Cellulose ethers (CE) are generally used as viscosity modifying admixtures in cement-based materials. However, previous investigations scarcely focus on the effect of CE on the calcium leaching behaviors of host materials. This work studied the calcium leaching behaviors in CE-containing cement pastes. The resistance to the calcium leaching was evaluated by the leaching depth, pH values and compressive strength. Electrochemical impedance spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and mercury intrusion porosimetry were implemented to reveal changes in the cement hydrates and microstructural properties to disclose the underlying mechanisms. Results indicate that CE decrease the amounts of CH and C-S-H because of the retardation effect on cement hydration. CE-containing samples exhibit CH crystals with eroded edges and a smaller size, and C-S-H phases with a disordered morphology and smaller dimension, thus increasing the rate of decomposition of CH and C-S-H. CE increases the total porosity by inducing capillary pores and large pores, which results in the decreasing pore connectivity and increasing tortuosity in cement pastes. The degradation of cement pastes during calcium leaching is prominently decided by the content of CH and C-S-H, instead of the initial pore structure. Consequently, CE increase the leaching degree of cement pastes with increasing the CE contents. Additionally, a non-destructive method is proposed to determine the leaching depth for CE-added cement pastes through establishing relationships between the leaching depth and damage factor.

中文翻译：

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含水泥浆体纤维素醚的钙浸出行为研究


纤维素醚 （CE） 通常用作水泥基材料中的粘度改性外加剂。然而，以前的研究很少关注 CE 对主体材料钙浸出行为的影响。这项工作研究了含 CE 水泥浆中的钙浸出行为。通过浸出深度、pH 值和抗压强度来评估对钙浸出的抵抗力。采用电化学阻抗谱、X 射线衍射分析、热重分析、傅里叶变换红外光谱、扫描电子显微镜和压汞孔隙度测定法揭示水泥水合物和微观结构性质的变化，揭示其潜在机制。结果表明，由于对水泥水化的延迟作用，CE 减少了 CH 和 C-S-H 的量。含 CE 的样品表现出边缘侵蚀和较小尺寸的 CH 晶体，以及形态无序且尺寸较小的 C-S-H 相，从而增加了 CH 和 CSH 的分解速率。CE 通过诱导毛细孔和大孔来增加总孔隙率，从而导致水泥浆中的孔隙连通性降低和弯曲度增加。钙浸出过程中水泥浆体的降解主要取决于 CH 和 CS-H 的含量，而不是初始孔隙结构。因此，CE 随着 CE 含量的增加而增加水泥浆的浸出度。此外，还提出了一种非破坏性方法，通过建立浸出深度和损伤因子之间的关系来确定添加 CE 的水泥浆的浸出深度。