Investigating workability loss in cement-based pastes during hydration, primarily marked by an irreversible yield stress increase, is crucial for cement-based materials application and development. This paper presents a model for quantifying the irreversible yield stress evolution by incorporating microstructural changes involving physical, chemical, and physicochemical effects. By systematically integrating solid volume and cement interparticle forces, including van der Waals forces and ionic correlation forces from C-S-H bridges, the model is formulated and then validated against experimental results. The relative contribution of interparticle forces and solid volume, as well as polycarboxylate (PCE) superplasticizers impact on yield stress is explored. The results indicate the model effectively captures microstructural changes and predicts the yield stress increase predominantly driven by interparticle forces. Notably, the PCE superplasticizer dosage significantly reduces yield stress, potentially to 0 Pa at saturation plateau. This study provides a comprehensive, quantitative understanding of irreversible yield stress evolution in cement-based paste.

中文翻译：

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基于微观结构的模型，用于量化水泥基浆体在水化过程中不可逆屈服应力的演变

研究水化过程中水泥基浆体的和易性损失（主要表现为不可逆的屈服应力增加）对于水泥基材料的应用和开发至关重要。本文提出了一种通过结合涉及物理、化学和物理化学效应的微观结构变化来量化不可逆屈服应力演化的模型。通过系统地整合固体体积和水泥颗粒间力，包括范德华力和 CSH 桥的离子相关力，制定模型，然后根据实验结果进行验证。探讨了颗粒间力和固体体积的相对贡献，以及聚羧酸盐 (PCE) 超增塑剂对屈服应力的影响。结果表明，该模型有效地捕获了微观结构变化，并预测了主要由颗粒间力驱动的屈服应力增加。值得注意的是，PCE 高效减水剂用量显着降低了屈服应力，在饱和平台时可能降至 0 Pa。这项研究提供了对水泥基浆体中不可逆屈服应力演变的全面、定量的了解。