Fire Resistance of Structural Glued Laminated Timber Treated with Wood Preservatives

There is no regulation for wood preservatives in the Japanese Agricultural Standard (JAS) for glued laminated timber. Glued laminated timber (GLT) treated with wood preservatives is not qualified as a JAS product and we cannot use it for quasi-fireproof construction material considering the charring rate during accidental fire. It is necessary to clarify that the incising process and impregnation of chemicals do not affect the fire safety of treated GLT in order to use it just the same as normal GLT. Treated GLT beams whose laminae were incised mechanically and impregnated with wood preservatives (alkyl ammonium compound (AAC) or azole neonicotinoid compound (AZN)) were made for a 45-minute-quasi-fireproof test. The beams were not destroyed during the fire test and their char depths were less than 35 mm. The fire performance was the same as of a normal GLT beam. The results of vacuum-pressure delamination tests met the requirement for use environment A.