Proceedings of

International Workshop on Bamboo Industrial Utilization

Editor: Chen Xuhe, Lou Yiping, Hao Ying

International Network for Bamboo and Rattan

Hosted by

Hubei Provincial Government & Xianning Municipal Government

October 2003

Content

Forward

Preface --- Opening Speech

Jiang Zehui

Part 1 Bamboo Industrial Utilization

Structures of a Bamboo Culm Affecting its Utilization

Walter Liese

Recent development on bamboo utilization

Zhang Qisheng

Development of sustainable building and new bamboo construction material

Chen Xuhe

Technical Innovation to Increase the Competitive Capability of Bamboo Products

Jiang Zhengchan and Yu Gang

Technology of pigmentation of bamboo strips by carbonizing and dyeing treatment

Xie Manhua and Guangjie Zhao

Bamboo in Construction

Lionel Jayanetti

Bamboo, a sustainable building material in Western Europe

Pablo van der Lugt, Andy van den Dobbelsteen & Jules Janssen

Technology of Sawing Bamboo Veneer

Li Li，Yang Yongfu & Guo Jianfang

Technological Innovative Course and Prospect of Bamboo-based Panel of China

Zhao Renjie, Chen Zhe & Zhang Jianhui

Study on Properties of Bamboo and Manufacture

Wang Zheng, Guo Wenjing & Gao Li

Part 2 Bamboo Resources, Environment and Trade

Bamboo Resources, Uses and Trade: The future?

Ian Hunter

Studies on technical systems and comprehensive benefits of converting agricultural land into Bamboo in Sichuan

Chen Qibing & Sun Jun feng

Implement the Ecosystem Management in Bamboo Plantation to Improve the Synthetical Benefits

Xiao Jianghua

Present Situations and Development Countermeasures of Paper-pulp Bamboo Resources in Hubei Province

Xiong Deli

Promote Xianning Bamboo Industry and Develop Regional Economy

Zou Jizhou

Evaluation on Shoot Quality of Excellent Sympodial Bamboo Species and Hybrids

Wang Yuxia & Zhang Guangchu

Bamboo product processing industry and income of bamboo farmers

Chen Suijun

Silviculteral Technique of Dendrocalamus farinosus on Returning Steep Slope Cropland to Forestland

Dong Wenyuan, Gao Yanping& Liu jun

Study on In-vitro Rapid Propagation of the Clumping Bamboo

Zhang Guangchu, Wang Yuxia, Tan Yuanjie, & Li Xingwei

Why giant panda became extinct in Central China: An appraisal of mountain bamboos in Shennongjia

Zhaohua Li, Manfred Denich & Thomas Borsch

A Study on the Conservation and Development of Dendrocalamus sinicus, A Giant Bamboo From Yunnan

Hui Chaomao, Chen Fang, Zhang Guoxue, & Yang Yuming

The Retrospective and Prospective of China’s Bamboo Industry

Wang Shudong

FOREWORD

The China Bamboo Trade Fair is held every two years and aims to promote sustainable development of bamboo industries in China, also in the world. The 4th Fair was held on 9-11 October 2003 in Xianning City, Hubei, China. It was co-sponsored by the State Forestry Administration of China, the Provincial Government of Hubei and the International Network for Bamboo and Rattan (INBAR) and hosted by the Xianning Municipal Peoples’ Government. It was attended by more than 1,000 people. There were four concurrent events:

¨ The Bamboo Industry Expo and Xianing Economic and Trade Exhibition

¨ A National Forum on the Bamboo Industry

¨ Meeting of the Executive Directors of the China Bamboo Industry Association

¨ Cultural events reflecting the significance of bamboo in local lives

The Bamboo Trade Fair attracted more than 100,000 visitors. Bamboo products worth 1.2 million US dollars were sold during the fair and total contracts valued at 75 million US dollars were signed during the Fair. Many new products were on show.

INBAR with support from the local authorities – Provincial Forestry Administration of Hubei and Xianning Municipal Peoples’ Government, organized the international Workshop on Bamboo, with an emphasis on bamboo industrial utilization. This workshop set the stage for exchanging and sharing the updated information on research and development of the bamboo cultivation and utilization of bamboo resources and utilization.

The workshop was attended by about 150 diplomats, scholars, entrepreneurs, policy-makers from around 30 countries of all continents. Notable amongst them were Prof. Jiang Zehui, Co-chair of the INBAR Board, and 20 diplomats from 18 embassies in Beijing and international organizations.

In the Workshop twenty international and Chinese speakers presented their papers. About 30 papers in English or in Chinese were shared on the workshop on the bamboo resource management and utilization. This proceedings are a compilation of the part of the papers presented at the workshop by the participants for disseminating the knowledge to a wider audience. It is our hope that this will encourage an increasing interests in utilizing bamboo resources for the purposes of environmental protection and poverty alleviation in the different parts of the world, esp. in Africa and South America where are rich in natural bamboo resources.

The workshop and the compilation of the papers would not have been possible without the hard work of a number of individuals and institutions. Full acknowledgement should be given to the Forestry Administration of Hubei Province and Municipal Government of Xianning, without whose marvelous facilities and considerable logistical support the workshop would not have run as smoothly as it did.

Finally, the workshop would never have happened without the full dedication and many long hours of hard work from our INBAR colleagues. Ms Hao Ying took on the thankless administrative and logistical burden, and Dr. Lou Yiping pulled together this compilation of the papers. Thanks and appreciation to them, and the others who participated in the process.

Ian Hunter Chen Xuhe

Director General of INBAR Deputy Director General of INBAR

April, 2004

Preface

Speech on the International Training Workshop on Bamboo Industrial Utilization by Professor Jiang Zehui

Distinguished guests, friends, ladies and gentlemen:

Good Morning!

First, on behalf of the Chinese Bamboo Society and the Board of International Network for Bamboo and Rattan, I would like to extend my warm welcome and sincere gratefulness to the ambassadors, diplomats, experts and scholars and guests participating this international seminar during the bamboo cultural festival.

The topic of this seminar is bamboo industrial utilization. As we all know, bamboo grows fast and can be used for many purposes, it has important economic, environmental and social value. Bamboo can play an important role in regional economic development and poverty alleviation if we improve bamboo processing technologies and management system, and accelerate the industrialization of bamboo utilization. This workshop will discuss and explore key issues concerning the above, which are significant for the future bamboo cultivation and processing development. Now, I would like to introduce the status of China’s bamboo industry and the development of bamboo utilization, I will also give some suggestions for the future development of bamboo industrial utilization.

I. Main Progress in China’s bamboo industry development and bamboo industrial utilization

China is the homeland of bamboo, it has the richest bamboo resources in the world. The number of species, plantation areas and biomass of bamboo in China are all among the world’s top list. Bamboo utilization is one of the important part of Chinese culture. Bamboo is widely used in construction, transportation, furniture, pulp making, handicrafts, etc.. Since the implementation of the opening and reform policy, China’s bamboo industry has been developing fast, from resource cultivation, processing to international trade, the bamboo sector has become a newly erected industry of the nation. The development of bamboo panel products and machine-made bamboo pulp indicates that China’s bamboo industry has entered a new stage of modern industrial utilization.

China’s bamboo industry has three characters: fast development; high involvement of science and technology; emphasis on ecological environment protection.

In the aspect of bamboo forest area: in the recent years, the world bamboo forest area has been increasing at the speed of 3% per year, although the world forest coverage is dropping dramatically. The world bamboo forest area now in total is about 22 million ha. China’s bamboo forest area is 7.2 million ha, including 4.2 million ha of plantations and 3 million ha natural stands in high mountainous.

In the aspect of scientific utilization: As bamboo fast propagation technologies are extended and applied, the areas of intensive managed bamboo plantation are increasing continuously, the bamboo processing and utilization are widened, bamboo panel and bamboo pulp making technologies are getting matured, the bamboo processing and utilization is advancing towards finer finishing, completed utilization of the bamboo material and high added-values, the economic effects of bamboo industry is improved remarkably.

In the aspect of environmental effects: in the recent years, people began to pay more and more attention to the eco-function of bamboo. Bamboo is applied to soil and water control, conservation of water heads; rehabilitation and preservation of vegetation in habitats of rare wild lives, such as pandas and Snub-nosed monkeys (Rhinopithecus roxellanae), etc; it is also applied in the greening of urban areas, landscape construction and bamboo eco-tourism. Bamboo landscape plantation has just take on a look in Beijing, it will become a new scenery in the 2008 Beijing Olympic Game.

China’s bamboo industrial utilization made significant advancements these years in the following aspects:

1. Various bamboo panel products

China has developed bamboo mat plywood, bamboo composite plywood, bamboo particleboard, bamboo skin laminated plywood, bamboo-wood composite board, etc. In China, bamboo composite plywood and bamboo flooring production now has grown and expanded to certain scale, the products are widely used for construction moldboard, the bottom board of trucks, trains and boats, and indoor decoration board.

2. Bamboo laminated board furniture

China has a long tradition of using bamboo culm for furniture processing, Chinese traditional furniture are of primitive simplicity, and are refreshed and elegant, they are often seen in Chinese restaurants and hotels. However, traditional bamboo furniture is disadvantaged for its big volume and inconvenience when knocking down or assembling, and high cost for storage and transportation. The International Network for Bamboo and Rattan, Zhejiang Forestry Research Institute and other collaborators introduced the pack-flat concept of wood products to the designing and manufacturing of bamboo furniture, and successfully developed bamboo pack-flat furniture, this new style of bamboo furniture has small volume and can easily be stored and transported at low cost.

3. Bamboo pulp and paper

Presently, only 12.2% of China’s pulp industry use wood pulp; In the recent several years, China has imported paper and pulp to meet domestic demand, the value reached 5 billion USD. Because China is one of the biggest bamboo producers in the world, and bamboo is the second most important fiber material for pulp making, bamboo utilization in pulp making is significant to the development of China’s pulp industry and industrial utilization of bamboo.

