The effect of aggregate shape on the chloride diffusivity of concrete is studied. To represent the heterogeneity of concrete, a three-phase composite ellipse model is constructed and the relative dimensions are determined by calculating the area fraction of interfacial transition zone in a numerical manner. The height of each bar in the lattice mesh is derived analytically. The lattice method is then used to estimate the chloride diffusivity of concrete. After the validity of the numerical method is verified with experimental results, the effect of aggregate shape on the chloride diffusivity of concrete is evaluated in a quantitative manner.

A three-phase composite circle-lattice modeling method was presented for predicting the chloride diffusivity of concrete.Based on the stereological analysis of aggregate distribution,an analytical algorithm for the interfacial transition zone(ITZ) area fraction was given.By applying the principle of energy equivalence,an analytical relationship of chloride diffusivity between the beam element and continuum body was derived.By modeling concrete as a three-phase composite circle,the stiffness matrix of each beam element was determined and the chloride diffusivity of concrete was calculated with the aid of the lattice modeling method.After the validity of the proposed numerical method in this paper was verified with experimental results,the effects of the maximum aggregate diameter,chloride diffusivity of ITZ,aggregate gradation and ITZ thickness were evaluated in a quantitative manner.

A lattice model was developed for predicting the chloride diffusivity of concrete.By applying the principle of energy equivalence,an analytical relationship of chloride diffusivity between the lattice beam and the continuum body was derived.Based on the simulated aggregate distribution and the relative posi-tions between the lattice beams and the aggregates,the stiffness matrix of each lattice beam was deter-mined.By finite element analysis,the chloride diffusivity of concrete was obtained.The effects of the maximum aggregate diameter,chloride diffusivity of interfacial transition zone(ITZ)and aggregate grada-tion were evaluated in a quantitative manner.Based on the numerical results,it iS found that the chloride diffusivity of concrete decreases with the increase of the maximum aggregate diameter,but increases by in-creasing the ITZ chloride diffusivity.It is also found that the aggregate gradation has a larger influence on the chloride diffusivity of concrete.