Physical And Chemical Properties Of Bamboo Environmental Sciences Essay

Chapter 1 has been drafted in a manner that it is to draw the context of this dissertation. It defines the locality, and has an insight into the North East Indian Bamboo industry. It attempts to justify the use of bamboo as a primary construction material in the area, due to its abundant availability. It tries to highlight the faults in the current and traditional methods prevalent in the region which are a hindrance to bamboo being more often used for construction. The dissertation research looks into gathering substantial proofs to support the hypothesis which comes after understanding the problems of the area.

1.1: Bamboo – Distribution

1.1.1 World Wide Distribution

Bamboo is a plant belonging to the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. In bamboo, the internodal regions of the stem are hollow and the vascular bundles in the cross section are scattered throughout the stem instead of in a cylindrical arrangement. Bamboo is a native to five continents around the world : Asia, Africa, South America, North America and Australia. It is found at all elevations from the coast of the Philippines up to 15,000 feet above sea level in the eastern Andes.

Bamboo grows in the tropical, subtropical and temperate regions of all continents except Europe, geographically divided into 3 zones: the Asia- Pacific zone(around 700 species), the America zone (around 400 species) and the African zone (around 50 species). There are totally 70 genera and 1200 species of bamboo all over the world that have been recorded, with some more in undeveloped regions to be discovered and identified. Over 2.5 billion people worldwide use or trade in bamboo worth 4.5 billion US Dollar every year (INBAR 1999).

1.1.2 South East Asia

Bamboo is found in abundance in South East Asia, the tropical scenario, temperature and soil conditions in the area widely promotes the growth of bamboo in the area. China is known as the Kingdom of Bamboo, with around 500 bamboo species native here, naturally distributed in 16 provinces and 1 municipal city, among which Yunnan takes up 220 species due to its diversified climate and geographical characteristics. Due to its abundance in availability, from the starting of time bamboo as such has been a part of all South East Asian traditions. Bamboo is an inseparable part of south east Asian culture, medicine , music, construction and food.

In construction, bamboo provides pillars, floors, walls, doors, window frames, rafters, room separators, ceilings and roofs. The meeting houses of some New Guinea villages are 20 m tall and more than 40 m long, with huge bamboo poles set deep into the ground and bent over in the shape of Gothic arches to carry the thickly thatched roof, creating some of the boldest structures built with minimal equipment and technology. Japanese houses are far more sophisticated, but are still typically built of wood, paper and bamboo. Bamboo is used to make guard houses in rice fields, roadside food shops, hot houses for growing mushrooms, smoke houses for drying tobacco or rubber, store houses for rice and other produce, and livestock sheds. Bamboo is also used to make pegs which replace nails. Bamboo scaffolding finds extensive use in Asian cities, even on very tall buildings. Bamboo is used throughout rural Asia to build bridges of many types and sizes; they can be as long as 25 m, often involving sophisticated technology as suspension bridges, but also with simple technology in the form of pontoon bridges (Kurz 1876). Many villagers use bamboo shingles, with the large stems split in half and laid with the convex and concave sides alternately facing upwards, with their edges overlapping. In coastal areas, roofs often are made of thatch woven from nipa palm around long slivrers of bamboo.

Location Bamboo Area

(10,000 hectare) Bamboo Species

China 500.00 500

India 400.00 136

Burma 217.00 90

Thailand 81.00 60

Bangladesh 60.00 30

Cambodia 28.70 –

Vietnam 13.00 92

Japan 13.80 230

Indonesia 6.00 30

Malaysia 2.00 44

Philippines 2.00 55

Korea 0.80 13

Sri Lanka 0.20 14

In countries like China, Japan and Korea, bamboo also is a frequently used popular motive for poets and painters. Philosophers and literateurs took bamboo as a symbol for a good personality: making progress; modest; straight (Wang 2000) ¿½ there, bamboo is not only a useful material for their everyday life, but also has already been developed into a so called ¿½bamboo culture¿½ through the long time of cohabitation with people.

1.1.3 India – Why North East India?

India is home to about 45% of the world¿½s bamboo production. There are 125 species of bamboo in India spread across 18 genera. According to a survey by BMTPC (Building Materials and Technology Promotion Council) India produces about 13.5 Million Metric Tons of bamboo annually from 9.6 Million Hectares land area (used only for bamboo plantation). Sympodial bamboo consists of 67% of growing stock and monopodial bamboo comprises of 20% of growing stock. Out of this amount the North Eastern part of India alone has the gross share of 66% of the total production. So, it can be said that potentially this region has the widest range climate and topography suitable for growth of bamboo.

Distribution of Bamboo in North East India

(Area in sq km * )

S. No. State Area under Bamboos Area under Muli Bamboo Area under other Bamboo Spp. Area expected to flower Area accessible (Flowered)

1. Arunachal Pradesh 4590 100.00

2. Assam 8213 2950 1456

3. Manipur 3692 1592 400

4. Meghalaya 3100 400 2700 400 200

5. Mizoram 6646 5100 1500 5100 1200

6. Nagaland 0758 250 250

7. Tripura 2397 960 1437 2397 300

Bamboo is a vital element of India’s North Eastern region comprising the states of Assam, Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim and Tripura. Bamboo has been a traditional material of construction that has been used in the north east region from quiet some time. In Borneo and the Naga Hills of India, large communal houses that may be 100 m long are built of bamboo. In Arunachal Pradesh, large suspension bridges have been made out of bamboo, In Assam houses made of bamboo are the typical house type in villages which stand the test of floods and earthquakes in the region. Bamboo is the material of choice when it comes to arts and craft in the region. A number of traditional musical instruments are also made from bamboo.

