Synergistic Mechanical Enhancement in a Novel Hybrid Sawdust/Coir-Reinforced Epoxy Composite Bars: A Sustainable Material for Structural Applications

Daerefa-a Mitsheal Amafabia¹, Sotonte Emmanuel Jack²

¹ Senior Lecturer, Department of Mechanical Engineering, Rivers State University, Port Harcourt, Rivers State, Nigeria.

² Lecturer II, Department of Mechanical Engineering, Rivers State University, Port Harcourt, Rivers State, Nigeria. 

Abstract

The integration of industrial and agricultural waste into high-value composites is a cornerstone of the circular economy. This study presents a comprehensive investigation into the mechanical properties and reinforcing mechanisms of a novel hybrid composite bar utilizing sawdust (SW) and coir fibre (CF) as reinforcements in an epoxy matrix. Four composite specimens were fabricated with varying reinforcement ratios: equal fibre blend (65% resin, 15% sawdust, 15% coir), coir-dominant (65% resin, 25% coir, 10% sawdust), sawdust-dominant (65% resin, 25% sawdust, 10% coir), and high-fibre content (60% resin, 20% sawdust, 20% coir). Mechanical tests, including tensile strength, Charpy impact resistance, and microstructural analysis, were conducted using a Universal Testing Machine, a Charpy impact testing machine, and metallography microscopy, respectively, in accordance with ASTM standards. Results showed that the coir-dominant specimen exhibited the highest ultimate tensile strength (19 MPa), while the equal fibre blend achieved the highest average impact resistance (2.18 J). The sawdust-dominant specimen recorded the lowest tensile strength (12 MPa), indicating weaker fibre-matrix bonding. Microstructural analysis revealed that uniform fibre distribution and effective resin penetration enhance mechanical performance, while voids and particle debonding limit it. These findings confirm that sawdust/coir-epoxy composite bars are viable for applications such as furniture, packaging, and low-cost structural components, contributing to waste valorisation and sustainability.     

Keywords: Charpy impact resistance, Coconut coir, Eco-friendly composites, Epoxy matrix, Hybrid composite bars, Microstructural analysis, Natural fibre composites, Sawdust, Tensile strength

References

1. Ajiri, M.A., Edomwonyi-Otu, L. and Okieimen, F.E. (2024) ‘Use of sawdust and coconut fibre as fluid loss control additives for water-based mud,’ J. Pet. Sci. Eng., 223, pp. 211–220.
2. Bui, T.T., Tran, V.T. and Nguyen, H.T (2020) ‘Physical and mechanical properties of raw and treated coconut fibres for construction materials,’ J. Nat. Fibres, 17(8), pp. 1123–1135.
3. Daniel, I.M. and Ishai, O. (2006) Engineering mechanics of composite materials. Oxford, U.K.: Oxford Univ. Press.
4. Deswal, P. (2025) ‘Article 6 of the Paris Agreement: A comprehensive review of mechanisms, progress, and persistent challenges’, International Journal of Technology, Health and Sustainability, 1(2), pp. 111-125. https://ijths.com/wp-content/uploads/IJTHS-010235.pdf
5. Farid, S., Razzaq, S. and Sajid, M. (2026) ‘Impact of balanced use of fertilizer on crop production and its quality for human health’, International Journal of Technology, Health and Sustainability, 2(1), pp. 29-38. https://ijths.com/wp-content/uploads/IJTHS-020143.pdf 
6. Garba, A. and Abdullahi, M.G. (2026) ‘Evaluation of climatic trends in Dass LGA, Bauchi State, Nigeria’, International Journal of Technology, Health and Sustainability, 2(1), pp. 52-56. https://ijths.com/wp-content/uploads/IJTHS-020147.pdf
7. Gibson, R.F. (2016) Principles of composite material mechanics. Boca Raton, FL, USA: CRC Press.
8. Gurusamy, S., Kumar, R. and Prasad, V. (2024) ‘Effect of fine powder loads on hybrid composites of Malabar Ironwood sawdust and COCO dust,’ Polym. Compos., 45(3), pp. 245–256.
9. Hasan, K.M.F., Horváth, P.G. and Alpár, T. (2020) ‘Mechanical properties of coconut fibre-reinforced polymer composites,’ J. Reinf. Plast. Compos., 39(15), pp. 567–578.
10. Mallick, P.K. (2007) Fiber-reinforced composites: Materials, manufacturing, and design. Boca Raton, FL, USA: CRC Press.
11. Oladele, I.O., Okoro, A.M. and Adewuyi, B.O. (2020) ‘Development and characterization of hybrid sawdust–coconut fibre composites in polyester matrix,’ J. Compos. Mater., 54(12), pp. 1567–1578.
12. Prakash, R., Anandh, S., Nachiar, S.S., et al. (2020) ‘A study on mechanical and durability properties of coconut shell concrete using coconut fiber and sawdust,’ Mater. Sci. Eng., 912, 062068. DOI 10.1088/1757-899X/912/6/062068
13. Singh, A., Singh, N. and Khare, N. (2026) ‘Eco-friendly synthesis and evaluation of silver nanoparticles (agnps) using Azadirachta indica: A greener approach to boosting antimicrobial power’, International Journal of Technology, Health and Sustainability, 2(1), pp. 233-237. https://ijths.cFaridom/wp-content/uploads/IJTHS-020180.pdf
14. Soutis, C. (2005) ‘Fibre reinforced composites in aircraft construction,’ Prog. Aerosp. Sci., 41(2), pp. 143–151.
15. Tawasil, M.R., Ibrahim, R. and Ahmad, Z. (2021) ‘Coconut fibre and sawdust as green building materials: Physical and mechanical properties of hybrid particleboards,’ Constr. Build. Mater., 271, pp. 121–129.
16. Thébault, F., Clément, A, Fréour, S., et al. (2024) ‘Comparison of fiber volume fraction measurement methods from composite micrographs,’ Composites Science and Technology, 282, 111689. https://doi.org/10.1016/j.compscitech.2026.111689.
17. Uchendu, I.F., Akaninwor, G.C. and Nna, G. (2026) ‘Evaluate the performance of biodegradable composites made from lime and mango peel’, International Journal of Technology, Health and Sustainability, 2(1), pp. 195-200. https://ijths.com/wp-content/uploads/IJTHS-020171.pdf 
18. Uesaka, M., Onizawa, K., Kasahara, N., et al. (2025) ‘Strength of materials and structural mechanics.’ In: Nuclear Structural Engineering.  Singapore: Springer Nature. https://doi.org/10.1007/978-981-97-3519-8_2