The International Association for Automation and Robotics in Construction
Publications / 2025 Proceedings of the 42nd ISARC, Montreal, Canada
Evaluating the Carbon Neutrality of Concrete Recycling Using CO2 Capture Technologies from Cement Production
The construction industry encounters significant environmental challenges, primarily due to concrete waste from demolitions and high CO2 emissions from cement production. Concrete waste is recycled into aggregates, generating a significant amount of waste concrete powder (WCP) as a byproduct. However, the application of WCP in recycling processes is limited, leading to landfill disposal and environmental risks. This study explores the potential of combining carbon-neutral technology with large-scale concrete production by using WCP as a partial substitute for both cement and fine aggregates. Active carbonation is highlighted for its ability to capture CO2 while improving the properties of recycled concrete aggregates (RCA) and WCP. Although technological advancements exist, a thorough evaluation of financial viability is essential. This research focuses on assessing the economic feasibility of integrating carbon-neutral technology into concrete recycling, particularly by carbonating waste concrete using flue CO2 from cement plants. Thus, the paper proposes a method to incorporate environmental assessments into an activity-based costing (ABC) model, enabling a dual evaluation of financial costs and environmental impacts. By linking environmental impact assessment results to costs, this approach facilitates a comprehensive evaluation for involved stakeholders. An assessment of the Hong Kong market showcases the practicality of the proposed matrices. The comparison of recycling methods indicates significant environmental improvements, with 362% and 440% reductions in CO2 emissions from cement plants and natural material processing, respectively, underscoring the potential of carbonization technology and the need for government support.
