Flexural properties of southern pine plywood overlaid with fiberglass-reinforced plastic

This paper presents experimental results of the significant improvement of the flexural properties of southern pi ne plywood when overlaid on both sides with two layers of polyester-impregnated woven roving fiberglass. In the direction parallel to face veneer grain, stiffness and strength of the overlaid 3-ply plywood improved by 27 and 57 percent, respectively, and that of the overlaid 5-ply plywood improved by 22 and 34 percent, respectively. In the direction perpendicular to face veneer grain, stiffness and strength of the overlaid 3-ply plywood improved by 718 and 310 percent, respectively, and that of the overlaid 5-ply plywood improved by 94 and 246 percent, respectively. It is recommended that future studies of such reinforced plywood panels should include the assessment of edgewise shear strength, plate shear modulus, and resistance to surface penetration.