INNOVATIVE MATERIALS

Behzad Sodagar BSc MPhil PhD, Cariona Tuite BA(Hons) PG Dip, Anne -Louise Duignan BA(Hons) PG Dip, Dorota Spychala BA(Hons) PG Dip, Chrysa Chaina BSC(Hons) PG Dip Lincoln School of Architecture, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, UK. Email: [email protected]

1. INTRODUCTION

The purpose of this paper is to investigate the practicality and feasibility of certain sustainable and innovative materials, as opposed to traditional building materials. There are mountains of by- products of our civilization which can be reused as building materials. These are the natural resources of the twenty-first century. The paper examines the potential of these materials by considering design issues such as; availability and ease of production, cost, durability/ life span, construction time and aesthetics.

Two materials have been chosen, as case studies, to demonstrate the potential of these materials. They are: Paper/Cardboard –It examines the use of cardboard tubes and reinforced paper panels called Sonoboard Bamboo – It examines the use of bamboo as a fast growing materials

2. PAPER AS A BUILDING MATERIAL

The Japanese have always had a special interest in paper as a building material. Paper shoji screens and lanterns define the traditional Japanese house. Shigeru Ban is a pioneer of paper tube structures (PTS). He has come up with a building system based on cardboard tube columns. In the last decade Ban has designed recyclable and easy to mount cardboard houses as well as designing shelters for refugees and disaster victims.

Ban first began experimenting with alternative materials in 1986, when he used paper, instead of wood, to build his Alvar Aalto exhibition display. He was surprised at the strength of the paper and then began to use paper tubes as structural systems. Although Ban has become an icon for advocates of 'green' and 'eco-friendly' architecture, his intention behind his work is slightly different. It's more an ideology against waste. It's about invention, curiosity, discovery, and about tackling problems with a sense of humour. That paper as fragile, flammable and cheap material is also suitable for making real buildings seemed unthinkable, until recently. There are of course a lot of finishing materials in which paper is processed. For example plasterboards, wallpaper and eco-insulation from paper shreddings. When buildings are meant to last for a short time, one should try to use materials that are easily recycled. Reasons to use paper and cardboard, as a construction material are because cardboard is made from recycled paper, and can be recycled too. Using paper as a building material has a number of advantages:

Durability: Paper tubes, made of recycled paper, have stable qualities and are highly durable. In this sense, they can be regarded as "evolved wood."

Weight: Paper tubes as structural materials are much lighter than wood, let alone steel or concrete. This characteristic is one of the great merits of paper tubes, because we can build light weight buildings Environmental benefits: Paper tubes can be easily manufactured and processed. More importantly, they are recyclable. Therefore, if we use paper tubes, the risk of destroying the environment is quite small when obtaining the materials or disposing of surplus waste. Aesthetic- Paper tubes are simple, yet powerful and beautiful.

3. CASE STUDIES

In June 1995, Shigeru Ban designed houses which were assembled out of paper tubes for the victims of earthquake. The simplicity of the structure of these houses made it possible for a house to be assembled in 6 hours by unskilled labours. Teflon-coated tenting was used for the roof and plastic beer crates raised the structure off the damp ground. He established that not only could recycled cardboard be moulded into load-bearing columns, bent into beautiful trusses and quickly assembled, but it could also be made waterproof and fire resistant. In the space between the paper tubes, self- adhesive waterproof sponge tape was applied to both sides. The foundation was made of sand-filled beer cases, the walls of paper tubes and the ceiling and roof of tent material. The roof and the ceiling were kept separate in summer to allow air to circulate and closed in winter to retain warm air.

Figure 1. Paper tube houses for the Kobe earth quake victims

In the church designed for the same victims, Ban used paper as the main building material. The church was constructed in only 5 weeks by 160 church volunteers Although it was originally intended to be a temporary structure, due to its popularity it is still there! (figures2). Tube walls were built up from laminated layers of recycled paper to a thickness of 16mm and wooden stoppers

inserted at both ends, resulting to a strong structural column, capable of supporting half the weight supported by a column of wood. The tubes were then sealed and made waterproof by hand, (a process which has to be repeated every year). Each tube was 5 metres in length, 330 mm in diameter, with a thickness of 16 mm.

