Effects of various fire-retardants on plate shear and five-point flexural shear properties of plywood

Abstract

The influence of four fire-retardant systems on the planar (rolling) shear properties of structural hardwood plywood is evaluated using two possible ASTM D2718 test methodologies: the plate-shear method and the five-point flexural shear method. Knowing the planar shear properties and the potential of the various fire-retardant systems to affect properties is critical in engineering design. The various fire-retardant systems were found to reduce plate shear properties for plywood more than flexural shear properties depending on the fire-retardant chemical and its chemical loading level. We also found the inherent variability of plate shear data was greater than it was for flexural shear data. We conclude that there exist practically important differences between the results derived in the two planar (rolling) shear test methods for fire-retardant treated plywood.