¿½The virtues of bamboo are not new, but the interest in it is,¿½ says Antonios Levissianos, UNIDO senior industrial development officer. ¿½Bamboo is no longer seen as a poor man¿½s timber, it is growing to be the most promising substitute for wood and there is great scope for further generating rural employment. India¿½s current demand for bamboo is an estimated 27 million tones. However, only 50 per cent of that demand can be met because of lack of facilities for value addition and transportation.¿½

1.2: Why Bamboo?

Bamboo is one of the foremost sustainable naturally available material that has been used in construction since ages. Bamboo is the traditional material of choice that has been in use in the North East region of India since time immemorial. Bamboo is enduring, versatile and renewable, and due to its vast production (13.5 million metric tonnes annually), it was also the material of choice in construction. Bamboo can replace a variety of woods that are being increasingly used for construction today, and thus help in saving forests which today are in a critical stage of deforestation. Also, bamboo converts more carbon-di-oxide, than most other plants, and hence a more eco-friendly material. The growth rate of bamboo is also three times to eucalyptus and it can be harvested four times in the same period, hence its production and availability is much more compared to wood. So, bamboo should be the material of choice in the field of construction and not only as a scaffolding option as it is mostly used today, at least in the regions where it is readily available and in bounty.

1.2.1 Physical and chemical Properties of bamboo

Physical Properties

Physical properties of bamboo varies greatly from species to species, and to some extent within a species. Culms are generally long and straight and the hollow internodes make it comparatively light. The strength of bamboo varies within the species, age of culm, moisture content and portion of culm and generally increases until it reaches maturity. The tensile strength of a bamboo pole is high parallel to the grain. Bamboo however, fails in shear before it fails in tension and so modulus of rupture is used to calculate strength. Due to its weak transverse bonds between its fibres, it can be spilt easily along the length (radial or tangential)

Chemical Properties

The main constituents of the bamboo culm are: cellulose, hemicellulose and lignin. Other constituents consist of resins, tannins, waxes and inorganic salts. The composition varies based on years of growth, season, species and the part of the culm. Studies on moisture, ligno-cellulosic, starch and silica content are presented in this section. The main percentage composition of a bamboo pole are mainly:

¿½ Cellulose Fibers – 40%

¿½ Parenchyma – 50%

¿½ Vessels (voids) – 10%

Mechanical Properties

The fibers contribute 60-70% of the weight of the total culm tissue. They are long and tapered at their ends. The ratio of length to width varies between 150:1 and 250:1. Fiber length has showed considerable variation within species. There is also variation in strength properties along the culm height as well. Compressive strength tends to increase with height [Espiloy 1987; Liese 1987; Sattar et al. 1990; Kabir et al. 1991]. The strength increases from the central to the outer part. There is more than 100 percent variation in strength from the inner to the outer layers [Narayanamurti and Bist 1947].

1.2.2 Bamboo In comparison to other prevalent construction materials

A comparative study of the energy required to produce a unit of a building material with a certain level of load-bearing capacity gives an idea of the sustainability of bamboo.

Due to its hollowness and the fibres being in the longitudinal direction, bamboo is a very efficient material for structural design, as less material is needed than in case of traditional construction materials such as steel and concrete as massive sections can be avoided. In case of load bearing mass, due to its tubular structure bamboo behaves as a I-shaped cross-section, in each of the direction of its load, but it is less efficient than other cross sections in one or two directions.

The mechanical properties, the high extent of flexibility, its exceptionally fast growth rate, comparatively lower weight and low cost make bamboo a preferable building material over other construction materials. Although, in its natural state bamboo is little efficient to be used as a construction material due to its proneness to decay and insect attack, so, bamboo needs to be treated before it can be used as an extensive construction material.

1.2.3 Bamboo as a sustainable construction material

Bamboo is not a tree, it is a grass, so unlike trees it does not yield timber. Bamboo¿½s environmental benefits arise largely out of its ability to grow and spread quickly ¿½ in some cases three to four feet per day ¿½ without the need for fertilizers, pesticides or much water.

A bamboo grove also releases some 35 percent more oxygen into the air than a similar-sized stand of trees, because of this, planting bamboo is a great way to reduce your carbon footprint and help fight global warming, a perfect selection for going green and it matures (and can be replanted) within seven years (compared to 30-50 years for a stand of trees), helping to improve soil conditions and prevent erosion along the way. Bamboo is so fast-growing that it can yield 20 times more timber than trees on the same area.

As a building material, bamboo is also ideal in that it is sturdy, and can be cut and laminated into sheets and planks, just like wood. The quality of bamboo laminate varies between manufacturers and the maturity of the plant from which it was harvested; the sturdiest products fulfill their claims of being up to three times harder than oak hardwood but others may be softer than standard hardwood. Again, the many varieties of bamboo give it the advantage of versatility. For countries who are poor and struggling to move away from polluting industries, growing bamboo has the potential to become a viable economic and environmental solution. Bamboo if used as a major construction material, addresses three major areas:

ECOLOGICAL SECURITY: conservation of forests through timber substitution, alternate materials to non-biodegradable & high energy consuming materials like metals and plastics

SUSTAINABLE FOOD SECURITY: bamboo based agro -forestry system, maintenance of soil fertility of adjoining agricultural lands, and bamboo shoots.

