Properties And Fabrication Of Bamboo As A Building Material

1. How successful was it?
2. How could your own group’s particular experience have been improved.
3. How did this integration impact, negatively or positively on the final outcomes of the proposal

Properties of Bamboo

Bamboo is one of the most suitable and widely used building material especially when constructing makeshift houses and homes for people affected by calamities such as floods, wildfires, landslides, earthquakes, storms, etc. (Gambhir & Jamwal, 2011). The reason why bamboo was selected as he building material for this project is because of its properties (Escamilla & Habert, 2014); (Ma'ruf, 2017). Some of these properties include the following:

Bamboo is a flexible material that can accommodate nearly any kind of design so as to meet the specific artistic impression needed. It can be cut and bent easily in any form.

The size of bamboo used for making beams and columns is 150 mm while that for purlins is 70 mm. The size of bricks used to construct the foundation is 150 mm. The standard length of bamboo used in this project was 2.4 m.

Bamboo is a very strong material compared with other building materials. It is hallow shaped, making it three times stronger than most of the typical solid building materials. The material’s compressive strength, which is within the range of 40-85 N/mm², is greater than that of wood, concrete or wood. Its tensile strength, which is within the range of 200-400 N/mm², is almost close to that of steel. Therefore bamboo has the capacity to meet the strength requirements of the houses in this project. The tensile and compressive strength of bamboo used in this project is 80 N/mm² and 355 N/mm² respectively.

Bamboo has high elastic modulus because of the fibers present in its outer parts. The quality of bamboo is directly proportional to its elastic modulus. This property makes bamboo a very important building material in areas prone to earthquake risks.

Bamboo is highly resistant to fire. This is because of its high silicate acid content. When it is filled up with water, a bamboo tube can withstand temperature of up to 400 °C (Raj & Agarwal, 2014).

Properties of bamboo in longitudinal direction are different from properties in its transverse direction. Longitudinal direction has cellulose fibers that are stiff and strong, but transverse direction has lignin that s brittle and soft (Kumar, et al., 2017).

Bamboo has nodes positioned along it, which helps in preventing buckling. The nodes allow bamboo to bend substantially without rupturing. The average distance from one node to another was 450 mm.

Bamboo is highly resistant to earthquake shocks and several other forces that affect stability of buildings made from other materials. This property is as a result of the transverse or dividing wall present in each of the bamboo’s nodes that maintain high strength (Schroder, 2008).

Fabrication Process of Bamboo for Building Material

Bamboo is very light compared with other building materials such as brick, concrete, wood or steel. The material has a high strength-to-weight ratio, making it suitable for the houses in this project considering that they will be constructed in flood prone areas and have to float on oil tanks during flooding. Its hollow section also makes it lighter.

Bamboo is a natural material and is used in its natural form. It is also easy to transport, cut, join and assemble. The whole construction process is done using simple tools that do not expose workers to safety risks (Sharma, et al., 2014). In general, this material does not have any health or safety risks to builders, end users or the environment.

Muli bamboo, the species of bamboo that was used in this project, is easily available and widely used in Bangladesh. It is also the cheapest, strongest and most durable species of bamboo in Bangladesh. This material is also easy to cut and shape using basic tools. All these factors helped in reducing the cost of the bamboo house in this project.

In the context of this report, fabrication process entails all processes involved in preparing the building materials and converting them into the final houses for the end users. These processes are discussed below

The first process was selecting the bamboo to harvest. The selected bamboo culms were long and those that appeared to be strong and straight. Once harvested, the bamboo culms were inspected thoroughly to remove the ones that had been infected with bugs, fungi or those with any other defects. The bamboo culms were also cut to an average height of 3 m. The best time to harvest bamboo is dry season as there are minimal insect attacks during this season. During harvesting, the branches were removed carefully from the culms so as not to damage their outer skin.

