Cellulose Nanocrystals Obtained from Agave tequilana Weber Bagasse as Reinforcing Agents for CPC-30R Portland Cement Mortar

Cellulose nanocrystals (CNCs) have been widely investigated as reinforcing agents in different matrices because of their unique properties, including high specific mechanical properties, biocompatibility, and durability. CNCs can be obtained from lignocellulosic residues such as Agave tequilana bagasse, a byproduct of the tequila industry. In this study, cementitious mortar matrices were reinforced with CNCs produced by acid hydrolysis using sulfuric acid (CNC S) and hydrochloric acid (CNC H). Mortar containing different CNC contents, expressed relative to cement mass, was prepared and evaluated in terms of compressive and flexural strength. The resulting materials were further characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). CNC incorporation increased both compressive and flexural strength, with the best-performing formulations containing 0.35 wt.% CNC S and 0.5 wt.% CNC H. SEM observations showed fewer and smaller microcracks and a narrower interfacial transition zone (ITZ) in CNC-containing mortars than in the control. Thermal and structural analyses indicated that CNC incorporation modifies cement hydration and the organization of hydrated phases. FTIR spectra also showed changes in bands associated with hydroxyl, sulfate, carbonate, and silicate environments, suggesting different interactions of CNC S and CNC H with the cementitious matrix. Overall, Agave-derived CNCs show potential as low-dosage reinforcing additives for Portland cement mortars while providing a value-added route for agroindustrial waste.