Relationships Between Composition, Structure, Reactivity, and CO2 Uptake in Calcium Aluminosilicate Glasses

The production of OPC is responsible for 5-8% of global anthropogenic CO₂ emissions, with about 50% of these emissions arising from the decomposition of CaCO₃, a primary ingredient in cement. Among the strategies to mitigate these emissions, CO₂ mineralization and the substitution of OPC with supplementary cementitious materials (SCMs) are the most practical and cost-effective solutions. However, the complexity of SCMs due to their heterogeneous phases and chemical compositions presents challenges in understanding their behavior, prompting research into alternative, engineered SCMs. As a result, identifying and evaluating alternative SCMs, including engineered SCMs, has become a critical area of research. Therefore, in this thesis, we leverage pure-phase material as a model system for understanding the existing SCM systems. The pure-phase model systems, containing a broad range of pure calcium aluminosilicate materials (CAS), provide a controlled platform to gain a fundamental understanding of the composition-structure-reactivity-CO₂ uptake relationship essential for understanding and advancing current and future SCMs. This thesis is composed of three studies. 

Composition-structure relationships in calcium aluminosilicate glasses (S1): This study provides a comprehensive structural characterization of a broad range of CAS glasses using advanced experimental techniques, filling a significant gap in existing literature that has primarily focused on low CaO compositions. 

Reactivity and reaction kinetics of calcium aluminosilicate glasses (S2): This study focuses on the reaction kinetics of CAS glasses, assessed through heat release measurements, suggesting that CaO content is ‘good enough’ to measure reactivity, and time and effort spent determining complex structural descriptors may not provide any added value.

 CO₂ Uptake in Calcium Aluminosilicate Materials (S3): This study investigates the carbonation potential of several CAS systems with varying degrees of amorphization, highlighting a trade-off between SCM reactivity and carbonation.