Development of carbon capture coating to improve the durability of concrete structures

A novel carbon capture (CC) coating was developed using CO2-activated dicalcium silicate, aiming to enhance the durability of concrete structures and sequestrate CO2. The carbonation products, microstructure and effects validation of the CC coating were investigated. The results showed that the CC coating could achieve a relatively high carbonation degree of 23.3% after 30-min carbonation. The moisture-saturated environment in the CC coating facilitated the formation of a gradient structure with relatively homogeneous carbonation products, i.e. small CaCO3 crystals (calcite, aragonite, and amorphous CaCO3) and highly polymerized silica gel, thereby rapidly densifying the microstructure. The CC coating with a thickness of approximately 200 μm significantly improved the concrete durability (decreasing the capillary water absorption by 20.5% after 30-min carbonation) and exhibited a satisfactory bonding strength (2.74 MPa after 30-min carbonation), which has a promising application scenario in extending the service life of concrete structures and reducing the carbon emissions.