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Browsing School of Built Environment (SBE) Collections by Author "Ainomugisha Safiki"
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    Green Engineered Nanoparticles from Sugarcane Biomass Waste as Supplementry Cementitious Materials
    ( 2025-12-08) Ainomugisha Safiki
    In recent years, several studies have reported that effective processing methods for supplementary cementitious materials (SCMs) are crucial for mitigating the challenges associated with them. However, micro-processing has been the primary processing route, rendering the SCMs merely as fillers with limited pozzolanic activity, thereby failing to realize their full effectiveness as SCMs. Nano-processing stands out as a more effective method that can enhance most performance properties of SCMs. Yet pathways for producing and applying nanoparticles (NPs) as SCMs have focused on toxic, non-eco-friendly, hazardous precursors such as tetraethyl orthosilicate (TEOS). Meanwhile, greener biomass ash-derived NPs with tailored properties have not been well understood. This study systematically developed optimized protocols for engineering eco-friendly NPs from sugarcane bagasse ash (SCBA) using mechanical milling and sol-gel synthesis methods. An experimental mix design based on the Box-Behnken approach within response surface methodology was employed to model the key factors influencing the quality of nanoparticles (NPs) produced as SCMs. Furthermore, the study evaluated the efficacy of the green-engineered NPs as SCMs. The study successfully engineered small-sized SCBA NPs (5–20 nm) with disfigured crystalline SiO2 networks (amorphization) by ball milling. Engineered mesoporous silica (pore diameter < 50 nm) with a high surface area (≈ 700 m²/g), highly amorphous, and with a silica purity of up to ≈ 97% was produced. A comparison of nano-additive and clinker-replacement approaches revealed that each 1.5% nano-SCBA can effectively substitute up to 15% of cement clinker, with an 18% improvement in early cement strength. Mortars containing low-medium surface area n-SiO₂ (263–579 m²/g) outperformed high-SSA materials at w/b = 0.5, with 3% n-SiO₂ of SSA 579 m²/g attaining compressive strength improvement of 41%. Cement paste sample HP1 (3% of 428 m²/g SSA n-SiO₂ and 0.5 w/b) exhibited improved hydration kinetics by minimizing the time to start and end of the dormancy period, as well as the time to attain maximum heat for both C3S and sulphate depletion, by 64.3%, 73.63%, 87.08%, 58.86%, and 47.02%, respectively. In conclusion, this study successfully engineered green NPs with improved properties as SCMs, demonstrating that nanotechnology-enabled processing of SCBA is a viable route to sustainable SCMs. This work provides optimized synthesis protocols, mechanistic insights, and application guidance to support the broader adoption of biomass-derived NPs in cementitious systems.