CREOSOTE TREATMENT EFFECT ON HARDWOOD GLULAM BEAM PROPERTIES

Flexure tests were conducted to determine the effect of creosote treat ment on the performance of Combination A northern red oak, yellow popl ar, and red maple glued-laminated (glulam) beams. This testing was con ducted in accordance with ASTM D198-84 (ASTM 1987a), and the beams wer e fabricated in accordance with AITC 119-85 (AITC 1986), ANSI/AITC 190 .1-83 (AITC 1983b), and AITC 200-83 (AITC 1983a). Shear tests were als o conducted on samples taken from the beams to determine the glueline shear strength and percent wood failure (WF). There was no significant difference (P < 0.05) between the modulus of rupture (MOR) of creosot e-treated and untreated northern red oak beams. However, the MORs of t he creosote-treated red maple and yellow poplar beams were significant ly (P < 0.05) higher than those for untreated beams. There was no sign ificant difference (P < 0.05) between the treated and untreated appare nt modulus of elasticity (MOE) of each species. Therefore, the post-fa brication creosote treatment process from 145.92 to 215.76 kg/m(3) (9. 11 to 13.47 pcf) average weight retention did not adversely affect the strength (MOR) or stiffness (MOE) of northern red oak, red maple, and yellow poplar Combination A glulam beams. Glueline shear strengths fo r treated and untreated specimens of each species met or exceeded mini mum performance criteria in AITC 200-83. Creosote treatment significan tly (P < 0.05) increased glueline shear strength of red maple, but had no effect on the shear strength of red oak and yellow poplar specimen s. Mean percentage wood failure of treated shear specimens was signifi cantly (P < 0.05) greater than of untreated specimens in each species. Mean percentage wood failures of red oak and yellow poplar gluelines exceeded AITC 200-83 performance criteria; percentage wood failure of untreated (48%) and treated (59%) red maple shear specimens did not me et AITC 200-83 performance criteria.