Variation of density, flexural strength and anatomical features of finger jointed wood products in Sri Lanka.

Abstract

Timber is considered to be an ecological friendly building material with less construction energy requirements (Muthumala et. al, 2019). Finger jointed technique is used to eliminate wood defects which weaken the strength of swan wood plank. Surface properties are not considered to be the only factors affecting bonding in wood. Bond quality is also affected by density, porosity, moisture content and shrinking properties. Variations in flexural strength and anatomical features of six common timber species used in furniture industry in Sri Lanka were studied. Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) were measured with and without finger joint specimens of 13 mm and 19mm finger lengths of six timber species. The 3-point bending tests were performed by using Universal Testing Machine (UTM 100 PC). Transverse, radial and tangential section at the range of 10-15 micrometer thickness were taken using a sledge microtome (Model Leica SM2000 R). Measurements were obtained using Micrometers of SE Premium 4 software available at Wood Laboratory, Research division of the State Timber Cooperation, Sri Lanka. Quantitative wood anatomical features such as mean vessel diameter, vessels per square millimeter and ray heights were measured. The relationship between wood density, mechanical properties and anatomical features of finger jointed and clear timber species were analyzed by regression models. There was a positive correlation between total vessel area and flexural strength of 13mm finger joint specimens. Mean ray height and flexural strength are not found to be affected significantly in finger jointing works and clear specimens.