学驱动力呈正相关，说明钙离子浓度对无机外加剂的作用起着重要的调节作用。这项工作发现了C3 S溶解在水泥早期水化中的关键作用，也为无机化学物质对水泥水化的影响和水泥水化机理提供了新的见解。(C)2020爱思唯尔有限公司保留所有权利。
Calcium salt and other inorganic chemicals have long been used as the accelerators of cement hydration; however, the underlying mechanism remains to be resolved. In this contribution, thermodynamic analysis of cement systems with calcium chloride (0.06 M and 0.12 M), potassium hydroxide (0.28 M and 0.56 M) and hydrochloric acid (0.09 M and 0.18 M) were combined with quantitative analysis of the calorimetric curves of these systems. Calorimetric tests show that calcium chloride and hydrochloric acid would increase hydration rate, whereas lower dosage of potassium hydroxide would decrease hydration rate. Thermodynamic analyses show that in all the systems, the chemical driving force of C3S dissolution keeps increasing whereas that of calcium silicate hydrates (C-S-H) precipitation keeps decreasing, indicating that the dissolution of C3S could be the limiting step of cement hydration. This is further confirmed by the facts that the chemical driving force of tricalcium silicate (C3S) dissolution is positively related to both the intensity of the silicate peak and the occurring time of the silicate peak time, and that the chemical driving force of C3S dissolution is negatively related to the length of induction period. Furthermore, the calcium concentration of pore solution is positively related to the chemical driving force of C3S dissolution, implying that calcium concentration could play a critical role in regulating effect of inorganic admixtures. This work finds the crucial role of C3S dissolution in early cement hydration and also provides new insight into the effect of inorganic chemicals on cement hydration and the mechanism of cement hydration. (C) 2020 Elsevier Ltd. All rights reserved.