Impact of Cellulose Nanomaterials on the Hydration and Performance of Phosphogypsum-Rich Supersulfated Cement

This study investigated the influence of cellulose nanomaterials (CNMs) on the strength performance of supersulfated cement (SSC) with high phosphogypsum (PG) content. Cotton-based CNMs, particularly sulfated cellulose nanocrystals (S-CNCs) at a dosage of 0.05%, exhibited superior strength enhancement effects at 28 days compared with carboxylated cellulose nanocrystals (C-CNCs), despite a slight reduction in early-age strength. In contrast, wood pulp–based CNMs negatively affected strength performance across all ages. C-CNCs and S-CNCs inhibit hydration and alter the structure of the main hydration product, C─(A)─S─H gel, resulting in shorter silicate chains and reduced cross-linking. Furthermore, adding these CNMs mitigates the excessive formation of ettringite (AFt), a common issue in high-gypsum blended systems. Despite the inhibition of hydration, C-CNCs and S-CNCs refine the pore structure of SSC through the physical filling effect of CNC particles, counteracting the negative impact of loosely dispersed unreacted gypsum particles on porosity.