DEVELOPMENT OF 3D PRINTED CEMENTITIOUS COMPOSITES INCORPORATING WASTE DERIVED MICRO-FIBRILLATED CELLULOSE AND HYBRID NATURAL FIBERS
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The growing environmental footprint of the construction industry, particularly due to the widespread use of cement, has led to increased interest in sustainable materials that can reduce embodied energy and greenhouse gas emissions. This research focuses on the development and characterization of 3D printed cementitious composites reinforced with micro-fibrillated cellulose (MFC) derived from waste apple pulp (AMFC) and hybrid natural fibers. AMFC was extracted using a sequential chemical treatment process involving bleaching, alkaline treatment and acid hydrolysis followed by high-shear mechanical processing. The extracted fibers were characterized by optical microscopy, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) confirming effective removal of lignin and hemicellulose, increased crystallinity and high aspect ratios. The AMFC was incorporated into cement matrices at various weight fractions and processed using three fabrication techniques: hand mixing, syringe extrusion, and large-scale 3D printing. Mechanical performance was evaluated through flexural testing in accordance with ASTM C293 standards after 28 days of curing. Results showed that optimal fiber content of 0.5 wt.% and alignment via extrusion led to significant increase in flexural strength, modulus and toughness compared to control specimens. SEM analysis of fractured surfaces confirmed fiber bridging and alignment of fibers along the direction of extrusion. Macro fibers like sisal and hemp were incorporated with AMFC and analyzed. Results indicated an increase in toughness, though the increase was not as significant as observed in the cement specimens with only AMFC. This research highlights the potential of waste-derived AMFC as a bio-based reinforcement in cementitious composites, especially for additive manufacturing applications. The use of AMFC not only increases toughness but also supports sustainability goals by valorizing agricultural waste and reducing reliance on synthetic, petroleum-based fibers. The integration of MFC into 3D printable cementitious systems demonstrates the potential for future applications in green construction. Further research into hybrid reinforcement systems, long term durability, and field-scale implementation is recommended to fully realize the potential of natural fiber-reinforced 3D printed construction materials.