Effect of high surface area alumina platelets on squeeze flow properties of geopolymer pastes

Abstract Geopolymers are alkali‐activated inorganic polymers emerging as a leading alternative to ordinary Portland cement that have also garnered significant interest for additive manufacturing, particularly in refractory applications. Reinforcing geopolymers with alumina platelets enhances their mechanical strength and thermal stability, making them ideal for high‐temperature environments. In this study, the rheological properties of potassium geopolymer reinforced with alumina platelets were systematically investigated, with the goal of assessing their applicability in additive manufacturing processes. The study explored the influence of platelet size, reinforcement content, and deformation rate (squeezing rate). The high specific surface area of the alumina platelets introduced jamming and collision‐based effects at higher reinforcement levels, while phase separation dominated at lower squeezing rates. Higher squeezing rates led to more homogenous deformation, with load responses showing different behaviors. For instance, with 5‐µm platelets, a super linear increase in load was observed at low reinforcement levels. A percolation threshold was identified for the 5‐, 25‐, and 50‐µm platelets in relation to load response, reinforcement content, and squeezing rate. Finally, the work‐to‐squeeze values were calculated, providing quantitative insights into the material performance and its potential for use in additive manufacturing.