Investigating the steel–cement interface in high-temperature, high-pressure carbon dioxide environments

This study investigates the impact of high-temperature, high-pressure carbon dioxide on the steel-cement interface, crucial in engineering structures and carbon capture storage systems. Experiments conducted on N80 steel and ordinary portland cement in synthetic aquifer brine revealed that CO₂ exposure significantly exacerbates steel corrosion and cement degradation. The corrosion current density of steel increased to 1.2 μA/cm² after six months in CO₂, compared to 0.3 μA/cm² in unexposed samples. Cement samples showed a marked decline in mechanical properties, with hardness reducing from 1.25 GPa (giga-Pascal) in control samples to 0.65 GPa after six months. The steel—cement interface integrity also diminished, as evidenced by a decrease in acoustic impedance from 45.0 M-Rayl to 34.0 M-Rayl over six months. These results emphasize the need for advanced materials and strategies to enhance the durability and safety of structures in CO₂-rich environments.