Cellulose-Mediated Hydration Interactions Enable Mechanically Durable Hydrosetting Geopolymers

Abstract Developing geopolymers that combine a low-carbon composition with high performance through tailored rheology, hydration-guided curing, and mechanical reinforcement is essential for commercial and residential construction. Herein, we examined biobased cellulose nanocrystals (CNCs) and northern bleached softwood kraft pulp fibers (PFs) as additives in metakaolin-based geopolymers. Both CNCs and PFs resulted in a substantial enhancement of the mechanical properties. Compared with pristine geopolymers, the incorporation of 6 wt % PFs resulted in a 93.25% increase in compressive strength and a 103.85% increase in flexural strength, whereas incorporating 4 wt % CNCs led to increases of 60.12% and 126.92%, respectively. Notably, we discovered that CNCs and PFs interact with and redistribute water through distinct hydration-mediated pathways. CNCs are associated with a greater perturbation of the geopolymer-associated water population, whereas PFs preferentially retain more mobile water and delay its incorporation into the evolving geopolymer network. The two fundamentally different hydration strategies, together with the CNC/PF-mediated heterogeneous structures, provide a pathway for developing high-performance hydrosetting constructs from geopolymers.