2018 Volume 64 Issue 4 Pages 156-163
To investigate the influence wood preservatives on glued-laminated-timber (GLT), sugi (Cryptomeria japonica D.Don) laminae were treated with five kinds of wood preservative (ACQ, NCU, CUAZ2, NZN, and AAC), and 5-ply GLTs with low and high density were fabricated using resorcinol-formaldehyde (RF) and phenol-resorcinol-formaldehyde (PRF) resin adhesives. They were subjected to 10 years of outdoor exposure testing, and after 1, 3, 5, and 10 years of exposure block-shear tests were conducted. As the result, for GLTs treated with ACQ, NCU, or CUAZ2, which contain copper as the main ingredient, the specimens sawn from both lateral sides were more degraded than the specimens sawn from the middle part. In GLTs treated with ACQ, NCU, or CUAZ2 the glue-layers closer to the upper horizontal surface tended to show greater deterioration. In addition, in some GLTs the lower glue-layers also deteriorated. From the results of the specimens sawn from the west side of GLTs exposed outdoors, of exposure tests of 2 years, and of accelerated-aging tests using block-shear specimen with 10 mm and 25 mm width, reduction curves (plots of deterioration vs. exposure time) of shear-strength were obtained and compared. The reduction curves of GLTs exposed outdoors were similar to those of the outdoor exposure tests using block-shear specimen of 25 mm width.
