Microstructural Characterization of Cellulose Nanocrystals and Microcellulose from Bamboo (Bambusa longispatha) for Reinforcing Ordinary Portland Cement Matrix

This study investigates the microstructural characterization of cellulose nanocrystals (CNC) and microcellulose (MC) extracted from bamboo fibers (<i>Bambusa longispatha</i>) and their potential as reinforcement agents in ordinary Portland cement (OPC) composites. CNC with a mean particle size of 29.3 nm and MC with a mean size of 14.6 × 10³ nm were incorporated into OPC at varying concentrations (0.1%, 0.2%, 0.4%, and 0.6% by cement mass). The compressive strength analysis revealed that increasing MC content led to a decrease in strength, with reductions ranging from 8.8% to 25.9% relative to the control OPC, while the CNC-enhanced composite at 0.4% achieved the highest compressive strength of 43.2 MPa. Flexural strength analysis indicated a minor increase in strength with MC addition (from 7.5 MPa to 8.1 MPa), while CNC addition at 0.1% improved flexural strength to 8.2 MPa but declined with higher concentrations. SEM and stereo microscopy demonstrated MC and CNC dispersion and highlighted microstructural differences, including pore distribution in the composites. XRD analysis showed increased crystallinity for CNC composites compared to pure OPC, with the highest crystallinity index of 52.2% observed at 0.4% CNC. This study highlights that CNC at specific concentrations can enhance OPC mechanical properties, while higher MC and CNC additions may impact strength properties variably due to their microstructural integration and crystallinity. These findings support the potential for bamboo-derived cellulose materials in enhancing cementitious composite performance.