InTrans / Aug 14, 2018

Wood preservation — Preservative treatment for hardwood glued-laminated bridges

Pressure-treating cycle guidelines were developed to
obtain satisfactory penetration and retention of creosote
preservatives in red oak, red maple and yellow poplar
glued-laminated timbers. The creosote-treating cycle
was used to treat a red oak glued-laminated timber
bridge. A retention of 192.2 kg/m3 (12.0 pcf) of
creosote was obtained with penetration of more than
12.7 mm (0.5 inch). The treating cycle guidelines were
slightly modified and used to treat a red maple gluedlaminated
timber bridge. Penetration ranged from 50.8
mm (2.0 inches) to completely through the cross section
of the laminated beam with retention exceeding 240.3
kg/m3 (15.0 pcf). Treatment of red maple bridge
material also used a revised ‰ÛÏpost conditioning‰Û cycle
with a low-temperature/vacuum, post-creosote treatment
cycle. The modified cycle resulted in an excellent
creosote treatment of the red maple glued-laminated
timber bridge and the post-treatment was successful in
cleaning the surfaces and in controlling bleeding of the