We developed a simplified coupled model to simulate the chloride ingress of cement paste and mortar fabricated with CEM II/C-M (S-LL) and CEM VI (S-V) cements. Diffusion of chloride, calcium, sodium, potassium, sulphate and hydroxyl ions is considered, resulting in a set of coupled mass balance equations. Source and sink terms are introduced to represent the dissolution/precipitation processes due to leaching, and interactions between free chloride and hydrated phases are considered through binding isotherm curves. Electrodiffusion phenomenon is introduced through a modified Poisson equation to enforce local electroneutrality. The model is applied to simulate bulk diffusion tests with exposure solutions containing NaCl, and NaCl + KOH to reduce leaching. The main features observed experimentally are correctly reproduced: a higher chloride content is predicted for the materials made with CEM II binder, and a much clearer peaking behavior near the exposed surface is predicted in the case of NaCl exposure.

中文翻译：

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使用 CEM II 和 CEM VI 水泥制成的水泥浆和砂浆中氯离子扩散试验的模拟


我们开发了一个简化的耦合模型来模拟使用 CEM II/C-M (S-LL) 和 CEM VI (S-V) 水泥制造的水泥浆和砂浆的氯化物侵入。考虑氯离子、钙离子、钠离子、钾离子、硫酸根离子和氢氧根离子的扩散，产生一组耦合的质量平衡方程。引入源项和汇项来表示由于浸出引起的溶解/沉淀过程，并通过结合等温曲线考虑游离氯化物和水合相之间的相互作用。通过修改泊松方程引入电扩散现象以强制局部电中性。该模型用于模拟含有 NaCl 和 NaCl + KOH 的暴露溶液的体扩散测试，以减少浸出。实验观察到的主要特征得到了正确的再现：预计使用 CEM II 粘合剂制成的材料具有更高的氯化物含量，并且在 NaCl 暴露的情况下，预计暴露表面附近会出现更清晰的峰化行为。