Physical, mechanical, chemical, and durability assessment of water leaching treatment of bamboo

Abstract

Water leaching is a traditional bamboo treatment method in which fresh bamboo poles are immersed in running water for at least 30 days to leach out water-soluble substances such as starch and carbohydrates. This method is easy to apply and does not require additional chemicals. Although water leaching is widely applied, its influence on the physical, mechanical, and chemical properties of bamboo and its effect on the durability of bamboo against termites has not been fully explored through experimental methods. This paper assesses the effects of water leaching treatment on bamboo and identifies the potential and limitations of this treatment. A 23% reduction in the density of bamboo after water treatment was found, which can be related to the removal of water-soluble extractives from the material. A significant (15%) increase in the modulus of rupture and a 20% increase in the modulus of elasticity were identified using a three-point bending test after water treatment while keeping a similar fibre volume fraction. Water leached bamboo had less dimensional stability and higher water absorption than untreated bamboo. As the density of the bamboo decreased, more space became available in its bundles for water. A darkened surface was observed after treatment, but no chemical modifications were found through FT-IR spectroscopy. Termites can use cellulose as a source of food, and the removal of starch from bamboo did not improve its resistance against this insect. On the contrary, the free space created after treatment favoured the action of the termites, leading to a higher mass loss percentage for treated bamboo. The water leaching system should not be used as the only treatment method in bamboo being utilized for structural purposes, and the reduction of dimensional stability and the darkened surface must be considered when using the bamboo for furniture and handicraft applications.