4. Bamboo fiber development and utilization

Fresh bamboo materials softened by high temperature can be manufactured into fibers for textile. Bamboo fiber is hollow inside, thus, it is breath-free, fabric of bamboo fiber and hemp or silk or wool has better performances than common fabrics. Bamboo fiber is the second Chinese invented new fabric material that has independent intellectual property after the development of soybean protein fiber, it is estimated that bamboo fiber will bring good social and economic effect in the future.

5. Bamboo Charcoal and Vinegar

Recent research shows that bamboo charcoal has comparatively larger surface area and adsorbability, it is good at purify water and air, as well as adjust the moisture. Bamboo charcoal contents many microelements such as calcium, magnesium, aluminium and kalium, etc., it can be utilized health products and anti-static products. Related products have been developed and put into market in Japan and Korea.

Activated bamboo charcoal has outstanding performances in adsorbing, is able to adsorb pigment and other impurities from gases or solutions; it can also be used as catalyzers or carriers of catalyzers in the industries of food, medicine, chemical, metallurgy, national defense. These shows that bamboo activated charcoal has a bright prosperous in the high-tech industries.

Bamboo vinegar is a by-product of bamboo charcoal, it contents certain chemicals and active bio-matters, can be used for deodorization, sterilization, plant growth promotion, soil improvement, it has a bright prosperity in agricultural, medical, health care and environment sanitation areas.

6. Effective elements in bamboo leaves

Bamboo leaves contents flavone, amino acid and microelements, these elements are of excellent biological efficacies in anti-oxidation, anti-consenescence, and strengthening human immunity, these functions have attracted attentions in the fields of food, nutrition and medicine researches. Up to date, health care products developed with flavone extracted from bamboo leaf, beverages contents bamboo leaf extracts are already developed and put into markets, these products attracts wide attention from all circles of the society.

II. Challenges in China’s bamboo industrial utilization

As China’s bamboo industry is developing, some challenges and problems come in the way and resolutions are needed:

One challenge is the construction of resource bases. Although China has such a rich bamboo resources as 500 hundred species, but only not more 20 are developed and utilized, the rest are still laid waste in the wild. More than 50% of the monopodial bamboo plantations in China are low-yielding plantations that needs improvement; 95% of the 1 million ha sympodial bamboo plantations are under extensive cultivation. It is extremely necessary to establish high quality, sustainable and efficient resource bases.

The other challenge is that most bamboo processing enterprises are of small-scale, with simple and lagged-behind equipments, low innovation capacity, low technologies, are weak at regeneration. Only a small number of China’s bamboo enterprises have passed the ISO certification. However, none has passed the certification of ISO14000 environmental management standard systems. The world recognized forest certification system is another goal that Chinese bamboo enterprises should try to meet.

III. Suggestions to the future development of bamboo industrial utilization

Drawn on the new research results of China’s Sustainable Forestry Development Strategy, the State Department recently issued the Decision on Accelerating Forestry Development, which urged the establishment of a sustainable development strategy prioritizing ecological construction, thus, establish a land eco-security system mainly with forest vegetation, and the integration of plantations and pastures, to achieve the goal of constructing a eco-civilization society.

In the past, the high growth rate of China’s GDP was based on the increasing investments, industrial expansion and the mass consumption of resources. In the new historic period of forestry development, our bamboo industry should aim at the national goal of sustainable development, and follow the strategy of eco-construction, eco-security and eco-civilization, by improving technologies and personnel qualities, develop new types of bamboo industry with high-technologies, high economic efficiency, low resource consumption, low pollution and full play of personnel advantages. Therefore, I would like to propose the followings:

1. Pay attention to the construction of bamboo forest resource bases

Bamboo industrial utilization must follow the rules of sustainable development. The productions of pulp, fiber, panels, charcoal, as well as bamboo food products mainly with bamboo shoots and bamboo beer, need large amount of bamboo resources. It is necessary to apply industrial plantation management models and establish product oriented resource bases, which are of high-quality and high-yielding capacity and are intensively managed. The guarantee of resource supply, will improve t he efficiency of bamboo enterprises and increase farmers’ income.

2. Enhance the upgradation of bamboo industry structure

In order to meet the needs of ecological construction and changes of market demand, the bamboo industry need restructure to prioritize the resource allocation, and form a new development pattern with efficient supply of bamboo resources, led by fine and deep processing industries, and sustained by technology improvement. The aims are improving the comprehensive utilization of bamboo, develop high-tech, high-added value and characteristic bamboo products, create famous band, and improve product competitiveness.

3. Enhance scientific innovation

It is important to strengthen the collaboration of production, study and research, gradually establish the technology innovation system centering leading high-tech enterprises, strengthen the researches and development of key technologies in industry structure upgradation and improvement of product competitiveness.

4. Enhance macro-guidance and trade management

Different bamboo producing regions of China have different local natural and social conditions, the development of bamboo industrial utilization should consider local facts and needs, and accordingly, make the plans for local resource development and utilization. Local government and Bamboo Societies should play the role of trade management and provide policy supports in bamboo resource management, protection and utilization, as well as improve local investment environment.

5. Further international exchange and cooperation

Initiated by China and Canada, the International Network for Bamboo and Rattan (INBAR) was established in November 1997. It is the first international organization headquartered in Beijing. In its 6 year’s existence, INBAR has developed into a global network of 27 member states and 350 individual and institutional affiliate members. INBAR did not only improve bamboo and rattan researches, international cooperation and exchanges, but also helped the bamboo and rattan development in developing countries, which contributes to the economic and environment of these countries.

The Chinese Government has always been supporting INBAR’s growth and development. President Jiang Zemin wrote the inscription of International Network for Bamboo and Rattan, the new INBAR headquarters building built by the Chinese Government was put into use. We will strengthen cooperation with INBAR in order to further our international cooperation in bamboo industrial utilization.

Lets collaborate our efforts and make new contributions to the sustainable development of the bamboo industry in China and in the world.

Thank you!

Prof. Jiang Zehui

Deputy Director, Population, Resource and Environment Committee of the Chinese’s Peoples Political Consultative Conference

Co-Chair, Board of Trustees, International Network for Bamboo and Rattan

Chair, Chinese Bamboo Society

President, Chinese Academy of Forestry

12 October, 2003

Structures of a Bamboo Culm Affecting its Utilization

Walter Liese, Prof. Dr.

University Hamburg, Chair for Wood Biology, P.O.Box 800 209, D- 21002, Hamburg. Germany. Phone: +49 40 7223402. Fax +49 40 7228991. E-mail: Wliese@AOL.com

1. INTRODUCTION

The numerous possibilities to utilize a bamboo culm are considerably determined by its structural composition. Continuous research has focused to evaluate the relationships between structures, processing and product quality. At the International Symposium on Industrial Use of Bamboo December 1992 in Beijing some reviews were presented by Abd. Latif and Jusuh, Espiloy and Liese, which are to be elaborated further.

2. MAIN STRUCTURES OF A BAMBOO CULM

The anatomical construction of a bamboo culm appears rather uniform, compared with wood. The differences between the around 1.200 bamboo species are comparatively small. Nevertheless, certain differences exist, so that some species are preferred for certain uses, whereas others are neglected (Liese 1998).

Figure 1 Three dimensional view of the culm tissue with vascular bundles and fibre sheaths embedded in ground parenchyma, Oxytenanthera abyssinica

In general, the culm wall consists of about 50% parenchyma cells, 40% fibres and 10% conducting tissue (vessels, sieve tubes with companion cells). The obvious structural characters on a cross-section are the darker vascular bundles with their fibre agglomerates (Figure 1). All the bamboo culms exhibit striking differences in the distribution of their cells within the culm wall. The percentage of fibres is distinctly higher at the outer third than in the inner one. The base contains more parenchyma, the upper part many smaller vascular bundles with a high portion of fibres, providing a superior slenderness.

3.STRUCTURES INFLUENCING CULM UTILIZATION

3.1 Culm morphology

The bamboo culm is separated by nodes into internodes. Its diameter tapers from bottom to top, with differences between species. Base and middle portions are utilized generally for construction work, furniture, mats and boards. The reduction in diameter is accompanied by a reduced wall thickness, whereby the outer, stronger part will remain at the loss of the inner more parenchymatous tissue. Culm diameter and wall thickness are positively correlated to shrinkages. The mechanical properties increase with height and density, but decrease with increase of internode diameter and culm wall (Abd. Latif and Liese 2002).

Internodal length differs considerably between species. It is longest in the middle of a culm. Long internodes are preferred for furniture. The strictly parallel arrangement of the fibre arrangement as sheaths and bundles is disturbed at the nodes, so that for splitting and weaving species with long internodes are preferred, like Bambusa textilis up to 60 cm.

3.2 Structures of an internode

3.2.1 Outer and inner layers. The culm wall is on both sides covered by a special tissue. Its outer part, the cortex, as a water-tight seal prevents any moisture loss of the living culm. The structural composition of compact fibre bundles with thick walls provides also a protection against mechanical wounding.

As consequences for processing hinders the compact structure the loss of moisture during drying of culms, as well later the penetration of any preservative liquid for protection against bio-deterioration. A surface decoration of culms by lacquer or varnish could be hindered by a siliceous-waxy layer on the epidermis, which may be removed by alkali pre-treatment.

At the inner side towards the central cavity, the lacuna, layers of parenchyma cells form a special tissue. These are often heavily thickened, may contain sclereids and exhibit distinct differences between species. A recently developed Vertical-Soak-Diffusion (VSD)-treatment by filling the inner space of fresh standing culms with preservative depends on the diffusion through this layer into the culm wall, so that structural obstacles can influence the preservative effect (EBF 2003).

