Wet Carbonation of Industrial Recycled Concrete Fines: Experimental Study and Reaction Kinetic Modeling

Carbon dioxide mineralization via wet carbonation of industrial Recycled Concrete Fines (RCFs) offers a promising pathway for mitigating emissions in the cement industry, necessitating reliable kinetic models for technology scale-up. This work proposes a validated diffusion-based Shrinking Core Model describing the wet carbonation kinetics of RCFs. The model, based on parabolic diffusion law, is rigorously selected and calibrated among mineralization models in wet systems. Experimental results demonstrate a maximum carbonation efficiency of 0.81, corresponding to 95 kg CO2 uptake per tonne of RCFs, and acceptable compressive strength development when incorporating RCFs up to 10% in blended cement. Reaction rates showed a minimal temperature impact due to the offset between the CO2 solubility and diffusion through the product layer. Compared to Recycled Cement Paste (RCP) carbonation, higher diffusion coefficients are predicted, likely caused by looser product layer. Analysis highlights the importance of particle size and the CO2 partial pressure, providing insights for efficient scale-up.