Experiments of CO2-Basalt-Fluid Interactions and Micromechanical Alterations: Implications for Carbon Mineralization

Basalt rich in Ca, Mg and Fe enables fast CO2 mineralization, making carbon storage in basalt an alternative technology for reducing carbon emissions. The Leizhou Peninsula in China holds great potential as a key region for basalt carbon storage. However, the scarcity of extensive research on basalt carbonation reactions and the resulting mechanical response poses a significant obstacle to the implementation of this technology. Therefore, a series of basalt carbonation experiments were carried out. The results showed that diopside had the highest dissolution rate and acted as the primary source of divalent cations. Within one month, smectite was formed, followed by the precipitation of carbonate minerals. Initially, aragonite and dolomite were the primary carbonation products, but over time, dolomite dominated with a higher percentage of Mg. The dissolution and precipitation of minerals also led to degradation of the micromechanical properties of the basalt. With the progress of the reaction, the average elastic modulus and hardness continuously decreased with maximum reduction rates of 87.66 and 84.38%, respectively. The dissolution-dominant reaction caused an increase in defects on the surface of the basalt sample. Furthermore, the newly formed carbonate and clay minerals exhibited weaker mechanical strength, exacerbating the overall mechanical performance. This mechanical weakness poses a long-term safety risk for carbon storage. This study can provide valuable insights for the implementation of CO2 mineralization in the Leizhou Peninsula, Guangdong Province, China.