混凝土杨氏模量预测的三相复合球模型

提出了混凝土杨氏模量预测的三相复合球模型。在细观水平上将混凝土看成是一种由分散相骨料、中间相界面和连续相水泥浆所组成的三相复合材料。应用混凝土细观结构模拟技术, 获得了任一级配骨料的界面体积分数。模拟结果表明, 李氏近似法高估了界面体积分数, 界面体积分数在很大程度上取决于界面厚度、最大骨料直径和骨料级配。引入三相复合球模型, 给出了混凝土杨氏模量的解析解。将解析解与实验结果进行比较, 证实了本文模型的有效性。数值结果也表明, 对于给定的骨料体积分数, 混凝土杨氏模量随着最大骨料直径和界面杨氏模量的增大而增大, 但随着界面厚度的增大而减小, 骨料级配对混凝土杨氏模量也有较大影响。

THREE-PHASE COMPOSITE SPHERE MODEL FOR THEPREDICTION OF YOUNG’S MODULUS OF CONCRETE

A three-phase composite sphere model is presented for the prediction of Young's modulus of concrete. At a mesoscopic level, concrete was considered as a three-phase composite material with aggregates as dispersed phase, interfacial transition zone (ITZ) as interphase and cement paste as continuous phase. Applying the simulation technique of concrete mesostructure, the ITZ volume fraction was obtained for a given aggregate grading. Simulation results show that Li's approximate method overestimates the ITZ volume fraction and that the ITZ volume fraction is dependant on the ITZ thickness, largest aggregate diameter and aggregate grading to a great extent. By introducing a three-phase composite sphere model, the analytical solution of Young's modulus of concrete was given. By comparing the results of both the analytical solution and laboratory experiment, the validity of the model presented is verified. It is also demonstrated by numerical results that, for a given aggregate volume fraction, the Young's modulus of concrete increases with the increase of the largest aggregate diameter and ITZ Young's modulus, but decreases with the increase of the ITZ thickness. The aggregate grading also has a greater influence on the Young's modulus of concrete.