國產直交集成板之強度與燃燒性能

Abstract

本試驗以伐自臺灣大學實驗林管理處之柳杉（Cryptomeria japonica, Japanese Cedar）、臺灣杉（Taiwania cryptomerioides Hayata, Taiwania）及杉木（Cunninghamia lanceolata, China fir）國產材製作成集成元，依據CNS 16114（2019）之標準，以連續性機械分等機將集成元分等後使用間苯二酚甲醛樹酯（Resorcinol formaldehyde resin, RF）及乙烯脲酯膠合劑（Vinyl urethane adhesive, KR）二種膠合劑配置成各組5層5單片直交集成材試材。 木材應用於工程和結構用途之前，需要對木材的集成元強度進行分級。為了快速、準確地獲得木材的靜態彈性模數，本研究採用超音波和連續機械應力分等機以及兩種非破壞檢測方法，分析非破壞檢測測量值與靜態彈性模量之間的相關性的彈性值。亦評估了板材的送料方向、正向進料和反向進料方向、送料速度和孔洞造成斷面積比的影響。分析結果表明，透過連續機械應力評級設備測定的彈性模量值與靜態彈性模量值相關性最高。而且，根據結果，板材的送料方向、正向和反向送料方向以及送料速度並不影響連續機械應力額定設備彈性模量值的預測。同時，為確保連續機械應力評級設備彈性模量檢測值的準確性和均勻性，需要避免木材在製備過程中斷裂面積率過高。 本研究以三種樹種、三種集成元等級、兩種膠合劑及兩種燃燒時間做為檢測CLT燃燒性質之試驗變因，其結果指出炭化速率方面，燃燒60分鐘之試材有較高之炭化速率，隨著集成元等級之提升，會有炭化速率減緩之趨勢。而檢視不同試材之升溫曲線可發現，第一層集成元於燃燒過程中會有溫度快速提升之趨勢，相較於此第二層集成元於則無明顯溫度劇烈變化，說明燃燒熱之影響對曝火面影響最大，而其中隨著集成元等級之提升，CLT表面之耐燃性質亦隨之增加，另一方面使用KR之CLT表面其耐燃性質會較RF穩定，使用RF及KR二種膠合劑對於CLT燃燒性質的影響程度並不顯著。另一方面，由CLT煮沸剝離率方面可以發現，RF之剝離率明顯低於KR，說明其具有較佳之膠合性質。抗壓載重方面可發現經燃燒後，樹種變因之強度趨勢皆為柳杉>臺灣杉>杉木，顯示選用較高的集成元強度等級將可獲得較高的抗壓載重，當隨著燃燒時間增加，其抗壓性能將顯著下降。

This study evaluates the combustion properties of lamina made respectively of three different coniferous wood from Taiwan: Taiwania cryptomerioides, Cunninghamia lanceolate and Cryptomeria japonica from the Experimental Forest of the College of Bioresources and Agriculture, National Taiwan University. The fabrication process followed the standards outlined in CNS 16114 (2019). A continuous mechanical stress rating method was employed to classify the composite components, followed by applying two types of adhesives: Resorcinol formaldehyde resin (RF) and Vinyl urethane adhesive (KR). The resulting mixture was configured into test materials, each consisting of five layers and five pieces of orthogonal laminated material. The laminas are graded into three levels and are glued with two types of adhesives being resorcinol formaldehyde (RF) and vinyl urethane (KR) adhesive to compose cross laminated timbers (CLTs). The test results show that the weight loss in the CLTs after initial combustion holds an inverse relationship with their mechanical stress grading. Specifically, CLTs made of C. japonica with M30 and M90 laminas show the significant difference (p < 0.05). After 30 min combustion tests shows that the separate combinations of different grades of C. japonica along with KR and RF as the adhesive holds similar amounts of weight loss and charring rate (p > 0.05). After 60 min of combustion test, RF can be used as CLT adhesive to obtain lower weight loss and charring rate than KR. There was no significant difference in weight loss and charring rate between non-edge-glued and edge-glued CLT of the same grade after burning for 30 min (p > 0.05). Additionally, with a gluing shear strength in the range of 0~3%, RF glued CLTs have lower delamination rate than KR which indicates that using RF as adhesive holds better gluing properties compared to KR. In addition, the compressive strength reduction rate of CLT after combustion was between 30-40% of which the variable factors such as timber species, adhesive type and lamina grading level show no significant effect on strength reduction.