Physical and mechanical properties of a suitable constructional timber of Bangladesh
A K Lahiry
The study of physical and mechanical properties of lohasirish timber (Derris robusta Roxb.) grown in Bangladesh revealed that the sapwood is whitish to yellowish white, heartwood is dark grey to blackish in colour; the texture is moderately fine, the grain in mostly straight and coarse with whitish rings of parenchyma; shrinkage is moderate; the EMC ranges from 12% to 16%; fuelwood colorific value is higher; workability is moderately difficult but suitable for constructional works; the wood is heavy, the density is 750 ± 5% kg/m3 and 134% of Bangladesh teak (Tectona grandis); the sapwood is perishable and heartwood is moderately durable to durable; kiln-drying is moderately difficult to difficult; sapwood is easily pressure treatable but heartwood is refractory to treatment. The modulus of rupture (MOR) at green condition is 70 ± 2% N/mm2 which is about 100% of Bangladesh teak. The timber is very suitable for all constuctional and structural uses including electric anchor logs, crossarms and railway sleepers, beams, door frames etc.