Figure 2. Paper church for the Kobe earth quake victims

'Environment' was the theme of the in and the concept of the Japanese pavilion was to create a structure whose materials could be recycled when it was dismantled. The pavilion designed by Shigeru Ban was a paper tunnel supported by a matrix of recycled paper tubes as structural elements. While paper tube structure was sufficient enough to withstand the loads, a compromise was made by including a supporting wooding structure to satisfy the German building codes. To avoid the use of PVC (a common substance for tent-like structure) that emits dioxin when burned, the pavilion was covered with specially designed water resistant and fire retardant paper roofing which was also light penetrating. After the exhibition, the pavilion was recycled.

Figure 3. Structural Details of EXPO 2000 Japanese

4. BAMBOO AS A BUILDING MATERIAL

Bamboo is another renewable material with adequate properties to be used in buildings. 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 South East Asia. Bamboo is a high-quality, high-strength material with enormous building potential. It has an amazingly short growth cycle when we compare it with a tree. To grow the bamboo to build a one-family house, there is needed an average of 500 square meters of land for five years. In 5 years, using a space as large as 1/4 of , one could grow enough bamboo to shelter the 100 million homeless people. It is a true alternative to cutting down precious tropic trees in the rain forest. Bamboo is the fastest growing woody plant on earth. It grows one third faster than the fastest growing tree. The project FUNBAMBU in Costa Rica made the construction of about 1000 bamboo houses annually possible. The building material came from bamboo plantations of only 60 hectares. To build the same number of houses an area of 500 hectares of tropical rain forest would have to be felled!

Bamboo has adapted itself world-wide to diverse ecological conditions; The bamboo belt runs through tropical, subtropical and temperate climates around the globe, up to 45° North and South. Bamboo has an amazingly short growth cycle. Some bamboo species constitute the world’s fastest growing plants. Some species grow at an incredible rate of 1m per day. Size ranges from miniatures to towering culms of 60m.

Bamboo has unique properties; It is high-strength, stiffened by the nodes, but because of its cavities extremely light and elastic. Its physical qualities are partially far superior to timber. The heartwood is the strongest part of timber, so strength decreases from the centre outwards, whereas the strongest part of the bamboo culm is at the outer edge of the culm wall - a much more stable construction for example for multi-storey buildings.

Another advantage of bamboo is its low weight. It can be transported and worked easily. It can be bent using heat and when growing. Structures made out of bamboo have remarkable flexibility against earthquake and storm forces. They can withstand wind gusts of 100 km/h.

Bamboo is classified, according to the DIN 4102 (Burning behaviour of building materials), as flammable but hardly combustible. The ignition susceptibility depends particularly on the position of the component so horizontal components are less susceptible as diagonal or vertical components. On a horizontal bamboo cane, the flame spreads annularly to the next knot point (node). There the fire dies down because the flame cannot pass easily the hardly combustible node to the next segment. A bamboo tube that is filled with water can stand up to 400°C at the bottom side, while the water cooks in the tube.

One of the problems associated with bamboo is its susceptibility to infestation by insects and fungi once harvested. This problem can be easily overcome by traditional Japanese method of smoking. Burning leftover pieces of harvested bamboo in a large oven, smokes the bamboo poles and extracts the pyrolytic acid from inside the bamboo and evenly applies it to its surface making it resistant to infestation. Treated bamboo may last up to 500 years.

One of the most important disadvantages of bamboo as a building material is it is not possible to use it if it is broken. Broken outer fibres are razor-sharp because of the silicified layer and therefore easily lead to injuries. The bamboo canes differ from each other and cannot be cut like timber - they cannot be standardized. Bamboo shrinks more than wood when it loses water. Moreover, the mechanical qualities of bamboo depend on the botanical species, its habitat and the age of the cane at the date of harvest, the moisture content and of course on diameter and wall thickness. So it is recommended to sort the culms accordingly.

