Abstract: The construction system includes a composition that includes Portland cement, nano-TiO2, and slag cement. The composition may also include water. The composition is cured via a CO2 curing process to produce a self-cleaning photocatalytic composite with lower carbon footprint and may be more economically manufactured than known cement-based photocatalytic composites. The unveiled synergistic effect of using slag cement and applying a CO2 curing process may reduce the porosity of the material and reduce the penetration of the pollutants that will accumulate in the surface. Thus, pollutants will be more exposed to UV light and decompose the pollutants in a greater rate. The construction system is self-cleaning in that water, such as from rainfall, may effectively clean the cured composition to reset the sequestering capabilities for the construction system to continue to remove toxic gases for the atmosphere.