Pilot-scale validation of CO2 utilization for greener and tougher infrastructure through carbonation curing of bendable concrete

This paper presents a pilot-scale study on carbonation curing of ductile Engineered Cementitious Composites (ECC), also known as bendable concrete. We aim to advance the technology maturity for broader deployment by validating its performance in a real fabrication and service environment, marking the first demonstration beyond the laboratory scale. To achieve this goal, we examined the mechanical properties and net climate impact of ECC cured in large volumes and then fabricated a set of non-reinforced slabs with the carbonated ECC. These slabs were installed for a sidewalk renovation project located in Southeast Michigan for long-term tests. Based on typical M45-ECC, we revealed a prominent size effect on the carbonation efficiency, with the total CO 2 uptake decreasing from 26.6% to 4.3% (by cement mass) as the specimen thickness increased from ½ to 4 inch. The carbonated slabs manifested a “sandwich” structure comprised of a heavily carbonated surface and nearly non-carbonated core. This structure, despite its limited capacity for CO 2 storage, was found to improve the slab's flexural strength by 31.7% while maintaining a high intensity of fine cracks. The durability improvement was also evident, and the carbonated ECC showed a marginal compromise in strength and ductility for 3 years and remained intact after 34 months in service. Compared to the emissions offset by direct CO 2 uptake, carbonation curing demonstrates a greater potential of emission mitigation by improving the load-carrying capacity (thus leveraging smaller structural dimensions and lower cement usage). These findings indicate that carbonation curing can be implemented for ECC's low-carbon design and fabrication beyond laboratory scales and offers a feasible path towards sustainable and resilient infrastructure developments through CO 2 utilization.