Standards about building with bamboo are still missing, which impedes the application of bamboo in countries with strict technical regulations. But there exists a draft of the ISO about bamboo testing methods. Like timber bamboo can be glued to form slats, boards, arches and I-beams. Tests at the Universidad National de Colombia on glued bamboo products have showed that glued bamboo slats serve very well as source material for high-quality products with good material properties.

5. CASE STUDIES

Colombia pavilion for Expo 2000 in Hanover (figure4), designed by Simón Vélez, demonstrated the potential of bamboo as a building material. The primary building material was 4000 pieces of bamboo (Guadua - with concrete-filled joints) forming a space 14 meters in height and 40 meters in diameter. That pavilion was the only one at the EXPO built twice; once in Colombia for testing and once in Hanover.

Pereira Church (figure 5) and Social Housing project in Armenia (figure 6) by the same architect, are further proof of bamboo as main building material. The 500 homes Simon Velez design as parts of an international challenge to build homes with bamboo for 250,000 people demonstrated the economical and constructional advantages of bamboo structure. The estimated cost for one two-story house is Euro 7,000, favouring it compared with the cost of traditional methods of construction.

Figure 4. Colombia pavilion for Expo 2000 in Hannover

Figure 5. Pereira Church

Joints can be strengthened by injecting concrete into internodes and adding steel reinforcement. Like gluelam timber beams, bamboo can be glued to form slats, boards, arches and I-beams.

Figure6. Social Housing project in Aemenia

6. CONCLUSION

It is necessary to note that some traditional construction methods do more harm than good. They are damaging our planet. Our ability to evolve beyond these systems is becoming increasingly necessary. If we learn to live with alternative production and construction systems, we could radically slow down the destruction of the planet and possibly reverse certain aspects of the deterioration. For centuries, buildings have been built from found materials such as rock, earth, reeds and logs. These finite resources are being exploited and alternatives need to be found. Many of alternative materials have similar properties to those of traditional materials. There is no reason why these materials cannot be used more widespread in the construction industry. In fact some of them had greater strengths and durabilities than traditional materials.

For example, the physical qualities of bamboo are far superior to timber. The heartwood is the strongest part of timber, so strength decreases from the centre outwards, whereas the strongest part of the bamboo is the culm, this is at the outer edge. This provides a much more stable construction. Bamboo is ready for harvesting within three to six years, whereas oak, cherry, maple and exquisite rain forest hardwoods take more than 100 years to grow to maturity.

This paper looked at just two materials, i.e. paper and bamboo as two alternative building materials. There are lots of other similar materials and/or by products which can be used in the building industry to replace traditional materials.

7. REFERENCES

Ban, Shigeru, The Japan Architect, Japan, Chikuma Shobo, Japan. 1998 Ban, Shigeru, Paper Tube Architecture from Rwanda to Kobe, Chikuma Shobo Co, Japan. 1998 Ban, Shigeru, Projects in Process, TOTO Shuppan, Japan. 1999 Ban, Shigeru, Paper Architecture, Princeton Architectural Press, USA. 2001 Gili, Gustavo, Shigeru Ban, GG portfolio, S.A., Spain. 1997 Janssen, J.J.A, Bamboo in building structures, Thesis Eindhoven University, Holland. 1981 Janssen, J.J.A, Designing and Building with Bamboo, London. 2000 Janssen, J.J.A, Building with bamboo, Intermediate Technology Publications, London. 1995 Janssen, J.J.A, Mechanical properties of Bamboo, Academic Publishers, London. 1991 Jayanetti, D.L., P.R. Follett, Bamboo in construction , Cambridge. 1998 Villegas, M. Tropical Bamboos, Thomson Publishing, London. 1990