"An Enzymatic Carbon-Negative Structural Material"
Dr. Nima Rahbar
White Family Distinguished Professor and Department Head, Department of Civil, Environmental, and Architectural Engineering
Worcester Polytechnic Institute
Friday, November 22, 2024
12:00PM: Boxed lunches available
12:15PM - 1:15 PM: Presentation
Peter Kiewit Institute Room 160 (Omaha), Kiewit Hall A253 (Lincoln), or Zoom
Please use the form below to RSVP for lunch or the Zoom link by Tuesday, November 19, 2024 at 5 PM.
The United Nations has declared climate change as the defining issue of our time. Concrete is the most widely used material in the world, and its production and transport are responsible for 8% of global carbon emissions. It is inherently brittle and requires frequent repair or replacement, which are expensive and generate large volumes of CO2. Therefore, a self-healing cement paste is needed to overcome this problem. The leading self-healing mechanism uses spores, bacteria, and microbes, which are slow and have limited applications and unknown health effects. Inspired by the highly efficient process of CO2 transfer in biological cells, this talk introduces a method to develop a self-healing mechanism in a cementitious matrix using trace amounts of the enzyme Carbonic Anhydrase (CA). CA catalyzes the reaction to create calcium carbonate crystals with similar thermomechanical properties as the cementitious matrix. The crystal growth rate using this method is orders of magnitude faster and more efficient than bacterial methods, resulting in the healing of significant flaws on timescale orders of magnitude shorter. This inexpensive method is biologically safe, actively consumes CO2, and avoids using unhealthy reagents. Our enzymatic mechanism further led to the development of the carbon-negative Enzymatic Structural Material (ESM), providing a new pathway to substitute concrete. Moreover, ESM production can be a viable carbon sequestration method. ESM shows high water stability compared to other biologically inspired construction materials with a strength of 26 MPa, which is close to the compressive strength of structural concrete, making it a promising candidate for construction applications. Importantly, ESM production consumes 8.5 kg of CO2 per m3, in contrast to traditional concrete production, which emits approximately 400 kg of CO2 per m3.