LIVELIHOOD SECURITY: generation of employment in planting and primary processing for manufacturing mat based composites and other market driven bamboo products.

Bamboo poles can be used to make papers and clothes, and the process is environment friendly as little harmful chemicals are required to make paper and clothes out of the bamboo plant. The environmental impact of bamboo is what makes it an ideal material for construction in both interior and exterior of any building.

1.3: Bamboo Usable in Construction

1.3.1 Durability of bamboo structure

Bamboo is a natural composite with remarkable growth rate, and potent physical and mechanical properties which makes it one of the most suitable replacement for wood and a major and most sought after sustainable building material in the region of its growth. But bamboo in its natural state is not a very durable material and is very prone to infestation and decay. Thus, most bamboos used for structural purposes in rural and tribal housing deteriorate in a couple of years, putting heavy pressure on the resource, owing to increased demands for frequent replacements. This adversely affects the supplies of bamboo, even in bamboo rich regions.

India, with an annual production of about 3.2 million tones of bamboos, ranks second only to China in bamboo production (Pathak, 1989). Over 136 species in 30 genera occur in India (Suri and Chauhan, 1984). The two most widely distributed genera in India are Bambusa and Dendrocalamus. In South and Southeast Asia, the most economically important species for structural uses from the point of view of easy availability are Bambusa balcoa, Bambusa bambos, Bambusa blumeana, Bambusa nutans, Bambusa polymorpha, Bambusa tulda, Barnbusa vulgaris, Dendrocalarmus hamiltonii, Dendrocalarnus strictus, Melocanna barnbusoides, Gigan tochloa spp., Ochlandra travanicorica and Oxytenathera nigroeiliata.

Unfortunately, like most lignocellulosic materials, bamboo has very low resistance to biological degrading agents. Several techniques to enhance its durability have, therefore, been developed.

Natural Durability of Bamboo

Worldwide and mainly in the South East Asian mainland where bamboo grows in abundance there are a great many traditional and chemical methods for the preservation and enhanced durability of bamboo. However, here we mainly discuss briefly the traditional method of increasing the durability of bamboo which are tested and practiced in the north east Indian region which is the main producer of bamboo in the country. Variation in durability has also been observed along the length of the culm and the thickness of the wall. The lower portion of the culm is considered more durable, while the inner part of the wall deteriorates faster than the outer harder portion. This is probably related to the anatomical and chemical nature of the woody cells.

Because of the lack of any toxic constituents, bamboos form a ready food source for a variety of organisms. The presence of considerable quantities of starch in green or dry bamboo makes it more attractive to such organisms, especially stain fungi and borer beetles. Some sap sucking insects have been reported to attack bamboo plantations as well (Chatterjee and Sebastian, 1964,1966; Singh, 1988). The most serious borers of felled bamboos are three species of Dinoderus (celluris, minutes, brevis) and Lyctus, which attack bamboo rich with starch (Casin and Mosteiro, 1970; Sandhu, 1975). They cause immense damage during drying, storage, and subsequent use. Carpenter bees and termites also attack bamboo (Beeson, 1938;Sensarma and Mathur, 1957). Bamboos are attacked by marine organisms as well (Anon, 1945).

It is reported that bamboos harvested during summer are more rapidly destroyed than those felled in the rainy season (Liese, 1980). Culms of bamboo plants which have flowered are more resistant to beetles because of starch depletion. Hence, the first point of consideration for the durability of bamboo is harvesting.

Harvesting of Bamboo

In bamboos, soluble sugars are the principal nutrients for parasites. Thus, bamboos with depleted carbohydrates become reasonably resistant to the attack of borers and staining fungi. Methods adopted for lowering the sugar content at the time of harvesting of bamboos are:

(i) Life Cycle:

Felling of bamboo at maturity when sugar content is low:- Sugar content in bamboos varies with age. It is lowest during the first year but felling of one-year-old bamboo is not desirable because of very low strength and yield. Normally, bamboo matures at 3-4 years

(ii) Annual Cycle:

Felling of bamboo during low-sugar content season:-Sugar content in almost all plants varies with seasons. In India, for example, it is higher in spring than in winter (Joseph, 1958). Therefore, it is advisable to harvest bamboos between August and December, which is basically the dry season before monsoons.

(iii) Daily Cycle:

Felling of bamboo after sunset:- During the day time due to the availability of sunlight a lot of photosynthesis occurs in the bamboo plant and hence a lot of movement of food occurs resulting in increased starch content in most parts of the bamboo tree. But during the night mainly stored food is used and no photosynthesis happens, so it is advisable to fell the bamboo tress after sunset.

Leaching of Bamboo

The bamboo available after harvest is not ready yet, it still has a large amount of sap content which makes it prone to infestation and decay. Leaching is the removal of sap after harvest. The sap levels in harvested bamboo are reduced either through leaching or postharvest photosynthesis. A variety of leaching practices are used to remove the sap content, the mostly used include:

1. Cut bamboo is raised clear of the ground and leant against the rest of the clump for one to two weeks until leaves turn yellow to allow full consumption of sugars by the plant.

2. A similar method is undertaken, but with the base of the culm standing in fresh water, either in a large drum or stream to leach out sap.

3. Cut culms are immersed in a running stream and weighted down for three to four weeks.

4. Water is pumped through the freshly cut culms, forcing out the sap (this method is often used in conjunction with the injection of some form of treatment).

