Identification of Strength Parameters in Finger Jointed Timber Sections

Abstract

Timber is widely used as a building material in the construction industry. As it is in short supply, there is now a high demand for timber in the construction industry. This has made waste timber utilization for construction important. Finger jointing can be used to connect two small pieces of waste timber. Machinery is now available in Sri Lanka to fasten, using finger jointing, the timber pieces that are used for the manufacture of furniture. As it is important to determine the structural properties of finger jointed (FJ) timber, three-point bending and compression tests using a universal testing machine (UTM) were conducted on samples of selected timber species commercially available in Sri Lanka, in accordance with BS 373:1957 to determine these properties. Samples were finger jointed with a finger length of 19 mm using the adhesive, Fevicol SWR. Satin with its high resistance to bending is found to be the most suitable species for finger jointing. The tests carried out indicated that when finger jointed, the bending strength of Satin gets reduced by only 9.5%. In the compression parallel to grain test, Jak displayed the minimum reduction of 1.53% in its compressive strength. In the timber species tested, finger jointing was found to be 100% effective in resisting compression perpendicular to grain. The compressive strength of Pine is found to be increased by 27.39% when it is under compression perpendicular to grain. Strength classes of the timber species selected were identified from BS 5268-2:2002. The compressive strength of finger jointed Grandis and Pine are found to be too poor for use as structural elements. Finger jointing of Teak is found to be cost effective. Finally, it is recommended that further studies be done on using finger jointed local timber waste.