A clean and sustainable CO2 storage method in construction materials

Production of building materials emits 11% of global carbon dioxide (CO2) emission. The greenhouse gas emission from the construction industry has been tried to mininmize from early 1980s; but after four decades of development, it is not fully sustainable. Cement is the second most consumed material in the world, after water and cement production contributes for 8% of global CO2 emission. We produced a greener cement from abundantly available waste: fly ash, blast furnace lag, and rice husk ash to significantly minimize the greenhouse gas emission. Discarded aluminium foil becomes one of most landfilling waste that has high potential for recycling. On other hand, cement carbonation is a curing method that stores significant amount of CO2 into cement with lesser cost and energy compared to commercial carbon sequestration. Therefore, we incorporate aluminium foil waste and CO2 waste from industry to improve the engineering and environmental performance of the cement. We compared changes in carbonation when using gaseous carbon dioxide (gCO2) and supercritical carbon dioxide (scCO2) and found that the scCO2 condition achieves higher compressive strength and yielded a stronger barrier against leaching. Hence, this carbon cured cement can be widely used in underground applications, where the heavy metal leaching is a critical issue. Projections show our greener cement reducing CO2 emission by 55% compared to Portland cement and reducing direct costs by 35%. Also, our cement ultimately reduces hydrogen gas demand by recycling aluminium, which releases pure hydrogen during the production process, and this effect reduces annual CO2 emission by 35 million tonnes from this hydrogen production alone. Adopted globally, the system would permanently store 72 million tonnes of CO2 in a stable composite annually. On whole, our cement production significantly reduces the energy requirement for cement manufacturing and releases future energy, hydrogen gas, as by product.