Bamboo as Bldg. Mat

8/18/2019 Bamboo as Bldg. Mat.

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BAMBOO ASBUILDING MATERIAL


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Introduction•Bamboo plays an important role in lies o!

"or #erbiores $ !odder$ #uman palate % !or curry and pic&les

En'ineerin' needs % a material (it# e)ceptional

mec#anical properties !orest $ a soil * (ater conserer• +ommercial importance o! Bamboo is a ,Modern Times-• Britis# era S(ades#i resulted only in

paper consumption pac&a'edmar&etin' etc.

•India is t#e only country usin' bamboo as a !eed stoc& !orpaper industries .

i. +#ina uses only /0 1ii. India apportions oer 2*3 o! its e)traction


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Ener'y crunc# and bamboo• since #e (orld approac#in' ener'y crunc# specially in#ousin' sector.• conentional Buildin' materials

re4uire lot o! ener'y •Bamboo re4uires t#e least ener'y.• 5#ile its stress carryin'

capacity is more.•Besides t#is potential o! bamboo in t#e sector o!

• Domestic utilities• "urniture• 6e#icle buildin'.

Is enormous i! proper support isproided (it# desi'n inputs.


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Bamboo t#e 7lant• Essentially a all perennial 'rass.• Belon's to t#e !amily 'raminae. 8the grasses: chiefly

herbaceous but some woody plants including cereals)

• 7laced at t#e top in eolutionary ladder i.e. t#ey are #i'#lyeoled and recent in ori'in.• 9o(eer (it#in t#e !amily bamboo is most primitie• It #as :; 'enera (species are multiplied and genera are formed )• Embracin' some /200 species.• Out o! (#ic# /


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Bamboo t#e 7lant• Distributed all oer #e tropics and sub tropics• Bamboo coers /= million #ectares o! !orest lands• Oer #al! o! t#is spra(l lies in India.• India is t#e lar'est bamboo 'ro(in' country

• :0 1 o! t#e Geo'rap#ic area o! India is t#e• Natural Bamboo #abitat• 5it# : nort# eastern states supportin' a

'reat density and a eritable cro(d o! species• Bamboo 'ro(s (it# ease in tropical re'ions.


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Bamboo t#e 7lant• T#e Important indian species are

i. Bamboosa arundinaceaii. Bamboosa polymorp#a

iii. Dendrocalamus 9amiltonili. Dendrocalamus strictus . Melocanna bamboosoides i. Oc#landra traancorica.

• Amon' t#ese t#e most abundant and important isDendrocalamus strictus.


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Bamboo $ ma>or &inds• Bamboo can be distin'uis#ed as

i. Monopodial 8Temperate species? Are t#e residents o! colder climate

And can (it# stand sub @ero temperature

•T#ey sand !ree li&e a ro( o! trees.


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Bamboo $ ma>or &inds• And

ii. Sympodial 8Tropical species? Are clump !ormin' residents o!

Tropics and dominate t#e bamboo sceneIn India.


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7arts o! Bamboo• T#e R#i@omes

i. T#is is an under'round part o! t#e clumpii. S#o(s up a se4uence o! node and internode

• T#e Leptomorp# R#i@omes !ound under t#e monopodial bamboo

i. Are lon' and cylindricalii. More li&e culm itsel! iii. Bears a culm o! t#ic&er dia.

•


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7arts o! Bamboo


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7arts o! Bamboo• T#e 7ac#ymorp# R#i@omes !ound under

t#e +lump !ormin' o! sympodial bambooi. Are s#ort

ii. Asymmetricaliii. Spindle s#apedi. And soil bearin' +ulm

. O! smaller dia.•


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7arts o! Bamboo• T#e +ulm

i. An indiidual +ulm o!ten considered as plant.ii. But is a par o! t#e plant called +lump.

iii. Or a s#oot.i. All #e culms in t#e clump are inter connectedBy means o! r#i@omes

. Aerial part lon' erect i. Branc#ed or un branc#ed ii. +opious olume o! lus# 'reen !olia'e

iii.T#e len't# ran'es !rom !e( +m. to 30 M.i). T#ic&ness !rom about a !in'er t#ic& to 300 mm dia.


