Hygrothermal characterization of biobased particleboards for the construction industry

The valorisation of agro-forestry by-products is essential for promoting a circular bio-economy and reducing the consumption of virgin natural resources in the construction sector. However, despite their potential, there is a lack of scientific data on the integrated hygrothermal behaviour of these residues when combined with sustainable bio-adhesives for low-density applications. This study aims to evaluate the functional properties (thermal conductivity (λ), water vapour permeability (δ), moisture buffer value (MBV) and water vapour sorption isotherms) of low-density particleboards manufactured from four different agro-forestry residues (corn cob, corn stalk, hemp shive and wood fibers and particles) bonded with a tannin-based bio-adhesive compared to a commonly used urea-formaldehyde adhesive. The research focused on understanding how the interaction between the adhesive and the residues’ intrinsic porosity may influence indoor climate regulation. The results were benchmarked against those of a standard particleboard (PB) and a medium-density fiberboard (MDF). The incorporation of agro-residues significantly reduced the board density (average of 447 kg/m 3 ) compared to PB and MDF (average of 650 kg/m 3 ). This reduction led to a notable improvement in thermal performance (average of 0.084 W/(m.K) vs . 0.113 W/(m.K) for references). Regarding water vapour permeability, the innovative particleboards outperformed the commercial references, with the low-density wood-based series reaching up to 5.75 × 10 -11 kg/(m.s.Pa), representing a significant increase in water vapour permeability compared to ordinary PB (0.76 × 10 -11 kg/(m.s.Pa)). Furthermore, most bio-boards achieved an “Excellent” rating for MBV (> 2.0 g/(m 2 .%RH)), particularly the wood-based low density series. Complementarily, sorption isotherms revealed a superior moisture storage capacity for the new particleboards, with corn-based boards reaching an equilibrium moisture content of 10.6% at 90% RH, compared to 7.0% for conventional boards. These results confirm that the use of such by-products offers an innovative low-carbon alternative. The environmental benefits reported here relate specifically to density reduction and thermal / hygric performance. Broader claims regarding the carbon-footprint would require a dedicated life-cycle assessment, which has been identified as a task for the future. In conclusion, the boards demonstrate promising properties for interior cladding and partitioning due to their excellent thermal and moisture-regulation performance. While low density wood-based boards excel in thermal insulation, corn-based boards offer superior moisture buffering, providing versatile and sustainable solutions for indoor environmental control.