Stength properties of exterior adhesives on preservative-treated hardwoods
1992
Janowiak, J.J. | Manbeck, H.B. | Blankenhorn, P.R. | Kessler, K.R.
Glueline properties of shear strength and percent wood failure were determined for three hardwoods and southern pine. The hardwoods selected were chosen because they are underutilized and have potential to provide quality laminated products. The hardwoods examined were chestnut oak, red maple, and yellow poplar. Several commercial exterior-grade adhesive formulations were evaluated for each species under control (no preservative) conditions, along with preservative treatments including waterborne chromated copper arsenate (CCA) and oil diluent pentachlorophenol (penta). The adhesives used were neat resorcinol, phenol-resorcinol, and phenol-formaldehyde (PF) formulations. The effect of moisture content (MC) on bonding performance was also examined for each species-adhesive combination. MCs for gluing the materials were 12 or 18 percent. Assessing the bond performance was conducted with the ASTM D 905 test method. Test evaluation for quantifying glueline properties was also conducted after a water vacuum pressure soak (VPS) exposure treatment. A comparison of test results revealed higher glueline shear strength for the CCA materials over the control materials for most treatment level combinations. In contrast, glueline performance was reduced for several species-adhesive combinations with penta. Bonding at higher MCs produced some adverse effects, as did the VPS treatment. The PF adhesive was found to be most sensitive to bonding at the higher MC and exposure treatment. Between the various treatment levels, chestnut oak had the widest range of glueline shear strengths and was classified as problematic for effective structural bonding.
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