Abstract
One approach to the corrosion protection of composite bridges is to construct an enclosure round the steel girders which support the reinforced concrete deck. The environment inside a number of such bridge enclosures has been characterised in terms of corrosivity, temperature, relative humidity and time of wetness. Results show that enclosure can produce an atmosphere in which the corrosion rate of initially uncorroded steel is very low. Moreover, enclosure substantially reduces the rate of corrosion of steel which is already corroding. The benefits of the enclosure technique are compared with standard protection methods, particularly painting.