Biochar reinforced epoxy composites: improved mechanical and physical properties for concrete protective coating applications

Adverse climatic and environmental conditions have compromised the durability and structural integrity of concrete in construction projects. Environmentally friendly composite material systems that are lightweight and enhance the erosion resistance, water impermeability, and mechanical performance of concrete surfaces, thereby mitigating the reduction. In this study, biochar obtained from the anaerobic pyrolysis of pineapple leaf fibers (PALF) was used as a reinforcing agent in epoxy/PALF composites at 2%, 4%, and 6% by weight. Electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) methods were used to characterize the morphological, chemical composition, and surface functionality of the biochar. The addition of biochar reduces porosity, strengthens interlayer bonding, and improves the mechanical strength of the epoxy/PALF material, resulting in tensile strength of 45 MPa, compressive strength of 52 MPa, impact toughness with the addition of 2% biochar, and flexural strength of 68 MPa with the addition of 4% biochar. The biochar-infused coating increases the compressive strength of M300 concrete by up to 46% and significantly improves adhesion compared to epoxy/PALF materials. The research results show that the biochar/epoxy/PALF system provides a durable, high-performance, UV-resistant coating that protects concrete structures for the long term.