Stopping the rot

Corrosion of reinforcing steel in concrete necessitates more than #500 million worth of corrosion prevention to preserve the motorway and trunk road system in England and Wales. All reinforced concrete is susceptible to the effects of air and moisture and will eventually crack and spall. New British Standards for concrete repair (BS EN 1504) are now in place. These emphasise proper design and whole-life costing. The European Commission has established a network on concrete repair, CON REP NET, which consists of a network of companies and research organisations investigating concrete structures across Europe. The principles of cathodic protection are explained and sacrificial anode cathodic protection and impressed current cathodic protection are described. After the collapse of part of the Pipers Row car park in Wolverhampton in 1997, it is now a legal requirement to assess concrete structures in the UK regularly. Corrosion can be assessed by visual inspection, delamination surveys, concrete cover measurements, carbonation depth, chloride content, concrete resistivity measurements and electrochemical potential measurements.