Carbonic Anhydrase as a Sustainable Corrosion Inhibitor for Concrete

Concrete, the most widely used material globally, accounts for 8% of all CO2 emissions, with corrosion being a primary factor limiting its lifespan. This study investigates the use of carbonic anhydrase (CA), a bioenzyme, as a cost-effective corrosion inhibitor. Concrete specimens with varying CA dosages─Control, CA-1X, CA-5X, CA-10X, and CA-20X─were made and tested under accelerated corrosion tests. Results show that CA-5X achieved the lowest corrosion rate, reducing rebar corrosion depth to 109 μm─34% lower than the control. Additionally, CA-5X delayed crack initiation by 24 h, demonstrating superior corrosion mitigation. Faraday’s law analysis provided quantitative insights into corrosion kinetics, while thermogravimetric analysis (TGA) and mercury intrusion porosimetry (MIP) revealed mechanisms of corrosion resistance, including crystal precipitation and significantly improved pore structure in the cementitious matrix. These findings highlight CA’s potential to enhance durability and sustainability by extending concrete service life and reducing repair needs, thereby mitigating its environmental impact.