Monitoring corrosion protection provided by fibre reinforced composites

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 represents a summary of some of the most significant findings during that time, as well as a comparison of those results with some of the results obtained in the field investigation.