CAREER: Toward Geomimetic Concretes

University Of California-Irvine, Irvine CA

Investigators

Abstract

Inspired by the exotic chemical reactions in earth’s crust, this award focuses on the fundamental understanding of the chemical reactions at the fluid-solid interfaces and leverages this basic insight to design carbon-negative geomimetic concrete materials. The production of ordinary Portland cement-based concretes is responsible for about 7 percent of global anthropogenic carbon emissions and about 9 percent of industrial freshwater withdrawals worldwide. This necessitates the development of infrastructure materials that are not only carbon sink but also water conscious. The progress in designing such sustainable material technologies is in principle confounded by the complexity of chemical reactions occurring at the carbon dioxide-water-solid interfaces. The breakthrough in understanding the mechanistic picture of such heterogenous chemical reactions will not only benefit the design of eco-friendly construction materials, but also entails numerous implications in tuning soil-hosted reactions, determining the fate of contaminants in the geosystems, and understanding environmental catalysis. This Faculty Early Career Development (CAREER) award will also instigate synergistic educational efforts to engrave the significance of sustainable construction materials in K-12 and undergraduate students, especially bilingual Hispanic early-learners, who make up a significant portion of the US English language learner population. When it comes to describing the carbonation process with humidified CO2-rich fluids, the long-standing paradigms for bulk aqueous fluid-mediated carbonation via the dissolution-precipitation process become simply irrelevant. Such a change in paradigm is particularly evidenced in geological settings with reports of accelerated carbon mineralization in water-poor fluids. The enhanced carbonation kinetics is hypothesized to be closely related to the formation of interfacial water films that exhibit unique reactant/solvent chemophysical properties and serve effectively as a nano-confining bath mediating chemical reactions. Despite the vast technological implications in developing carbonated concretes, the mechanistic picture of the interfacial processes accountable for the enhanced reactivity in water nanofilms and the associated thermodynamics and kinetics remain elusive. By integrating molecular simulations and in situ and ex situ spectroscopy techniques, this research provides a molecular-level understanding of the nanoconfined processes that govern carbon mineralization in nanoconfined media. These processes include multi-phase fluid segregation in nanoporous media, nanoconfined crystallization processes, and diffusive mass transport in the adsorbed water layers and cation-leached glassy silicates. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.