Tailoring Cementitious Materials Towards Value-Added Use of Large CO2 Volumes

Period of Performance: 07/31/2017 - 07/30/2019

$1MM

Phase 2 SBIR

Recipient Firm

Metna Co.
1926 Turner Street Array
Lansing, MI 48906
Firm POC
Principal Investigator

Abstract

Concrete is the primary material of construction. The challenges relating to the health, efficiency, and maintenance and construction costs of our infrastructure point at the need to develop concrete materials of improved durability at reduced cost. Close to 5% of global energy use and 10% of anthropogenic CO2 emissions are attributed to Portland cement and concrete production. A novel method is developed for economical and sustainable production of a high-performance hydraulic cement. This method employs energy-efficient ‘mechanochemical’ effects at room temperature and atmospheric pressure. The resultant ‘hybrid’ cement can make value-added use of landfill-bound industrial by-products (e.g., low-grade coal ash and metallurgical slags) and combustion emissions. The hydrates and carbonates which form in concrete yield improved barrier, durability, mechanical and (heavy metals) immobilization qualities. The production cost of the hybrid cement is about half that of Portland cement; it also doubles the service life of infrastructure systems. The energy use and carbon emissions associated with production of the hybrid cement are 70-75% less than those for Portland cement. In addition, the hybrid cement comprises 10-15 wt.% of carbon dioxide as a valuable raw material.Viable chemistries of the hybrid cement and its hydration mechanisms were identified. The raw materials selections and formulations suiting this chemistry were selected, and the mechanochemical processing conditions in an environment of combustion emissions were established. Selected raw materials formulations, comprising largely of coal ash and metallurgical slags, were processed in laboratory. The formulations and processing conditions were refined empirically to meed standard performance and safety requirements. The resultant hybrid cement and concrete materials were thoroughly characterized, emphasizing their barrier, durability, immobilization and carbon capture qualities. A theoretical basis was developed for scale- up of the process, and the technology was implemented at pilot scale in a natural gas-burning power plant where the flue gas was used successfully to produce the hybrid cement. The operation conditions of the pilot-scale system were refined empirically, and the scalability of the process was verified. The hybrid cement produced at pilot scale was used successfully in construction applications. The Phase IIA project will advance the technology to a level that could be implemented at industrial scale. The selections of (primarily by-product and emission) raw materials will be further expanded to enable economical implementation in diverse geographic locations. Quality control methods will be developed for reliable production of the hybrid cement. Two pilot-scale runs will be implemented in collaboration with cement and power industries. The first pilot-scale run will simulate the continuous operation conditions of a cement manufacturing plant where stack emissions will be used as a source of CO2 and also as a gas stream for grading of cement particles. Both the prevalent ball and vertical roller mills will be used. The second pilot-scale run will be conducted in a coal-burning power plant were the solid residues and the emissions of coal combustions would constitute the primary raw materials. Adjustments will be made in mechanochemical processing to suit the coal combustion emissions. The resultant hydraulic cements will be characterized in laboratory and also in field in order to verify that they meet the prevalent standards and practices. Outcomes of the pilot-scale runs will be used to verify the performance, cost, safety and sustainability benefits of the technology. The hybrid cement offers significant savings in the initial and life- cycle costs of infrastructure systems. The longer service life and the reduced maintenance requirements of infrastructure systems would improve the efficiency of the economic and societal functions they support. The technology promises to reduce global energy use by up to 3.5%, and anthropogenic carbon emissions by up to 10%. The robust chemistry and effective immobilization qualities of the hybrid cement would divert up to 3.5 billion tons/yr of industrial by-products from landfills, thus preserving an equivalent amount of natural resources.