The origin of early age expansions induced in cementitious materials containing shrinkage reducing admixtures
The origin of early age expansions induced in cementitious materials containing shrinkage reducing admixtures
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DOI：
10.1016/j.cemconres.2010.12.004
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发表时间：
2011-03
影响因子：
11.4
通讯作者：
G. Sant;B. Lothenbach;P. Juilland;G. Saoût;J. Weiss;K. Scrivener
中科院分区：
文献类型：
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作者：
G. Sant;B. Lothenbach;P. Juilland;G. Saoût;J. Weiss;K. Scrivener
对含有减缩外加剂 (SRA) 的水泥浆、砂浆和混凝土的早期收缩行为的研究表明，这些混合物经常在凝固后不久表现出膨胀。虽然膨胀的幅度已被注意到是水泥化学性质和外加剂用量的函数；扩张的原因尚不清楚。这项研究使用自生变形、X 射线衍射、孔隙溶液分析、热重分析和扫描电子显微镜测量来研究早期性能，并描述使用和不使用 SRA 制成的 OPC 糊剂的膨胀机制。孔隙溶液的组成表明，SRA 的存在增加了溶液中的硅酸钙石过饱和水平，这可能导致更高的结晶应力，从而导致膨胀。这一观察结果得到了所检查系统的变形计算的支持。
Studies on the early-age shrinkage behavior of cement pastes, mortars, and concretes containing shrinkage reducing admixtures (SRAs) have indicated these mixtures frequently exhibit an expansion shortly after setting. While the magnitude of the expansion has been noted to be a function of the chemistry of the cement and the admixture dosage; the cause of the expansion is not clearly understood. This investigation uses measurements of autogenous deformation, X-ray diffraction, pore solution analysis, thermogravimetry, and scanning electron microscopy to study the early-age properties and describe the mechanism of the expansion in OPC pastes made with and without SRA. The composition of the pore solution indicates that the presence of the SRA increases the portlandite oversaturation level in solution which can result in higher crystallization stresses which could lead to an expansion. This observation is supported by deformation calculations for the systems examined.