Title: Influence of Cracks on Chloride Ingress into Concrete

Author(s): Olga Garces Rodriguez and R. Doug Hooton

Publication: Materials Journal

Volume: 100

Issue: 2

Appears on pages(s): 120-126

Keywords: concrete; crack; scanning electron microscope

DOI: 10.14359/12551

Date: 3/1/2003

Abstract:
Although it is generally recognized that cracks promote the ingress of chlorides in concrete, the lack of sufficient knowledge on this subject does not yet allow reliable quantification of their effects. In the current study, the influence of artificially created, parallel-wall cracks with widths ranging from 0.08 to 0.68 mm on chloride ingress was examined. The effect of crack wall surface roughness was evaluated as well. Cracked and uncracked samples were exposed to a 40-day chloride bulk diffusion test. Lateral movement of chlorides from the crack wall into the bulk of the sample was analyzed using scanning electron microscopy with energy dispersive x-ray (SEM/EDX). Based on the results, it was concluded that chloride diffusion in concrete was independent of either crack width or the crack wall roughness for the ranges studied. The transecting, parallel-wall cracks were found to behave like a free concrete surface, resulting in a case of two-dimensional diffusion and greatly promoting chloride ingress.