'Crack-free' and smart `self-sealing' composites with improved microstructure, early-age properties, and durability

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NECESSITY***Infrastructure in Canada and around the world is aging rapidly. According to estimates, the deficit to repair Canadian bridges alone has exceeded $8 billion. A key factor responsible for the reduced life of structures is premature deterioration of construction materials. Our aging infrastructure needs innovative and durable materials for new and rehabilitation projects. There is a dire need to monitor health of our infrastructure using advanced non-contact Non-destructive Evaluation (NDE) techniques to predict safe remaining life of structures.******PROPOSED PROGRAM***In recent years, use of Carbon Nanotubes (CNTs) to reinforce cement-based materials has been investigated. While cementitious composites are traditionally characterized at the macroscale, for full understanding of the influence of CNTs, studies must also be conducted at the nanoscale. The proposed program will focus on studying characteristics at the nanoscale to develop “Nano Scale Hybrid Fiber Reinforced Cement Composites” (NHyFRCC). Hybrid combinations of CNTs and micro carbon fibers will allow lowering the cost while addressing issues faced with mixing and dispersing this combination. One of world's highest magnification electron holography microscope at UVic will be utilized to study the reinforcement dispersion and microstructure modification.******Early-age behavior of cementitious materials greatly influences its long-term durability, hence early-age shrinkage cracking potential will be studied. This self-sealing' and crack arresting ability of NHyFRCC will be quantified using a patented technique invented by the applicant.******Constitutive properties of NHyFRCC in compression, tension, and flexure will be investigated. A mathematical model defining the relationship between the reduced electrical impedance (due to presence of carbon reinforcement) and dimension change will be developed to quantify the sensing capabilities. The developed material will be applied as a thin overlay on an existing instrumented test bench at UVic to simulate field conditions on a bridge deck. Field performance of both materials (including debonding) from the substrate will be monitored using sensors, remote monitoring, and NDE techniques including one of its kind portable Laser Scanning Vibrometer (LSV) in Canada.******BENEFITS***This research program will advance the fundamental understanding about the behavior of cementitious materials reinforced at the nanoscale. NHyFRCC is expected to be the next major breakthrough in the construction industry with wide applicability as a thin overlay that is crack-free, self-sealing and has sensing capabilities. The use of LSV will change the way we assess condition of our aging infrastructure. Highly qualified personnel including graduate and undergraduate students will gain specialized training and valuable experience related to various aspects of infrastructure management.**