BAMBOO CONSTRUCTION

By deepanker

INTRODUCTION…ø Bamboo has been in wide usage since ancient times

as a low-cost material for houses, bridges etc.ø Recently started appearing in designer homes as

flooring, walling and paneling materialø Is viewed as a material preferred only by the poor or

for temporary constructionsø Unpopular in conventional construction due to low

durability, lack of structural design data, exclusion from building codes etc.

Facts about bambooø Bamboo is a perennial grass

and not a tree as is commonly perceived.

ø 1450 species are found in diverse climates across the world, however, not all of these are suitable for construction.

ø One of the fastest growing plants on Earth. Its growth rate ranges from 30cm to 1 m in 24 hours.

ø The strongest part of a bamboo stalk is its node, where branching occurs.

ø Bamboo has also long been used as scaffolding; the practice has been banned in China for buildings over 6 storeys but is still in continuous use for skyscrapers in Hong Kong.

advantagesø Strength - Bamboo is an

extremely strong natural fibre, on par with standard hardwoods, when cultivated, harvested, prepared and stored properly.

ø Flexibility - Bamboo is highly flexible. During its growth, it may be trained to grow in unconventional shapes. After harvest, it may be bent and utilized in archways and other curved areas.

ø Earthquake-resistance - It has a great capacity for shock absorption, which makes it particularly useful in earthquake-prone areas.

advantagesø Lightweight - Bamboo is extremely lightweight.

Consequently, building with bamboo can be accomplished faster with simple tools than building with other materials. Cranes and other heavy machinery are rarely required.

ø Cost-effective – Economical, especially in areas where it is cultivated and is readily available. Transporting cost is also much lesser.

ø Durability - As long-lasting as its wooden correlates, when properly harvested and maintained.

How to protect bamboo…

UNTREATED BAMBOOø Untreated bamboo has the

following life spans in different conditions

> Exposure to soil and atmosphere = 1-3 years> Under cover = 4-7 years> Very favourable conditions = 10-15 years

ø Natural durability also depends on the species of the bamboo

How to protect bamboo…BORAX – BORIC ACID PRESERVATION TREATMENT

Depending on the diameter of the bamboo, different sized drill bits, attached to a long steel rod, are used to drill into the centre of the bamboo culms throughout their whole length.

At the preservation treatment pool, bamboo soaks in borax-boric acid solution (1:1.4) for 2 days to allow the mineral to penetrate all the nodes and diaphragms.

Bamboo is removed and stacked vertically so the solution can drain and be reused.

How to protect bamboo…

Preservative solution is recharged after four cycles by adding water and the chemicals. Preservation treatment costs a minimum charge of INR 4.50 per pole.

BORAX – BORIC ACID PRESERVATION TREATMENT

Next, the bamboo poles are left to bask in the sun depending on the amount of sunlight

The bamboo poles are left to dry slowly in a cool, dry place until they are used for construction.

How to protect bamboo…ø During the casting and curing of concrete, reinforcing bamboo absorbs water and expands

ø The swelling of bamboo pushes the concrete away

ø Then at the end of the curing period, the bamboo loses the moisture and shrinks back almost to its original dimensions leaving voids around itself

ø The swelling and shrinkage of bamboo in concrete create a serious limitation in the use of bamboo as a substitute for steel in concrete.

ø One effective treatment is the application of a thin layer of epoxy to the bamboo surface followed by a coating of fine sand.

How to protect bamboo…NEEM SEED OIL TREATMENT

ø Oil obtained from neem seeds can be used to improve water resistance and dimensional stability of bamboo culms particularly at high oil-treatment temperature.

ø Bamboo samples soaked in hot neem seed oil at 60°C for 4 hours had better water resistance and dimensional stability than samples soaked in oil at room temperature for 24 hours.

Bamboo foundations

COMPOSITE BAMBOO-CONCRETE FOUNDATIONS

Single Post Footing

Strip Footing

Bamboo foundationsBAMBOO PILESø Bamboo compacts soft soil, thus increasing the bearing capacity of soil.

ø The friction provided by the construction-grade bamboo increases its load-bearing capacity.

ø Treated split bamboo piles 8m long and 80 to 90mm in diameter were filled with coconut coir strands wrapped with jute.

A sustainable house in Thiruvananthapuram, Kerala where bamboo piles have been used as foundation . The foundation is further strengthened by bamboo reinforced concrete.

