Dynamic Life Cycle Assessment of Concrete Structures: An Approach to Easily Integrate the Carbonation Process

This study introduces a dynamic Life Cycle Assessment (LCA) approach tailored to the concrete industry, proposing an index to measure CO2-equivalent emission reductions per square meter (m2) across the service life of conventional concrete structures. Following a review of current LCA methods, the research identifies gaps in existing approaches, particularly the frequent omission of CO2 absorption due to carbonation and environmental variability throughout the lifecycle of concrete elements. To address these issues, an index has been developed to ease the quantification of CO2 absorption by structural components. The method is applied to multiple cement types classified under the EN 197-1 standard, which allows the performance of comparative environmental impact assessments across different materials. Results are presented according to variations in cement substitution percentages, compressive strength, the cement-to-concrete ratio in kilograms per cubic meter, and exposure class. In order to validate the proposed index, a case study is conducted on thin-walled elements made with Cementitious Textile Composite (CTC), evaluating the carbonation potential of different cementitious mixtures with diverse percentages of supplementary cementitious materials (SCMs). The analysis considers elements with thicknesses of 3 mm and 7 mm under different exposure classes, assessing their carbonation rates and the respective CO2 sequestration over a 20-year period. The results highlight how elements with higher surface-to-volume ratio present a greater CO2 uptake, leading to a more pronounced cooling effect and a reduction in Global Warming Potential (GWP). The validation phase highlights the impact of initial emissions and the absorption on the overall GWP balance, demonstrating this dynamic LCA method's potential for reducing emissions more effectively than conventional static approaches. Finally, this LCA proposition may enable the incorporation of carbonation accounting in more reliable and accurate ways across existent building and construction LCA tools. Furthermore, such approach could also assist designers and other stakeholders to familiarize with carbonation processes and complex LCA modelling.