Direct CO2 Mineralization Through Foaming Cement and Concrete

ABSTRACT The use of carbon dioxide (CO2) in the development of products including concrete and oil well cementing is attracting great attention of industry, academia, and government in mitigating climate change. Out of total global energy-related production of ~ 31.5Gt CO2, 8% is by cement production plants. Herein we demonstrate possibility of utilizing a total of 0.378Gt CO2 or 1.2% of total global CO2 by foaming into cement and Concrete. Hydration of Portland cement results in production of 15-20% of Ca(OH)2 (Calcium Hydroxide or Portlandite). All these Calcium Hydroxide can be mineralized into CaCO3 by CO2 foaming. We have developed a proprietary laboratory size blender that can blend CO2 at up to 1000psi. The testing allows us to monitor irreversible conversion of CO2 to CaCO3. We were able to prepare very light weight cement designs by using foamed CO2 technology, with up to 20% enhanced compressive strength compared to commercially available technology without carbonation, such as water extended, and/or silica fume based. Laboratory testing has been performed to optimize the CO2 foaming efficacy and quality. Thermogravimetric analysis has been performed to quantify the percentage of carbonation. Permeability and compressive strength measurement have been performed to ensure that the carbonation does reduce the former and enhance the latter, wherein both changes are improvement towards longer term integrity of cement and concrete. Direct incorporation of CO2 into the matrix of cement and concrete blends reduces the hardening time significantly which is another way of reducing loss of net productive time (NPT) towards sustainability. In addition, it also maximizes the amount of CO2 that can be utilized in this process. The CO2 foaming into cement and concrete is a novel process and have huge potential to directly mineralize large amount of CO2 in useful products.