In the process of water leaching, the bamboo is dried slowly and evenly in the shade to avoid cracking in the outer skin of the bamboo, thereby reducing opportunities for pest infestation.

Storage of Bamboo

The bamboo after removal of the sap content is than ready to be stored in storages but certain precautions are taken to enhance the durability of bamboo, they are:

1. Bamboo is not stored in the open to avoid exposure to climatic forces such as rain and direct sunlight.

2. Bamboo is stored in a semi closed area to allow wind movement through its stacks.

3. Bamboo is stored a bit (app. 10cm) above the ground to avoid infestation from below, also an insect repellent may be sprayed on the ground.

4. Bamboo is stacked in vertical manner, and it should be noted that a minimum of 30% of the moisture in bamboo should be retained.

These measures taken ensures that the bamboo is stored properly and is well protected from reagents, and ready for selection and grading.

Selection/ Grading of bamboo

The bamboo culms are now ready for selection and grading into various categories, which are then accordingly put to use in the construction as per the nature of demand of the work. The main characteristics of a good, durable and structurally usable bamboo culm are based on the following key points along with a idea of advisable range of values.

1. Age and Maturity : – plus 5 years

2. Dimensional Characteristics : – 4″ – 6″

3. Wall Thickness : – 12mm – 25 mm

4. Inter Nodal Distance

5. Straightness and Uniformity

1.3.2 Treatment processes of bamboo

Although a great deal of care is taken in increasing the durability of bamboo right from the beginning from the process of harvesting to the selection and grading, the natural bamboo still is not good for long standing structures due to its still proneness to infestation. Hence, the bamboo is made to go through a number of treatment and preventive processes.

Natural means-

1. water seasoning – 3-4 months

2. smoke seasoning

3. heat seasoning

Chemical means-

1. internodal injection treatment- petro based chemical, creosote oil+diesel (1:1) 25-40ml

2. borax boric solution- 1:1 in hot 25L of water 50g of each

3. vacuum pressure treatment

4. brochh-vsie treatment – gravity based

1.4: Current State of Problems

1.4.1 A Glance at the drawbacks of traditional bamboo construction in North East India

Since time immemorial bamboo has been an integral part of the traditional practices of the people of north east India. The north eastern parts of India, bamboo is in abundance due to its topography and geographical conditions, and bamboo has found its use in many variations and utilities, ranging from bamboo as a construction material, a key element of interiors such as furniture’s and home decor, to daily household usable commodities. Bamboo shoot is a delicacy exquisite to the North Eastern region of India.

Although available in bounty in nature, the state of bamboo usable for construction purposes is in a state of bother in the region. The traditional methods of bamboo usage and construction can be said to be inadequate to meet long term goals of sustainable and long lasting and permanent structures. ¿½The virtues of bamboo are not new, but the interest in it is,¿½ says Antonios Levissianos, UNIDO senior industrial development officer. ¿½Bamboo is no longer seen as a poor man¿½s timber, it is growing to be the most promising substitute for wood and there is great scope for further generating rural employment. India¿½s current demand for bamboo is an estimated 27 million tones. However, only 50 per cent of that demand can be met because of lack of facilities for value addition and transportation.¿½ According to Antonios if proper infrastructure is provided for transportation, either by way of roads or canals, bamboo can be a material with great potential to be used in the construction industry in the NE region of India.

If we are to highlight a few key points as to what leads to the failure of the current traditional system of bamboo usage in the construction industry we can consider the following key points:

(i) Bamboo not Treated:

In the current practice system of bamboo usage in the region the bamboo after the process of harvesting as discussed in section A3 : 3.1, it undergoes little treatment procedures, which makes it prone to infestation and attack from natural reagents.

(ii) Lack of Proper Joinery:

The current practice involves crude joinery mechanisms to join two bamboo structural members, which are derogatory and have inverse effects on the life of bamboo and also tend to cause in rupture of the bamboo members.

(iii) Lack of Safety measures from Climatic Forces:

This is one of the major cause of failure of current bamboo structures, as the natural climatic forces have an adverse effect on the untreated bamboo. The lack of solid and stable joinery is exploited by the wind in the region whereas, the rain and floods play an even dangerous effect to the untreated bamboo.

1.4.2 Identifying the Possible problems in constructing with bamboo

The state of bamboo in the North Eastern region of India can be easily be improved if we identify and improve upon the key points or the distinct nodes of the problems, that are associated with the traditional method of construction of bamboo. After a look into our study so far, if we are to list some key issues which needs to be addressed upon as the main nodes to look at for making bamboo a suitable and efficient material of construction we can list out the following points.

1. Appropriate technology for bamboo treatment and working tools

The region does not have a proper treatment facility for the treatment of harvested bamboo which will protect it from insect and reagent attacks as well as slow its decay process due to effect from natural forces. Moreover, no specialized tools are available for working with bamboo and most of the work is done with tools developed for wood/timber as such it results in rupture and wear and tear of bamboo elements which can be avoided by proper use of tools developed especially for bamboo.

2. Design of proper joinery system- conducive effective production to bamboo material

The current joinery type used for bamboo based construction is either by tying by ropes or bolting with iron bolts as shown in Fig. 11, the rope tied bamboo joints tend to fail the test of time and climatic forces, whereas the bolting results in unwanted cracks and rupture of the structural bamboo elements.

