Evaluation of wheat straw for the development of bio-based panels

This study explores the potential of wheat straw (Triticum aestivum) for producing structural panels suitable for use in the building industry. The research was motivated by the large volume of agricultural waste that is commonly underutilized or burned, and the opportunity this presents for countries with limited wood resources to develop sustainable, value-added bio-based panels. To fully explore the potential of this resource, four types of panels were fabricated: (a) panels made entirely from wheat straw, (b) panels made from a mixture of wheat straw and wood strands, and (c) panels with wood strands in the outer layers and wheat straw in the core along with (d) control panels made entirely from wood strands. Wheat straws were cut into 85 ± 15 mm pieces, while the commercial wood strands measured between 112.5 ± 12.5 mm. After being sprayed with adhesive, the core layer, comprising 40% of the total panel weight, was oriented perpendicular to the outer layers, each accounting for 30% of the panel weight, to replicate the strand alignment used in commercial OSB manufacturing. Polymeric diphenylmethane diisocyanate (pMDI) adhesive was sprayed on wheat, while phenol–formaldehyde (PF) adhesive was applied to the wood strands. Following ASTM D1037, specimens cut from these panels were evaluated using bending, internal bond, vertical density profile, direct screw withdrawal, water absorption, and thickness swelling tests. Compared with the control panels, the panels with wood strands in the outer layers and wheat straw in the core showed a 4% increase in internal bond strength, while modulus of rupture and bending stiffness increased by 1.5% and 7.8%, respectively, and screw withdrawal strength increased by 1.2%. The results demonstrate that wheat straw can partially replace wood strands in structural panels without chemical pretreatment, offering a viable alternative for regions with limited wood resources.