EVALUATIONS OF 3 ADHESIVE SYSTEMS FOR CCA-TREATED LUMBER

Three adhesive mix types were evaluated for bonding chromated copper a rsenate (CCA)-treated lumber for possible glulam industry application. The adhesives included a commercial resorcinol-formaldehyde adhesive, a commercial emulsion-isocyanate adhesive, and a laboratory-modified resorcinol adhesive mixture. The adhesive application and assembly con ditions for the laboratory glulam billets were simulated to represent industry cold-press curing conditions. All lumber pieces were assayed for CCA components (individual chemicals and total retentions). A. ser ies of glulam billets was bonded using selected resin-adhesive mixes a nd then tested by compression block-shear and cyclic delamination test s. The two resorcinol resin adhesive systems provided excellent block shear and delamination test results according to the standards from th e American Institute of Timber Construction for routine production ins pection of approved adhesives. The third emulsion-isocyanate system sh owed promise.