3. Skilled labour- workmanship

Although bamboo has been the choice of material since long in the region , a relatively low quantity of labours can come up to the level of being called a primary bamboo construction workman. This is a major setback as to when an architect or builder decides on constructing with bamboo as there is serious lack of skilled labour for bamboo construction. So, the region demands a specialized center for training persons in bamboo construction who can in turn come up to be the skilled bamboo works man for the region. This can inturn help to generate employment for the local public, who after being trained can work as bamboo craftsman in the industry.

E.g. Hong Kong Bamboo Scaffolding Factory

4. Change in Social mindset

A major setback related to bamboo construction in the region is the social mindset of the people who are of the idea that bamboo is “a poor man’s timer”, and fail to understand the potential and beauty of the bamboo material. A through policy for propagate to mass with appropriate technology has to be introduced in a systematic manner which is competitive, durable, aesthetically pleasing and eco friendly.

CHAPTER 2: HYPOTHESIS

2.1 STATEMENT

Bamboo is a natural material, it is non-uniform, and degradable in its natural state. However it is one of the most sustainable building materials used till date. However, the key area of concern and the biggest obstacle in the bamboo being used more often in construction is, due to its dimensional constraints the joinery system for the structural elements of a bamboo construction becomes extremely difficult and non-durable. However, custom made joints, which are flexible and also adjustable can help solve the problem as it can convert a non-standardize construction material to a standardize material. Moreover, factory setups for availing the construction industry with well treated, and standardize bamboo elements as well as products can help a great deal in making bamboo the material of choice for construction in the region.

¿½Customization of the joinery system of bamboo elements along with better industrial setup for bamboo and bamboo based products will make bamboo a primary construction material.¿½

2.2: METHODOLOGY

Literature comprising books, research notes, websites, published papers, news articles and e-mail correspondence were means of research undertaken. the author also visited Assam from 13/05/2012 to 10/06/2012 for observations and discussions with professionals. There were site visits conducted during the period.

The understanding developed was in the form of why the traditional method of bamboo construction is inadequate and what are the major problems which limit bamboo usage as the primary construction material. These were then explained in terms of case studies with examples from India and rest of the world. The case studies and the problems are then evaluated to reach a conclusion which hint at possible solution to make bamboo a standard and primary construction material

Chapter 3: CASE STUDIES

Bamboo itself has a lot of advantages using it for building houses, bridges… . It is a cheap, fast growing material with excellent statistics according to the mechanical properties. However, although it is abundantly available in North East India there are some major problems related to bamboo based construction in the region which has been discussed in clause 1.4.2 of chapter 1 of this report. There may be a lot of solutions possible for the above mentioned problems, which are a hurdle to the establishment of the hypothesis statement. In order to throw some light on as to how these problems can be looked at and approached, the following case studies are picked from India and abroad.

3.1 : Case Studies Addressing to Standardization of Bamboo Material

Standardization of the bamboo material is a very important aspect towards establishing bamboo as a primary construction material. Bamboo is a natural material, and is non uniform and degradable in nature. Moreover, in the current industry setup there are no specific tools to be worked on bamboo, this as a result makes bamboo a vulnerable material of construction in the region. But, if the bamboo material is somehow standardize, be it whole bamboo or split bamboo, and specific tools are applied for its processing than it is possible to use bamboo and bamboo based products in a way we now use brick and concrete.

3.1.1 : BMTPC Initiative

The BMTPC (Building Materials and Technology Promotion Council) of the Ministry of Housing & Urban Poverty Alleviation Government of India is looking forward to promote the increased use of Bamboo throughout the country. According to the BMTPC, the strength of bamboo culms, their straightness and lightness combined with hardeners and range and size of hollowers, with good physical and mechanical properties, low shrinkage and average density, it is well suited to replace wood in several applications. The BMTPC propagates the preservation of bamboo through the IS9096:2006, Code of Practice for preservation of bamboo for structural purpose. It covers the type of preservation, the treatment procedure for structural purposes like posts, scaffolding, walls, trusses etc.

For the process of standarization the BMTPC has put forward a number of products and intiated industrial setup for their production. Among these one of the most promnent, is the Bamboo Mat Corrugated Sheet, which has immense potential as a roof material, and is eco-friendly, highly resilient, low weight, low thermal conductivity and has good aesthetic apperarance.

BMTPC and IPIRTI have jointly developed this technology for manufacturing Bamboo Mat Corrugated Sheets (BMCSs) particularly for North-Eastern region. This technology has been transferred to M/s Timpack Pvt. Ltd. who have set up a commercial plant at Byrnihat, Meghalaya with a production capacity of 3000-4000 sheets per month. Some of the important properties of BMCS (Bamboo Mat Corrugated Sheet) are as follows:

Size

1.05m X 1.8 m X 3.5 mm

Weight 6.5 ¿½ 7.90 kg/sheet

(app. half that of ACCS)

Load Bearing Capacity 4.8 N/mm width

Deflection at Breaking Point 85 mm

Thermal Conductivity :0.1928 k cal/m OC

(app. half that of ACCS)

Fire Resistance :Conforms to flammability test

Energy Requirement Highly Energy Efficient

Development of the BMCS in the factory at Byrnihat, Meghalaya, is one such way as to increase the awareness and usage of bamboo as a construction material, it not only provides employment for the local people but also help in producing bamboo trained professionals who can greatly contribute to the bamboo construction industry. BMTPC in cooperation with CBTC and State Govts. is establishing 8 BMPCs in the States of Mizoram, Meghalaya, Tripura & Assam. This is one of the many such setup by BMTPC for the processing of split bamboo to make ready to use products such as bamboo mat panel door or bamboo furnitures.

