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Abstract

This thesis investigates the enhancement of durability of concrete structures in marine environments through the development and application of geopolymer concrete (GPC). Recognizing the vulnerability of conventional concrete to marine conditions—characterized by chloride ingress, carbonation, and various forms of chemical attack—this research focuses on the potential of GPC as a more resilient and less carbon-intensive alternative to Portland cement-based concrete. The primary objectives encompass the formulation of a user-friendly GPC mix that can be cast and cured under ambient conditions through membrane curing, a method aimed at overcoming the usability challenges associated with traditional geopolymer concrete production, such as the necessity for high temperature curing and the handling of highly alkaline activators. The study delves into the kinetics of carbonation and chloride diffusion within GPC matrices, evaluating the impact of microcracks and fibers on the degradation and transport mechanisms of these processes. This includes comparative analyses of the effect of bulk diffusion of chloride, carbonation, and the simultaneous effects of both on GPC mixes with different precursors and activators. By advocating for the use of ion chromatography over conventional titration or potentiometric methods, the research introduces a more accurate and efficient approach to assessing chloride penetration, a critical factor in the corrosion of steel reinforcement in concrete structures. This comprehensive study aims to not only advance the understanding of GPC's behavior in harsh marine environments but also to contribute to the development of more sustainable construction practices through the implementation of innovative materials and improved testing methodologies.