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Construction with Bamboo
Diplom-Ingenieur Christoph Tönges |
basics   |
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basics |
Purchase
There are many bamboo dealers usually located near small urbanizations. With the
introduction of modern but expensive building materials like brick and reinforced
concrete, the "cheap" bamboo became the building material of the poor. At present,
a change of this view takes place again. This development is favored by popular
projects of the architect Simón Vélez, but also since
handicraft and furniture industry
discovered the material for diverse uses.
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(29) Simple bamboo dealer | ||
Because of the increasing demand for selective use, there are more and more
specialized dealers. The raw material is partially from plantations, the culms
are pre-sorted and optionally immunized.
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(30) Specialized dealer | ||
Storage and Desiccation
Sometimes the hollow culms of the recently felled bamboo are filled up with
water. Therefore they must be dried slowly first before they are graded
according to curvature, diameter, weight and sound test. Bamboo for sale
has been cut two or three months before. At this time its relative humidity
is approximately 30 to 50 percent.
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(31) Storage | ||
Traditionally they are also stored and dried standing upright. The desiccation
by air lasts four to six months according to the climate. The desiccation in an
oven lasts only two to three weeks, however, rips and splits may occur.
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(32) Traditional storage | ||||
Timber protection
Bamboo can be attacked by fungi (in particular if the moisture content
(MC) lies over 18 percent), by woodworms and termites (the critical
MC area lies between 12 and 18 percent). They damage the structure
to such an extent, that parts have to be exchanged or become useless.
Some bugs (Dinoderus, Bostrichidae, Lyctidae) cause large damage by
perforation to felled and living culms as well.
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(33) Insects of the habitat Guadua | ||
The chemical wood protection is more expensive, so it is only recommended
objects with special uses and intended for longevity. To apply wood
protection to the inside of the culm wall, either all internodes have to
be drilled from outside (for the injection) or all diaphragms have to be
pierced (watering).
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(34) Old bamboo construction | ||
Methods to extend lifespan:
Harvest time The harvest of Guadua proved to be favorable if it takes place one week after full moon. At this time there is less capillary water in the culms due to the weaker gravitation of the moon. This has two advantages: on the one hand the bamboo is not so heavy and on the other hand it dries faster, thus tends less to tearing. |
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(35) Transport of the harvest | ||
The branches together with the leaves should remain on the culm at first,
to remove the free capillary water using the natural evaporation process
(bound water is in the cells); unfortunately this is often neglected for
"commercial" reasons. On the basis of photosynthesis, in the course of
the morning the bamboo transports starch from the roots into the leaves,
furthermore there is more water in the culm (weight! > gross density).
If the harvest therefore takes place before sunrise, the starch is still
in the roots. The more starch is in the culm, the more nutritious and
attractive it is to
wood-eating insects.
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(36) Still green Guadua | ||
Fumigate
If bamboo culms are fumigated (the own branches and leaves are used for this)
for a longer time, they become inedible to
insects.
The culms are smoked with an air temperature of 50 to 60 degrees Celsius and
changing air moisture. The goal is to prevent the tar from condensation, so
that it can ingress into the fibres in a gaseous condition. This is gained
by shifting between smouldering (tar production through pyrolysis) and heating
fire.
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(37) Fumigator | ||
Watering
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(38) Watering | ||
Watering with Borax
Borax is no insecticide (natriumpentaborat + boric acid). The effect is that
the crystals immediately destroy the digesting insect stomach!
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(39) Piercing of the Diaphragmen | ||
There are different ways to immunize the prepared culms. Frequently, a basin
is used immerse the culms. It is important to prevent the culms from surfacing,
so that they will stay completely dived.
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(40) Dip tanks | ||
The solution can also be injected through before drilled holes.
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(41) Injection | ||
In Costa Rica an installation ('Bouchery-Modificado') has been developed, with
which it is possible, to press the wood preservative with high pressure into
the bamboo (Gonzales/
Janssen).
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(42) 'Bouchery-Modificado' | ||
Coatings
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(43) Patina | ||
Tools and processing
Bamboo can be processed with the simplest tools, like machetes, saws, chisels
(for example to make a
'fish mouth').
Since the silicified outer part of the tube is very hard, tool wear is somewhat
higher compared with processing timber.
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(44) Processing with chisel | ||
Cutting and carving
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(45) Circular saw | ||
Splitting
Due to the axial fiber alignment, the bamboo tube can be split fast and
cleanly with a wedge.
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(46) Annulus cutter | ||
Breaking
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(47) Breaking open Guadua | ||
Drilling
Stone and metal drills are very suitable because of their higher longevity.
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(48) Special drill | ||
Cold bending
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(49) Cold bent! | ||
Bibliography
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Links
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The Chinese philosopher Konfuzius said:
"Without meat, we can live, without bamboo, we must die." |
basics   |
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