Bamboo foundationsBAMBOO PILES

ø The sections were then tied with galvanised iron wire. After installation of the piles @2m c/c by drop hammer, the area is covered with a 2.5m surcharge of sandy material.

Bamboo WALLS

WOVEN BAMBOO

WALL

VERTICAL HALVED CULMS

BAJAREQUE

WHOLE BAMBOO CULMS

WATTLE AND DAUB

RESISTANCE TO EARTHQUAKESø High residual strength to absorb shocks and impacts.ø Flexure coupled with its very low mass.

ø Prototype house built with bamboo sheet roofing and bamboo-reinforced concrete walls withstood a simulated earthquake measuring 7.8 on the Richter scale

ø A bamboo house in Bhutan that withstood an earthquake that occurred at Sikkim (epicenter) measuring 6.9 in September 2011

ø 30 houses at the epicenter of a 7.6 magnitude earthquake survived without any damage in Costa Rica in 1991

MECHANICAL PROPERTIES

Property Value

Density 0.5 – 0.9 gm/cc

Compressive Strength 53 – 100 MPa

Tensile Strength 111 – 219 MPa

Bending Strength 86 – 229 MPa

Bending Elasticity 6882 – 20890 MPa

bamboo column AND BEAM

Bamboo Reinforced Column Bamboo Beams

Comparative analysis

Rate of construction per sq.foot in INR

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Con-crete

Comparative analysis

Concrete structure

Wood structure Bamboo structure

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Energy consumption during construction

Limitations and drawbacks

Few considerations currently limit the use of bamboo as a universally applicable construction materialø Jointing techniques - Although many traditional joint

types exist, their structural efficiency is low. Considerable research has been directed at the development of more effective methods.

ø Flammability - Bamboo structures are not fire-resistant, and the cost of treatment, where available, is relatively high.

ø Lack of design guidance and codification - The engineering design of bamboo structures has not yet been fully addressed. There is little or no data containing specifications of bamboo.

Species of bamboos (preferable for construction) in india

• Bambusa nutans• Dendrocalamus brandisii• Oxytenanthera stocksii• Melocanna bambusoides• Dendrocalamus strictus• Dendrocalamus hamiltonii• Dendrocalamus giganteus• Bambusa bambos• Bambusa polymorpha• Bambusa balcooa

Bambusa nutans

• Local namesBidhuli, Mukia ASSAM . Malla UTTAR PRADESH . Mallo, Mahi bans SIKKIM: LEPCHA . Badia bansa ORISSA . Kali, Beng, Makla TRIPURA

• Habitat & distributionGrows best at altitudes of between 500-1500 m. Thrives on moist hill slopes and flat uplands, and well-drained sandy loam to clayey loam soils. Commonly found and cultivated in the North East, Orissa and Bengal.

• CulmThe culm is up to 20 m tall, dark green, loosely clumped, straight and smooth.

• Flowering Flowers gregariously at an interval of 35 years. Sporadic flowering is also observed.

• UsesHouse construction, basketry and craft.

Dendrocalamus brandisii

• Local namesBulka BENGAL . Wanan MANIPUR

• Habitat & distributionPrimarily found in tropical forests. Found in the Jiribam area of Manipur. Introduced into Coorg (Karnataka).

• CulmThe culm is up to 20 m tall, ashy grey to greenish-grey, and smooth.

• Flowering Gregarious and sporadic.

• UsesHouse construction and basketry, and to make han

Oxytenanthera stocksii

• Local namesKonda, Oor-shema KARNATAKA . Uyi, Mula KERALA . Chivari, Mes MAHARASHTRA .

• Habitat & distributionTypically grows from sea level to altitudes of 800 m. Confined and endemic to southern peninsular India.

• CulmThe culm up to 10 m tall, straight at the top, yellowish green, erect.

• Flowering Sporadic.

• UsesSuited for construction purposes. Also used for making furniture, ladders and supports.

Melocanna bambusoides

• Local namesMautak MIZORAM . Tarai ASSAM: BRAHMAPUTRA VALLEY . Arten ASSAM: KARBI-ANGLONG . Muli BENGAL, TRIPURA, ASSAM: BARAK VALLEY . Watrai MEGHALAYA: GARO HILLS . Moubi MANIPUR .Turiah NAGALAND

• Habitat & distributionFound chiefly in the north - eastern part of the country. It grows best on low hills and in undulating countryside.

• CulmCulms arise singly from the rhizome at a distance.

