Significance of Paste-Sand Interfaces in Micromechanical Behavior of Concrete

拟议调查的目的是引入一种新的 混凝土细观力学性能研究的探讨 将材料科学和结构工程学结合起来， 根据对质量和 水泥浆砂颗粒的定量意义和作用 混凝土应力应变行为的界面， 承受纯单轴压缩力。在 实验部分，砂浆圆柱体具有砂粒， 测试不同填料特性的应力， 应变行为及其微观力学性能。 混凝土 还将测试气缸，以比较 粗骨料与砂粒。 然后将这些数据 与使用SEM的微观结构特性相关， 背散射电子分析和图像分析能力， 压汞法和电导率 测量技术在分析部分， 开发的描述微观力学行为， 具体并定量地界定了 界面参数在模型开发中， 断裂力学方法采用有限元 方法作为分析裂纹扩展和局部化的工具 变形 裂纹扩展与砂土的关系 将研究颗粒堆积特性。 在这 方法，界面被视为弱面或初始缺陷。 这项调查的结果可以推广到其他案件 包括耐久性、徐变和收缩考虑，以及 常规与先进混合料优化配合比 水泥基复合材料

The objective of the proposed investigation is to introduce a new approach to the study of the micromechanical behavior of concrete by combining its materials science and structural engineering aspects, based on the assessment of the qualitative and quantitative significance and role of cement paste-sand particle interfaces in stress-strain behavior of concrete that is subjected to pure uniaxial compressive force. In the experimental part, mortar cylinders having sand particles of different packing characteristics are tested for their stress- strain behavior and their micromechanical properties. Concrete cylinders will also be tested to compare the significance of the coarse aggregate with the sand particles. These are then correlated with the microstructural properties using SEM with backscatter electron analysis and image analysis capabilities, mercury intrusion porosimetry, and electrical conductivity measurement techniques. In the analytical part, a model is developed which describes the micromechanical behavior of concrete and defines quantitatively the role and significance of interfacial parameters. In the model development a nonlinear fracture mechanics approach is taken using the finite element method as a tool to analyze crack propagation and localized deformation. The relationship between crack propagation and sand particles packing characteristics will be studied. In this approach, interfaces are treated as weak planes or initial flaws. Results of this investigation can be extended to other cases including durability, creep, and shrinkage considerations, and optimum mixture proportioning of conventional and advanced cement-based concrete composites.