Machines being Installed at BMPCs

Strength Properties of BMCS in comparison with other existing Roofing Sheets

A tripartite MoU between BMTPC, CBTC and local partners identified by the respective State Govts. The local partners providing infrastructure facilities such as land development, boundary wall/fencing, storage space for raw material and finishes goods, water & electric connections and working capital for running the Centre at their own cost. All the machinery, equipment and shed is being provided by BMTPC. The training of the managers/supervisors/workers of the respective BMPCs are being provided by CBTC. The production capacity of each BMPC will be 200 mats per day. It is estimated that the Centers will be able to produce the mat at a very reasonable price. This will provide employment generation of nearly 150 women/men per day i.e. 45,000 women/men days per year per Centre. Besides the above, the Centers can also generate income by supplying bamboo sticks made out of bamboo waste, to the artisans for making handicraft items.

3.1.2 Indian Plywood Industries Research & Training Institute, Bangalore

The Indian Plywood Industries Research & Training Institute (IPIRTI), is a government initiative looking to preserve natural forests in India and hence it also promotes the usage of bamboo as a construction material. Its main aim is to develop technologies and industrial setup for primary and industrial processing of bamboo and bamboo based products, then it be whole bamboo or split bamboo. The primary processing machines developed and used by IPIRTI are as follows,

The IPIRTI, looks at developing new and improved composites for the bamboo construction industry which are eco friendly, to ensure its cause it has established a Institute cum factory at Chennai, India. A variety of products are manufactired at this institute with the help of tools developed specifically for bamboo.

Industrial Products Developed at IPIRTI

1. Bamboo mat based products

? Bamboo mat board

? Bamboo mat veneer composite

? Bamboo mat corrugated sheets

? Bamboo mat tray

? Bamboo mat moulded skin door

? Bamboo mat ridge cap

2. Bamboo strip based products

? Bamboo-wood (laminates) from Indian bamboos

? Development of transport vehicle flooring

3. Bamboo in round / split / composite from

? Bamboo based housing system

? Bamboo match sticks

Physical & Mechanical Properties of BMB (Bamboo Mat Boards) of different thickness

A variety of products have been developed by IPIRTI, which have been mentioned above , from a range extending from roofing materials to interior furnitures, such setup promotes the use of bamboo as a construction material as it provides the market with standarazize bamboo products which can be readily used in construction and such a setup in the North Easter part of India is very necessary.

3.1.3 : National Mission on Bamboo Applications (NMBA) Initiative

The Mission has carried out extensive testing and an assessment of inherent characteristics of Indian species of bamboo. The results were matched with existing and potential uses of bamboo. Bamboo has played an important part in the lives of the people of Assam. It has been an integral part of the cultural, social and economic traditions of the State, and is an important component of the wealth of Assam. It grows in natural forests, and is cultivated in homesteads, groves and on private plantations. It is utilised in many ways, for housing, fencing, functional articles, agricultural implements, basketry, and even fuel and food. People possess traditional skills of working with the material, and knowledge of the cultivation and management of bamboo.

Cane & Bamboo Technology Centre (CBTC), Guwahati

The CBTC, established at Guwahati with support from a UNIDO project, is supported by the Department of Science and Technology, Government of India. It is tasked to:

¿½ Identify and promote technologies to enhance income and employment in the North East

¿½ Network with resource, support and sectoral agencies

¿½ Impart training and provide access to improved technologies

¿½ Function as an information hub

CBTC has carried out a NMBA supported project for development and demonstration of structural applications involving the use of bamboo and based material. This project adapts traditional techniques of construction, to build well designed, architecturally innovative and comfortable structures, with bamboo and bamboo composite material as the dominant structural elements.

3.1.4 : Bamboo Treatment plant in Thailand

What the North East India lacks is a treatment plant which can provide well treated and durable whole bamboo for structural application in the construction industry, these greatly limits the usage of bamboo as a construction material. Below is the treatment process carried out at Chiangmai Life Construction

Construction preferable bamboo is 3-5 years in age and should be dry to prevent insect infestation. The bamboo on arrival is separated according to usage.

Species wise bamboo has different usage, smaller ones can be used to weave mats and substructure for roofs.

The thicker, more mature are used for structural columns and beams.

The diameter of the bamboo determines the size of the drill bits which are inserted into the bamboo culms along its entire length.

This is to longitudinally penetrate the bamboo¿½s nodal diaphragms before preservation treatment.

Here at the preservation treatment pool, the bamboo soaks in the borax for 7 days to allow the mineral to penetrate all the nodes and diaphragms.

Borax* or sodium borate is a soft, colourless, powdery mineral that dissolves easily in water. It is used here as an insect repellent and preservation.

After a few days, the bamboo is pulled from the pool and stacked vertically so the preservation solution can drain and be recycled in the pool.

Next, the bamboo poles are left to bask in the sun for 1 week depending on the amount of sunlight here in Chiang Mai.

The poles are rotated daily to avoid cracking. The sun bleaches the bamboo to a golden yellow colour that is more attractive as construction material.

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

3.1.5 Inferences:

The above mentioned case studies be it the BMTPC, IPIRTI, NMBA or the treatment facility at Thailand all clearly state a single point that if proper industrial setup is promoted with updated technologies it will help a non-uniform material like bamboo to become standardize and play a major role in the construction industry.

