Research on preservation techniques for bamboo used in construction

Nguyen Thi Bich Ngoc

Forest Science Institute of  Vietnam 

In Vietnam, bamboo is popularly used as materials for house building in the countryside. The bamboo is preserved according to traditional methods such as soaking the bamboo into a pond or lake, and fumigation as they are easily harmed by insects and fungi and lose force resistant capacity after 4-5 years of use. To improve the effectiveness of bamboo, the Forest Science Institute of Vietnam has conducted research on technical methods for bamboo preservation for use in construction by some effective and environmentally friendly preservatives.

Materials: Bambusa blumeana, and Dendrocalamus membranaceus: 3-5 years old; Forest product preservatives: LN5, XM5Research method: Conduct experimental research to determine specifications of the bamboo preservation process for use in construction according to methods of resin replacement and normal soaking.

Research on scientific basis of preservative seepage process of bamboo: The heterogeneous structure of bamboo has a big influence on the possibility of preservative seepage. The possibility of seepage in vertical bamboo fiber is the best, the tangential possibility of seepage is better than radially. Have specified liquid seepage index of bamboo on the basis of specifying the water seepage rate through bamboo sample in 60 seconds under compression pressure number is of 1,2 and 3.105 Pa placed in one end of sample. The seepage index of Bambusa blumeana gains 9,4 (Darsi), and Dendrocalamus membranaceus gains 8,6 (Darsi).

          Research on preservation technique of bamboo used in construction:

+ The preservation technique of bamboo according to resin replacement method: Apply to preserve tubular bamboo, wetness of bamboo ≥70%. Preservatives LN5, XM5 diluted at concentration of 5% to preserve bamboo in house, 7-10% if the soaked bamboo is used outside. Place the bamboo section in straight, pour preservative solution into the upper bamboo internodes whose core has been worn out. On watching color of solution pouring out from the beneath of bamboo root is similar as color of initial preservative solution, complete the soaking process. The soaking period of 5 meter -bamboo section takes 50-60 hours in average.

+ The preservation technique of bamboo according to normal soaking method: Apply to bamboo with wetness of bamboo ≤50%. Preservative LN5, XM5 at concentration of 5% to preserve bamboo for using in house construction, preservative XM5 at concentration of 7-10% if the soaked bamboo is used outside. Pile bamboo into soaking tank, lock the bolt against floating. Pump preservative solution into the soaking tank. The bamboo must be submerged under surface of preservative solution at minimum of 10 cm. The minimum soaking time is from 2-4 days for bar-sawn bamboo and 6-8 days for tubular bamboo.

Research has been conducted on the two species: Bambusa blumeana and Dendrocalamus membranaceus; on the structural characteristics and influence of bamboo structure in the seepage process of preservative. Basic parameters of the bamboo soaking process according to preservation methods of resin replacement and normal soaking have been specified and as basis of establishing the seepage procedure. These are preservation methods with simple technical requirements, easily applicable in Vietnam’s countryside to preserve bamboo using in construction. 

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