考虑界面过渡区非均质性的混凝土弹性模量预测

A Prediction Model for Elastic Modulus of Concrete Considering the Inhomogeneity of Interfacial Transition Zone

混凝土骨料与水泥浆体间界面过渡区(ITZ)厚度虽小,却表现出较强的微观结构非均质性,并对混凝土弹性模量产生显著影响。本研究充分考虑ITZ的非均质特征,由水泥浆体与其中的孔隙形成等效基体,非均质ITZ与骨料形成等效颗粒,再由等效基体与等效颗粒形成混凝土等效均质体,基于细观夹杂理论提出了一种混凝土弹性模量预测的多相夹杂模型,模型预测结果与试验结果吻合较好。定量分析还表明:界面过渡区非均质性对混凝土弹性模量影响显著,ITZ非均质程度越高,混凝土弹性模量越低;弹性模量随界面过渡区厚度、水泥浆体孔隙率的增大而逐渐降低,随骨料含量的增大而增大。

Despite small thickness,the interfacial transition zone(ITZ)between aggregate and cement paste has remarkable influence on the elastic modulus of concrete with its strong inhomogeneity in microstructure.In consideration of the inhomogeneity of ITZ,a multi-phase prediction model for the elastic modulus of concrete was proposed based on the meso-inclusion theory,in which the matrix phase containing voids and cement pastes was considered as the equivalent matrix,and the inclusion phase consisting of aggregate and inhomogeneous ITZ was considered as the spherical equivalent particles with different diameters,and finally an equivalent homogeneous concrete consisting of equivalent matrix and equivalent particles was formed.The predicted values of elastic modulus agreed well with Stock’s experimental results.In addition,quantitative analysis unveiled that the inhomogeneity of ITZ had a profound influence on elastic modulus of concrete:the higher inhomogeneity level of ITZ,the lower of elastic modulus.The elastic modulus of concrete also declined with the increases of ITZ thickness and the porosity of cement paste,while increased with the volume fraction of aggregates.