界面裂纹对混凝土氯离子扩散系数的影响

将混凝土看成是一种由骨料、界面和水泥石基体所组成的三相复合材料,平行界面裂纹位于骨料表面,据此构建出圆形单元细胞模型,并采用推进前沿法尽可能准确地剖分单元细胞,然后应用有限元法获得混凝土氯离子扩散系数的数值解。通过与已有实验结果的比较,初步验证了文中数值方法的有效性,并定量评价了混凝土细观结构对氯离子扩散系数的影响。数值计算表明,混凝土氯离子扩散系数随裂纹张开角、界面厚度的增大而增大,但随着骨料直径的增大而减小,且骨料级配对混凝土氯离子扩散系数有很大的影响。

Effect of interfacial cracks on chloride diffusion coefficient of concrete

Concrete was considered as a three-phase composite material,consisting of aggregate,interfacial transition zone(ITZ) and cement paste,with interfacial cracks located on the aggregate surfaces,and thus a circular unit cell model was developed.Since the ITZ thickness was much smaller than the aggregate size,the advancing front method was adopted to divide the unit cell as accurately as possible,and the finite element method was then used to obtain the numerical solution to the chloride diffusion coefficient of concrete.The validity of the numerical method proposed herein was preliminarily verified with the experimental data,and the effect of the mesostructure of concrete on the chloride diffusion coefficient was evaluated quantitatively.Based on the numerical result,it is found that the chloride diffusion coefficient of concrete increases with the increase of the interfacial crack angle and ITZ thickness,but decreases with the increase of aggregate diameter,and that the aggregate gradation is of significant influence on the chloride diffusion coefficient of concrete.