Comportement mécanique et durabilité du béton vert à base de ciment vert renforcé de plastique recyclé fonctionnalisé

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Background: Each year, value created by the Canadian construction industry totals over $250 billion USD. Here, reinforced concrete is an important technology because it can be formed into complex shapes and resists corrosive environments better than steel or wood. However, concrete's lifecycle has negative environmental effects, with cement production alone accounting for 5% of global CO2 emissions. Our long-term goal is to develop concrete with similar mechanical properties as current technology but with a lower carbon footprint and greater sustainability: green concrete. Our approach uses green cements reinforced with recycled plastic. Reinforcement with single-use plastics (polypropylene (PP), polyethylene terephthalate (PET)) can help manage plastic waste, while improving corrosion resistance and strength. To date, the success of plastic-cement composites has been very limited because plastic hydrophobicity prevents interaction with hydrophilic cements. Biological materials, such as seashells and bone, stem their excellent mechanical properties not only from their combination of biominerals and organic polymers, but also from the strong integration between these components. Inspired by these observations, we demonstrated that modifying the surface chemistry of plastic fibers by adding phosphate binding sites improves their integration with inorganic cements and subsequently increases the fracture toughness. These surface chemistry modifications are achieved using diazonium treatments, which we have shown to be extremely versatile with the ability to covalently bind phosphate and carboxylate moieties to a wide range of plastics.Our hypothesis is that cements with a lower carbon footprint reinforced with surface-treated recycled plastics will result in concrete with competitive mechanical behavior and improved sustainability compared to current standards. Our aims are to optimize diazonium treatments to functionalize plastic waste, examine and optimize mechanical behavior by varying cement composition and the geometry of plastic reinforcement, analyze material sustainability through artificial accelerated aging and perform a lifecycle assessment to investigate sustainability and environmental impact.Methods & Expertise: Green concrete will be fabricated from Portland and magnesium cements and reinforced with recycled plastic (PP, PET). Plastic surfaces will be treated with diazonium chemistry to introduce phosphate and carboxylate groups. Surface interactions will be investigated with electron microscopy and x-ray photo-electron spectroscopy. Mechanical properties will be measured in terms of compressive strength, bending strength and fracture toughness. Material sustainability will be assessed with artificial accelerated aging through fatigue testing, thermal cycling, and exposure to corrosive environments. A lifecycle assessment will analyze the full impact of the product from raw materials through disposal to determine the costs per year and the environmental impact in comparison to current technology.The team has complementary expertise in materials design, mechanical characterization in multi-scale materials, material surface modification and interface phenomena in materials, development of inorganic cements, and lifecycle analysis. Expected outcomes: If successful, the development of green concretes will reduce carbon emissions from the construction industry, promote the use of recycled materials, and increase sustainability of building materials.