3.2.2 Types of vascular bundles.

The vascular bundles consist of the two metaxylem vessels and the metaphloem (sieve tubes with companion cells). They are the obvious components on a cross section and the most varied structures within a culm. This is mainly due to the agglomerated fibres, which are attached as fibre sheaths or as additional fibre bundles. Their form and shape is genetically determined, whereby six types with 8 subtypes can be distinguished (Liese & Grosser 2000). Leptomorph species with individual culms, like Phyllostachys edulis, have four surrounding fibre sheaths, whereas the tall pachymorph species growing as a clump like the genera Bambusa and Dendrocalamus present isolated fibre bundles additionally (Figure 2). Apart from this diversification the large culms of the pachymorph genus Guadua show extensively formed fibre sheaths. The amount of fibres, as sheaths or additional bundles, is closely related to the specific gravity, which increases within the culm from base to top and influence consequently the strength properties.

Since no ray cells exist as in wood, the arrangement of the vascular bundles results in a higher radial shrinkage than tangential. Shrinkage starts both in wall thickness and diameter as soon as its looses moisture, unlike wood. This is due to the high amount of parenchyma cells, which loose their moisture first.

The typology of the vascular bundles influence also the visual appearance of bamboo products, like furniture and parquet.

Chopsticks are mainly made from leptomorph genera, like Phyllostachys , with only fibre sheaths.

Figure 2 The composition of vascular bundles determines its appearance.

Left: Phyllostachs spec., middle: Guadua spec., right: Dendrocalamus spec.

3.2.3 Metaxylem vessels.

The metaxylem consists of two large vessels and provides the water transport within the culm (Figure 1). They are considerable bigger at the inner culm part and smaller towards the outside. Their volume amounts to only about 6-8% of the total tissue. Consequently its easy conductivity is vital for the transpiration of the culms leafs, as well later for any axial treatment of the culm, like by the sap-replacement process. Properly applied the easiness of the water conductivity provides the best treatment result (Liese and Kumar 2003).

3.2.4 Fibres.

Fibres are present as sheaths and also as isolated strands at the vascular bundles. They amount to about 40% of the culm mass and 60-70% of its weight. Their length follows a definite pattern across the culm wall and along its heigth. It varies considerable between species, between 1.5 and 3.5 in the average, being much longer than those of hardwoods. Content and length influence specific gravity (0.5 to 0.9 g cm²) and strength properties as well as pulping. Fibre length is strongly correlated to fibre diameter, cell wall thickness, as well as to the modulus of elasticity and to compression strength. The outer part of the culm with its denser arrangement of fibres has a far higher specific gravity than the inner, more parenchymatous part. In Vietnam, species with fibers up to 4 mm, like Neohouzeaua dulloa, are preferred for mats and weaving lady’s hats.

The fibre wall is made up by numerous layers with a varied orientation of their microfibrils, especially at the outer part (Figure 3). This microstructure contributes to the great flexibility of fibres and culms. It also influences the fractured appearance of culms after breaking.

Bamboo fibres are increasingly used as matrix material, either for strengthening their properties or for filling. The behaviour of bamboo fibres being separated depends much on the species and specific defibration parameters. The fibre of the bundles are easier separated, but become twined with an unequal distribution during mat formation. Raw material preparation and fibre defibration were difficult working procedures during producing bamboo MDF (Xu et al. 2001).

Figure 3 left: Cross section of a fibre wall with alternating broad and small lamellae,

Right: Surface view on lamellae with different orientation of their microfibrills Phyllostachys edulis

3.2.5 Parenchyma.

The parenchyma cells form the ground tissue, in which the vascular bundles are embedded. They contribute to the stabilility and also flexibility of the bamboo culm. The pits on their tangential wall ease a radial diffusion of liquids, like preservatives. Parenchyma cells are vital for the storage and mobilization of the culm’s energy. Starch particles closely stacked fill the cell lumina and are mobilized before shoot production (Figure 4). As starch is the main attractant for beetles and also blue-stain fungi the changing content during the season helps to reduce the culms liability for infections. Nevertheless, Bambusa vulgaris is much preferred by beetles because of its general high content.

For later processing starch retards the setting reaction in cement-bonded particleboards, so that soaking or chemical additives should reduce the sugar content below 0.5% (Chew et al. 1992). Bamboo fibres suspension is also applied for stabilization of cement tubes.

Parenchyma cells contain also silica, which affects cutting and pulping properties. It is mostly located at the cortex and species dependent, so that the ones with a low content are preferred for furniture.

Figure 4 Starch particles filling the parenchyma cells, Phyllostachys viridiglaucescens

3.3 Structures of a node

At the nodes the parallel cell structures of the internode become diverted with intensive interconnections among the vessels as well as the sieve tubes to insure a horizontal distribution through the partition wall, the diaphragm. The fibres are shortest at the nodal region, so that young culms break easily at this level. Nodes have a great influence on the culm’s mechanical strength due to their higher specific gravity, a lower volume shrinkage and lower tensile strength because of shorter fibres and distorted vascular bundles. Nodes have lower holocellulose content, but more extractives, pentosans, lignin and ash than the internodal portion. Nodes produce pulp of lower strength quality, but can hardly be excluded.

3.4 The rhizome

The rhizome is one piece of the modified branch of a bamboo plant. It serves for the uptake, transport and storage of nutrients as well as for the vegetativ production by forming the new shoots at their nodes. Leptomorph species show in contrast to their rather uniform culm structure distinct anatomical differences. Parenchyma and conducting tissue for storage and transport increase considerably on the expense of fibres, amounting to around 20% only. Remarkable is the presence of large air canals in the cortex of several species, like Phyllostachys heteroclada, nidularia and stimulosa (Figure 5) This structural speciality indicates its growth in an aquatic environment for soil establishment. (Ding et al. 1993).

3.5 Structural changes during life time

During life time the culms undergo an ageing process, specially during its maturation period of 3-4 years, but also still later (Liese & Weiner 1997, Murphy & Alvin 1997). This process changes certain structures and consequently properties and utilization. Fibres and also parenchyma cells exhibit a thickening of their cell walls by deposition of additional lamellae on the existing wall layers with subsequent lignification

(Figure 6). The wall thickening is expressed by an increase of density and strength properties.

Figure 5 Cortex with large air canals, Phyllostachys heteroclada

Figure 6 Fibres of a 1-year (left) and a 12-year-(right) old culm, Phyllostachys viridiglaucescens

Younger, immature culms with a lower lignin content can be more easyly split. They are preferred for handicraft work. The lower lignin content is also beneficial for pulping. However the harvest of young culms is detrimental for the vitality of the stand, since they have to produce and store the energy for the growth of the next year’s generation.

Senescens of a culm-after around 10 years- affects the functional efficiency, but not the technological properties. This natural ageing occurs as blocking-off the water-conducting vessels by tylosis and slime-like substances and the “sugar” transporting sieve tubes by callose occlusions and tylosoids. The functional inefficiency results in the dying of an individual culm within a clump or grove.

Quite contrary appear the structural consequences for a dying culm after flowering. The tissue structure becomes brittle and the whole culm often bends down and breaks. Since this phenomenon is not associated with any bio-degradation, it must result from biochemical changes affecting the lignin-cellulose complex. In spite of the great impact for the utilization of the masses of dying culms, the processes are not yet fully understood.

Site conditions influence more the morphological characters then anatomical parameters, which appear as rather stable (Abd. Latif and Liese 2001). A higher fibre content, resulting in higher density and increased strength properties may occur in drier areas and on slopes.

Fertilization affects shoot production, but apparently not the anatomical composition and hence not the main technological properties.

The wounding of a living culm, either by borers or mechanically, produces structural defence reactions to protect the water conducting system against air blockage. The vessels will be filled up by slime and tyloses, produced by the surrounding parenchyma cells. Culm utilization will be ornamentally affected by a local discolouring of its surface and by a reduced permeability of the vessels for their drying and also for the entry of preservative solutions.

3. CONCUSIONS

Research on utilization aspects is presently more properties then products oriented. It has to be intensified to recognize the prospects and limitations of the various species and to utilize their potentials in the best way. Notable is a “Bamboo Products Matrix” being developed by one working group of the ongoing EC funded Bamboo Thematic Network. In a cooperation of institutions and industrial partners from Europe and Asia it (i) combines the existing knowledge of bamboo properties and qualities with end uses of the material, (ii)focuses on applications for both rural and large scale industries in developing countries, and (iii) aims to provide means of identifying linkages of specific end uses and possible future applications of bamboo biomass. Special attention is paid to bamboo panels, boards and composite materials (BTN 2002).

REFERENCES

Abd. Latif M. and W Liese. 2001. Anatomical Features of Bambusa vulgaris and Gigantochloa scortechinii from four harvesting sites in Peninsular Malaysia. Journal Tropical Forest Products 7, 10-28.

Abd. Latif M. and W. Liese. 2002.Variability in culm characteristics of two bamboo species with age, height and site. In: Bamboo for Sustainable Development. Proc. V International Bamboo Conference Eds. A. Kumar, I. V. Ramanuja Rao, Ch. Sastry. VSP and INBAR, 257-268.

Abd. Latif M. and Mohd. Z. Jusuh 1992. Culm characteristics of Bambusa blumeana and Gigantochloa scortechinii and its effects on physical and mechanical properties. In: Bamboo and its Use,. Ed. S. Zhu, W. Li, X. Zhang. ITTO, CAF, Beijing, 118-128.

BTN: Bamboo Thematic Network. 2002. A project funded by the European Commission and coordinated by Oprins Plant NV, Belgium< www.bamboonetwork.org>

L. T. Chew, S. Rahim and K. Jamaludin. 1992. Bambusa vulgaris for urea and cement-bonded particle board manufacture. Journal Tropical Forest Science, 4, 249-265.

Environmental Bamboo Foundation (EBF). 2003. Vertical Soak Diffusion for Bamboo Preservation. Ed. Linda Garland, Ubub, Bali, 26 pp., <www.bamboocentral.org>

Z.B. Espiloy. 1992. Properties affecting bamboo utilization. In: Bamboo and its Use, Ed. S. Zhu, W. Li, X. Zhang, Z. Wang. ITTO, CAF, Beijing, 139-142.

