Interfacial Chemistry of Ti₃C₂Tx MXene in Aluminosilicate Geopolymers for Enhanced Mechanical Strength

The incorporation of fillers into the geopolymer matrix has been recognized as crucial for enhancing fracture toughness and inhibiting crack propagation, thereby mitigating the inherent brittleness of geopolymer materials. Herein, we present a simple and scalable hybrid approach that utilizes titanium metal carbide or MXene (Ti3C2Tx) (Tx = −OH, −F), in conjunction with fly ash and dolomite to enhance mechanical properties, such as setting times, flowability, compressive strength, and water absorption. The improved characteristics are ascribed to a fundamental charge-balancing mechanism that facilitates the formation of stable MXenes and composites with calcium aluminosilicate hydrate (C–A–S–H) or sodium aluminosilicate hydrate (N–A–S–H). Besides, Raman spectroscopy of MXene in aluminosilicate geopolymers elucidates the interfacial chemistry, while density functional theory (DFT) emphasizes the significance of intermolecular hydrogen bonding between MXenes and C–A–S–H in augmenting mechanical properties. Overall, the suggested mechanical properties are observed to increase by 53% with the addition of MXene, attributed to the dense structure, resulting in a 3.6% reduction in water absorption. This current investigation paves the way for the advancement of sustainable MXene-based construction materials through innovative material design and a fundamental understanding of nanocomposite interactions with benefits for industrial waste utilization and reduction of carbon footprint.