Evaluations of three adhesive systems for CCA-treated lumber.

Three adhesive mix types were evaluated for bonding chromated copper arsenate (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 conditions 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 series of glulam billets was bonded using selected resin-adhesive mixes and then tested by compression block-shear and cyclic delamination tests. The two resorcinol resin adhesive systems provided excellent block shear and delamination test results according to the standards from the American Institute of Timber Construction for routine production inspection of approved adhesives. The third emulsion-isocyanate system showed promise.