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

具有适应性流变的可流动混凝土，如自固结混凝土，是一种新兴技术，它使混凝土的浇筑无需传统混凝土所需的任何机械固结。在可流动混凝土中，通常加入增粘外加剂以增强流动性并防止液固相分离，即在运输、放置和原位固结过程中发生出血和离析。这项发现基金提案的重点是开发和使用新一代低环境影响、基于红藻的增粘外加剂（vma），以设计创新的可流动混凝土，其特点是比当前加拿大和国际标准中覆盖的传统混凝土具有更高的和易性。该研究计划将(i)研究从藻类细胞中提取的卡拉胶聚合物的性能，并与目前混凝土工业中使用的vma进行比较；发展一个全面的科学基础，研究作为vma的Kappaphycus alvarezii和kappa- carragean粉末在选定的具体应用中的性能；（iii）研究卡拉胶生物聚合物在模型悬浮液（即惰性悬浮液）和胶凝系统中的作用方式；（iv）通过离子调节胶凝体系改善卡拉胶的性能，包括其增稠行为、结构动力学和硬化速率，并确定影响其在胶凝体系中的行为的离子机制；(v)验证所开发的经离子调整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。红藻在混凝土中的选矿是建筑工业中一项非常重要的技术进步。这将通过开发具有低环境足迹和生产成本的高性能建筑材料，为建筑行业带来增值效益，这与在水泥基基质中使用VMA相关。拟议的研究计划还将提供全面的科学基础，以支持最佳使用卡拉胶生物聚合物来设计具有适应流变学和触变性的高性能混凝土，以适应不同的建筑应用。

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.