Monitoring corrosion protection provided by fibre reinforced composites: Fid-Bau Portal

Monitoring corrosion protection provided by fibre reinforced composites

Wheat, H.G. / Jirsa, J.O. / Fowler, D.W.

A laboratory research programme was initiated to complement a field investigation in which composite materials were being used to wrap 12 corrosion damaged bridges in Texas. The programme, which started in 1997 and was sponsored by the Texas Department of Transportation, included more than 60 laboratory specimens that were designed to simulate bridge bents and columns. The primary objective was to determine whether composite wrapping could be used as a means of rehabilitating corrosion damaged structures. Since that time, the laboratory specimens have been subjected to intermittent exposure to saltwater conditions. They have been monitored using corrosion (half-cell) potential measurements that indicate the probability of corrosion activity. In addition, corrosion rate measurements have been determined on some of the specimens after exposure. Selected specimens have been removed from testing and subjected to thorough post exposure examination on a regular basis. The focus has been on the difference in the behaviour of the wrapped and unwrapped specimens. The composite systems used included a vinyl ester resin and two epoxy resins in combination with a selected fabric containing glass fibres. The laboratory specimens have been exposed to saltwater for more than four years. This paper focused on three of the nine specimens that were removed after four years of exposure; one wrapped with a commercial epoxy system, one with a generic vinyl ester system, and one that was unwrapped. Forensic analysis of the three specimens confirmed earlier results that chloride contents after exposure were lower for the wrapped specimens. The wraps also helped to minimise corrosion activity in the wrapped portions that were initially free from cracks and chlorides. Detailed analysis of each bar in each specimen removed after four years revealed a difference in the corrosion activity associated with the wrapped and unwrapped specimens. Under the particular circumstances of the investigation, both composite wrapping systems inhibited chloride ingress and its effect on corrosion.