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7arts o! Bamboo• T#e Roots

i. 9e roots emer'e !rom t#e r#i@ome node (and sometimes the Culm node) rin'

ii. "ree !rom node p#enomenon

iii. eep maintainin' !ibrous naturei. Ma) in / cm dia.

. E)tend up to a meter in searc# o! !ood.• "lo(erin'

i. T#e mode o! !lo(erin' in t#e bamboo plants is a

mystery to t#e botanistii. Most species !lo(er >ust be!ore t#eir deat# and only

t#at once in t#eir li!e timeiii. As an e)ception Bambusa 6ul'aris #as not &no(n

to !lo(er to sum up Indian species.


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7#ysical 7roperties o! Bamboo• In the wood of Bamboo

i. The bonding between the vascular bundle within theinternodes is very week.

ii. s the con!unctive tissue between them is the thin walled

"arechymn.iii. The length of the fiber the principal source of strength is

also variable. #onger fibers can be seen more in mature bamboos Towards the e$terior than in the centre. In themiddle of the inter nodes than in the nodes and on the

basal region of the Culm than in the upper region.iv. %ere is a thick deposit of wa$ and silica on the epidermis ofthe entire Culm length&branches

v. This build into hard wearing' water repellent shell defies weather and most insects.


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Bamboo 6ertical section

"arechymn

ode

Internode

Cavity' * "ith surface'+ Inner wall' , -uter wall' /pidermis

Bamboo +ross section


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Mec#anical 7roperties o! Bamboo

o Speci!ic 'raity 0. to 0.:= Gms*+m3

oModulus o! Elasticity Green

Dry mature +ulm iln dried8One Simple?

/00.00 ' &m3

/2000 to /=000 '*+m3

22000 '*+m3

oModulus o! Rupture =00 tp /:00 '*+m3

o+ompressie stren't# 3/ to :2 '*+m3

0aterial 1orking stress(&mm*)

0odulus ofelasticity (&mm*)

1orking strain(23)

4train energystored(5&kg)

Concrete 6 *'222 +22 2.

4teel 32 *2'222 622 6.*

1ood 7. '222 722 ,.+

Bamboo 2.7 *2'222 22 ,.*

5anssen (86)

9orest research institute' ehradun


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• The weakness of transverse bond between the fiber and con!unctive

tissues reduces the shear strength

• 0odulus of ;upture can Compute strength of overall structures.

• odes do provide strong transverse bond and

• The presence of greater number of nodes improves the strength and

stiffness of a given member.


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• Bamboo is best harvested when it is three to si$ years old.

•This is considered the typical time when the plant has reached a mature

stage and the strength values have reached their peak.

•%arvesting is best accomplished in the fall and winter or during the dry

season once growth has slowed.

• It is recommended to cut the bamboo !ust above the first or second node

•Bamboo contains a high >uantity of starch vulnerable to attack by insects'

and high moisture content attracts mold and fungi.

Bamboo treatment and preseration


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• If bamboo is left untreated and e$posed to the elements' the e$pected

service life can be as little as one or two years.

• If bamboo is untreated and yet properly protected its life can be

e$tended to 2? years.

• In addition to e$tending the service life of bamboo' treatment may also

be used

•to add a degree of fire resistance. Bamboo can burn rapidly due to itshollow form and thin walls.

•rying bamboo is important because it makes the bamboo lighter' more

dimensionally stable' and less vulnerable to insects.



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• number of methods have been used to treat bamboo.

