Effect of flexure induced transverse crack and self-healing on chloride diffusivity of reinforced mortar

摘要

Cracks in reinforced concrete are unavoidable. Durability is of increasing concern in the concrete industry, and it is significantly affected by the presence of cracks. The corrosion of reinforcing steel due to chloride ions in deicing salts or sea-water is a major cause of premature deterioration of reinforced concrete structures. Although, it is generally recognized that cracks accelerate the ingress of chlorides in concrete, a lack of consensus on this subject does not yet allow reliable quantification of their effects. The present work studies the relationship between crack widths and chloride diffusivity. Flexural load was introduced to generate cracks of width ranging between 29 and 390 mu m. As crack width was increased, the effective diffusion coefficient was also increased, thus reducing the initiation period of corrosion process. For cracks with widths less than 135 mu m, the effect of crack widths on the effective diffusion coefficient of mortar was found to be marginal, whereas for crack widths higher than 135 mu m the effective diffusion coefficient increased rapidly. Therefore, the effect of crack width on chloride penetration was more pronounced when the crack width is higher than 135 mu m. Results also indicate that the relation between the effective diffusion coefficient and crack width was found to be power function. In addition, a significant amount of self-healing was observed within the cracks with width below 50 mu m subjected to NaCl solution exposure. The present research may provide insight into developing design criteria for a durable concrete and in predicting service life of a concrete structures.