Multiscale Mechanisms of Dissolution and Reactivity of Calcium Aluminosilicate Glasses: Towards Rational Design of Low-Carbon Cement Substitutes

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Cement, the binding agent of concrete, is the most widely used human-made material worldwide and is responsible for about 5 percent of global carbon emissions. Replacing cement in concrete has therefore emerged as one of the most effective strategies to mitigate the environmental impact of the concrete industry. The aim of this project is to formulate physics-based guidelines, using computer simulations and experimental testing, to advance the design of low-carbon cement substitute materials. Currently available low-carbon cement substitutes exhibit slow reactivity, and their availability continues to decline as the key supplier industries are phasing out for environmental reasons. The ability to predict and design the reactivity of low-carbon cement substitutes remains limited because of the poor understanding of the basic mechanisms that govern these reactions. This research aims to provide fundamental insight into the multiscale mechanisms that govern the reactivity of calcium aluminosilicate glasses, which are the main reactive phases in cement substitute materials. A comprehensive outreach plan developed in collaboration with local non-profit partners will also be implemented. The focus of the outreach plan is to promote scientific literacy and environmental leadership among K-12 students, especially those from underserved communities and underrepresented minorities in STEM. The goal of this research is to develop a fundamental understanding of the dissolution and reactivity of calcium aluminosilicate glasses as a function of glass structure and composition. The research will combine a multiscale framework based on density functional theory, molecular dynamics, and kinetic Monte Carlo simulations, together with glass characterization, dissolution measurements, and reactivity testing. This hybrid approach will bridge the gap between molecular-level understanding of glass reactivity and macroscopic reactivity measured in experiments. This research will result in the following outcomes: (1) full characterization of the reactivity spectrum of calcium aluminosilicate glasses at the molecular level, (2) fundamental understanding of the mechanisms that govern the dissolution behavior of calcium aluminosilicate glasses at the mesoscale, and (3) comprehensive understanding of the relationship between glass structure/composition, dissolution, and reactivity for a wide range of glass compositions. The findings from this work will shed light into the reactivity of disordered materials, which has broad cross-disciplinary applications, and will pave the way for the rational design of highly reactive low-carbon cement substitutes, a key step towards sustainable concrete.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.