Effect of Fire-Retardant Treatment and Redrying on the Mechanical Properties of Douglas-Fir and Aspen Plywood

摘要

Exterior grades of Douglas-fir and aspen plywood were treated with interior-use fire-retardant (FR) chemicals and redried after treatment using several kiln-drying or press-drying temperatures. FR treatments included borax-boric acid, chromated zinc chloride, minalith, pyresote, and a commercial proprietary formulation. Bending strength (MOR), load-carrying capacity (RZ), modulus of elasticity (MOE), stiffness (EI), work to maximum load (WML), and horizontal (rolling) shear strength (TAU) were evaluated. With the exception of chromated zinc chloride, all of the FR treatments appeared to have similar 'relative' effects on the mechanical properties tested. Chromated zinc chloride treatment reduced strength and stiffness more than the other FR treatments tested.