Novel viscosity- and thixotropy-enhancing agents for innovative construction materials

自固结混凝土等具有自适应流变性的流动性混凝土是一种新兴的技术，可以在不进行传统混凝土所需的任何机械固结的情况下浇筑混凝土。在流动混凝土中，通常掺入增粘外加剂，以提高流动性，并防止在运输、浇注和就地固结作业过程中发生液-固相分离，即渗漏和分离。这份Discovery Grant提案的重点是开发和使用基于红藻的新一代低环境影响、增粘外加剂(VMA)，以设计具有比现行加拿大和国际标准所涵盖的传统混凝土更高工作性的创新流动型混凝土。这项研究计划将(I)将来自藻细胞的卡拉胶聚合物与目前混凝土工业中使用的VMA进行比较；(Ii)建立一个全面的科学基础，以研究卡巴卡拉胶粉末作为VMA在选定的混凝土应用中的性能；(Iii)研究卡拉胶生物聚合物在模型悬浮液(即惰性悬浮液)和水泥体系中的作用模式；(Iv)通过离子调节改善卡拉胶在水泥体系中的性能，包括它们的增稠行为、结构动力学和硬化速率，并确定影响它们在水泥体系中行为的离子机制；(V)验证开发的经离子调节改性的卡拉胶在不同混凝土应用中的性能，包括高层建筑，以减少模板的侧向压力并实现3D打印，并强调其成本效益方面，以支持其被混凝土行业接受。红藻在混凝土中的浓缩是建筑业的一项非常重要的技术进步。这将通过开发高性能建筑材料为建筑业带来增值效益，这些材料具有较低的环境足迹和与在水泥基基质中使用VMA相关的生产成本。拟议的研究计划还将为优化使用卡拉胶生物聚合物设计具有适应流变性和触变性的高性能混凝土提供全面的科学基础，以满足不同的建筑应用。

Flowable concrete with adapted rheology, such as self-consolidating concrete, is an emerging technology that enables the casting of concrete without any of the mechanical consolidation required with conventional concrete. In flowable concrete, viscosity-enhancing admixtures are commonly incorporated to enhance flowability and prevent liquid-solid phase separation, i.e., bleeding and segregation, during transport, placing, and in-place consolidation operations. This Discovery Grant proposal focuses on the development and use of new generation of low-environmental impact, viscosity-enhancing admixtures (VMAs) based on red algae to design innovative flowable concretes characterized by higher workability than those of the conventional concrete covered in current Canadian and international standards. This research program will (i) Investigate the performance of carrageenan polymers derived from algal cell in comparison with the current VMAs used in concrete industry; (ii) Develop a comprehensive scientific basis on the performance of Kappaphycus alvarezii and kappa-carrageenan powders as VMAs in selected concrete applications; (iii) Investigate the mode of action of carrageenan biopolymers in model suspensions (i.e., inert suspensions) and in cementitious systems; (iv) Improve the performance of the carrageenan by ion-ajustement in cementitious systems, including their thickening behavior, structuration kinetics, and rate of stiffening, and identify the ionic mechanisms affecting their behavior in cementitious systems; (v) Validate the performance of the developed carrageenan modified by ionic adjustment in different concrete applications, including tall buildings, to reduce the lateral pressure on formwork and enable 3D printing, and emphasize its cost-effectiveness aspects to support its acceptance by the concrete industry. The beneficiation of red algae in concrete constitutes a very important technological advance in the construction industry. This will deliver value-added benefits to the construction industry by developing high-performance building materials with low environmental footprints and production costs associated with using VMA in cement-based matrices. The proposed research program will also provide a comprehensive scientific basis to support the optimal use of carrageenan biopolymers to design high-performance concrete with adapted rheology and thixotropy for different construction applications.