W. Liese. 1992. The structure of bamboo in relation to its properties and utilization. In: Bamboo and its Use, Ed. S. Zhu, W. Li, X. Zhang, Z. Wang. ITTO, CAF, 1992, 95-100.

W. Liese. 1998. The anatomy of bamboo culms. INBAR Techn. Rep., No. 18, 204 pp.

W. Liese and D. Grosser. 2000. An expanded Typology for the Vascular Bundles of Bamboo Culms. Proc. Bamboo 2000 Intern. Symposium, Chiangmai, Thailand. Eds. L. Puangchit, B. Thaiutsa, T. Songkram, 121-134.

W. Liese and S. Kumar. 2003. Bamboo Preservation Compendium. INBAR Tech. Rep., No. 22, 224 pp.

W. Liese and G. Weiner. 1997. Modifications of bamboo culm structures due to ageing and wounding. In G. Chapman, ed. The Bamboos, Linnean Society, London, UK. 313-322

R.J. Murphy and K.L. Alvin. 1997. Fibre maturation in bamboos. In G. Chapman, ed. The Bamboos, Linean Society, London, UK, 293-303.

Y. Xu, Y. Zhang, and W. Wang. 2001. Study on the manufacturing technology on medium density fiberboard from bamboo. Symposium on Utilization of Agricultural and Forestry Residues. Nanjing, China, 117-123.

Characteristic and Prospects of Processing Approaches for Bamboo Resources

Zhang Qisheng

Academician of Chinese Academy of Engineering

President of Zhejing Forest College

Professor of Nanjing Forestry University

Nanjing Forestry University, Xinzhuang No.9, Longpan Road, Nanjing 210037, P. R. China. Phone: +86-25-5427133/5428901. Fax: +86-25-5421325. E-mail: zhang-qs@jlongline.com

1. Processing characteristics of bamboo resource

Bamboo plants are in the subfamily of Bambusoideae, family of Gramineae. Both Bambusoideae and Gramisoideae are under the family of Gramineae. The differences are as follows: Plants of Bambusoideae are perennial with high-developed woody and hard stems. Members of Graminsoideae are herbs with herbaceous stems and most of them are annual. ~~Contained in t~~The stems of Graminsoideae plants ~~are~~ have higher cellulose and lower lignin content such as straw with 35% to 36% cellulose and 9% to 15% lignin. On the other hand, the characteristic of Bambusoideae plants is that the content of both cellulose and lignin is higher than that of Graminsoideae ones. Fore example, bamboo stems include 40% to 60% cellulose and 16% to 34% lignin. Consequently, it is said that bamboo is similar to wood but not wood, and similar to herbage but not herbage. Bamboo is very woody, but its morphology is similar to Gramisoideae plant with the features of cylinder – formed stem with nodes, coating wax and silicon on the surface of stem, which is not being wetted with adhesive. Because of the special structure of bamboo, the processing and utilization methods for bamboo plants have ~~themselves~~ their own characteristics that are different with woody plants. They are as follows: (1) Bamboo stems are small in diameter, hollow inside, thin in wall, large in taper, and different in component between inner, middle and outer layers. The diameter of most of Phyllostachys pubescens, which is larger in diameter among bamboo plants, ranges from 70 mm to 100 mm with average wall thickness less than 10 mm. A few of bamboo species are small in diameter ranging from 30 mm to 50 mm with mean wall thickness 4 –6 mm. So most of wood working machinery and technologies can’t be indiscriminately applied in bamboo processing. As a result, the technologies used in bamboo processing get largely behind wood industry. (2) Most of bamboo products can be manufactured with machines, but a few procedures or products can’t avoid of handwork, and ~~say nothing~~ not mension of continuous or automatic production. Consequently, the production rate of bamboo industry is ~~less~~ several times even ten times less than that of wood industry. (3) Because the outer skin and inner players of a bamboo culm can’t be wetted by adhesive, the very portion that can be used is mainly the middle portion of bamboo wall. So the utilization percent of bamboo is much lower, ranging from 20% to 50% of volume or weight. (4) Bamboo is difficult to be dealt like wood, which can be manufactured into boards or blocks of large size. It is usually machined into strips of 20 mm to 30 mm wide by 5 mm to 8 mm thick that can’t be used directly. (5) The difference, not only in structure but also in chemical composition, between bamboo and wood is obvious ~~for~~ because bamboo contains much more nutrition substances such as hemicellulose, starch, protein, sugar etc. As a result, bamboo products have lower resistance against insects and fungi. The properties against insects and fungi of a product should be strengthened if it will be used in outdoor circumstance.

Because of above characteristics, bamboo processing couldn’t imitate wood working methods. Some of products can be made of wood but can’t be ~~composed of~~ produced by bamboo because of the troubles caused by technique or economy. For example, wood can be sawed into block or board but bamboo can’t because of its special structure. Moreover, wood can be easily manufactured into 3 layers or multi-layered plywood via peeling, but bamboo is difficult both in technology and economy. If bamboo and wood plywood are in the same use, the peeled bamboo plywood is not feasible on the economic opinion though it seems to be feasible in technology. Consequently, bamboo utilization should be based on understanding its structure, properties, and processing characteristics.

2. Prospect of bamboo utilization approaches

China has tremendous bamboo resource. It is the number one both in bamboo forest area and in bamboo productivity. Last twenty years, the bamboo processing industry has been quickly developed because of the market demand to wood, which priced over international market for a long time, caused by the social and economical development, and the support and help from governments. At present, there are thousands bamboo processing enterprises in China with bamboo based panel and bamboo flooring productivity more than 100 million cube meters, and product value tens billions RNB. But most of enterprises are in small scale with behindhand equipment. Though some of bamboo products are reasonable and scientific in structure, which is called “ exceeding wood”, most of them belong to “labor-dense” ones without scientific innovation and to low value-added ones. Bamboo processing industry was developed during 1950’ in Japan and 1960’ in Taiwan, China. Since then it waned because of increasing labor cost. Along with the development in society and economy and the progress of economic combination around the world, the competing predominance of “labor- dense” products is coming down gradually. Consequently, we should think of bamboo utilization approach strategically. How to survive and develop in violent market competition is an important theme that bamboo industry has to face. In my opinion, the bamboo utilization approaches should be focus on the following:

2.1 These bamboo articles for daily use should be reserved and developed that can richly utilize local bamboo species, have enormous market potential, adapt to the shift of consumer’s opinions, and have local particular features.

Bamboo articles for daily use, which suit the people who advocate and return nature, are composed of the bamboo culms of various diameters by means of a series of procedures such as sawing, splitting, planning, sanding, sculpting, weaving, and painting etc. Making and using bamboo articles have long history in China, but these products are still vigorous because of the progress of technology, consuming opinion change, and new products continuous emergence. Bamboo articles for daily use include chopstick, slip and toothpick, skeleton of joss stick, mat, cage, weaving articles, dead stocks, sculpt handicraft, fence, canopy, indoor decorate boards, furniture etc.

In many bamboo production areas, people took advantage of local bamboo species to make bamboo products with particular feature in a large scale, which won reputation home and abroad with themselves brands. These places where bamboo articles are outstanding are as flows: Anji county, Zhejiang Province is called “hometown of bamboo mats”, and the mats is made of Phyllostachys pubescens; Shuichang and Quxian Counties, Zhejiang Province are named “ hometown of bamboo charcoal” that is made of Phyllostachys pubescens, Chengxian and Xinchang Counties, Zhejiang Province are known well as “ hometown of bamboo weaving” that is composed of Phyllostachys pubescens: Xinyi County, Guangdong Province is also called “hometown of bamboo weaving”, but the species is Lignnania chungii; Linan and Deqing Counties, Zhejiang Province are named “ hometown of bamboo shoot” that make use of Phyllostachys praecox and P. primatina ; Longmen County, Guangdong Province is famous as the name “ hometown of bamboo toothpick”, and the local species is Lignnania chungii; Guangning County, Guangdong Province is called “ hometown of skeleton of joss stick” and the local species is bambusa textiles. We hope there are more particular feature bamboo products in future. The bamboo articles market home and abroad. Setting up a plant needs less investment for simple machinery and the scale of the plant might be large or small. Though the selling price of bamboo articles is not high, the big productivity can bring good profit. So there are 38 plants producing bamboo articles with larger scale underling Zhejiang Bamboo Industry Association and hundreds in small scale. A few of new and particular feature products should be continually exploited in the production of bamboo articles in future.

2.2 Bamboo based panel industry should continually improve technique and exploit new products and avoid by all means to set up new plants blindly and subsequently to decline prices each other.

Three series of bamboo based panel products, e.g. platform floor for truck and bus, concrete forming, and laminated board or flooring, are successfully used as structural and ornamental materials for many years. They pioneered the industrial utilization of bamboo but isn’t only approach for bamboo. Based on existing products, it should be developed in a great deal the end products of laminated bamboo timber and flooring by utilizing large diameter bamboo resource. Moreover, the light and strong composite structure materials and decorative panels should be intensely exploited in future. Each plant must think of special conceptive products that will be potential in market. In the other word, every plant go itself way not be all through a narrow bridge. Only in this way can the bamboo based panel market be increasingly broadened.

