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

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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.