One of the major drawbacks of using bamboo as a building material is that it loses a significant amount of moisture when dried. The loss of water causes the bamboo to shrink and contract thus decreasing its diameter & wall thickness, and structural soundness & integrity. Therefore green bamboos should not be used as building materials as they are prone to shrinking and contracting, and fungi/insect and mould attacks. To resolve this problem, bamboo must be dried first before being used. The drying in this case was done by air drying where the culms were stored vertically under a shade that was adequately supplied with natural air. The bamboo was dried for 6 weeks, during which they were protected from direct sunlight, rain and soil moisture. Alternatively, the bamboo culms can be dried or cured faster using heating method. This method involves putting bamboo culms in a gas grill or kiln and turning the heat to high. The bamboo is then left in the grill until its color changes slightly, an indicator that the culms are strengthening as the resin rises to the surface. After that, an old rug is used to rub the resin into the culms of bamboo until there is a change in color from deep to mint green. Holes are then poked into the inner membranes of bamboo culms using a tool like sharp scissors.

Conclusion

After drying, we separated good bamboo culms from the bad ones (those with defects). It is rather obvious that some culms can develop defects during drying and therefore they must be checked. The sorting also involved choosing the right bamboos for the intended use, such as flooring, walling, roofing, etc.

The bamboo culms in this project were straightened using fire. This was so as to reduce the cost of using other alternatives such as kilns.

Bamboo is susceptible to insects, fungi and pests attack and moulds caused by dampness. To ensure longevity, the bamboo must be treated. There are different methods of treating bamboo. In this project, the bamboo was preserved using borax-boric acid solution. A pressure pump was used to feed the solution through the bamboo poles. The bamboo culms were also vertically soaked in the borax-boric acid for a few minutes. Other methods that are also commonly used to preserve bamboo include: immersion (immersing freshly cut bamboo culms in stagnant water for fur to twelve weeks) and heating (heating bamboo culms in a kiln at a temperature of about 150 °C).

Depending on specifications and properties, the bamboos were grouped based on their use – flooring, walling, roofing, joints etc.

This involves cutting bamboo into desired sizes and shapes depending on the intended use. The bamboos were cut into the desired sizes using a saw or machete. Some of them were split into halves lengthwise.

When bamboo gets in contact with moisture in the ground, it tends to deteriorate and start decaying faster (Nall & Putra, 2016). To avoid this problem, anchor steel piles were used on all the four sides of each house. The piles were driven into the ground by use of drop hammer. To minimize building settlement and stabilize soft soils (by increasing soil bearing capacity) (New Zealand Digital Library, (n.d.)) on which the houses were being built, split bamboo piles of diameter 100 mm and length 8 m were installed using drop hammer. Coconut coir filaments bound with jute were filled in the split bamboo piles. A wire was then used to tie the sections. The piles were installed at a spacing of 1.2m center to center, as shown in Figure 1 and 2 below. After installing the anchor steel piles and bamboo piles into the ground, a 2 m surcharge of coarse aggregate (sandy material) was used to fill the surrounding area.

Bamboo flooring is very economical, environmentally friendly and sustainable hence it was a good choice for this project (Noriega, 2011). The flooring of each house comprises of bamboo beams (Figure 5 below) that are fixed to the foundation and the flat bamboo culms as shown in Figure 4 below. The beams were made from bigger pieces of bamboo culms and were fixed on the bamboo and steel piles as shown in Figure 6 below. The distance from one center of the beam to another is 1.5 m.

Bamboo strips of equal lengths were cut and set aside. An adhesive resin was used to coat the strips, which were then pressed together horizontally and nailed down closely onto the bamboo beams to form the floor, as shown in Figure 7 below (Lewitin, 2017). The flat strips were laying on top of each other. Nevertheless, this floor had some spaces between the bamboo culms. This could allow water penetration in case the water storage space underneath the floor got flooded. To prevent this problem, bamboo laminated floorboards were nailed on top of the bamboo strips to cover them. A smooth finish of the floor was then obtained by polishing the floorboards using sand paper. This flooring is also very easy to maintain as it can be swept, vacuumed, moped or cleaned using bamboo floor cleaner (Lewitin, 2018). 