2.3 Paying greatly attention to bamboo chemical utilization to exploit the application technologies of bamboo charcoal and vinegar

Researching bamboo charcoal and vinegar emerges last a few years. Preliminary research demonstrated that bamboo charcoal has strong capacity to adsorb harmful gas, to purify water and air, and to adjust indoor air humidity because of its large specific surface area. Bamboo charcoal contains a lot of microelements such as calcium, magnesium, aluminum, and kalium, etc., which can increase the microelements in water, lessen the water molecule to make it easy to be absorbed by human when bamboo charcoal is boiled in water for a certain time. Furthermore, bamboo charcoal made in higher temperature conducts electron well and can emit infrared ray. These properties can be used in health care and antistatic-electron fields. Above properties of bamboo charcoal are been studied home and abroad. Batch of products making use of these properties have exported to Japan, South Korea. They sell well in domestic market. Moreover, the bamboo briquette charcoal, which is made up from bamboo processing residue, is used to barbeque and has good market potential. The bamboo charcoal has very broad application prospect in killing-bacteria, decomposing harmful gas, and dealing with sewage etc after it is altered properties. Bamboo vinegar is a kind liquid with light brown color gotten by condensing smoke during pyrolyzing bamboo. It contains many chemical components and organic active substances and has broad prospect using many fields such as pesticide, medicine, health care, and sanitation etc. At present, we should fasten the speed of developing bamboo charcoal and vinegar to promote them into people’ daily activities for prolonging human being’ life span and improving indoor surrounding. Making bamboo charcoal and vinegar can realize the purpose of “full bamboo culm” utilization because it utilizes not only large or small culms but also processing residue.

Bamboo fiber for textile is a new product that was developed last year and is also a new innovation in bamboo utilization. It is made up from fresh bamboo that is immerged in a sort of special extraction liquid and then softened under high temperature. Textile can be greatly improved by blending this bamboo fiber with hemp fiber, silk, wool etc. So experts called this kind fiber a new spinning material with our own intellective property right besides soy protein fiber in China. It will benefit people in both society and economy.

There are more mysteries in bamboo development that need to be explored, especially in bamboo chemical utilization.

2.4 Highlighting on the research and exploit on precise and deep processing of bamboo

It is very important to exploit the value-added products requiring precise and deep processing technology and the our own intellective property right ones based on existing bamboo products in which most of them are labor-dense products not needing complicated techniques. Besides bamboo weaving products, bamboo flooring is one of highest value-added products because it needs exact match in color, precise processing, and refine painting in manufacturing. At present, the bamboo planned laminal sheets and rotary laminal veneer prolonged with tooth joint are been exploiting. They can form new decorate material by coasting them on the surfaces of panels or woody furniture. Of course, the producing technique is relative complicated and precise. Because of enormous market potential, they are worth developing.

2.5 Developing bamboo pulp and paper

Wood pulp consumed in our nation depends upon import for a long time because of insufficient forest resource. Pulp and paper making technology progressing recently, there is no obstacle technologically to take advantage of bamboo for papermaking. Especially, sympodial bamboo, which is planted on a large scale in southern China of Yunan, Hainan, and Guanxi provinces, is the good raw material for paper making because of big biomass, which is 7 to 10 time bigger than that of Phyllostachys pubescens, and high fiber content. The efficiency is no difference between bamboo and wood papermaking, but the sympodial bamboo cost is lower than that of wood. Consequently, it will benefit both nation and people to develop sympodial bamboo on a large scale forming bases and bamboo papermaking.

Promotion of Bamboo for Poverty Alleviation and Economic Development

Prof. Chen Xuhe

Deputy Director General, International Network for Bamboo and Rattan (INBAR), P. O. Box 100102-80, Beijing 100102, P. R. China. Phone: +86-10-64706122. Fax: +86-10-64702166. E-mail: xhchen@inbar.int

1. INTRODUCTION

Bamboo is a fast growing, renewable, wide spread, low cost, environmental enhancing resource with great potential to improve poverty alleviation and economic development. Bamboo forests and plantations are mainly distributed in rural areas. Bamboo industry， largely featured in labor intensive, low to medium investment, and simple in technology and equipment, is making important contribution in providing food, housing and income generation for 2.2 billion people in the world. As the market for environment friendly green bamboo products is growing, it is estimated that the world bamboo market would grow from the present size of US$ 8.5 billion to over US $ 20 billion by 2015.

2. BAMBOO DEVELOPMENT IN CHINA

China has long history in cultivation and utilization of bamboo, also been one of the major innovators of new bamboo products. In the past 20 years, bamboo resources in China increased at an annual rate of 1.8%, the total area of bamboo forests expanded from 3.67million ha in 1980 to 5 million ha at present, and bamboo industry is playing more and more important role in poverty alleviation and economic development.

At present there are about 3,000 companies around the country engaged in the production of various bamboo based panels, bamboo flooring, bamboo pulping, bamboo charcoal, edible bamboo shoots, and other daily use articles.

In 2002 the production of bamboo based panels was over one million m³, bamboo flooring 10 million m², bamboo shoots canned products 250,000tons.

Bamboo based panels are used for building floors, walls, ceilings, and interior decoration of houses and platforms for lorry and train carriages. Thin bamboo panels made by DASSO have been used for ceiling at Madrid International Airport Terminal in Spain.

Bamboo has been made into paper for hundreds of years. More recently paper mills have begun to make laser-printer and photo-copier standard paper out of bamboo. INBAR uses such paper for routine purposes and considers that it should have a bright future in western markets provided environmental standards are adhered to.

At present, China produces bamboo pulp about 200,000tons and imports pulp and paper valued 5 billion USD annually. Three big bamboo pulp and paper projects (one each in Shichun, Guangxi and Guizhou) were launched in recent years, with total new capacity of 520,000tons.

3. INBAR/WWF -SUSTAINABLE BUIDLING PROJECT

Bamboo has been used as a housing material for millennia. In Bangladesh for example the majority of the population live in bamboo houses. INBAR has had a continuing program in improving the quality of housing for all levels of society although it takes a particular interest in housing for the poor. INBAR is working with an Ecuadorian NGO “Hogar de Cristo” in developing an extremely cheap bamboo house for the poor , only $10/m² of floor area with total cost of $380 per house, and attempting to transfer the technology for hosing to India and China.

INBAR formed a partnership with WWF-China in March 2002 to see if the team of Dutch architects who had been involved in the design of energy-efficient houses in Holland could achieve the same results in China. The key concept of this project is to link energy savings technologies and the use of bamboo /bamboo panels as part of the building materials. Four concept designs have been completed: Dai Village House, Mengzi Town House, Jinghong Hotel and Pingbian School.

The Embassy of Japan in China has made a direct payment of 620,000RMB to the Pingbian Education Bureau to construct the Pingbian School. Main construction of the buildings will be concrete floors and concrete columns but bamboo beams will be used for roof trusses and bamboo panels for walls of the building. The construction of the school building will be completed by February 2004.

3. INBAR’s new efforts to assist bamboo development in eastern African countries

Co-funded by the Common Fund for Commodities (CFC), INBAR and the Forest Resources Research Institute of Uganda, a Regional Workshop on Market based development with bamboo in Eastern Africa was held in Kampala, Uganda, July 2003. Participants of universities/research institutions/NGO from the four countries and representatives from CFC, FAO attended. Representative of Minister of Environment of Uganda and Mr. Philips, Uganda Ambassador to China presented the Opening of the Workshop.

Actionable recommendations were made on developing production and markets for bamboo products to improve livelihoods in Eastern African countries including Uganda, Ethiopia, Tanzania and Kenya. Draft CFC/INBAR Project proposal “Market based development with bamboo in Eastern Africa ” was prepared.

Invited by Ministry of Agriculture of Ethiopia, INBAR expert team visited Ethiopia in July 2003 to make field trips of typical bamboo resources and discuss with relevant officers on utilization of these bamboo resources and identify cooperation areas with INBAR. The team met with Chinese Ambassador, Vice Agriculture Minister, Mayor of Addis Ababa, Vice Minister of Industry and Trade, President of Ethiopia Chamber of Commence, Investment Authority. The Team made a field trip to three regions(Beni Shangul,Gambela, Southern) covering 3000kms visited lowlands bamboo forests & highland bamboo forests, Bamboo Handicraft Training Centers, enterprises, Regional Bureau of Agriculture , Wondo Forestry College, Ethiopia Agricultural Research Organization, Tourist Trading Enterprise, etc. It has found that Bamboo is very important to Ethiopia. In the country the high forest coverage is only 2.7%, and still decreasing but bamboo resources is rich, possessing 67% of that of Africa, development of industrial utilization of bamboo would help to solve problems of housing and furniture shortage and provide more jobs opportunities.

There are two indigenous species of bamboo in Ethiopia i.e. the highland or African alpine bamboo (Arundinaria alpina K. Schumach.) and a monotypic genus, lowland bamboo (Oxytenanthera abyssinica (A. Rich.) Munro.

The highland bamboo. Total area: 30,000ha, in attitude 2200-3500m at temperature 10-20⁰C with annual rain fall 1500-2500mm; 12-20m tall, 5-13cm diameter, internodes 30cm, wall 5-16mm thick with density (OD) 0.48g/cm³, mature stand 5870culms/ha, average biomass of the culms amounts to 51.3 tons/ha, annual increment 1000 new culms, yielding 8.6tons/ha. Current uses: furniture, construction, fencing, and handicrafts.

The lowland bamboo. Total area: 800,000ha; distributed in attitude 700-1800m with annual fall more than 1500mm. Culms 6-16m tall, 6-10cm diameter, internodes 20cm, wall density 0.61g/cm³. Per ha 8000 living culms plus 4000dead culms, average biomass of culms amounts to 70.3 tons/ha. The mean annual increment of oven dry culms is 10.1tons/ha. Current uses: construction, fencing, and furniture.

It may be important for Ethiopia:

-- To give priority to bamboo development in both national level and international cooperation, including bilateral cooperation with the China

-- To set up National Bamboo Development Office under Ministry of Agriculture for Coordinating R & D in bamboo to improve networking in bamboo sector and Preparing sustainable bamboo development plan at national level

The following suggestions were also made for consideration by Ethiopia authorities:

a）to develop Bamboo mat corrugated board. At present, Iron corrugated sheet is used as the major roof materials. It needs imports and is poor in heat and sound insulation properties. Bamboo mat corrugated board can be made from Ethiopia bamboo and would be better in heat and sound insulation properties and more cost effective. Comparing with iron sheet board ,plastic composite board and asbestos board, the bamboo mat corrugated board has the best heat and good sound isolation properties, the lowest density， but high water absorption rate.

b) Sustainable management of bamboo forests in Ethiopia.

c) Introduction of exotic and economic important bamboo specie to Ethiopia for bamboo production security, as there are only two indigenous species of bamboo in Ethiopia.

d) Establishment of a demonstration bamboo base near Addis Ababa.