•Traditional methods are relatively effective' use little energy'

•and are ine$pensive. These methods include

• clump curin' (leaving the leaves on after harvest to draw moisture out

of the Culm)'

•smo&in' (using heat and smoke to kill insects and fungi)

@4tacks of bamboo are smoked above fire places or in special chambers'

destroying the starch and making the outer wall layer unpalatable to

insects. %owever' cracks can occur' which eventually facilitate insect

attack.'



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•Soa&in' (submerging in water to draw out starch and sugars that serve asfood for insects)@Immersion of bamboo in (preferably flowing) water for , to * weeksremoves starch and sugar which attract borer beetles. #arge stones are neededto keep the poles submerged. and a ariant• Eart# curin' (submerging in mud).

• Application of lime slurry or coat of cow dung' creosote (a product of coaltar distillation) and• bora$' though not indoors' because of strong odours.•Brushing and spraying of culms' which has only a temporary effect' becauseof the low penetration of the preservatives.• Immersing the lower portion of freshly cut culms

(which still have leaves)' in a preservative solution' which is drawn up the capillary vessels by the transpirationof the leaves. This method (called AsteepingA)only works with fairly short culms' as the li>uidmay not rise to the top of long culms.


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/ffective resistance to termites' most types of fungus and fire is achievedmainly by c#emical treatment.

•%owever' great care must be e$ercised in the choice of preservative'

application method and security measures.

•In most industrialied countries' a number of highly poisonous preservatives

are banned'

• o chemical preservative should be used without full knowledge of its

composition' and those containing T (dichlor@diphenyl@trichlorethane)'

"C" (pentachlorphenol)' #indane (gamma@he$achloro@cyclohe$ane) and

arsenic 4%-D# B/ E-I/.


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/ffective resistance to termites' most types of fungus and fire is achievedmainly by c#emical treatment.

•%owever' great care must be e$ercised in the choice of preservative'

application method and security measures.

•In most industrialied countries' a number of highly poisonous preservatives

are banned'

• o chemical preservative should be used without full knowledge of its

composition' and those containing T (dichlor@diphenyl@trichlorethane)'

"C" (pentachlorphenol)' #indane (gamma@he$achloro@cyclohe$ane) and

arsenic 4%-D# B/ E-I/.


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• Tools and workabilityT9E ma>ority o! materials !ound in nature must be (or&ed in order tosere as e!!ectie elements in a building structure. 1ith bamboo' one primary operation is to saw the cane into elements havingappropriate length and diameter.In most cases' the ma!ority of work operations are concerned with !oinery.To make !oints' the designer and builder need to take the material properties'form' and dimensions into consideration' as well as the force conditions acting onand through the !oint.In some respects' working with bamboo is not unlike working with wood.Both materials are relatively softand can be worked with simple hand tools' suchas knives' saws' chisels' and drills. %owever' most species of bamboo are harderthan most wood species. In addition' the epidermis (or skin) of the bamboo culm has high silica content' and is >uite hard' and therefore tends to dulltools >uite >uickly.s a result' it is typically recommended that tools designedspecifically for working with bamboo or steel be used.

Bamboo material !or buildin' construction


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• Tools and workabilityCare must be taken to not scar into the bamboo face or cause tears in the cane as aresult of cutting or drilling operations. 4uch scars or tears may open the bamboo fibers sufficiently to allow splitting once force is applied to the area.Bamboo is also typically more prone to splitting than is wood. In many bamboo

species the horiontal shear resistance e$ceeds that of wood species%owever' wood is commonly used in thicknesses that e$ceed typical wall thicknesses of bamboo' andtherefore has a greater sectional area to resist horiontal shear force.

Bamboo material !or buildin' construction

Bamboo hatchet4plit bamboo basket


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Splittin' a cane in #al!

Bamboo splitter


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T9E met#od used to connect bamboo structural members istypically ery di!!erent !rom t#at used (it# (ood.This is in part due to the geometry of the bamboo cane (round tube) vs.the typical sawn rectangular wood member.

