Optimizing accelerated carbonation of carbon-eating concrete on early age microstructure and durability improvement

초록

This study explores the development of Carbon-Eating Concrete (CEC) using electric arc furnace slag (EAFS), examining the potential of accelerated carbonation to enhance both the mechanical properties and durability of concrete. Various parameters, including CO2 pressure and curing temperature, were optimized using Response Surface Methodology (RSM). Among the experimental conditions, the compressive strength of CEC reached 36.09 MPa at 5 bar and 80 degrees C, while the RSM-optimized condition of 6.7 bar and 80 degrees C resulted in a slightly higher strength of 37.67 MPa, validating the optimization. Microstructural analyses including thermogravimetric analysis (TGA) showed CaCO3-related mass loss of 12.44 % in C-OPC and 8.75 % in C-CEC at the surface layer (0-18 mm), indicating substantial carbonation in both cases. Mercury intrusion porosimetry (MIP) revealed a lower total intrusion volume at the surface of C-CEC (0.043 ml/g) compared to C-OPC (0.067 ml/g), suggesting a denser pore structure in C-CEC. Consequently, the abrasion resistance of CEC improved, as reflected by a lower final abrasion depth of 0.57 mm, compared to 0.74 mm in OPC. In chloride ion penetration tests, the reduction in penetration depth due to carbonation was more pronounced in CEC than in OPC, further demonstrating the superior durability performance of carbonated CEC. These findings confirm that CEC, when subjected to accelerated carbonation, exhibits not only enhanced mechanical strength but also improved durability characteristics. Based on these performance enhancements and the use of industrial by-products, CEC demonstrates strong potential as a scalable and environmentally viable alternative to conventional concrete.

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