CORROSION RESISTANCE IN STEELS FOR MOTORWAY BRIDGES . DEVELOPMENTS IN STRUCTURAL ENGINEERING. PROCEEDINGS OF THE FORTH RAIL BRIDGE CENTENARY CONFERENCE, HERIOT-WATT UNIVERSITY, ENDINBURGH, SCOTLAND, AUGUST 21-23, 1990. VOLUMES 1 AND 2

During the 1980s steel has shown a steady increase in share of the highway bridge market and one of the factors that has led to this growth has been improvements in corrosion protection. The principal corrosion protection options that are available to the bridge engineer are discussed. The majority of steel bridges are protected by the application of painting systems. Typical Department of Transport specified systems involve the application of 5 or 6 coats to produce a total dry-film thickness of 200-300 microns and require minor maintenace after 6 years and major maintenance after 15 years. Recently a high-build elastomeric urethane coating has been used on a new steel bridge over the River Ythan. Plate girders were blast cleaned in the shops and treated with a single, spray-applied coat to a minimum dry-film thickness of 1000 microns. A period of at least 20 years to first maintenance is anticipated. Weathering steels account for about 10% of the steel bridge market. They form a stable protective oxide coating and achieve a low terminal corrosion rate. Their limitations are described and suggestions for their future use are made. Finally, the enclosure of structural steelwork on composite bridges is described as a method of corrosion protection which will receive much greater emphasis in the future.(A) For the covering abstract of the conference see IRRD 832490. (Author/TRRL)