Strength index-based timber classification of Sri Lankan timbers and potential for finger-joint production from wood off-cuts

Shorter sections of sawn timber material resulted from timber industry are considered to be wastes; thus regularly dumped by sawmills. Finger-joint, a method which connects two small pieces of timber together is recognized as a sound technique to minimize the wastage. In this process, sections of different timber species are bonded together for making finger-joint boards. In this connection, selection of the best possible combination of timber species is vital as the success largely depends on the mechanical properties of the pieces. In this study, commonly used 32 timber species were employed to develop a timber classification system based on strength properties of timber species. Cluster analysis was used in grouping the species with similar strength properties. Accordingly, timber species were grouped into five strength classes as very low, low, medium, high and very high. A significant correlation (P = 0.000) between the strength index and timber density was also observed.