It is largely due' however' to the vulnerability of the bamboo cane tolocalied stresses.Therefore' typical !oints in traditional timber framing' such as the peg !oint or mortise and tenon !oint' are rare in bamboo building construction.

Bamboo structural connections

Las#in' is t#e traditional met#od !or connectin' bamboo structuralmembers


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Traditional lashing"refabricated bamboo connector

"refabricated clamp connector


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The roots of bamboo are called rhiomes' which grow sideways below the ground.The rhiomes of sympodial bamboomultiply with short links symmetricallyoutward in a circle from which the bambooshoots grow' forming clumps. 0onopodial bamboo sends its rhiomes in all directionscovering a large area with widely spacedculms.

The hollow' cylindrical bamboo culmscomprise a fibrous' woody outer wall'divided at intervals by nodes' which arethin' hard transverse walls that give theplant its strength. Branches and leavesdevelop from these nodes.

4ympodial bamboo

0onopodial bamboo


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General•T#e use o! bamboo as a buildin' material probably dates

bac& to t#e inention o! t#e earliest tools !or construction.•T#us bein' suc# an old and (ell establis#ed traditionaltec#nolo'y it #as produced a 'reat (ealt# o! !orms andconstruction tec#ni4ues• (#ic# resulted !rom all &inds o! re4uirements andconstraints 'oerned by climate enironment reli'ionsecurity social status and so on.•But despite t#is immense ariety o! applications o! a sin'le

material it eidently possesses an almost unlimitedpotential !or t#e deelopment o! ne( !orms and met#ods o!construction ma&in' use o! its c#aracteristic properties.


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Gro(t# c#aracteristics Bamboo is a perennial 'rass !ound in most tropical andsubtropical re'ions and also some temperate @ones. 5ell oer/000 species o! some 0 'enera are &no(n t#e lar'est numberoccurrin' in Sout#ern Asia and t#e islands bet(een Fapan andFaa. Bamboos di!!er !rom 'rasses in t#e lon' li!e$span o! t#e culms8#ollo( stal&? t#eir branc#in' and li'ni!ications 8deelopment o!

(oody tissues?. Li&e lea!$bearin' trees t#ey s#ed t#eir leaesannually and 'ro( ne( branc#es increasin' t#eir cro(n eery

year.


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Bamboo is the fastest growing plant' and has beenreported to grow more than one metre in a single day.Bamboo culms can reach their full height (giantspecies grow + metres or more) within the first si$

months of growth' but it takes about + years todevelop the strengths re>uired for construction' andfull maturity is generally achieved after or 3 years ofgrowth. Bamboos flower only once in their lifetime.epending on the species this happens every 2 to

*2 years' and every bamboo of the same species'even if planted in different countries' will flowersimultaneously. The leaves that are shed beforeflowering are not replaced by new ones and the culmsdie. ;egeneration takes place after 2 or more years.In places where a bamboo species constitutes a

valuable natural resource' its death can have seriouseconomic conse>uences for the people. But alsoanimals' like the rare giant panda in ChinasFs 4ichuan"rovince' are threatened with e$tinction now thattheir food source' the arrow bamboo' is flowering anddying en masse.


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There are two main types of bamboo:a) sympodial' or clump forming bamboo'found in the warmer regions' and b) monopodial' or running bamboo' found inthe cooler ones.


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%arvesting and preservation Dntreated bamboo deteriorates within * or + years' but with correctharvesting and preservative treatment' its life e$pectancy can increase about ,times. 0ature culms ( to 3 years old) have greater resistance to deterioration than'

younger culms. 4ince fungal and insect attack increases with the moisture content' bambooshould be harvested when the moisture content is lowest' that is in the dryseason in the tropics' and autumn or winter in cooler ones. The culms should be cut to +2 cm above the soil level immediately above anode' so that no water can accumulate in the remaining stub' as this could

destroy the rhiomes. The freshly cut culms' complete with branches and leaves' should be leftstanding for a few days (avoiding contact between the cut surface and thesoil)' allowing the leaves to transpire and reduce the starch content of theculm. This method' called Aclump curingA' reduces attack by borer beetles' buthas no effect on termites or fungi.


