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新拌的水泥基材料是典型的屈服应力流体,由不同粒径的固体颗粒形成的悬浮液组成,其固体颗粒的范围从亚微米级到厘米级。当受到剪切作用时流体内部存在两种相反的作用,分别会导致流体发生剪切稀化和剪切增稠,流体的流变特性由二者共同决定。本文对新拌水泥基材料的流变机理、模型以及流变仪测量方面的研究进展进行了综述,对具有代表性的流变模型,包括Bingham模型、Modified Bingham模型和Herschel-Bulkley模型等的特点、适用条件等进行了分类总结。影响流变特性的主要因素是固体颗粒体积分数和剪切速率,当剪切速率与剪切应力之间存在非线性关系时,难以根据流变仪的测量数据建立流变方程。本文中讨论了一些建立模型的新方法,通过计算流体力学和离散元理论相结合可以较好地模拟水泥基材料流变特性。
The fresh cementitious material is a typical yield stress fluid consisting of a suspension of solid particles of different particle sizes with solid particles ranging from submicron to centimeter. When subjected to shearing, there are two opposite effects inside the fluid, which cause the shear thinning and shear thickening of the fluid, respectively. The rheological properties of the fluid are determined by both. In this paper, the rheological mechanism and model of fresh cement-based materials and the research progress of rheometer measurement are summarized. The representative rheological models, including Bingham model, Modified Bingham model and Herschel-Bulkley model, are reviewed , Applicable conditions were classified summary. The main factors influencing the rheological properties are the solid particle volume fraction and the shear rate. It is difficult to establish the rheological equation based on the rheometer measurement data when there is a non-linear relationship between the shear rate and the shear stress. In this paper, we discuss some new methods to establish the model. By combining computational fluid dynamics with discrete element theory, the rheological properties of cement-based materials can be well simulated.