压缩荷载作用下混凝土中氯离子扩散行为细观模拟

Meso-scale Simulation of Chloride Diffusivity in Concrete Subjected to Compressive Stress

将外荷载作用的影响等效为外荷载引起的混凝土孔隙率的改变,来研究其对混凝土中氯离子扩散特性的影响,提出了压缩荷载作用下非均质混凝土氯离子扩散行为的细观模型.首先对混凝土在压缩荷载作用下的力学行为进行模拟分析;然后,将荷载作用后的"结果输出"作为氯离子扩散模拟的"初始输入"条件,以单轴压缩荷载为例,将混凝土看作由骨料、水泥浆体基质及界面过渡区组成的三相复合材料,建立了混凝土在力学与物理耦合作用下的细观模型,研究了压缩荷载对混凝土中氯离子扩散特性的影响,得到了氯离子有效扩散系数与压缩应力水平之间的关系式,揭示了压缩应力水平的影响规律.

The effect of the external mechanical stress on chloride diffusivity in concrete can be equivalent to the effect of porosity change on chloride diffusivity induced by external mechanical stress.And based on this viewpoint,a meso-scale model and analysis method were proposed to study the chloride diffusivity in heterogeneous concrete under compressive stress.In this approach,the mechanical simulation was performed first by using the meso-scale finite element method.The outcomes of the mechanical response of concrete were then used as input data for the simulation of chloride diffusivity.The concrete at the mesoscale was assumed to be a three-phase composite composed of aggregate,cement paste matrix and the interfacial transition zones.The meso-scopic numerical model of concrete under uniaxial compressive stress was built to investigate the chloride diffusivity behavior.The effect of compressive stress on chloride diffusivity was explored,and the quantitative relationship between effective chloride diffusion coefficient in concrete and compressive stress level was obtained.