3.2 : Case Studies Addressing to Customized Bamboo Joinery System

Before we talk of customized bamboo joinery it is very important to understand why a special type of joinery is required for bamboo. Bamboo is a natural composite material and using the traditional means to make bamboo joints such as with ropes, nails and pegs is not too suitable to the bamboo element for the following reasons,

¿½ Bamboo has got a round profile. Creating connections with round profiles are leading to difficult geometric structures at the knot.

¿½ Bamboo fibres only grow in the longitudinal direction.

¿½ Bamboo is hollow. There is no material to tighten the bamboo in the middle of the cane.

¿½ The face of the cane is very slippery and hard.

¿½ Bamboo is not suitable for loads in cross direction, because there are no cross fibres.

¿½ Bamboo is a natural material, that varies in diameters, length and quality according to the climate.

3.2.1 Modern connection by Shoei Yoh in 1989.

For his bamboo roofs in Fukuoka, Shoei Yoh used a steel tube put into the bamboo and which is connected to the cane with bolts. The steel tube is strong enough to withstand the pressure of the tightened bolts. In addition there are two bolts in vertikal direction. For the connection to the knot a steel bar is welded into the tube and again it is screwed to the knot. Because of the numerous bolts the connection is also suitable for greater loads. The result is a very technical but strangely overstyled looking connection.

3.2.2 Modern connection by Renzo Piano Building Workshop in 1997.

Italian architect Renzo Piano has experimented with bamboo cane edifices. The methods he has devised for connecting bamboo canes involve light metal components such as tubes or plates, which are at times inserted into the canes, sometimes connected to them. The canes are connected to a special designed steel element via binding wire. Instead of a bolt driven through bar and cane, a wire is tied through the holes and tied around the bamboo. A fine artwork but because of the fine wire seemingly only for small forces. In this way, bamboo can be integrated into light metal construction in an innovative way.

3.2.3 ZERI Pavilion on the EXPO 2000

Simon Velez, is a Columbian architect who designed the ZERI pavilion with bamboo for the EXPO 2000. Simon Vel¿½z¿½s project is a circular bamboo structure, or more precise a ten-sided polygon 40 meters in diameter with a peripheral overhang seven meters wide, so not only the interior of the open pavilion but also the construction is protected from rain. The building rests on two concentric courses of 20 supporting wooden pilars measuring 8 to 14 meters height. The pavilion provides 2,150m¿½ floor-area on two levels (1,650m¿½ at ground level and 500m¿½ on first floor galllery).

The roof is typical the architecture of Simon Vel¿½z’, who calls himself a “roof architect”. The roof overhang, which is much bigger than necessary for construction, is a special topic for Vel¿½z. The pavilion with its wide roof looks like a mushroom. The organic form accentuates the materiality of the pavilion. In addition to this mushrooms play a important role in one of ZERI’ s farming projects. He developed a new technology to connect the bamboo canes using thread rods and concrete/mortar injections. This new technology allows to realize impressive constructions and great spans.

The outer pillars consist of 6, the inner pillars of 4 bundled aliso round timbers. They are connected by thread rods and flat steels. Only 2 of the 6 respectively 4 round timbers give the load to the foundations. The other round timbers increase the flexural rigidity. For bracing in peripheral direction there are struts. The lower very stable part of the bamboo plant was used for the struts. The inner pillars are standing on a foundation ring. The outer pillars are standing on single foundations, which are connected trough foundation beams.

detail section foundation

detail foot

Connections

Two methods have been developed to connect two sticks orthogonal with each other. First of all this connections have to transfer tractive forces.

¿½ Type A mortarted thread pole

¿½ Type B lateral steel strap and mortar bolt

Type A mortarted thread pole

In order to connect a cane firmly with another, transferring tractive forces, you have to puncture two or three diaphragma (intermediate base), interlock a thread pole and fill the internodia (cavity) with mortar injections from the outside. Then the second bamboo stick has to be vertically punctured and put on the thread pole. At least a nut with an curved washer is screwed onto the thread pole, the punctured internodia is filled with mortar.

Type B lateral steel strap and mortar bolt

For this variant of connection two or three internodia at the end of the bamboo stick have to be punctured vertically. Thread poles were put through the holes, after that, the internodia were filled with mortar. The second bamboo stick is placed vertically at the end of the first stick. A steel strap is wraped round the bamboo and then screwed to the thread poles. So the steel strap presses the second bamboo at the other, like a belt or a loop. The bamboo¿½s internodia which is wraped had to be injected with mortar, because otherwise the stick would collabse.

Assessment of the connections

The experiments of the FMPA Stuttgart, an institute where materials are tested, resulted for type A in nearly no initial slip. Wedging the tube at the thread poles has caused the bamboo¿½s breakdown. The maximum load rose up to 70kN. Type B had an initial slip of 1.5 mm, but was able to withstand 140kN. This connection had a maximum load twice as high as the other one. The breakdown was caused by flaring the holes of the steel strap or wedging the bamboo¿½s tube.

3.2.4 Digital Fabrication of bamboo

It seems quite surprising that a non standard material like bamboo can be standarized with the help of digital fabrication. But by the use of 3D Printer the joints for bamboo can be made customized and flexible.

The above structure is made of varying diameter PVC pipes and 3d printed connectors, the same can be applied for bamboo where the connectors can be digitally designed to have the slight adjustment variable for the bamboo poles.

These structures and its joints can then be digitally designed and it will prove to be a revolution for the bamboo industry.

3.2.5 Bamboo Cycle with Carbon based Joints

The above picture refers to a bamboo cycle build with carbon based joints, the same technique can be applied for bamboo elements structural joints for a building. It is only a matter of innovation and experimentation with bamboo and its possible joinery system which limits its wide range of activities.

