Bamboo as a building material

Bamboo is one of the oldest construction materials. It has been used all over the world as the building materials in the form of walls, roofs, foundation, reinforcements and decorations.
At the same time, it acts as the good earthquake resistance material.

1. BAMBOO AS A BUILDING MATERIAL PREPARED BY, S.Indhu M.E -Structural engineering

2. INTRODUCTION: Building with bamboo looks back on an ancient tradition in the regions in which the plant grows in abundance, such as South America, Africa and, in particular, in South-East-Asia. Bamboo is one of the oldest construction materials. It has been used all over the world as the building materials in the form of walls, roofs, foundation, reinforcements and decorations. At the same time, it acts as the good earthquake resistance material.

3. PROPERTIES: A) Tensile strength: The fibres of the bamboo run axial. T he outer zone are highly elastic vascular bundle, that have a high tensile strength. The tensile strength of these fibres is higher than that of steel, but it’s not possible to construct connections that can transfer these tensile strengths. The common tensile stress in steel reinforcement is 160 N/mm 2 and in bamboo is 370 N/mm 2 . The mass per volume of steel is 7850 kg/m 3 and of bamboo is about 500-600 kg/m 3 . Evidently bamboo will be cheaper because the price of bamboo per weight will be less than half that of steel.

4. B) Shrinking: Bamboo shrinks more than wood when it loses water . The canes can tear apart at the nodes. Bamboo shrinks in the cross section 10-16 %, in the wall thickness 15-17 %. Therefore it is necessary to take essential measures to prevent water loss when used as a building material. C) Fire resistance: The fire resistance is very good because of the high content of silicate acid. Filled up with water, it can stand a temperature of 400° C while the water cooks inside. D) Elasticity: The enormous elasticity of bamboo makes it to a very good building material for earthquake danger areas. Another advantage of bamboo is its low weight. It be transported and worked easily, the use of cranes is mostly unnecessary.

5. E) Modulus of Elasticity: The distribution of these fibers increases from the inside to the outside. The E-modulus for cellulose is 70,000 N/mm2 and about 50% of the cross-section of the fiber is cellulose; the E-modulus of the fiber is 35,000 N/mm2. In most bamboos, fibers constitute about 60% on the outside and 10% on the inside. The density of the fibers in the cross-section of a bamboo shell varies along its thickness. This presents a functionally gradient material, evolved according to the state of “ stress distribution” in its natural environment. F) Anisotropic Properties : Bamboo is an anisotropic material. There are cellulose fibres in the longitudinal direction, which is strong and stiff and in the transverse direction there is lignin, which is soft and brittle .

6. G) Durability : Bamboo with low humidity is less prone to mould attacks especially when humidity content is less than 15%. Quality of bamboo increase with a decrease in its humidity content. Bamboo to be treated with a preservative, needs to be dry to facilitate penetration. Bamboo can be dried in air, or by greenhouse process, or by oven, or by fire. The durability of bamboo depends strongly on the preservative treatment methods in accordance with basic requirements. Its chemical composition should not have any effect on the bamboo fiber and once injected it must not be washed out by rain or humidity. Many steel and concrete structures built in the past 30 years reveal serious deterioration caused mainly by the corrosion of the steel reinforcement

7. USE OF BAMBOO IN CONSTRUCTION: Scaffolding Reinforcement Roofing Walling Flooring Foundation Doors & Windows Decoration

8. In Scaffolding: Bamboo poles lashed together have been used as scaffolding in high rise structures due to their strength and resilience. Bamboo Column and Beam Bamboo are used as the reinforcement in beams and columns in the building construction. Fig 1: Bamboo Reinforced Column Fig 2: Bamboo Beams

9. In ROOFS such as: Bamboo trusses Bamboo tile roofing Thatch roofing

10. In Bamboo flooring such as: Bamboo can be used as flooring material due to its better wear and tear resistance and its resilience properties. Whole culms act as frame work and the floor covering is done using split bamboo, bamboo boards, mats etc by means of wire lashing these to the frame

11. In Bamboo walling/ceiling Bajareque wall: This wall-building technique is very well-known in Latin America . Bamboo strips are tied on either side of timber and then intermediate space is filled with mortar. Bamboo board wall: This is a common method of construction in Indonesia. In Door & Windows (Reed Boards): Reed boards are made by flat pressing the reed at high temperatures. These reed boards are used in elements like flooring, walls, ceiling and roofing. They can also be used for partitions, doors, windows etc.

