Effect of Coffee Husk-to-Pine Sawdust Ratio on the Physical–Mechanical Performance of Binderless Lignocellulosic Particleboards: Experimental Assessment and Finite Element Analysis

The valorisation of lignocellulosic residues as feedstock for low-impact wood-based panels requires a clear understanding of how formulation affects densification, mechanical performance and moisture stability. This study evaluated six pine sawdust/coffee husk mass ratios (100/0, 90/10, 80/20, 70/30, 60/40 and 50/50) in binderless boards hot-pressed at 90 °C for 5 min under a hydraulic-system reading of 40 MPa. Apparent density, perpendicular tensile strength, three-point bending, flexural modulus, compression, water absorption and thickness swelling were assessed. The 100/0 and 90/10 formulations showed the highest perpendicular tensile strength (~2.07 MPa), whereas 80/20 showed the highest flexural strength (5.035 MPa) and compressive strength (5.422 MPa). Water resistance was the main limitation: 24 of 30 specimens lost or severely compromised their integrity after 24 h immersion; among measurable specimens, water absorption ranged from 119.67 to 154.77% and thickness swelling from 98.99 to 249.54%. An ANSYS finite-element model based on representative-volume-element homogenisation reproduced relative trends more consistently in bending and compression than in tension. Because the model loads were derived from the experiments and von Mises stress is not a direct failure criterion for this brittle heterogeneous material, the FEM results are interpreted qualitatively. The results identify formulation as an important design variable but show that moisture control, pressing optimisation and standardised validation are required before practical particleboard applications can be proposed.