Project Summary

Portland cement manufacturing has significant impacts on climate change impacts, arising from CO2 emissions from the calcination of limestone (CaCO3 → CaO + CO2). Demand for cement is expected to increase in the next few decades due to rapid urbanization. Reducing the embodied carbon of cement-based construction materials is thus critical to achieving decarbonization targets set by the Paris agreement. A high impact but currently underdeveloped technology in the cement and concrete domain is CO2 mineralization utilizing CO2-rich industrial flue gas that could be provided from co-located processing facilities. The minerals formed during carbon curing (CaCO3 for cementitious materials) are atmospherically stable and can permanently store CO2. Furthermore, these minerals are micro-crystals, which densify the pore structure and improve durability for ideal process conditions and material compositions. This result can be achieved through accelerated carbon curing of building components, which can occur either at the manufacturing facility or during transportation. However, there are challenges with current carbon curing techniques that must be addressed to upscale this technology. First, (i) cementitious building materials manufactured using the molding process limits the diffusion of CO2 to near-surface layers due to disconnected pore structure with increase in hydration. This process limits the total amount of CO2 that can be sequestered. Second, (ii) flue gas from industrial sources, including coal-fired power plants and cement manufacturing, contain water vapor, particulate matter, sulfur oxide (SOx), and nitrous oxide (NOx) along with CO2. Contaminants from these mixed gas streams may significantly affect the CO2 uptake and durability of CO2 mineralized concrete products through selective absorption or secondary reactions.