Characteristics of cross laminated timber made from fast growing species with a different number of layers

Abstract

Cross laminated timber (CLT) is one of the engineered wood products made by arranging a number of layers of wood crossing one another, which are then glued with adhesive. The purpose of this study was to determine the effect of timber spesies and number of layers to physical and mechanical properties of CLT, to investigate the number of layers and wood species of CLT constituent that produce the best characteristics and compare the physical and mechanical properties of CLT with solid wood. The wood species used in this study were mangium wood (Acacia mangium Willd.), afrika (Maesopsis eminii Engl.) and jabon (Anthocephalus cadamba Miq.). CLT beam was divided into 3 groups based on the number of lamina layers, 3 layers, 5 layers and 7 layers respectively. The adhesive used was Water Based Polymer Isocyanate (WBPI), applied on both surfaces to be bonded with the spreading weight of 280 g/m2. The test method of physical and mechanical properties of CLT was conducted based on ASTM D143-05 : Standard Test Methods for Small Clear Specimen of Wood. The study results showed that the type of wood and the number of layers significantly influenced the physical and mechanical properties of CLT. In comparison of the physical and mechanical properties of CLT with solid wood, the average density and stiffness of CLT were equivalent to those of its solid wood, the average value of moisture content in CLT was 2.3 to 5.6% lower compared to that of solid wood, the average value of bending strength for CLT with 5 layers was equivalent to that of its solid wood while the CLT of 3 and 7 layers was 18.3 to 18.6% lower compared to its solid wood, the average value of compressive strength parallel to grain of CLT was 21.8 to 26.1% lower than that of its solid wood, and the average value of shearing strength for afrika and jabon CLT was equivalent to its solid wood whereas that of mangium CLT was 26.8 to 47.4% lower when compared to its solid wood Key words : Cross laminated timber, fast growing species, physical and mechanical properties. . The layers number of CLT that produce the best characteristics is the 5 layers and the wood species that produces the best characteristics is mangium wood.