Synthesis and Characterization of Date Palm Fiber-Reinforced Geopolymer Composite

This study introduces the usage of date palm fibers (DPFs) as reinforcement of geopolymer matrices. The DPFs were subjected to alkaline treatment by immersion in alkaline solution (5 M) for 24 h at 40 °C. Because of the subsequent strong alkaline geopolymerization, the natural resin (lignin) was removed and the DPFs with a diameter around 600 µm on average broke down into microfibrils with an average diameter of 50 µm. The resultant microfibrils with a large surface area form a strong fiber-matrix adhesion force, thus leading to improved mechanical performance of the composite. The DPF-reinforced geopolymer composite (DPCs) are studied by examining their ductility, high elongation, and strain hardening with a modulus of 200 MPa. The experimental results indicate better mechanical properties of geopolymer composites when compared to the reference geopolymers. The flexural strength of the DPF-geopolymer composite is 12.5 MPa, more than four times the strength of reference geopolymers. The contribution of this research lies in developing attractive green composites based on DPFs and kaolinite. Reinforcement of the geopolymers with natural, abundant, recyclable, and reusable DPFs not only helps improve the mechanical performance of the composites, it also reduces CO2 emission from burning them. The novelty of this study is that microfibrils are extracted from the DPFs during the alkali geopolymerization reactions. These microfibrils are characterized by high surface areas, and subsequently high adhesion forces with the geopolymer matrix.