It is our wish that from the common efforts including the said CFC/ INBAR project, big progress can be made in the promotion of bamboo for poverty alleviation and Economic Development in eastern African countries.

Technical Innovations to Increase the

Competitive Capability of Bamboo Products

Jiang Changzheng

President of Shengda Wooden Products Co., 27th Floor, Gangdian Shibaida International Mansion, Chengdu, Sichuan Province 610016, P. R. China. Phone: +86-28 67888818. Fax: +86-28 6746269. http://www.shengdawood.com

Dr. Yu Gang

Director of Shengda R&D Center

Abstracts: Deep processing and developing of bamboo have become a new economic growth point of Chinese forestry. Shengda is a professional company producing bamboo and wood floorings. R&D on bamboo flooring to increase the key competitive capability of bamboo products are conformed to our long-term developing strategy. The latest R&D of Shengda on bamboo products was discussed in this article.

Key words: bamboo, bamboo fiber, re-combined bamboo, bamboo flooring, antimicrobial, fiber reinforced plastics

1. FORWARD

Bamboo forest is the second forest in the world. China has an abundant source of bamboo which consists more than 80% of the total bamboo forest in the world. Along with the adjustment of Chinese forest policy, the execution of prohibition for cutting natural forest and returning cultivated land to forest (or grassland), the deep manufacturing and developing of bamboo have become a new economic growth point in Chinese forestry. Shengda is a professional company producing bamboo and wood floorings. As the execution of “integration of forest and board” project and successful construction of Shanghai bamboo products factory, R&D on bamboo flooring to increase the key competitive capability of bamboo products are now conformed to our long-term developing strategy.

Based on mention-above, this article will discuss and forecast the latest R&D on bamboo products in our company.

2. ANTIMICROBIAL BAMBOO FLOORING

At present, most of the decorative materials function in making beautiful and comfortable livings for people. However, some of them give out organic gases or radiation emissions, which do harms to people’s health. The sustainable development, which emphasizes the harmony between life and environment, has become the focus of society today. People are requiring higher quality for the interior environment after decoration. Beautiful looking, safe and reliability, health and care are all within customers’ concerns.

However, there are various microbes, including bacteria, fungi (mildews, microzymes and agarics) and algae etc. in natural environment. They are hardly seen by naked eyes, but they are the very important components of the natural livings. Some microbes play significant roles in keeping circulation of elements such as carbon, oxygen and nitrogen in the natural world. On the contrary, some microbes are the pathogenic microbes of human, animals and plants, can bring about a great threat against health of human beings. Consequently, to inhibit harmful microbes from growing and propagating or kill them is a very important problem to be paid attention in scientific field as well as common people.

Unfortunately, while people are busy building a comfortable living space with warm in winter and cool in summer, however that also offers advantageous conditions for microbes to grow and propagate simultaneously, due to bamboo is the natural host for some parasites. Usually bamboo’s growth age is 4-6 years (shorter than wood), and have plenty of live thin-wall cell and cell solutes, so the distillates of bamboo(mostly are starch, balata, amino acid, fatty acid，water-dissolvable color matter, inorganic salt and so on, which consists about 5-10% of the dry material’s weight) is much more than that of wood (about 1.5-2 times of wood ), which can supply abundant nutrition for aphids, mildews and spores of fungi to grow and propagate (the most common fungi in bamboo are aspergillus, penicillium and cladosporium). In addition, because bamboo is lack of phenolic compounds, so its natural antimicrobial capability is not as good as wood, especially for those new cut or half dry bamboo, and bamboo products using in moist environment, which are easy to be moth-eaten, mildewed and corrupted. So that, the performances of bamboo and its products will go bad (Being moth-eaten and corrupting cause decrease of physical strength or even make the products useless; mildewing, which causes the stain on the surface, will strongly affect the external appearance).

As for bamboo flooring, since our country located in subtropical zone with warm and rainy climate at most of the areas, especially have continual high temperature and moist days in summer or season of plum rains, during the process of bamboo’s hag, transportation, manufacturing and using, it is very likely for bamboo to be moth-eaten, mildewed and corrupted. This is an important factor that restricts the development of bamboo flooring industry.

On the other hand, people frequently contact with the floorings in daily life, harmful microbes could be easily bred and spread on flooring, and thus threaten the health of people.

The property to inhibit microbe from growing and propagating is called microbe-inhibition, to kill the microbe or close the state of microbe free is called microbe-killing. The property, which has the characters of microbe-inhibition and/or microbe-killing is defined as microbe-resistance, which means bacteria-resistance and fungi-resistance, the latter can also be named mildewproof. Microbe-resistance is different from sterilization; the latter means can kill all of microbes absolutely.

Nowadays the bamboo flooring prevails in international market does not have the function of microbe-resistance. Although the high temperature carbonization can kill the insect and improve the protection of bamboo material, this method still can not eradicate the fungi and can deepen the natural color of bamboo. In fact, mildewing phenomenon is also found in bamboo flooring treated with high temperature carbonization (the mildew grows from the interior of bamboo strip to its surface, it can clearly be seen through the transparent paint coated on the surface of bamboo flooring), which will greatly affect the external appearance of bamboo products.

Considering the deficiency of technology and application in bamboo flooring industry of China, we use nanotechnology to explore the antimicrobial bamboo flooring based on our successful experience in antimicrobial laminated flooring.

We aim three aspects:

1) To prevent the performances of bamboo flooring become bad caused by moth-eating, mildewing and fungi-eroding;

2) To inhibit and/or even kill harmful bacteria on flooring surface, keep safe and healthy life surroundings;

3) To supply various products of good quality for our company－USP, unique sales point.

Comparing with traditional physical and chemical treatment methods, nano- antimicrobial-technology is high effective, broad-spectrum, long-term and safe, can also avoid the color change of bamboo and negative effect to human and environment.

3. HIGH PERFORMANCES BAMBOO FIBER REINFORCED PLASTICS (FRP)

It is well known that the composites of glass fiber reinforced plastics are widely used in various fields of national economy. From the point of environmental harmonicity view, using natural resources to develop FRP which is beneficial for environment has become the focus in R&D field of composites.

Our country has a long history of using bamboo as building materials. Among the natural fiber materials, bamboo is one resource with very high productive rate. The tensile strength of bamboo fiber is slight less than glass fiber, but the strength ratio and modulus ratio of bamboo fiber could be the same as or even over the glass fiber. Thus, we could name the fiber separated from bamboo as “natural glass fiber”, and use it to product high quality floorings with environment friendly.

The manufacturing processing of bamboo FRP is as following:

In the production of bamboo FPR, the processing of surface treatment or interface design plays a very important role. According to the forms of bamboo fibers (the ratios of length to diameter) and the types of resins (thermosetting adhesives, thermoplasts), the molding methods including molding press, extrusion and injection could be used. It should be noticed that as a special natural material with fine structure, bamboo fiber contains plenty of water inside, special molding technology should be used, especially the rheological property of bamboo FRP should be tested.

The flooring or decorative board made from bamboo FRP can still maintain the natural texture of bamboo. Meanwhile, since the tiny hole structure of bamboo fiber, the properties of impact resistance and sound absorption are outstanding. In addition, due to the bamboo fiber can be modified with various physic and chemical methods conveniently, some new functions (microbe-resistant, waterproof, size stable, abrasion resistant, fireproof, heat conductive, etc.) could be added on common bamboo flooring. Therefore, the windows of design and manufacture for bamboo products could be expanded.

4. RE-COMBINED BABMBOO

Re-combined bamboo timber is a new type of bamboo material, made with re-combined fasciculi of inferior bamboo materials (such as branches and small diameter bamboo) through the processing of applying glue, base assembly and heating press. The fasciculi of bamboo are processed into the forms of continuum in horizontal orientation, incompactness in vertical orientation and cross each other by grinding equipment, so that the re-combined bamboo products have high strength, large scale in size and natural texture structure of bamboo.

What should be pointed is that above processing is based on the precondition of keeping the basic characters of bamboo and no distorting the fiber arranging. By this way, the using rate of bamboo is up to 90%, which is 50 to 70% higher than common bamboo flooring technology. The mechanical properties of re-combined bamboo products are much superior to common bamboo products.

Re-combined bamboo technology is no longer subject to traditional cutting method. Being the excellent character of post-mechanics processing, size and density can be customized to individual demand, it has practical prospect applied on bamboo flooring and bamboo-wood assembled flooring. For example, bamboo flooring made with re-combined bamboo technology is of the advantages of more size stable and no binding gap caused by the combination of bamboo strips. While the veneer made from re-combined bamboo timber can be used as surface decorative material of bamboo-wood assembled flooring.

Technology of pigmentation of bamboo strips by

carbonizing and dyeing treatment

Manhua Xie

Beijing Forestry University, College of Material Science and Technology, Beijing100083, P. R. China. E-mail：xiemanhua77@sohu.com

Guangjie Zhao

Beijing Forestry University, Material Science & Technology College. vice director, Male，Doctor, wood science professor, doctor tutor, phone：01062329685 E-mail：zhaogjws@263.net

Abstract: In order to show the advantage of bamboo acting as decorative material best, it is necessary to settle some problems existing in surface treatment when bamboo act as decorative material, and to seek a kind of environment-protective, nontoxic and new technology of making bamboo to be a sort of excellent decorative material, it which can both avoid mildew and fungus and improve the surface character of bamboo. The paper discussed the surface character of pigmentation bamboo strips by carbonizing and dyeing treatment. The results indicate that the technology of pigmentation of bamboo strips by carbonizing and dyeing treatment is the primary technology of ~~realizing~~ making bamboo products become environmental-friendly, nontoxic first-rate surface decorative material.

