Effect of aggregate morphology on physical tortuosity of chloride diffusive path at meso-scale of concrete

Abstract

The effect of the aggregate morphology on the chloride diffusivity of concrete was evaluated from the perspective of the physical tortuosity of the diffusive path at meso-scale. Three morphological indices, i.e., convexity, aspect ratio and circularity, were defined. A novel method by using the Fourier transform was proposed to simulate the meso-scale model of concrete. The physical tortuosity was defined based on the chloride diffusive streamline at meso-scale. The effects of aggregate morphological indices on the physical tortuosity were analysed by the multiple linear regression. The results show that: (1) the physical tortuosity increases when: (1) the area fraction of the aggregate increases; (2) the circularity decreases while the convexity and aspect ratio of aggregates increase; 3) the ITZ diffusivity decreases. (2) the area fraction and circularity of the aggregate have the first and second dominant effects on the physical tortuosity, while the effects of the convexity and aspect ratio are ignorable. (3) The chloride diffusivity of the interfacial transition zone between the cement paste and aggregate has a noticeable effect on the physical tortuosity. Based on the results, analytical models were proposed to fast evaluate the physical tortuosity.