CAREER: Realizing Alternative Cements with Chemical Kinetics: Tuned Mechanical–Chemical Properties of Cementitious Magnesium Silicate Hydrates by Multi-Scale Synthetic Control

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).The high energy needs and environmental burden of the construction industry have driven efforts to discover new cementitious materials. Cements based on the bonding between magnesium and silicon, such as magnesium silicate hydrates (MSH), are among the less explored alternatives. The characteristics that control their cementitious nature, i.e., the rates of precipitation, structural mechanisms for strengthening, and stability in relevant environments, are not known and this hinders their widespread use. This Faculty Early Career Development (CAREER) project will reveal new pathways for the chemical synthesis of cementitious MSH and the chemical control of their consequent morphological, mechanical, and chemical properties. Meaningful undergraduate research experiences targeting women and underrepresented minority students at the home and neighboring institutions including a community college will improve STEM and transfer student outcomes, enrich graduate student training, and create a pipeline of students interested in materials science and engineering, cultivating the nation’s future workforce. To enhance the experience, the students will create educational videos that showcase the “Materials Science of Cements and Concrete” that will be distributed to small construction businesses in Dallas–Fort Worth to improve job appreciation and skill in the construction workforce that supports the area’s rapidly growing population through infrastructure development. This research will emphasize an integrated approach involving dynamic high-resolution methods to probe, drive, and manipulate MSH synthesis, structures, and properties from nucleation to bulk growth with a focus on the phenomena that occur at the MSH–fluid interface. This will be accomplished through the following steps. First, precipitation rates, morphologies, and compositions that quantitatively describe MSH growth kinetics will be investigated using a combination of in situ and ex situ surface-sensitive analytical methods and interpreted using mechanistic models applied to sheet silicates. Second, MSH mesocrystalline organization will be understood within the electric double layer theoretical framework and manipulated using polyelectrolytes and electrochemical forcing. Third, local mechanical and surface properties will be quantified and related to macroscale mechanical properties of MSH binders, and the rates and mechanisms of MSH degradation will be investigated. Key analytical methods used include atomic force microscopy, kinetic geochemical modeling, infrared spectroscopy, electron microscopy, electrochemical methods, and synchrotron X-ray scattering. This research will ultimately reveal processing–structure–property relationships in MSH cements, establishing their viability as a binder material for construction purposes and an alternative to ordinary Portland cement. The fundamental science and discovery gained will expand our understanding of low-temperature mineral crystallization processes and the subsequent property development across spatial and temporal scales.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.