Performance of Agro-Forestry Biomass Particleboards Bonded with Tannin-Based Bio-Adhesives

To promote circular economy in construction, this study evaluates the mechanical surface integrity and long-term water durability of sustainable low-density particleboards utilizing agro-forestry residues, such as corn cob, corn stalk, hemp shive and wood fibres. These are bonded using an ecological mimosa tannin adhesive in comparison to a conventional urea–formaldehyde-based adhesive. Performance was assessed through apparent density, surface cohesion, Shore A hardness and impact resistance. Furthermore, the water sensitivity was assessed through total water absorption (WA), thickness swelling (TS), and a customized cyclic immersion-drying protocol. Results showed a significant correlation between density and Shore A hardness (R2 = 0.77). While hemp- and corn-based boards showed surface performance competitive with commercial standards, the wood fibre series exhibited extreme water susceptibility, with mass variations exceeding 400% during cycling. Additionally, tannin-based boards showed evidence of leaching, with an 11% mass loss after three emersion cycles. These findings conclude that while tannin adhesives are viable renewable alternatives, these bio-boards are primarily suited for interior lining in dry environments, as lightweight formulations require additional protection to ensure durability in practical building applications.