Interaction of ordinary Portland cement and Opalinus Clay: Dual porosity modelling compared to experimental data
Interaction of ordinary Portland cement and Opalinus Clay: Dual porosity modelling compared to experimental data
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DOI：
10.1016/j.pce.2017.01.004
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发表时间：
2017-06-01
影响因子：
3.7
通讯作者：
Cloet, V.
中科院分区：
文献类型：
--
作者：
Jenni, A.;Gimmi, T.;Cloet, V.
混凝土和粘土之间的相互作用是由孔隙水中的强化学梯度驱动的，并涉及两种材料中的矿物反应。在放射性废物处置库的背景下，这些反应可能会影响安全相关的粘土性能，如膨胀压力，渗透性或放射性核素retaination.Interfaces之间的普通波特兰水泥和蛋白石粘土显示较弱，但更广泛的化学干扰相比，低pH值水泥和蛋白石粘土之间的接触。作为化学反应的结果，孔隙度的变化发生在水泥-粘土界面。这些变化更强烈，在低pH值水泥的情况下可能导致完全的孔隙堵塞。通过反应性输运模拟预测孔隙堵塞对扩散溶质通量、水泥熟料化学和相反应动力学的大小非常敏感。例如，考虑粘土中的阴离子贫化孔隙率会显著影响界面处的总体扩散和孔堵塞。本文提出了一种近似于Donnan平衡的双孔隙度模型的新概念，并将其应用于普通波特兰水泥- Opalinus粘土界面。该模型的预测进行了比较，从水泥-粘土相互作用（CI）在特丽山地下岩石实验室的现场实验数据（Switzerland），它们代表了5年的相互作用。主要观察结果如界面处水泥的脱钙作用、从界面脱离的粘土中Mg的富集以及从界面脱离的水泥中S的富集，通过新模型方法进行定性预测。模型结果揭示了多个耦合过程，创建所观察到的功能。如果关键输入参数（弯曲度、反应动力学，特别是粘土矿物）的不确定性可以降低，则建模数据和测量数据的定量一致性可以得到改善。(C)2017爱思唯尔有限公司版权所有
Interactions between concrete and clays are driven by the strong chemical gradients in pore water and involve mineral reactions in both materials. In the context of a radioactive waste repository, these reactions may influence safety-relevant clay properties such as swelling pressure, permeability or radionuclide retention.Interfaces between ordinary Portland cement and Opalinus Clay show weaker, but more extensive chemical disturbance compared to a contact between low-pH cement and Opalinus Clay. As a consequence of chemical reactions porosity changes occur at cement-clay interfaces. These changes are stronger and may lead to complete pore clogging in the case of low-pH cements. The prediction of pore clogging by reactive transport simulations is very sensitive to the magnitude of diffusive solute fluxes, cement clinker chemistry, and phase reaction kinetics. For instance, the consideration of anion-depleted porosity in clays substantially influences overall diffusion and pore clogging at interfaces. A new concept of dual porosity modelling approximating Donnan equilibrium is developed and applied to an ordinary Portland cement - Opalinus Clay interface. The model predictions are compared with data from the cement-clay interaction (CI) field experiment in the Mt Terri underground rock laboratory (Switzerland), which represent 5 y of interaction.The main observations such as the decalcification of the cement at the interface, the Mg enrichment in the clay detached from the interface, and the S enrichment in the cement detached from the interface, are qualitatively predicted by the new model approach. The model results reveal multiple coupled processes that create the observed features. The quantitative agreement of modelled and measured data can be improved if uncertainties of key input parameters (tortuosities, reaction kinetics, especially of clay minerals) can be reduced. (C) 2017 Elsevier Ltd. All rights reserved.