ITZ volume fraction in concrete with spheroidal aggregate particles and application: Part II. Prediction of the chloride diffusivity of concrete

Abstract

Owing to its importance in the durability assessment of reinforced concrete structures located in a marine or de-icing salt environment, it is essential to determine the chloride diffusivity of concrete. The intention of the present paper is to present an analytical solution for the chloride diffusivity of concrete with aggregate shape effect. A three-phase composite spheroid model for the concrete matrix is proposed to represent the heterogeneous nature of concrete and to take into account the aggregate shape effect. By reducing the three-phase composite spheroid to two two-phase composite spheroids, an analytical solution for the chloride diffusivity of concrete is derived. After the validity of the derived analytical solution is verified with two sets of experimental results, the effects of main factors that affect the chloride diffusivity of concrete are evaluated in a quantitative manner. It is found that the chloride diffusivity of concrete increases with the increase of the thickness and chloride diffusivity of the interfacial transition zone (ITZ), but decreases with the increase of the aspect ratio of spheroidal particles and the maximum aggregate diameter. It is also found that the aggregate gradation has a significant influence on the chloride diffusivity of concrete. The paper concludes that the analytical solution derived here can predict the chloride diffusivity of concrete with reasonable accuracy.