Understanding Rheology of Cement-based Materials through Intergrated Experiments and Computations at Multiple Scales

本项目的目的是开发一个预测模型来预测水泥基材料的流变行为。该模型使用浸没边界法(IBM)-离散元方法(DEM)相结合的方法，在多个尺度上将单个颗粒行为与水泥基材料的整体流变行为联系起来。主要的研究活动将包括：(1)利用原子力显微镜(AFM)实验来校准/验证IBM-DEM耦合模型，并捕捉水泥体系(纳米尺度)中的颗粒间相互作用；(2)建立改进的IBM-DEM耦合模型来预测水泥浆体在简单剪切流中的整体流变行为(中观尺度)；以及(3)通过各种水泥浆体的流变实验(细观和宏观尺度)来评估该模型的预测能力。这种研究方法最终将在未来产生更好的混凝土宏观模型。通过实验、理论和建模，该项目将对水泥基材料的流变行为有更好的了解。开发的模型将允许通过在混凝土实践中根据特定的流变性要求优化配合比来进行更经济的设计。关于颗粒相互作用的信息可以被水泥工业用于在水泥制造过程中改变水泥的化学和物理性质。拟议的工作需要混凝土材料、多相流建模以及纳米表面工程和力学方面的跨学科知识，因此，在这个项目期间，学生将接受各种补充研究技术的培训。

The objective of this proejct is to develop a predictive model for predicting rheological behavior of cement-based materials. Using a coupled immersed boundary method (IBM) - discrete element method (DEM), the model will link individual particle behavior to the bulk rheological behavior of cement-based materials at multiple scales. The major research activities will include (1) utilizing atomic force microcopy (AFM) experiments to calibrate/validate a coupled IBM-DEM model and to capture the interparticle interactions in a cement system (nanoscale); (2) establishing a refined coupled IBM-DEM model to predict bulk rheological behavior of a cement paste in simple shear flow (mesoscale); and (3) assessing the predictive capability of the model via rheological experiments of various cement pastes (meso and macro scales). This research approach/methodology will eventually lead to better macroscale models of concrete in future. Through experiments, theory and modeling, the project will provide a better understanding of the rheological behavior of cement-based materials. The developed model will permit more economical designs by optimizing mix proportions for specified rheological requirements in concrete practice. The information on the particle interaction can be adapted by the cement industry for modifying cement chemistry and physical properties during the cement manufacturing process. The proposed work requires interdisciplinary knowledge in concrete materials, multiphase flow modeling, and nanoscale surface engineering and mechanics, and therefore, students will be trained in a variety of complementary research techniques during this project.