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Strength Properties of Some East Pakistani Woods

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

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

Abstract/ Executive Summary:

Jarul and tali logs exhibited slightly inter-locked grain. The sapwood was from 1 to 3½ in. wide (1 in. in the case of smaller diameter logs viz., jarul and tali and 3½ in. for civit and gurjan) and quite distinct from heartwood. Test specimens were selected mostly from the heartwood portion of the log. The relative strength figures in air-dry condition are in most cases higher than the corresponding values in green condition. This may be attributed to the greater volumetric shrinkage of these species relative to teak.

Keywords: Strength properties, Swintonia floribunda, Dipterocarpus species, Lagersitroemia species, Palaquium polyanthum.

Location:

Start Date: 00-00-0000

End Date: 00-00-0000

Program Area: Postharvest and Agro-processing

Commodity: Wood

Objectives:

To determine the physical and mechanical properties of timber species grown in East Pakistan.

Methodology:

Test materials for this study were obtained from different forests of Chittagong and Chittagong Hill Tracts as indicated below :

Civit (Swintonia floribunda) : One 8-foot bolt from 11 to 18 feet above stump height was obtained from each of five 30 to 35 inches diameter¹ trees from Pablakhali Reserved Forest of Chittagong Hill Tracts. The trees were representative of the species in the locality. In each bolt test samples were taken from all the four cardinal directtions according to American Society for Testing and Materials Standards D143-52 (primary methods) (2)². The 8-foot bolt corresponds to the C-D bolt of ASTM Standards.Dholi gurjan (Dipterocarpus pilosus) : One 8-foot bolt from 11 to 18 feet above stump height was obtained from each of four representative trees of 32 to 36 inches diameter from Kassalong Reserved Forest of Chittagong Hill Tracts. Test samples were taken as in civit.Telya gurjan (Dipterocarpus turbinatus) : One 8-foot bolt from 11 to 18 feet above stump height was obtained from a representative trees of 32 inches diameter from Chunati Research Forest of Chittagong, and samples were taken as in civit.Dholya gurjan (Dipterocarpus alatus) : One trepresentative tree 20 inches diameter was obtained from Harbang reserved Forest of Chittagong. On the basis of the findings of Ali and Wallin (1), cardinal directions were not considered in sampling this species. Two samples per bolt were taken rendomly from each of five 8-foot bolts. Ali and Wallin observed no cardinal direction effect on strength properties of gurjan (Dipterocarpus pilosus) and recommended exclusion of this factor in future sampling.Baittya gurjan (Dipterocarpus scaber) : One representative tree of 20 inches diameter was obtained from Harbang Reserved Forest of Chittagong, and 2 samples per bolt were taken randomly from each of seven 8-foot bolts as in Dipterocarpus alatus.Jarul (Lagerstroemia speciosa) : Ten representative trees of 18 to 22 inches diameter were obtained from Pablakhali Reserved Forest of Chittagong Hill Tracts. The trees were cross cut into 8-foot bolts, and 5 samples per tree were selected randomly from all the trees. Cardinal directions were not considered.Tali (Palaquium polyanthum) : Ten representative trees of 15 to 20 inches diameter were obtained from Chunati Research Forest of Chittagong. The trees were cross cut into 8-foot bolts and 3 samples per tree were selected randomly from all the trees as in jarul.

Source of Information: Bulletin 1, Timber Physics Series, Bangladesh Forest Research Institute, Chittagong. 14 pp. 1970

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

All the bolts were straight and relatively free from defects. Small knots were, however, present in limited numbers in jarul and tali logs. These two species also exhibited slightly inter-locked grain. The sapwood was from 1 to 3½ in. wide (1 in. in the case of smaller diameter logs viz., jarul and tali and 3½ in. for civit and gurjan) and quite distinct from heartwood. Test specimens were selected mostly from the heartwood portion of the log.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, Jarul and tali exhibited higher strength in hardness, shear and tension perpendicular to grain. In static bending and compression parallel to grain they are, however, inferior to teak. The relative strength figures in air-dry condition are in most cases higher than the corresponding values in green condition. This may be attributed to the greater volumetric shrinkage of these species relative to teak.

Knowledge Management: Report/Proceedings