• Flowering Gregarious. Flowering cycle is about 40-44years.

• UsesUsed in the construction of houses and for making woven products. An important source for paper pulp.

Dendrocalamus strictus

• Local namesLathi bans NORTH AND CENTRAL INDIA . Kanka kara, Sandapa veduru ANDHRA PRADESH . Karal BENGAL . Nakur bans, Kiri bidiru GUJARAT . Kallanmula, Kurathimula, Korna KERALA . Narvel MAHARASHTRA . Salia ORISSA . Kalmungil TAMIL NADU

• Habitat & distributionFound normally at altitudes up to 1000 m, in dry, open deciduous forests. Widely distributed, it is the most common bamboo in India.

• CulmThe culm is up to 10 m tall, erect but slightly arched at the top.

• Flowering Flowering intervals are long (25-45 years).

• UsesThe culms are used as building material and for making furniture, mats, basketry and implements.

Dendrocalamus hamiltonii

• Local namesKako ASSAM . Fonay ASSAM: KARBI-ANGLONG . Pecha WEST BENGAL . Tama WEST BENGAL: DARJEELING . Unep MANIPUR . Wanoke MEGHALAYA: GARO HILLS . Pao SIKKIM: LEPCHA . Phulrua MIZORAM

• Habitat & distributionOccurs in fine-textured soil in semi-evergreen forests. Grows abundantly and well in the North East and Himachal Pradesh.

• CulmThe culm is large, up to 30 m tall, dull green.

• Flowering The flowering cycle is 30-40 years. commonly and periodically

• UsesUsed as edible shoot, for roofing and construction purposes.

Dendrocalamus giganteus

• Local namesMaipo ARUNACHAL PRADESH: KHAMTI , Worra ASSAM ,Maroobob MANIPUR, Bhalo bans SIKKIM

• Habitat & distributionGrows well in humid tropical and sub-tropical regions, in the North East, West Bengal and Bihar.

• CulmThe culm is large, up to 30 m tall, dull green, with a waxy appearance

• Flowering Sporadic. The flowering cycle is 40 years.

• UsesUsed for construction purposes and to make boat masts.

Bambusa bambos

• Local namesKotoha ASSAM .Behor bans BENGAL . Illi, Mula, Pattill KERALA . Kanta bans ORISSA . Nal bans PUNJAB . Saneibo MANIPUR Mungil TAMIL NADU . Bongu veduru, Mulla veduru ANDHRA PRADESH

• Habitat & distributionAttains the best growth in moist deciduous forests up to an altitude of 1000 metres. Prefers rich and moist soil, and thrives near perennial rivers and valleys. Found almost throughout India, and is common in Central and South India.

• CulmThe culm is up to 30 metres tall, cylindrical, dark green, erect, strong and hollow.

• Flowering Gregarious. Flowers at long intervals 40-60 years and the clump/plant dies after flowering.

• UsesIt is used as raw material for pulp and paper, to make panel products and handicrafts, and for thatching and roofing.

Bambusa polymorpha

• Local namesJama betwa, Betwa ASSAM, WEST BENGAL . Narangi bans MADHYA PRADESH . Bari TRIPURA

• Habitat & distributionPrefers deep, fertile, well-drained loam and riverine alluvial soil. Commonly found in Arunachal Pradesh, Meghalaya and Tripura. Also occurs in other parts of the North East.

• CulmThe culm is up to 25 m tall, light green or white grey to greyish-green.

• FloweringGregarious as well as sporadic. Flowering cycle is 55-60 years.

• UsesIt is a bamboo with many uses - as edible shoot, in woven form for handicrafts, and for house construction. It is also used for pulping.

Bambusa balcooa

• Local namesBhaluka ASSAM . Balku bans WEST BENGAL . Boro bans NORTH BENGAL . Wamnah, Beru MEGHALAYA: GARO HILLS . Barak TRIPURA

• Habitat & distributionOccurs at altitudes of up to 600 m. Prefers heavy textured soil with good drainage. A common homestead bamboo in North East India and West Bengal. Also occurs in Bihar, Jharkhand and Uttaranchal.

• CulmThe culm is up to 30 m tall, dark green and thick-walled.

• Flowering Gregarious. The clump/plant dies after flowering without setting any seed. The flowering cycle is 35-45 years.

• UsesThe most common use of this sturdy and strong bamboo is in house construction. It is a good bamboo for scaffolding and ladders.