Friday, January 17, 2020

BAMBOO IN CONSTRUCTION

Material Type : Bamboo


       Bamboo is one of the oldest and most versatile building materials with many applications in the field of construction, particularly in developing countries. It is strong and lightweight and can often be used without processing or finishing.
      The diminishing wood resource and restrictions imposed on felling in natural forests, particularly in the tropics, have focused world attention on the need to identify a substitute material which should be renewable, environmentally friendly and widely available. In view of its rapid growth (exceeding most fast growing woods), a ready adaptability to most climatic and edaphic conditions and properties superior to most juvenile fast growing wood, bamboo emerges as a very suitable alternative.

INTRODUCTION :
       Bamboo is a renewable and versatile resource, characterized by high strength and low weight, and is easily worked using simple tools. As such, bamboo constructions are easy to build, resilient to wind and even earthquake forces and readily repairable in the event of damage.



1) Durability :
    Bamboo is subject to attack by fungi and insects. For this reason, untreated bamboo structures are viewed as temporary with an expected life of no more than five years.
2)Jointing :
   Although many traditional joint types exist, their structural efficiency is low (Herbert et al. 1979). Considerable research has been directed at the development of more effective jointing methods.
3)Flammability :
   Bamboo structures do not behave well in fires, and the cost of treatment, where available, is relatively high.


PRESERVATION OF BAMBOO :
       Bamboo is subject to attack by micro-organisms and insects in almost any construction application. Unfortunately, like most lignocellulosic materials, bamboo has very low resistance to biological degrading agents. The service life is therefore mainly determined by the rate of attack.
      A variety of methods to improve the durability of bamboo have, however, been developed. Several of these techniques are described here with the aim of providing helpful guidelines to users.


DRYING OF BAMBOO :
       Green bamboo can have a moisture content of 100-150%, depending on the species, area of growth and felling season. The chemical composition of bamboo results in a comparatively higher hygroscopicity than wood. Additional problems in the drying of bamboo occur because the material lacks an efficient radial transport system and possesses a waxy coating. Therefore, the major pathway for the loss of moisture is from the ends of the culms.
     The liability to biological degradation and to deformation owing to excessive shrinkage (which occurs even above the fibre saturation point) necessitates quick drying of bamboo.


CONSTRUCTION METHODS :
        The majority of bamboo construction relates to rural community needs in developing countries. As such, domestic housing predominates and, in accordance with their rural origins, these buildings are often simple in design and construction relying on a living tradition of local skills and methods. Other common types of construction include farm and school buildings and bridges.
       Further applications of bamboo relevant to construction include its use as scaffolding, water piping, and as shuttering and reinforcement for concrete. In addition, the potential number of construction applications has been increased by the recent development of a variety of bamboo based panels.


SMALL BUILDINGS :


       Bamboo can be used to make all the components of small buildings, both structural and non-structural, with the exception of fireplaces and chimneys. It is, however, often used in conjunction with other materials, cost and availability permitting.

FOUNDATIONS :

  • Bamboo in direct ground contact 
  • Bamboo on rock or preformed concrete footings 
  • Bamboo incorporated into concrete footings 
  • Composite bamboo/concrete columns 
  • Bamboo reinforced concrete 
  • Bamboo piles
WALLS :


        The most extensive use of bamboo in construction is for walls and partitions. The major elements of a bamboo wall (posts and beams) generally constitute part of the structural framework. As such they are required to carry the self-weight of the building and also loadings imposed by the occupants, the weather and, occasionally, earthquakes. To this end, efficient and adequate jointing is of primary importance.

ROOFS :


       The roof of a building is arguably its most important component - this is what defines a construction as a shelter. As such, it is required to offer protection against extremes of weather including rain, sun and wind, and to provide clear, usable space beneath its canopy. Above all, it must be strong enough to resist the considerable forces generated by wind and roof coverings. 

DOORS AND WINDOWS :


        In traditional types of bamboo building, doors and windows are usually very simple in form and operation. Bamboo doors can be side hinged or sliding, comprising a bamboo frame with an infill of woven bamboo or small diameter culms.
       In higher grade buildings, wooden doors are common. Doors and shutters comprising bamboo mat board as panelling, or as flush skins for hollow core doors offer another solution. 
       Bamboo windows are generally left unglazed and can have bamboo bars, or a sash with woven bamboo infill. The sash can be side hinged or sliding, or, more commonly, top hinged to keep out direct sunlight and rain. At night, windows are closed to protect against insects and animals. Hinges are formed from simple bindings, or connecting bamboo elements.

WATER PIPES AND GUTTERS :


       Whole bamboo culms, with the diaphragms removed, can be used as water pipes either below or above ground. Below ground: the system is usually gravity fed. 
       To ensure watertight connections, the ends of the culms can be reamed and fitted into short sections of metal, pvc or bamboo pipe and suitably caulked. To control insect attack, the trench can be treated with insecticide before the pipes are laid. 

JOINTING TECHNIQUES IN BAMBOO :
        Effective jointing is fundamental to the structural integrity of a framed construction. Furthermore, the suitability of a material for use in framing is largely dependent upon the ease with which joints can be formed. Because of its round, tubular form, jointing of two or more bamboo members requires a different approach to that adopted for, say, solid timber.
 

      Despite its relatively high strength, bamboo is susceptible to crushing, particularly of open ends. It is also characterised by a tendency to split; the use of nails, pegs, notches or mortises can therefore result in considerable reductions in strength. Connections must also cope with variations in diameter, wall thickness and straightness.



 Traditional jointing methods rely principally on lashing or tying, with or without pegs or dowels. The basic joint types are:

TYPES :
Spliced joints 
Orthogonal joints 
Angled joints 
Through joints









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