Development of Nanostructured Cementitious Binders Incorporating Calcined Clays

混凝土基础设施的建造主要依赖于波特兰水泥及其水化相作为粘结材料的应用。这需要全球每年生产约40亿吨水泥，占全球二氧化碳排放量的5-8%。因此，有必要改进水泥技术和开发新的水泥粘结剂，以减少排放。煅烧粘土是补充胶凝材料的最有前途的来源之一，可以用作波特兰水泥的部分替代品。它们的应用，除了环境优势外，还可以有益于混凝土性能。偏高岭土是最具活性的煅烧粘土，目前用于需要高强度和改善耐久性的项目。偏高岭土的典型替代水平目前为波特兰水泥的约10- 20质量%。促进偏高岭土更广泛应用和允许更高替代水平的创新方法可以显著减少排放。此外，需要使用当地可获得的较便宜的煅烧粘土。该研究计划旨在使用纳米技术方法开发一类新的煅烧粘土基水泥粘结剂。首先将提供对水泥浆体的纳米结构的更深入的理解，该水泥浆体在早期和长期以及在暴露于潜在的侵蚀性环境条件下将煅烧粘土结合。然后将使用接种方法来修改钙铝硅酸盐水合物（C-A-S-H）的纳米结构，其是掺入煅烧粘土的混凝土中的主要粘结相。接种方法能够控制C-A-S-H相的化学计量和结构组成，从而允许针对各种应用对水泥体系进行纳米结构定制。将研究三种类型的煅烧粘土。它们包括高纯度和水泥级偏高岭土以及煅烧油砂细尾矿。尾矿管理是阿尔伯塔省油砂开采行业面临的一项重要环境挑战。该方案将为尾矿管理提供切实可行的解决方案。*该计划将对促进新型可持续粘合剂在建筑行业中的应用产生重大影响。它可以扩展到其他工业副产品，如粉煤灰和矿渣的使用。此外，还将为修改现行标准奠定基础，以便纳入长期生产大容量煅烧粘土水泥的规格。一批高素质的人才将接受培训，成为加拿大和世界各地设计和实施可持续基础设施材料的领导者。

Construction of concrete infrastructure relies primarily on the application of Portland cement and its hydrated phases as a binding material. This requires the annual production of about 4,000 million tonnes of cement worldwide which accounts for 5-8% of global CO2 emissions. Improvements in cement technology and development of new cementitious binders are, therefore, necessary to reduce the emissions. Calcined clays are among the most promising sources of supplementary cementitious materials which can be used as partial substitutions for Portland cement. Their application, in addition to the environmental advantages, can benefit the concrete performance. Metakaolin, the most reactive calcined clay, is currently used in projects where high strength and improved durability are required. Typical replacement levels of metakaolin are currently about 10-20% by mass of Portland cement. Innovative approaches to promote wider applications of metakaolin, and permit higher replacement levels can significantly reduce the emissions. In addition, the use of locally available and less expensive calcined clays is needed.***This research program is aimed at developing a new class of calcined clay-based cementitious binders using a nanotechnology approach. A more in-depth understanding of the nanostructure of cement pastes incorporating calcined clays at the early ages and long-term as well as in exposure to potentially aggressive environmental conditions will first be provided. A seeding method will then be used to modify the nanostructure of calcium-alumino-silicate-hydrates (C-A-S-H), the principal binding phases in concrete incorporating calcined clays. The seeding method enables control of the stoichiometry and structural composition of the C-A-S-H phases permitting nanostructural tailoring of cement systems for various applications. Three types of calcined clays will be studied. They include a high purity and a cement grade metakaolin as well as calcined oil sands fine tailings. Management of tailings is an important environmental challenge for the oil sands mining sector in the Province of Alberta. This program will provide a practical solution for the tailing management.***The proposed program will have a significant impact on promoting the application of novel and sustainable binders incorporating calcined clays in the construction industry. It can be extended for the use of other industrial by-products such as fly ash and slag. In addition, it will develop the basis for modifying the current standards to include specifications for production of high-volume calcined clay-based cements in the long-term. A diverse group of highly qualified personnel will be trained to become leaders in designing and implementing sustainable infrastructure materials in Canada and worldwide.