Maintenance, planning and performing restoration of reinforced concrete structures such as bridges require a precise condition assessment. Very important are information on the actual corrosion state and the future progress of corrosion. The factors influencing the corrosion rate are known as qualitative manner, but there is still a lack of quantitative information on the influence of wetting and drying processes, their intensity and frequency (exposure conditions) on the future behaviour of a structure that can be used by engineers for life-cycle cost calculations.
Provide continuous monitoring of exposure conditions (temperature, humidity) and concrete resistance and chloride content (in-depth profile) in order to get an improved prediction of future corrosion behaviour of different parts of a bridge according to the exposure conditions.
In this research project typical exposure conditions on bridges and substructures are selected and these sites are instrumented with sensors that continuously monitor changes in resistance, chloride content and corrosion rate. It will be thus possible to correlate exposure conditions with the corrosion for different concrete qualities and exposure conditions. Especially the critical chloride content (frequently set to 0.4 % by weigh of cement) will be established and realistic values will be defined.
Developed online monitoring system has been used successfully in various projects in practice.
The advantage of the new measurement system is that the installation of the sensor units requires no wiring and is therefore installed quickly and easily. The data loggers are optimized from the viewpoint of electronics on minimal power consumption, so that the devices durability is 5 to 10 years maintenance free function.