Electrically Conductive Nanocomposite Coating for Strain and Health Monitoring

FRP bridge decks are designed to withstand high load levels and a lifetime of several ten years, facing an extremely high number of load cycles. The fatigue life and degradation of the mechanical properties are needed to be essentially considered during the service of the FRP deck. In the present study, a novel electrically conductive coating was developed with a function of strain monitoring for the FRP bridge deck. An epoxy resin was modified with multi-walled nanotube (MWCNT) in order to achieve electrical conductivity. Processing, structure and properties of the MWCNT-epoxy nanocomposite were optimized, and the correlation between the strain level and electrical conductivity of the coating was set up. The conductivity of the coating on the FRP bridge deck is tracked with a simple electrical measurement, and the strain of the FRP bridge deck is obtained through the determined conductivity ∼ strain relationship. It is worth noting that the damage modes of the coatings (also the coated FRP surface) can be determined from the conductivity curves. Together with the easy application and data collection, such coating has a high potential for the application in stress/strain and health monitoring.