Rheological and early-age strength performance of biomimetically synthesised chitosan-templated C–S–H seeds grown on bamboo leaf ash

Biomimetic strategies for enhancing early-age performance of cementitious composites accelerate hydration while maintaining rheological control. This study investigates the rheological and early-age strength behaviour of chitosan-templated calcium silicate hydrate (C–S–H) seeds grown on bamboo leaf ash (BLA) at precursor molarities of 0.1, 0.5, and 1 M. Rheological parameters can act as indicators of early hydration processes, as the evolution of yield stress, viscosity, and thixotropy directly reflects the nucleation and growth of C–S–H networks within the cement matrix. Scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) analysis confirms that BLA can act as an effective nucleation substrate, with C–S–H coverage evolving from sparse (0.1 M) to uniformly distributed clusters (0.5 M) and dense agglomeration (1 M). Up to a 20% reduction in the spread diameter in mini-slump results for seeded cement pastes within 15 mins indicates accelerated particle structuration. The static yield stress increased significantly after 60 min, reaching approximately 20–35 Pa in the seeded systems. Moreover, the apparent viscosity at low shear rates increased by 55–85% relative to the control, by retaining the characteristic shear-thinning behaviour of the cement paste. Thixotropic recovery increases significantly from 45% in the control to 85–90% in seeded mixes, demonstrating enhanced structural rebuilding capacity. The compressive strength results show a consistent increase across all curing ages, with strength increasing by approximately 10–25% at 1 day, 15–30% at 3 days, and 20–35% at 7 days compared with the control mix. 0.5 M seeds achieve the best performance by balancing nucleation density and dispersion, leading to superior microstructural characteristics and controlled rheological evolution. 1 M systems exhibit reduced efficiency due to significant agglomeration. The findings highlight that controlled seed design is critical for achieving synergistic improvements in workability and early-age mechanical performance, rather than maximising C–S–H content. The proposed biomimetic seeding strategy contributes to sustainable infrastructure development and circular material utilisation.