Key Words: Bamboo Strips, Carbonization, Dye, Pigmentation Treatment

1. INTRODUCTION

Bamboo is a kind of nicer ecological material. Besides, it can act as a very good decorative material because of its compact structure, warm and smoothly feel and clear grain. However, starch, sugar and protein inside bamboo are all more than wood, and most of fiber tissues array longitudinally, thus bamboo more easily suffers all kinds of mildew. But, the mildew-resistant treatment of bamboo is not solved thoroughly yet, especially the low-poison and long-effect mildew-resistant treatment technology is not still broken through, which will affect greatly the advantage of bamboo acting as a decorative material. Furthermore, fresh bamboo’s color and luster is beautiful and bright, but the luster will lost gradually by a long period and even the color will change too^[1]. Therefore, seeking a kind of environment-protective, nontoxic, both mildew-resistant and fungus-resistant and surface character- improving new technology, which can make bamboo become a sort of high-quality surface decorative material, is extremely important.

The paper performed pigmentation treatment of bamboo strips by carbonizing and dyeing, and discussed the color and surface character of carbonized and dyed bamboo strips

2. EXPERIMENT

2．1 Materials

These experimental specimens were air dry mao bamboo strips peeled off blueness and bleached, which were provided by Cibi city in Hubei province with the original moisture content of 9%. The dimension of the specimens was 110（length）×7（width）×2（thickness）mm or 230（length）×10（width）×3（thickness）mm.

2．2 carbonizing treatment experiment

The air dry specimens were placed directly in constant temperature drier side by side, and then carbonized under different temperature and time.

2．3 dyeing experiment

The specimens were put into dye solutions with different mix ratio and concentration, then were placed in the water boiler with constant temperature. The diverse dyeing effects were mainly obtained by adjusting the ratio of mixture dyes, concentration, temperature and time, etc.

3．RESULTS AND DISCUSSION

3．1 The surface character of carbonized bamboo strips

Figure1 is for untreated bamboo strips, and from figure2 to figure13 are carbonized bamboo strips under different condition. From these figures, we can see that the color of bamboo strips all changed at some extent after carbonizing treatment. Uncarbonized bamboo strips’surface is glabrous and smoothness, and the color and luster is bright and natural. However, generally for carbonized bamboo strips, the color is deep, elegant, simple and unsophisticated, and the clear bamboo grain can still be sawn (figure5,6,7,13). Figure2 and figure4’colors incline to red, and show bright and vivid, so the vision effect is excellent. Figure3 shows orange-yellow, it can show the noble and elegant flavor if as a decorative material. From figure5 to figure8, only the carbonization temperature is different, all the other treatment condition is the same, and yet the surface character show great difference and the color’deep degree is distinct too. And figure6 show deeper color and bigger chromatism(figure14) with higher carbonizing temperature. Figure7 and figure8 have almost the same chromatism(figure14) since their carbonizing temperature is uniform. However, among figure 9(a,b,c,d), the carbonizing conditions are completely uniform,but their surface character also show greater difference. Some color is deeper, some is lighter, and the surface isn’t primely glabrous either and even exist white smear. The former is because of the difference of bamboo strips in

Figure 1 uncarbonized bamboo strips

Figure2 carbonization

Figure3 carbonization

Figure4 carbonization

themselves, such as the difference in color deep due to the age, or the changes in color of bamboo as a result of insect and mildew. The later is owing to no going surface treatment before carbonization. This is because the bamboo strips bleached weren’t cleaned out very well when bleach was finishing, and some bleacher still exist in the surface of bamboo strips. They didn’t show up under air dry until carbonized, since the bleacher do not react in the course of carbonizing. Thereby, the carbonized treatment of bamboo strips is related with the quality and the surface character of bamboo itself. Figure10 and figure11 is with the same carbonization temperature, but different carbonization time. We see that the carbonized color is different. From the chromatism figure14, it can be known that the chromatism of the later is much bigger than the former. So the longer carbonization time is, the bigger the chromatism is, and the deeper the color is. Figure12 and figure13 is of the uniform carbonization time and temperature, only the bamboo strips of figure13 went through surface coating before carbonization. It can be seen that the surface effect is also

31

32

Figure16 Figure17 Figure18

Figure17 (number 31) and figure19(number 33) are of the same dye proportion with number 9 in figure15. Nevertheless, the number 31 bamboo strip has higher dyeing temperature and longer dyeing time than the number 9. Moreover , additive(NaCl) is added to the number 33 bamboo strip during dyeing, but it has a little lower dyeing temperature than the number9, and has the same dyeing time. Figure23 show that the chromatism of the number 31 bamboo strip is bigger than the number 9, and that of the number 33 is bigger than the number 31 again. Figure18(number 32) , figure20(number 34) and the number 10 bamboo strip is another group going simultaneously, it also show the same result(in figure23). So it is obvious that additive has greater influence on dyeing, except for dyeing temperature and dyeing time.

The significance of the processing and use of bamboo, especially the middle, small diameter bamboo, will be greater for the future. For decorative material, it doesn’t need good mechanical capability, the most important is the fine appearance^[2]. The surface quality of bamboo can be improved and all kinds of color can be achived by carbonizing and dyeing treatment. At the same time, the two sorts of technical products all accord with the idea of environmental-friendliness of modern people, namely nontoxic and hurtless to the health of people. So they are good environmental-friendly products. In a word, carbonization and dye is the key technique of making the bamboo products become high grade products.

4．CONCLUSION

（1） The surface character of carbonized bamboo strips is related with carbonizing temperature ~~and~~ time, ~~the~~ surface quality of bamboo strips before carbonization and ~~the~~ age of bamboo. In general, the carbonizing temperature is higher, the time is longer, and then the chromatism is bigger. The older bamboo is , the more deep the carbonized color is if under the same carbonization condition.

（2） The surface character of dyed bamboo strips is related with dye proportion and dyeing technics. The concentration is bigger, temperature is higher, the dyeing time is longer, then the dyed color is ~~more~~ much deeper and the chromatism is bigger.

（3） The surface grain of carbonized bamboo strips is still clear and seeable, smooth and glabrous. Carbonized bamboo strips can better show the feeling of reality than dyed bamboo strips. But for dyed bamboo strips, some inherent surface flaw is concealed, such as the color changes arose by insect and mildew.

References

1． Qisheng Zhang, Fengsheng Sun. The development prospect of bamboo industry in china. China forest products industry, 4(26)3～5,1999.

2． Yonglin Yan. The design of machine for peeling off green of bamboo. Forest machine and wood processing equipment,2(28):16～17,2000.

Bamboo in construction

-Status and potential

Lionel Jayanetti

Head of TRADA International

(The original paper is with about 40 photos).

TRADA International, Stocking Lane, Hughenden Valley, High Wycombe Buckinghamshire HP14 4ND, U.K. Phone: +44-1494 569619 /563091. Fax: +44-1494 565487. E-mail: ljayanetti@trada.co.uk

1. INTRODUCTION

Bamboo is a well established cultural feature of many regions throughout the world. Its diversity and versatility are well documented - some 1250 species and 1500 traditional applications have been identified. Notably, the main users are the rural poor, and perhaps for this reason it has largely been taken for granted by the wider community. As such, bamboo has not received the mainstream recognition it deserves as a material resource.

Bamboo is the fastest growing woody plant on the planet, but it actually belongs to the grass family. Most species produce mature fibre in about 3 years, much faster than any tree species. Some species grow up to one metre a day, with the majority reaching a height of 30 metres or more.

Bamboo has exemplary ‘green’ credentials. It is adaptable to most climatic conditions and soil types, acting as an effective carbon sink and helping to counter the greenhouse effect. It is finding increasing use in land stabilisation, to check erosion and conserve soil. It can be grown quickly and easily – even on degraded land - and harvested sustainably on 3 to 5 year rotation. Bamboo is a truly renewable, environmentally friendly material

The bulk of bamboo is gathered from the wild or rural environment. However, in many areas bamboo resources have dwindled due to overexploitation and poor management, and this issue needs to be addressed through well organised and managed cultivation if bamboo utilisation is to develop on a sustainable basis. Plantations are already being raised in China and India to support the pulp and paper industry.

Plantation technology for large-scale cultivation of bamboo is known - standard practices have been developed with culm cuttings and tissue culture is gaining acceptance. National afforestation programmes can therefore be implemented to meet future demand. Furthermore, improved technologies for raising plantations of bamboo in degraded areas, on logged over forest and in agro-forestry initiatives can be achieved through further research into biodiversity, species selection and genetic improvement.

One billion people live in bamboo houses worldwide. For the most part they are low grade, impermanent buildings, which belies the material properties of bamboo and does little to promote its image as a viable construction material. At little extra cost, these buildings can be upgraded to provide safe, secure and durable shelter, benefiting the most vulnerable members of society.

Perhaps the major factor contributing to the view of bamboo as a temporary material is its lack of natural durability. Bamboo is susceptible to attack by insects and fungi, and its service life may be as low as one year when in ground contact. However, the durability of bamboo can be greatly enhanced by appropriate specification and design, and by the careful use of safe and environmentally friendly preservatives such as boron.

The main structural advantages of bamboo – its strength and light weight - mean that properly constructed bamboo buildings are inherently resistant to wind and earthquake forces. These properties can be effectively exploited through careful yet simple design and detailing.

Even when issues of durability and strength are resolved, the question of acceptability remains. A bamboo building need not look ‘low-cost’, nor need it necessarily look like bamboo! Imaginative design and the use of other locally available materials within the cultural context can make the building desirable rather than just acceptable.

2. BAMBOO – THE INTERNATIONAL VIEW

Bamboo has a long history as a building material. It is widely used in construction throughout the world’s tropical and sub-tropical regions, with a range of applications to match or even exceed those of timber. In Central and South America, bamboo buildings of every description can be found - from low-grade temporary shanties to exclusive, architect designed mansions.

Bamboo houses for the wealthy, Colombia

Bamboo products for use in construction are increasing in availability. These range from bamboo mat boards (flat and corrugated), through more sophisticated panel products such as fibreboard, ‘plyboo’ and flooring, to large laminated sections (currently under development) for use in external joinery.

