Screening Method Applied to a Large Set of Highway Structures Suspected of Delayed Ettringite Formation

A French highway manager, decided to launch a broad operation in order to detect bridges likely to be affected by DEF and to set up a policy of monitoring and management adapted to various situations. The first step of this operation consisted in identifying structures eligible for an adapted monitoring or immediate mitigation measures, and the challenge was to achieve this task without any specific investigations. A screening method was then developed, based on the information available in the structure files. Through this method, structural elements of the bridges were classified according to the probability of their being affected by DEF, to their visible degradation state and to how it could affect the global serviceability and security of the structure. This method has been applied to a set of 149 bridges. Then, the bridges have been classified amongst five different groups, for which different managing policies are proposed. Since it turned out that this screening method was not adapted to the foundation elements, a specific method was designed to discriminate them. In this communication, we will first describe the main features of the screening methods (the main one, and the one adapted to the foundations). Then, the results obtained for 149 bridges will be presented.