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Strength Properties of Some Bangladesh Timber Species.

Md. Yakub
Research Officer (Ex)
Seasoning and Timber Physics Division, Bangladesh Forest Research Institute, Chittagong-4000, Bangladesh.

M.O. Ali
Divisional Officer
Seasoning and Timber Physics Division, Bangladesh Forest Research Institute, Chittagong-4000, Bangladesh.

D.K. Bhattacharjee
Seasoning and Timber Physics Division, Bangladesh Forest Research Institute, Chittagong-4000, Bangladesh.

Abstract/ Executive Summary:

Strength properties of some Bangladesh timber species were studied. Civit is weaker than teak in most of the properties. In shear parallel and tension perpendicular to grain, it is equal to or stronger than teak. Dholi garjan is weaker than teak in all the properties except specific gravity based on air and oven-dry volumes and tension perpendicular to grain. Telya garjan is heavier than teak and stronger in shear parallel and tension perpendicular to grain. In all other properties, it is weaker then teak. Dholya garjan is inferior to teak in specific gravity, static bending and compression, but equal in shear parallel to grain.

Keywords: Strength properties, Timber species, Teak.

Location:

Start Date: 00-00-0000

End Date: 00-00-0000

Program Area: Variety and Species

Commodity: Timber

Objectives:

Strength data relative to teak have been work out for better understanding. It is hoped that the revised report will provide basic information on strength properties of a large number of common timber species of Bangladesh and serve as a useful guide to timber users. Results of tests on other species will be published in future reports.

Methodology:

Test materials were obtained from different Forests of Chittagong and Chittagong Hill Tracts as indicated below : Civit (Swintonia floribunda), Dholi garjan (Dipterocarpus pilosus), Telya gurjera (Dipterocarpus turbinatus), Dholya garjan (Dipterocarpus alatus), Baittya garjan (Dipterocarpus scaber), Jarul (Lagerstroemia speciosa) and Tali (Palaquium polyanthum), Batna (Quercus spp.), Dhakijum (Syzygium grande), Gamari (Gmelina arborea), Pitraj (Amoora rohiuka) and thinning Teak (Tectona grandis).Sawing of bolts and marking of test sticks : Top ends of all the bolts were marked into 2 ½ by 2 ½ inch squares and swan into nominat 2½ by 2½ in. by 8-foot sticks. The civit, dholi and talya garjan test sticks were marked with respect to tree, bolt and cardinal direction. Dholya garjan, baittya garjan, batna, dhakijam, gamari and pitraj test sticks were marked with respect to tree and bolt only. In jarul, tali and teak, the sticks were so marked that the tree can easily be identified. Selected sticks were obtained in pairs. From each pair, one stick was taken for test in green condition and the other one for test after air-drying. The sticks for air-dry tests were cross stacked species-wise and allowed to air season for a period of three to four months. The air-dried sticks were processed into 2½ by 2½ in. by 8-foot strips and conditioned to equilibrium at a temperature of 70⁰F and a relative humidity of 65 per cent. Corresponding to an equilibrium moisture content of approximately 12 per cent.

Preparation of test specimens : All the sticks (green and conditioned) were machined to obtain 2 by 2-in. by 8-foot strips. Clear specimens were obtained from these strips according to the sizes specified by the American Society for Testing and Materials (2). The cross sectional dimensions and length of each specimen were measured to one-hundred of an inch.

Testing procedure: All the specimens were tested in accordance with the specifications of the American Society for Testing and Materials. Except toughness, all other mechanical tests were performed with Riehle 60,000 and 20,000 pound capacity screw power type Universal Testing Machines. Toughness tests were performed in a toughness testing machine designed by the U.S. Forest Products Laboratory, Madison, Wisconsin.

Source of Information: Bulletin 2, Timber Physics Series. 1972. Bangladesh Forest Research Institute, Chittagong. 12 pp.

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Civit is weaker than teak in most of the properties. In shear parallel and tension perpendicular to grain, it is equal to or stronger than teak. Dholi garjan is weaker than teak in all the properties except specific gravity based on air and oven-dry volumes and tension perpendicular to grain. Telya garjan is heavier than teak and stronger in shear parallel and tension perpendicular to grain. In all other properties, it is weaker then teak. Dholya garjan is inferior to teak in specific gravity, static bending and compression, but equal in shear parallel to grain. Baittya garjan though heavier than teak, is weaker in compression parallel and perpendicular to grain. In bending strength it is stronger than teak. Jarul, tali batna and dhakijam exhibit higher strength in hardness, shear parallel and tension perpendicular to grain. In static bending and compression parallel to grain, jarul, tali and dhakijam are inferior to teak. The same properties are, however, higher in batna. Specific gravity is higher in batna and dhakijam. In addition, jarul, batna and dhakijam show higher strength in compression perpendicular to grain.

Knowledge Management: Report/Proceedings