The focus of the construction industry is now on developing a sustainable multifunctional material that improves the energy efficiency, functionality, and flexibility of the built environment. Hence, considering the potential of sea-based cementitious composites (CC), this study investigates their capabilities to address the shortcomings of conventional concrete in relation to environmental impacts, mechanical performance and electrical resistivity.
The research initiates a discussion of the multifunctional capabilities and ionic conductivity of sea-based composites (C-SW-SS) that entail aggregates of marine sand. The findings highlight that although there is a lack of conductivity with marine aggregates, they facilitate the formation of C-S-H or cation-exchanging calcium-silicate hydrate phases, leading to a composite with potential for energy storage, self-sensing capabilities and ionic conductivity.
Thus, continuing on this, the work introduces an innovative concept, ‘ion bridge’, that considerably improves the composites’ electrical properties. The incorporation of chopped carbon fibers (CCFs) as conductive fillers along with the cellulose microsheets (CMS) as dispersants form a strong conductive network in the SM or sea-based mortar, and this is then backed by C-S-H ion sponges, accomplishing a significant reduction in electrical resistivity, making these as strong candidates to be used in chloride control, energy storage and self-sensing structures in concrete.
Further, the SM’s mechanical properties are comprehensively investigated. The findings show that C-SW-SS mortars, especially when supported with optimal concentrations of CCFs and CMS, show higher compressive, tensile, and flexural strength in comparison to traditional mortars. Hence, it is noted that these materials have potential for high-performance construction use, especially in conditions where durability and strength are important.
The thermoelectric properties of the sea-based mortars (SM) are investigated, demonstrating their potential for energy harvesting. The composites exhibit p-type thermoelectric behavior, with significant Seebeck coefficients and power factors, even without the use of specialized conductive fillers. This suggests substantial potential for integrating thermoelectric functionality into large-scale construction projects, contributing to more energy-efficient building practices.
Lastly, dual functionality are also investigated via their electrochemical chloride extraction (ECE) and self-sensing capabilities. The collective endeavors of CCFs and CMS not only improve the sensitivity of stress but also enhance the efficiency of chloride extraction, providing a new approach to corrosion resistance and smart concrete.
Precisely, this thesis contributes to the development of sustainable multifunctional CC. By focusing on domestically accessible sea-based resources and reinforcement strategies, the study opens the doors for the next generation of infrastructure materials that are energy-efficient, resilient and smart.