Title: The Effect of Cracks on Reinforcement Corrosion in High-Performance Concrete in a Marine Environment

Author(s): Karin Pettersson, Oddny Jorgenson, and Per FidjestolI

Publication: Symposium Paper

Volume: 163

Issue:

Appears on pages(s): 185-200

Keywords: chlorides; corrosion; cracking (fracturing); silica fume; underwater structures; Materials Research

DOI: 10.14359/1358

Date: 8/1/1996

Abstract:
Research on high-performance concrete structures in the field have revealed large variations in chloride penetration into the concrete and in corrosion rates of the reinforcement. High-performance concrete is considered to be highly resistant to the initiation of reinforcement corrosion. The rate of chloride transport decreases with time to extremely low values (10 -13/10 - 14 m 2/sec). However, since concrete often is cracked, the occurrence and effect of cracks are also important factors for corrosion initiation in chloride environment. The effect of cracks on the corrosion rate of steel in high-performance concrete is under study in a Swedish research program. Reinforced concrete slabs with cracks of different widths are placed on floating platforms in the sea; the lower part of each slab is submerged, while the upper part is exposed in the splash zone. Corrosion rates, half-cell potentials (CSE), and concrete resistivities are measured regularly. Parallel specimens are similarly exposed in saline solution in the laboratory. This paper presents interim results of this project. The results so far show little effect of crack width and concrete cover thickness. Addition of microsilica (silica fume) is positive, by increasing the concrete resistivity and, thus, reducing the rate of corrosion; the corrosion behavior of such concretes is close to passive, even with cracks.