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;esearch on non@poisonous preservatives is still underway and full clarity onthe to$icity of the recommended and currently available chemicals has not yet been attained. %owever' it seems safe to use preservatives based on bora$'soda' potash' wood tar' beeswa$ and linseed oil. Their resistance to biologicalagents is less than that of the poisonous chemicals mentioned above' but can be e>ually effective in con!unction with good building design (e$clusion of

moisture' good ventilation' accessibility for regular checks and maintenance'avoidance of contact with soil' etc.). 4everal methods of chemical treatmentare possible: Brushing and spraying of culms' which has only a temporary effect' becauseof the low penetration of the preservatives. Immersing the lower portion of freshly cut culms (which still have leaves)' in

a preservative solution' which is drawn up the capillary vessels by thetranspiration of the leaves. This method (called AsteepingA) only works withfairly short culms' as the li>uid may not rise to the top of long culms.

4teeping


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Completely immersing green bamboo for about weeks in open tanks filled with a preservative solution. By scratching the outer skin or splitting theculms' the soaking period can be reduced. 1ith alternate hot and cold baths'the process can be still >uicker and more effective.

4teeping ;eplacing the sap with a preservative solution' by allowing it to slowly flowfrom one end of the culm to the other' where the sap is forced out. 1hen thesap is removed' the preservative solution can be collected and reused. Theprocess (called the ABoucherieA method) takes days' but can be reduced to afew hours by pressure treatment.


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pplications 1hole culms for pile foundations (but of low durability)' building framestructures' beams' trusses' grid shell structures' stairs' ladders' scaffolding' bridge constructions' pipes' fencing' furniture' musical instruments. %alf culms as purling' roof tiles' gutters' and for floors' walls' concretereinforcement (ABamboocreteA)' grid shell structures. 4plit bamboo strips for matting and woven panels' ornamental screens'concrete reinforcement' grid shell structures' fencing' furniture. Bamboo boards (split and flattened whole culms) for floor' wall and ceilingpanels' doors and windows. Bamboo fibres and chips for fibreboards' particle boards and fibre concrete.

dvantages Bamboo is abundantly available' cheap and is >uickly replaced afterharvesting' without the serious conse>uences known from e$cessive use oftimber (environmental acceptabilityG ). The annual yield by weight per unitarea can reach * times the yield of forests in which building timber is grown.Bamboo can be grown in the backyard.


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%andling during felling' treatment' transportation' storage and construction work is possible with simple manual methods and traditional tools. o waste is produced: all parts of the culm can be usedH the leaves can beused for thatching or as animal feed. The pleasant smooth' round surface re>uires no surface treatment. The high tensile strength to weight ratio makes bamboo an ideal material for

the construction of frames and roof structures. 1ith proper design and workmanship' entire buildings can be made of bamboo. Bamboo houses provide comfortable living conditions in hot climates. -n account of their fle$ibility and light weight' bamboo structures can withstand even strong earth>uakes' and in case of collapse' cause less damagethan most other materials. ;econstruction is possible within a short time and

at low cost.


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"roblems Bamboo has relatively low durability' especially in moist conditions' as it iseasily attacked by biological agents' such as insects and fungus. Bamboo catches fire easily. The low compressive strength and impact resistance limit its application inconstruction. 1rong handling' bad workmanship and incorrect design of

bamboo structures can lead to cracking and splitting which weaken thematerial and make it more vulnerable to attack by insects and fungus. ailscause splitting. The irregular distances between nodes' the round shape and the slighttapering of the culms towards the top end makes tight@fitting constructionsimpossible' and therefore' cannot replace timber in many applications.

