Innovative circular concrete for nuclear applications

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Belgium faces a unique and complex challenge in selecting concrete materials for two critical long-term programs in nuclear waste management: near-surface disposal, which is currently progressing but with its second phase still decades away, and deep geological disposal (DGR), which remains in the conceptual and research stages with implementation not expected until beyond the 2100s. These prolonged timelines introduce significant uncertainties in material selection and design strategies, raising questions about whether today's materials will remain viable in the future and how to ensure their durability and performance over centuries. At the same time, the global emphasis on low-carbon solutions has heightened interest in circular concrete, a sustainable option that repurposes industrial by-products to minimize environmental impact. Beyond sustainability, emerging next-generation concretes offer tailored properties, such as improved shielding for nuclear applications, but this innovation prompts key concerns: can existing structural design codes adapt to these novel materials, and how can long-term durability be guaranteed against degradation processes like chloride ingress, carbonation, and shrinkage?

This PhD research holds significant importance by directly contributing to Belgium's structural design strategies for nuclear waste disposal, providing a unique opportunity to operate at the crossroads of sustainability, advanced materials, and nuclear safety, ultimately influencing technologies that will endure for generations.

The scientific objectives of the project include a material-level investigation to gain a phenomenological understanding of the mechanical and durability properties of pre-selected circular concrete formulations, achieved through a design of experiments (DoE) approach with high ordinary Portland cement (OPC) replacement levels ranging from 50% to 90%, incorporating supplementary cementitious materials such as ground granulated blast-furnace slag, metakaolin, silica fume, and limestone fillers. This will involve a quantitative assessment of carbonation, chloride ingress resistance, and shrinkage potential in the targeted formulations. Additionally, the research will evaluate the applicability of current structural design frameworks to these next-generation materials and propose necessary updates to codes and standards where required.

This PhD offers a unique opportunity to engage in cutting-edge sustainability research with tangible real-world impact, address fundamental scientific questions about durability and performance spanning centuries, contribute to Belgium's nuclear safety strategy and future energy infrastructure, and collaborate with leading experts in concrete materials science, structural engineering, and nuclear technology.