BAMBOO CONSTRUCTION

TUSHAR CHOUDHARI ANKITA KOLAMKAR

6th batch - PGP-ACM

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

PRE-HARVEST AND POST HARVEST PRECAUTIONS

ø Felling during low sugar content season i.e. dry season

ø Felling of mature bambooø Post harvesting transpirationø Water soaking

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…

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Soaked bamboo samples at room temperature for 24 hoursSoaked bamboo samples at 60°C for 4 hoursSHRINKAGE

REDUCTION

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 foundationsCOMPOSITE 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

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Conventional ConcreteBamboo Reinforced Concrete

Comparative analysis

Comparative analysis

Concrete structure

Wood structure Bamboo structure

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Energy consumption during construction

Limitations and drawbacksFew 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.