Bamboo causes greater tool wear than timber. Bamboo preservative treatments are not sufficiently well@known' especiallythe high to$icity of some chemical preservatives recommended by suppliersand official bodies.


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;emedies Certain bamboo species have a natural resistance to biological attack' hencetheir cultivation and use should be encouraged. -nly mature culms should be used' properly treated (see %arvesting and

preservation)' not stored for too long (if at all' then without contact with theground)' carefully handled (avoiding cracks or damage of the hard outersurface)' and installed in carefully designed structures (ensuring dryconditions' good ventilation of all components' accessibility for inspection'maintenance and replacement of attacked members). 9ire protection is achieved by treatment with boric acid (also effective

fungicide and insecticide) and ammonium phosphate. "re@drilling is essential to avoid splitting' if nails' screws or pegs are used.9astening of !oints by means of lashing materials is more appropriate for bamboo constructions. Bamboo should not be used where tight@fitting components are re>uired.Instead the gaps between bamboo elements can be used to advantage in

providing ventilation. ;ecommendations for preservative treatments with chemicals should not befollowed blindly. ifferent opinions of e$perts should be sought. ndirrespective of the type of preservative used' care should be taken to protectthe skin and eyes from coming into contact with it. The need for thoroughsafety precautions cannot be overstressed.


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Bamboocrete constructionE5ORDSHSpecial properties Cheaper than other e>ually strong structuresEconomical aspects #ow to medium costs

Stability oodS&ills re4uired Bamboo and masonry construction skillsE4uipment re4uired Carpentry and masonry toolsResistance to eart#4ua&e oodResistance to #urricane oodResistance to rain ood

Resistance to insects #ow +limatic suitability ll e$cept very hot dry climatesSta'e o! e)perience/$perimental

SHORT DESCRIPTION:• The bamboocrete house shown overleaf was imlemente! in

"#$% b& Dr' ('C' )alita* et al +,ibl' -.' ""/* Re0ional Research1aborator&* 2orhat +3ssam/* In!ia'• On a concrete foundation with burnt brick base course and flooring, a

framework of secondary species timber provides the structural support for

infill panels and curved roofing elements made of split bamboo lattice-

work, plastered with cement mortar.


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The use of bamboo to substitute steel reinforcement in concrete is ofconsiderable economic interest' as steel is e$pensive and often imported.%owever' bamboo shrinks on drying @ over , times more than the concrete@ so that there is no bond between the bamboo and concrete. 9urthermore'the alkalinity of concrete gradually destroys the bamboo fiber' which

finally loses all its strength. ;ecent research (Bibl.*,.2) has shown some possible remedies:.Coating the bamboo with hot bitumen and improving bonding bycovering it with coarse sand' driving in * mm nails or tying coconut fiberropes around the bamboo (developed by . Jrishnamurthy)H *. Dsing onlythe outer section of bamboo (because of its higher tensile strength and

elasticity) and twisting bundles of three split@bamboo strips around eachother (developed by 2. %idalgo #ope). 9urther research is necessary' especially with a view to fiberdeterioration.


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4%-;T /4C;I"TI-: The e$amples of bamboo houses shown on the following pages are takenfrom the e$cellently illustrated bamboo construction manual by -scar%idalgo #ope (Bibl. *,.27). ll the structural components and most of the non@structural parts (floors

and wall cladding) are made of bamboo. -nly very little timber is used and theroof covering can be of any suitable' locally available material (eg thatch' fibreconcrete' ferrocement' metal sheeting' cement mortar' or even stabilied' water@resistant soil mortar). The bamboo components are !oined either by means of lashing materials'dowels' bolts or nails. great number of possible bamboo connections is

shown in the construction manual. -n account of its low resistance to biological attack and fire' protectivemeasures are necessary (see section on Bamboo).9urther information: -scar %idalgo #ope' Dniversidad acional deColombia' partado ereo ,6' Bogota' Colombia.

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Bamboo as Bldg. Mat