Improving shotcrete through modeling and research

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An increasing amount of financial and human resources are currently dedicated to repair and rehabilitation of our concrete infrastructure. The need for methods of intervention that are rapid, efficient, economical and, above all, durable is more important than ever as it is the key to durable design and service life optimization. Shotcrete is regularly used to place concrete on vertical and overhead surfaces without the need for formwork. Although the technique has been found to be rapid and economical, concerns still exist about its durability. The proposed research program was elaborated to meet three specific objectives: - Understand and describe the significance of the placement techniques on the microstructure of concrete and its evolution over time. - Pursue the modeling effort to understand and optimize the behavior of fresh shotcrete as it is transported in the hose, and as it goes through and exits the nozzle. - Offer unique training to a large number of students. The deliverables of this project will lead to a better understanding of the effect of the pneumatic application process on the structure and microstructure of the material produced, and therefore on its durability. The novelty and uniqueness of the approach is the coupling of full-scale production of shotcrete in a controlled environment and the optimization brought by the modeling; this will lead to both improvements of existing mixture design and new and innovative mixture design. The body of information generated added to that already in place in the shotcrete community will allow introducing and promoting the acceptance of new materials which are required to respond to the more and more stringent requirements imposed on shotcrete such as low rebound, high early strength, high abrasion resistance, extreme exposure conditions, emergency repairs, etc.