3.2.6 Inferences

By looking at the above sited examples it is understood that a variety of joints can be developed suiting to the material properties of bamboo which can be conducive to bamboo construction and help in development of customized joints for bamboo which are much more durable than the traditional joints. Moreover, with proper architectural intervention and digital designing and production tools a wide variety of easy to assemble and produce joints can be made for bamboo.

3.3 : Case Studies Addressing to Change in Social Mindset

Social mindset is an important aspect which needs equal attention if not more to establish bamboo as a prominent material of construction in the North East Indian region. Till today bamboo inspite of all its advantages and merits is considered to be a “poor man’s timber”, for lack of proper knowledge, and advertisement. It is of general belief that a good livable environment is not possible if built by bamboo, this misconception needs to be cleared out if we are to advance with bamboo construction in the region.

3.3.1 : Green Village Bali

Set within a river valley landscape along Bali¿½s sacred Ayung River, a master-planned community located within walking distance to the Green School is being designed and constructed based on the architectural concepts of sustainable principles and artisan craftsmanship that helped create the world famous campus.

According to Elora Hardy, CEO and lead designer for the Bali-based bamboo design and construction company honored as a finalist of the 2010 Aga Khan Award for Architecture, ¿½Even sustainable timber can¿½t begin to compare with bamboo as a conscientious building material. With very few resources or attention a bamboo shoot can become a structural column within three years, and that house could stand strong for a lifetime.¿½

¿½We are committed to changing people¿½s perspective on the infinite potential of bamboo,¿½ she says. ¿½Creating spaces where people can feel connected to nature without disrupting it is a thrilling design challenge for me.¿½

3.3.2 : wNw Cafe / Vo Trong Nghia, Vietnam

The wNw Bar and the Bamboo Wing, by Vietnamese architect Vo Trong Nghia, showcases a correlation between modern architecture and nature, with heavy use of bamboo and wood. In the wNw cafethe beauty of bamboo has been rediscovered ¿½ friendly but extraordinary. wNw cafe utilizes local and traditional architectural features to create an alternative/ escape from the chaotic surrounding city. The project uses the principles of aerodynamic design. When designing the caf¿½, computer simulations of the spaces were used to study the airflow and the cooling capacity of the water. These studies have allowed them to reduce the use of electrical energy such as air conditioning, lowering the buildings energy costs.

The whole building is constructed by 7,000 bambooelements which have been treated using traditional Vietnamese methods. The bamboo structure has no concrete columns, but uses wire bracing supports. The V-shaped roof relates to the surrounding trees and createsan open space with breathtaking views.

3.3.3 Inferences

These two projects are picked from regions with abundant bamboo availability, and they clearly show the wide range potential of bamboo used with proper architectural intervention. Such projects create awareness among the people that if properly used bamboo can give better aesthetics than most commonly used materials.

CHAPTER 4: EVALUATION

The problems of bamboo becoming a primary construction material in the North east Indian region are stated in clause 1.4.2, and chapter 3 involves variety of case studies into how these problems can be handled and overcome.

A through comparison of the problems and case studies show that, appropriate technology for treatment, industrialization and standardization of bamboo based products can negate the problem of bamboo being a non-uniform natural material. It clearly states that with proper treatment and handling bamboo can be made durable and free from insect infestation. Also, standardization of bamboo by producing more of bamboo based products like the BMB’s and the BMCS, bamboo can be used in every sphere of the building industry be it walls, columns, roofing, furnitures or interiors.

The case studies highlight that with proper architectural intervention and making use of the available digital technologies it is possible to eliminate probably the most important problem relating to bamboo construction , i.e. joiner mechanism. Moreover, the advents of pioneer architects like Simon Velez and Renzo Piano, shows that customised and flexible joinery systems can be developed for bamboo.

And projects like Green Village, can help in establishing the fact that incredible built forms are possible with bamboo which are user friendly and sustainable.

However, it is easier said than done, as a lot of infrastructure is required in the North east region of India to formulate and put in place all these practices, and currently although bamboo is available in plenty, bamboo in proper built form in a farfetched goal due to the cost factor involved. It would take some time and effort to establish bamboo as a primary material of construction in North East India.

CHAPTER 5: CONCLUSION

The dissertation Started by looking into bamboo as a material of construction, due to its plenty of availability it should be used more regularly as a construction material in the North East region of India, and what are the problems which prohibit this practice. Based on these the hypothesis is derived that if certain specific measures taken than bamboo can be used as a primary construction material in the region. The case studies also indicate as to what needs to be done and based on that the following three suggestions are made which if incorporated can help in establishing the hypothesis.

1. Government based initiative to setup more Bamboo based industrial facilities

2. Development of training institutes for bamboo based construction

3. Architecture innovation in bamboo construction and joinery

These measures are all interrelated as one will help the other in a way or two, treatment facilities will provide better bamboo for construction, better bamboo means more durable structures which can stand the test of time, trained professionals will have an idea as to how to make use of bamboo in a more innovative way with minimum wastage. Prefabricated joinery systems are the outcome of better architectural intervention, which result in easy to construct and elegant structures. Industrialization of bamboo based products means readily available building parts to fill in the superstructure, like wall panels doors, windows, furnitures and fixtures. And all of them together can concertize the fact that bamboo is not a “poor man’s timer”, it is the modern and sustainable building material of choice, which will lead us to a better future.