Self-sensing cementitious composites for infrastructure health monitoring

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The aging infrastructure in Canada and other parts of the world is susceptible to defects that may disrupt its performance. Traditional maintenance procedures rely on periodic inspections, which are time-consuming, labor-intensive, costly and highly subjective. Permanent monitoring systems use advanced sensing technologies to provide real-time information about the state of structures so that deficiencies can be detected and repaired promptly. ***This timely research focuses on developing self-sensing cementitious materials that can be used as sensors in long-term monitoring of concrete structures such as bridge decks. Cementitious sensors, prepared by incorporating conductive carbon fibres and nanotubes in cement paste, are self-sensing because changes in applied strain correspond to proportional changes in the electrical resistivity of the material. Cementitious sensors are particularly attractive because their similar physical and mechanical properties allow for seamless installations and compatibility. The sensors can be embedded in the structure for local sensing, or applied as a thin overlay or “sensing skin” to spatially map strains and defects. ***Previous research has successfully demonstrated the strain-sensing capability of cementitious sensors. This multidisciplinary research program will take the critical next steps towards field implementation through four short term objectives: (1) Developing and establishing standard fabrication methods for cementitious sensors and examining their durability; (2) Quantifying the effects of complex loading and external environmental factors on sensor response; (3) Developing cementitious sensing skins and using the spatial distribution of resistivity to detect strain and damage; (4) Validating the use of cementitious sensors/skins through large-scale tests. In the long-term, the research will evaluate the field performance of cementitious sensors and develop a decision-making framework that translates sensor outputs to timely and appropriate maintenance decisions. ***This research has the potential to revolutionize the way concrete structures are monitored by providing a less expensive and more compatible alternative to current sensing devices. More importantly, cementitious sensing skins will enable full-field damage detection versus discrete measurements offered by conventional sensors. With these applications, Canadians can benefit from safe, resilient and smart infrastructure. The proposed program will create a vibrant research environment where graduate and undergraduate students collaboratively conduct cutting-edge laboratory experiments and perform advanced numerical analyses. The trained highly qualified personnel will specialize in the necessary skills to implement and manage sensing systems that monitor the health of Canadian infrastructure.