PSI - Issue 67

G. Goracci et al. / Procedia Structural Integrity 67 (2025) 30–38 G. Goracci/ Structural Integrity Procedia 00 (2024) 000 – 000

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1. Introduction The rapid increase in atmospheric CO 2 levels, primarily driven by anthropogenic activities, constitutes a pressing global concern due to its significant contribution to climate change. Major sources of CO 2 emissions include the combustion of fossil fuels, industrial processes, and deforestation. Among these, the steel and cement industries are particularly notable for their substantial contributions to global CO 2 emissions. For instance, the production of Portland cement clinker, a fundamental component of concrete, is responsible for approximately 0.98 tonnes of CO 2 emissions per tonne of clinker produced (Liu et al., 2021; Wang et al., 2022) . This highlights the urgent need for innovative solutions to reduce these emissions. Addressing the CO 2 emissions from these major industrial processes requires a multifaceted approach that includes both direct emissions reduction and the development of novel CO 2 capture technologies. One effective method involves using alternative binders in cement production, which can significantly reduce CO2 emissions by lowering the clinkering temperature and utilizing materials that require less energy to produce ( Sharma et al., 2023 ). Additionally, strategies such as partially replacing cement with industrial by-products like fly ash or steel slag as CO2 activated binders show promise (Jiang et al., 2018; Li et al., 2023 ). These alternative binders offer a viable pathway to significantly reduce the carbon footprint of the cement industry while maintaining or even enhancing the performance of the final product. Regarding the strategy of capturing CO 2 from the atmosphere, advanced technologies like carbon capture and storage (CCS) are continuously evolving. This process generally involves separating CO 2 from industrial flue gases and permanently storing it in geological formations, depleted oil and gas reservoirs, or deep saline aquifers. Mineral carbonation, a naturally occurring weathering process, has garnered attention as a promising pathway for CO 2 sequestration (Liu et al., 2023; Liu and Meng, 2021; Zajac et al., 2020; Zhang et al., 2017) . This process leverages the reaction of CO 2 with alkaline earth metal silicates, primarily calcium or magnesium-based minerals, to form stable carbonates, effectively trapping CO 2 in a solid, environmentally benign form. Mineral carbonation has been successfully applied in the development of carbon-cured concrete. This innovative approach introduces high concentrations of CO 2 during the curing process of fresh cement-based materials, promoting the formation of calcium carbonate (CaCO 3 ) within the material's matrix. Another method involves adding carbonated aggregates derived from industrial by-products, such as steel slag, to concrete mixtures as a sustainable alternative to natural aggregates (Chen et al., 2024; Elyasi Gomari et al., 2024; Fang et al., 2024; Goracci et al., 2023; Li et al., 2024; Luo and He, 2021; Zhang et al., 2023) . These aggregates undergo pre-treatment with calcium ion-rich solutions, like portlandite (Ca(OH) 2 ), to enhance their carbonation potential. Accelerated carbonation techniques, where aggregates are exposed to high concentrations of CO 2 under controlled temperature, pressure, and humidity conditions, aim to speed up the carbonation process, making it more efficient for industrial applications. The specific reactions and the rate of carbonation can vary depending on factors like the type of aggregate, its chemical composition, and the carbonation method employed. Research suggests that concrete incorporating carbonated aggregates can exhibit comparable or even superior performance to conventional concrete. Urban areas face additional challenges related to CO 2 emissions, particularly the increased use of air conditioning during summer months. The urban heat island (UHI) effect, where urban areas experience significantly higher temperatures compared to their rural counterparts, exacerbates this issue (Mirzaei, 2015) . This temperature difference results primarily from the alteration of land surfaces and the concentration of human activities in urban environments. Urbanization leads to the replacement of natural landscapes, such as vegetation and water bodies, with buildings, roads, and other impervious surfaces. These surfaces absorb and retain heat more readily than natural landscapes, contributing to higher temperatures in urban areas. The UHI effect represents a significant urban environmental challenge, emphasizing the need for effective mitigation strategies to reduce its negative impacts. Mitigation strategies are essential to lower urban temperatures, reduce energy consumption, and improve overall urban livability. Among various solutions, the use of cool materials stands out due to its practicality and efficiency (AzariJafari et al., 2021; Dolado et al., 2023; Goracci et al., 2023; Kousis and Pisello, 2023; Morales-Inzunza et al., 2023; Wang et al., 2021) . Cool materials are engineered surfaces, such as cool roofing and cool pavements, designed to reflect more sunlight and absorb less heat compared to traditional materials. These materials leverage high solar reflectance and high thermal emittance to maintain lower surface temperatures. Reflective coatings can be applied to existing roofs to enhance their reflectivity, significantly lowering roof surface temperatures and reducing the need for air conditioning. Light-colored