Innovative sensor to better protect concrete coastal structures
City University London and Queen’s University Belfast have developed innovative sensors that will dramatically improve the ability to spot early warning signs of corrosion in concrete.
The sensors which are more resilient and longer lasting than traditional corrosion sensors will make monitoring the safety of structures such as bridges and vital coastal defences much more effective.
The unique sensors can withstand long-term placement within concrete. This means that the condition can be monitored constantly – enabling a warning message to be sent as soon as the conditions for corrosion threshold have been crossed.
Behind the new technique is a trio probe concept which monitors temperature, one for humidity while the other senses chloride and pH levels. Changes in these factors indicate the onset of the potentially destructive corrosion.
Tong Sun, Professor of Sensor Engineering at City and Principal Investigator on the project says: ‘Key to this successful prototype is our monitoring the variation of the sensor signals of a sample as an indicator of corrosion levels. This means we can use optical sensors made of polymer, which is much more resistant to the high alkaline environments of these structures than sensors currently on the market.’
Traditional corrosion sensors have only a limited lifetime of several weeks. The new sensors are instead expected to last for several years.
Professor Sun added: ‘Our design means several probes can be installed semi-permanently in a structure and then connected to a computer data logger, which will constantly collect readings. Remedial work will be simpler, cheaper and more effective at this stage, rather than waiting until there is visible damage, such as parts of the concrete coming away’
The four-year project ‘Corrosion Monitoring Systems for Structures in Extreme Marine Environments’, began in March 2006 and concluded in 2010. It received funding from Engineering and Physical Sciences Research Council (EPSRC).