The walls of the houses were completely made up of bamboo. To start making the walls, tools such as knives, handsaws, crowbars and chisels were used to split bamboo into small individual strips. The trips were then weaved together ensuring that each strip was very close and tightly attached to each other. The weaving is done by sliding 2 bamboo strips over one batten and under the next batten until the strips reach the final batten (YR Architecture + Design, 2017),

Bamboo posts were joined into the beams to act as columns. The main columns were erected at all corners of the house then subsequent ones were placed at a spacing of 1.2 m, all round the house envelope. These bamboo posts are structural elements that carry dead and live loads of the house to the beams which then transfers the loads to the foundation. The constructed bamboo walls were then fastened or fixed onto the bamboo columns using small nails ad driven directly into the bamboo beams at the bottom,

After fixing the bamboo walls into place, crushed bamboo paste was applied on both sides of the walls, the same way mortar is plastered on a brick or stone wall. The crushed bamboo paste is essential in providing strength and plasticity to the walls. The bamboo paste also acts as an infill that provides protection against wind, rain, insects, etc. It also offers privacy to the occupants of the house.

The roofs of the houses were made of split bamboo. The roofs were inclined at an angle of 30° to enable collection of rainwater, as show in Figure 13 below. To make the roofs, bamboo rafters were fastened on bamboo columns/posts. The rafters were slanting at 30°.

Spilt or halved bamboo culms were then placed over each other on bamboo purlins to create chain links or mesh as shown in Figure 15 and 16 below. Rubber tree oil was used to coat the halved bamboo.  

Solar panels were then installed on the roof of the house to harness solar energy for the families.

Bamboos are hollow and have nodes at different distances. This makes their joints quite complicated. However, the joints must be strong for the house to be strong. Different types of bamboo joints were used in this project.

This pile joint is known as splicing using dowels. It is on this pile that the horizontal bamboo beams were fixed. Details of the bamboo pile-beam connection are shown

Bamboo beams were cut to accommodate or fit the vertical bamboo columns/posts. Figure 19 and 20 below shows details of the cut bamboo beam before and after fixing the bamboo columns/posts.

Another type of joint used is the positive fitting connection. This connection is works together with lashing technique where a hole is cut through a vertical bamboo member to perfectly fit a horizontal member that is run through the hole. The joint is then tied using any kind of binding such as G.I. wire, rope, bamboo strips, etc., as

We successfully completed assignments 1 and 2 because of the cooperation, integration and cohesiveness of the group members. As a group, we worked as a team with a common goal from the very start. We owned this project equally and dedicated ourselves to see it delivered successfully. All the group members have a construction background and more so have worked on bamboo construction projects. This worked for us as we were able to share our past experiences in constructing bamboo structures to help homeless people in different parts of the world. The fact that we had a common background helped us understand and communicate with each other well and professionally. The first and second assignment were very successful as we managed to achieve all their respective goals and objectives.

In the first assignment, we comprehensively discussed several issues including: why we selected blooming bamboo house in this project and if it is fit for the intended purpose, major stakeholders involved in bamboo housing sector, design proposal of the blooming bamboo houses, drawbacks of the proposed houses, planning and redevelopment of design layout, construction and construction methodology of the houses (including details of materials and equipment), budget of the houses and strategies to keep the costs down, and modularity of the houses. From this assignment, we were able to have a clear plan on how the bamboo houses would be constructed faster and at the lowest cost possible, and serve the intended purpose effectively.

In the second assignment, we managed to develop the final proposal of the bamboo houses for the project. In this assignment, we discussed several issues including: aim of the project strategies, site overview, benefits of multidisciplinary teamwork on the project and how to ensure that the team works effectively, design of the houses and other facilities, construction overview of different structural elements, selection of bamboo species to be used, joint techniques, construction scheduling and budget.  

Looking at the requirements of assignment 1 and 2 and we did, we met all the requirements hence we completed these two assignments successfully.

Despite the fact that all the four group members had worked on similar bamboo construction projects before, there are several opportunities of improving their experience. One of them is including members of the community in the group. Two of the group members had worked on similar projects in China while the other two had worked in India. Since this project is being implemented in Bangladesh, it would be better to include a few members of the local community in the group. This would have helped the group members to have an in-depth understanding of the local building codes, unique needs of targeted end users and local approaches that can be used to keep costs down. Also, integrating local members into the group can improve our experience as we would be able to identify how we can use available resources, including local materials and labour, to reduce budget.     

