Impregnation as a Method of Active Bridge Mainte- nance

In Sweden, there are in all 27 000 bridges. The Swedish Road Administration is responsible for 12 000 of these bridges. 50 percent of them are built between 1950 and 1980 and have, thus, obtained an age at which the need of maintenance and repair usually increases. A hypothesis is that the preventive bridge maintenance could be optimised through thorough analyses of properties of the bridge element, actual mechanical stresses, and ambient microclimate. An active maintenance is defined as the optimised preventive maintenance allowing different measures to be selected for different bridge elements. The opposite is passive maintenance, a form of maintenance that is equal to all bridge elements independent of element properties, actual stresses, and ambient microclimate. Impregnation has been regarded as one of the most suitable methods of active bridge maintenance. This paper summarizes a literature survey on active bridge maintenance with focus on impregnation.