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

背景资料：每年，加拿大建筑业创造的总价值超过2500亿美元。在这里，钢筋混凝土是一项重要的技术，因为它可以形成复杂的形状，比钢铁或木材更能抵抗腐蚀环境。然而，混凝土的生命周期对环境有负面影响，仅水泥生产一项就占全球二氧化碳排放量的5%。我们的长期目标是开发具有与当前技术类似的机械性能但具有更低的碳足迹和更大的可持续性的混凝土：绿色混凝土。我们的方法使用了用回收塑料加固的绿色水泥。使用一次性塑料(聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET))进行加固可以帮助管理塑料垃圾，同时提高耐腐蚀性和强度。到目前为止，塑料-水泥复合材料的成功非常有限，因为塑料的疏水性阻止了与亲水性水泥的相互作用。生物材料，如贝壳和骨，其优异的机械性能不仅来自于它们与生物矿物和有机聚合物的结合，也来自于这些成分之间的紧密结合。在这些观察的启发下，我们证明了通过添加磷酸盐结合位来改变塑料纤维的表面化学可以改善其与无机粘结剂的结合，从而提高断裂韧性。这些表面化学修饰是通过使用重氮处理实现的，我们已经证明，重氮处理具有非常广泛的用途，能够以共价方式将磷酸盐和羧酸盐部分结合到各种塑料上。我们的假设是，与当前标准相比，表面处理过的再生塑料增强的碳足迹较低的水泥将产生具有竞争力的力学性能和更好的可持续性。我们的目标是优化重氮化处理以使塑料垃圾功能化，通过改变水泥成分和塑料增强材料的几何形状来检查和优化力学行为，通过人工加速老化来分析材料的可持续性，并执行生命周期评估以调查可持续性和环境影响。方法和专业知识：绿色混凝土将由硅酸盐和镁水泥制成，并使用再生塑料(PP、PET)进行加固。塑料表面将用重氮化学处理，以引入磷酸盐和羧酸基。表面相互作用将用电子显微镜和X射线光电子能谱来研究。机械性能将通过抗压强度、弯曲强度和断裂韧性进行测量。材料的可持续性将通过疲劳测试、热循环和暴露在腐蚀性环境中的人工加速老化来评估。生命周期评估将分析产品从原材料到处置的全面影响，以确定与当前技术相比的每年成本和环境影响。该团队在材料设计、多尺度材料的力学表征、材料表面改性和材料中的界面现象、无机水泥的开发以及生命周期分析方面拥有互补的专业知识。预期结果：如果成功，绿色混凝土的开发将减少建筑业的碳排放，促进再生材料的使用，并增加建筑材料的可持续性。

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.