Our group’s experience could also have been improved through training. None of us knows everything and it would be a good idea to organize for training sessions so as to acquire new knowledge or even skills on how to implement this project in the most effective and efficient way (Savelsbergh & Storm, 2010). Through training, senior structural designer, Mr. Narayana Reddy, would have developed a more efficient, environmentally friendly, sustainable, easy to construct and low cost house designs. The site execution engineer, Mr. Anil Kolluru, would have develop better strategies of ensuring that the project is implemented faster and more efficiently but without compromising the quality and functionality of the houses. The training could also help Mr. Haneef Shaik, the cost planner, to develop more accurate cost estimates of the project, identify reliable sources of funding for the project, ensure that resources are available when needed, ensure appropriate allocation and utilization of resources and eliminate or reduce waste. Mr. Anil Kumar, the planning officer would have gained from the training by creating a customized construction plan for this project and ensuring that all stakeholders, including government agencies, are involved in the project. This would help in ensuring that the project is executed as planned, from start to finish, without delays.

Besides acquiring knowledge and skills, training could also help the group members understand each other’s strengths and weaknesses, and get along well (Zehra, 2016). In other words, training has a positive impact on the integration and cohesiveness of the group.

Another great way in which the group’s experience could be improved is by supporting innovation (Kelly, 2015). If the client had made innovation one of the key pillar of this project, the team would have gone an extra step in ensuring that they create very creative and innovative design proposals.  

Project integration is very important on successful delivery of projects (Smith & Offodile, 2008). In this project, integration impacted the final outcomes of the proposal positively. First and foremost, integration helped in ensuring that different project activities were coordinated effectively. This was important because even though every group member was assigned specific activities, we were all working towards a common goal. It was therefore important to ensure that these activities were integrated. Second, integration helped us communicate effectively and at the most convenient time. Through integration, the group agreed on different communication methods, including use of phone calls, text messages, emails, meetings and social media. These facilitated easy and effective communication throughout the project. As a result, every member was timely updated about any developments or changes associated with the project. Third, integration helped us understand the strengths and weaknesses of each member. The understanding is what helped us assign tasks to the most qualified member. This ensured that each member’s abilities were utilized maximally because were all working in our areas of specialization, which is a major benefit of integration (Elorus, 2018). It also helped us work together to ensure that members capitalize on their strengths and get assisted to improve on their weaknesses.

Another positive impact of integration was quick and effective decision making. Numerous decisions had to be made in this project, and every decision had huge impacts on the proposal outcomes. To make any decision, we had to consult among ourselves and other relevant stakeholders. Integration played a key role in improving the time and efficiency of making decisions. Through integration, we all understood each other and what we wanted to achieve in this project. If we had to make any decision, we could quickly organize for a meeting to discuss the issue at hand and make a collective decision.  

Integration also helped us criticize each other’s work performance without offending. As a team, we exchanged our work amongst ourselves and each member gave feedback on the work he was reviewing. The feedback was taken as positive criticism to help ourselves improve on the areas we were working on. Likewise, integration helped us complement each other’s work.

Most importantly, integration helped us avoid one of the biggest problems associated with construction projects – conflicts. This project had several constraints, such as limited budget and time and environmental constraints, hence it was prone to conflicts. But through integration, we did not have any disputes between the project team. We discussed all issues openly, honestly, professionally and with integrity, and none of us had any self interest in the project.

In general, integration had the following positive impacts on the project outcomes: helped us analyze the project needs comprehensively and develop an efficient solution; enabled us assign various tasks to the most qualified group member; enabled us share our knowledge and past experiences on similar projects hence developing the best methodologies of executing this project successfully; helped us identify means of reducing the cost of the bamboo houses; improved coordination and collaboration among team members thus completing activities within the schedule; and it helped us learn from each other. The less knowledgeable and experienced members learnt from the more knowledgeable and experienced team members. In conclusion, integration contributed towards effective team building, it boosted productivity of individual members, promoted learning amongst ourselves, improved performance of the project, prevented conflicts; and left every member of the team satisfied with his contribution on the project.  

References

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