Mechanical Properties and Microstructural Analysis of Concrete Designed for Low and Intermediate Level Nuclear Waste Repositories

Abstract This study investigates the mechanical properties and microstructural characteristics of five concrete mixtures specifically designed for application in low and intermediate-level nuclear waste repositories. These repositories necessitate construction materials that not only offer durability and strength but also maintain a long service-life under the underground environmental conditions over extended period. The concrete mix design was formulated with a focus on optimizing durability and sustainability, incorporating supplementary cementitious materials such as silica fume and slag to enhance the concrete durability. Comprehensive microstructural analyses using petrographic analysis and Micro x-ray fluorescence (μ-XRF) provided insights into the hydrate phases and pore structure evolution, revealing that the concrete exhibits dense microstructures and low permeability, essential for reducing leaching and sulfate attack risks. Mechanical testing demonstrated high compressive strength and modulus of elasticity, showing the suitability of concrete mixtures for structural components in repository environment. Overall, the findings highlight the potential of this designed concrete mixture in meeting the demands of low and intermediate level nuclear waste storage, ensuring safety and stability while also supporting environmental sustainability using eco-friendly materials.