Drill and laser incising of lamina for fire-resistive glulam. Issue 3 (26th May 2016) - Ando, Keisuke
Abstract: Conventional glued-laminated timber (glulam) was not permitted to use to a wooden building in the fire preventive district since the amendments of the Building Standards. We already developed a one-hour fire-proof glulam made of Japanese cedar. We also succeeded to give one-hour fire performance to cross laminated timber by the same concept. The both structures are composed of three parts which are load-bearing part, fire-die-out part and surface part. The fire-die-out part is made of lamina incised by CO2 laser and impregnated the fire retardant evenly. As the handling of CO2 laser is not so easy for glulam manufacturer, we felt a growing need for drill incising technology. Therefore, we made pinholes of some diameters up to 2.5 mm to lamina of Japanese cedar, by a drill and investigated differences of hole position on two sides of the lamina. The maximum off-center for length and width directions was 1.8 and 3.3 mm, respectively. These off-centers are 2.3% and 41% of distances between neighboring hole on incising patterns. As the results of impregnating performance and fire-resistive performance of lamina incised by drill, significant differences were not recognized between drill incising and laser incising.