Valorization of Sugarcane Bagasse Ash (SCBA) in Cementitious Composites: Hydration Behavior, Nanomodification and Sustainability Performance

Sugarcane bagasse ash (SCBA) has been widely studied as a partial supplementary cementitious material; nonetheless, its hydration behavior and performance when combined with nanoscale modifiers remain insufficiently understood. The aim of this study is to assess the pozzolanic potential of SCBA, the hydration behavior of binary SCBA–cement composites and the mechanical performance of ternary mortars with silica nanoparticles (Si-NPs). SCBA reactivity was confirmed by a Chapelle index of ~300 mg Ca(OH)2/g, while hydration development in binary pastes (5–20 wt% SCBA) was quantified using TG/dTG and semi-quantitative XRD. Low SCBA replacement levels (5–10 wt%) enhanced the hydration degree by up to ~12% at 28 days compared with the reference paste. Ternary mortars incorporating 5 wt% SCBA and Si-NPs exhibited significant strength gains, with the optimal blend (2.5 wt% Si-NPs) achieving a 42% increase in 28-day compressive strength relative to the reference mortar. A sustainability assessment showed concurrent reductions in clinker intensity and CO2 intensity of approximately 33% and 32%, respectively. These findings support the sustainable and technical viability of combining agro-industrial waste and nanotechnology as complementary strategies for reducing clinker content while enhancing eco-efficiency in alternative cementitious composites.