12. WOVEN BAMBOO WALL VERTICAL HALVED CULMS BAJAREQUE WHOLE BAMBOO CULMS WATTLE AND DAUB

13. Bamboo Foundation (Bamboo Piles): Bamboo in direct ground contact : Bamboo is placed either on the surface or buried. For strength and stability, large diameter and thick walled sections of bamboo with closely spaced nodes should be used. Bamboo on rock or preformed concrete footings : where bamboo is being used for bearings, it should be placed out of ground contact on footings of either rock or preformed concrete. Bamboo incorporated in to concrete footings : the poles are directly fit into concrete footing. Composite bamboo/concrete columns : a concrete extension is given to a bamboo post using a plastic tube of the same diameter. 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.

14. Bamboo foundations: COMPOSITE BAMBOO-CONCRETE FOUNDATIONS Single Post Footing Strip Footing

15. HOW TO PROTECT BAMBOO: Untreated Bamboo: 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 Natural durability also depends on the species of the 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.

16. The bamboo poles are left to dry slowly in a cool, dry place until they are used for construction. 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. During the casting and curing of concrete, reinforcing bamboo absorbs water and expands. 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. The swelling and shrinkage of bamboo in concrete create a serious limitation in the use of bamboo as a substitute for steel in concrete. One effective treatment is the application of a thin layer of epoxy to the bamboo surface followed by a coating of fine sand. 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.

17. PRESERVATION OF BAMBOO: Can be done by 2 methods: Non-Chemical Method Or (Traditional Method) Chemical Method

18. NON CHEMICAL METHODS OR TRADITIONAL METHOD Smoking: Bamboo culms are placed above fireplaces inside the house so that the smoke and heat rises up and both dry and blacken the culms. This is considered an effective treatment against insects and fungi but aesthetically bad. White washing: Bamboo culms and bamboo mats for housing construction are often painted with slaked lime. Plastering is also a common practice using cow dung mixed with either lime Curing: Curing involves harvested culms, with branches and leaves intact, in open air. Soaking: The culms are submerged in either stagnant or running water, or mud for several weeks

19. CHEMICAL METHODS: IS 401:2001 Code of Practice for Preservation of Timber 1 . Surface application ( brushing, dipping) 2. Hot & Cold Method 3 . Boucheire Process 4 . Inter Nodal Injection

20. PRESERVATIVES RECOMMENDED: Coal Tar Creosote Copper – chrome - arsenic compositions Acid- cupric – chromate composition Copper – chrome- born composition Copper zinc – naphthanate

21. EARTHQUAKE RESISTANCE: B amboo is a perfect material for earthquakes. it is lightweight, and the hollow form gives much stiffness. The wall was fixed on a steel frame and using a hydraulic jack, a horizontal force was applied at an upper corner and in the plane of the wall. High residual strength to absorb shocks and impacts. Flexure coupled with its very low mass. Prototype house built with bamboo sheet roofing and bamboo-reinforced concrete walls withstood a simulated earthquake measuring 7.8 on the Richter scale. A bamboo house in Bhutan that withstood an earthquake that occurred at Sikkim (epicentre) measuring 6.9 in September 2011 . 30 houses at the epicentre of a 7.6 magnitude earthquake survived without any damage in Costa Rica in 1991.

22. ADVANTAGES: Bamboo is an extremely strong natural fibre. Shock absorbing and thus earthquake resistant. Strength - Bamboo is an extremely strong natural fibre, with standard hardwoods, when cultivated, harvested, prepared and stored properly. Flexibility - Bamboo is highly flexible. During its growth, it may be trained to grow in unconventional shapes. Earthquake resistance - It has a great capacity for shock absorption Lightweight - Bamboo is extremely lightweight. Consequently, building with bamboo can be accomplished faster with simple tools than building with other materials. Cost-effective - Economical, especially in areas where it is cultivated and is readily available. Transporting cost is also much lesser. Low-cost and environment friendly. Durability- As long-lasting as its wooden correlates, when properly harvested and maintained.

23. LIMITATIONS AND DRAWBACKS: Jointing techniques - Although many traditional joint types exist, their structural efficiency is low. Flammability - Bamboo structures are not fire-resistant, and the cost of treatment, where available, is relatively high. 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.

24. CONCLUSION: Since bamboo is an environment friendly material, it should give more importance. Bamboo is very light in weight with compare to steel so dead load of the member can be decreased with use of it . Bamboo is easily available material, so it is economic material and by using it, we can reduced the cost of construction. Since bamboo is very effective in seismic resistance, use of it should be safe .

25. Thank you