Development of Nanostructured Cementitious Binders Incorporating Calcined Clays

混凝土基础设施的建设主要依赖于波特兰水泥及其水化相作为粘结材料的应用。这需要全球年产约40亿吨水泥，占全球二氧化碳排放量的5%-8%。因此，水泥技术的改进和新型胶凝材料的开发对于减少排放是必要的。煅烧粘土是最有前景的辅助胶凝材料来源之一，可以作为波特兰水泥的部分替代品。它们的应用，除了具有环境优势外，还可以有益于具体性能。偏高岭土是活性最强的煅烧粘土，目前用于需要高强度和更高耐久性的项目。目前，偏高岭土的典型替代量约为波特兰水泥质量的10%-20%。促进偏高岭土更广泛应用的创新方法，并允许更高的替代水平，可以显著减少排放。此外，还需要使用当地可获得且价格较低的煅烧粘土。*本研究计划旨在利用纳米技术方法开发一种新型的煅烧粘土基水泥粘结剂。首先将更深入地了解水泥浆体的纳米结构，包括早期和长期的煅烧粘土，以及在潜在侵蚀性环境条件下的暴露。然后，将使用种子方法来修改水合硅酸钙铝酸盐(C-A-S-H)的纳米结构，C-A-硅酸钙-水合物是混凝土中含有煅烧粘土的主要结合相。晶种方法能够控制C-A-S-H相的化学计量比和结构组成，从而允许针对各种应用对水泥体系进行纳米结构剪裁。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焙烧油砂细尾矿。尾矿管理是艾伯塔省油砂开采部门面临的一项重大环境挑战。该项目将为尾矿管理提供一个实用的解决方案。*拟议的项目将对促进新型和可持续粘结剂在建筑业中的应用产生重大影响。可推广应用于其他工业副产品，如飞灰、矿渣等。此外，它还将制定修改现行标准的基础，以包括长期生产大量煅烧粘土基水泥的规范。一批高素质的多元化人员将接受培训，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.