Corrugated bamboo matboard (IPIRTI, India) and laminated bamboo flooring

Bamboo use is not restricted to building. Bamboo has been used as concrete reinforcement, and development work is continuing in this field. Bamboo is used for light traffic bridges, and the feasibility of constructing large span bridges carrying vehicular traffic has recently been demonstrated in Colombia. Bamboo as scaffolding is well known (40 storey construction is not uncommon in the Far East), and its use is set to increase as a result of the development of a design and erection guide in Hong Kong.

20m footbridge and 52m bamboo road bridge, Colombia

Bamboo scaffolding, Hong Kong

Other construction applications include ground stabilisation, through the use of retaining walls and piling, and coastal protection (recently trialled in Sri Lanka).

Bamboo retaining wall and bamboo-based erosion control system

3. BAMBOO –TRADA’S EXPERIENCE

TRADA has just completed the first phase of a project in India to develop and promote a cost-effective bamboo based building system. The project is designed to provide safe, secure and durable shelter at a cost that is within reach of even the poorest communities in developing countries.

The project has demonstrated that with careful specification, detailing and environment-friendly preservation, the life of bamboo can be extended to match that of other building materials. Prototype testing has been employed to provide an effective and visual demonstration of the performance and strength of components and assemblies, and the resistance of walls and roofs to wind, earthquake and impact forces.

A building system has been developed based around an integrated, resilient bamboo skeleton. Wire ties, bolts and straps ensure the entire framework is positively connected to become a single, composite unit. When cement mortar is applied to the walls, they become very strong but still retain their lightness and resilience. These characteristics make the construction inherently resistant to earthquake forces.

20m² bamboo house

The bamboo building system is sustainable and cost-effective. It is also simple to erect, strong and durable. As such, it incorporates all the essential requirements for affordable shelter. Moreover, the basic system can be enhanced through improved use of shape, space and colour at little or no extra cost. Overall, the system effectively demonstrates that desirability and quality are fully compatible with affordability.

90m² bamboo house

For the second phase, the project will be extended to Bangladesh and Sri Lanka, and the technology will be applied in the development of designs for larger community buildings such as schools and health clinics. In addition, the use of bamboo for the construction of footbridges in rural areas will also be investigated, with development and testing of prototypes.

4. FUTURE POTENTIAL

Taking into account all that bamboo has to offer, it is well placed to address four major global challenges:

4.1 Shelter security, through the provision of safe, secure, durable, affordable housing and community buildings.

4.2 Livelihood security, through generation of employment in planting, primary and secondary processing, construction, furniture and the manufacture of high value-added products.

4.3 Ecological security, by conservation of natural forests through substitution of primary timber species, as an efficient carbon sink, and as an alternative to non-biodegradable and high embodied energy materials such as plastics and metals.

4.4 Sustainable food security through agro-forestry systems, by maintaining the fertility of adjoining agricultural lands, control of erosion and, in the case of bamboo, as a direct food source.

The challenge now is how to share this knowledge – to bring it to the attention of a wider audience and demonstrate that the new technologies are equally viable in areas which have not had exposure to the “new thinking”. Above all, to deliver the benefits it promises to the poorest members of society.

5. FUTURE REQUIREMENTS

5.1 Sustainable supply

A policy of organised planting, careful management of plantations and natural stands, and appropriate regulation of supply are prerequisites to any other interventions aimed at promoting bamboo as a building material.

5.2 Standardisation

The lack of guidance on the use of bamboo in building has been a major obstacle to its wider adoption. A recently drafted international standard is the first step to addressing this problem, and new or amended national regulatory instruments such as manuals, codes of practice, specifications, building regulations and standards are now required.

5.3 Research and extension activities

The will must exist at government level to explore the potential of alternative materials, and to put in place the resources and mechanisms to carry out the necessary material developments and evaluations. Where this capacity already exists, it is often necessary to reorient the approach of research institutions to link them directly with the building industry, together with their government and private sector clients.

5.4 Training

Curriculum revision is required to give greater emphasis to the new technologies. This would apply to institutions training high level artisans or technicians for the construction industry, as well as professionals such as architects, building technologists, civil, structural and mechanical engineers, and quantity surveyors.

5.5 Fiscal policy

Financial incentives are required to encourage the establishment and support of industries involved with the new technologies. In addition, the widespread policy which limits the advance of bank loans and mortgage on ‘bamboo’ houses must be reviewed.

5.6 Demonstration and quality

Effective dissemination aimed at popularising the new technologies is vital considering the negative perceptions held by many about bamboo in building. Even when issues of durability and strength are resolved, the question of acceptability remains. Bamboo buildings need not look ‘low-cost’, nor need they necessarily look like the materials from which they are made! Imaginative design and the use of other locally available materials within the cultural context can make the building desirable rather than just acceptable.

The construction of model buildings is therefore essential to overcome prejudice and boost the confidence of specifiers and users. In this regard the quality must be of the highest level achievable, since any shortcomings in the standard of construction, detailing and finish will be reflected, unfairly, on the building system as a whole.

Bamboo, a sustainable building material

in Western Europe

Ir. Pablo van der Lugt

(The paper with 8 figures.)

Graduated (masters) February 2003, Faculty of Architecture, Delft University of Technology, The Netherlands. Email: Pablovanderlugt@hotmail.com

Ir. Andy van den Dobbelsteen

Department of Building Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology, PO Box 5048, 2600 GA Delft, The Netherlands. Tel: +31.15-2783563, Fax: +31.15-2781560, email: Andy.vandendobbelsteen@citg.tudelft.nl

Dr. Jules Janssen

Department of B-CO, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands, Tel: +31 40 247 2948. Email: j.j.a.janssen@bwk.tue.nl

1. INTRODUCTION

In the building industry, the selection of a building material is mainly determined through its costs and durability. However, with sustainability as a key issue in the last decades, especially in western countries, the environmental performance of building materials has also become a more important criterion. Bamboo, as a fast growing renewable material with a simple production process, is expected to be a sustainable alternative for more traditional materials like concrete, steel and timber. Indeed, in many publications (e.g. EBF, 2002; Dethier, 2000; Kries, 2000) bamboo is qualified as a very sustainable material. However, this has never quantitatively been proven. The environmental impact of many building materials has already been assessed using an international (ISO) approved method, LCA (Life Cycle Assessment). In the study presented (Lugt, 2003) an LCA was conducted for bamboo, in its original form (the culm) and in an industrial product application (a wall panel).

2. RESEARCH OBJECTIVES

The first research objective of the study presented was:

· Gaining more insight into the environmental performance of bamboo (products) compared to building materials more commonly used in Western Europe.

For this objective, the following research question needed to be answered:

· What is the environmental impact of bamboo (products) in Western Europe compared to building materials more commonly used?

2.1 Restrictions

The following bamboo products were environmentally assessed:

§ Air-dried culms of the bamboo species Guadua angustifolia, as produced during the National Bamboo Project in Costa Rica, based on use (including transport) in the Netherlands. Initially, an Asian bamboo species, Phyllostachus pubescens, would also be assessed. However, due to communication problems and lack of data this could eventually not be executed.

§ Bamboo panels (Plyboo natural plain-pressed two-layered bamboo panel) produced in Shanghai (China) based on use in the Netherlands, used as cover for inner walls.

2.2 Research method

Data of the production process of both the bamboo culm and panel were retrieved by interviews with experts involved in the production process and literature study. The data were processed in the TWIN²⁰⁰² model (NIBE, 2003), based on the LCA-methodology, by experts from the Dutch consulting company NIBE.

3. ENVIRONMENTAL ASSESSMENT OF BAMBOO

In 1990, Speth and Ehrlich & Ehrlich argued that in order to achieve sustainable development[1] in the future the pressure on the environment should be reduced by factor 20. This target has been adopted by many organisations and societies. One of the ways to achieve factor 20 environmental improvement in the building industry is using more sustainable and renewable materials.

3.1 Introduction LCA

Life Cycle Assessment (LCA) is the commonly acknowledged basis for environmental assessment of products. Principally, in an LCA all environmental effects occurring during the life cycle of a (building) product are analysed, from the extraction of resources until the end phase of demolition or recycling (‘from cradle till grave’). LCA was first developed in 1992 (Heijungs, 1992). Since then it has evolved to an international accepted ISO-certified method (ISO 14041).

The standard LCA includes environmental effects that can be quantified; some effects (e.g. ‘deterioration of eco-systems') are ignored until a generally accepted assessment method has been developed. Moreover, the standard LCA provides an outcome of different effect scores; a weighing method is not included and an overall judgement of products is therefore not possible. In order to obtain a single score and enable comparison of products, additional models are necessary. At present, many of these models are available, each one having advantages and disadvantages. The validity of these models is always subject to discussion, mainly about the applied weighing method (Dobbelsteen, 2002). The TWIN²⁰⁰² model, developed by NIBE (2003), was chosen for the environmental assessment of bamboo and its alternatives. This model is based on the latest version of the LCA-method and includes estimative methods for environmental effects that a 'pure' LCA lacks. Furthermore, TWIN²⁰⁰² adds a weighing methodology based on the principle of environmental costs: fictitious societal costs (monetary factors) connected to the prevention of environmental damage by certain interventions (e.g. emissions). The advantage of working with environmental costs, or eco-costs (Vogtländer, 2001), is the absence of a subjective weighing; the difficulty is the exact determination of monetary factors. TWIN²⁰⁰² includes the latest LCA data and environmental costs of building products.

3.2 Nuances

A couple of uncertainties are attached to environmental assessments, as by means of LCA. The reliability of some of the used data is also debatable. In order to compensate for this, the environmental assessment of bamboo took place following a worst case scenario. Moreover, some environmental aspects that could be favourable to bamboo, like the annual production of biomass of a bamboo plantation (which is 3 times as great as for the average timber productive forest, see Table 1), were not included in the assessment.

Table 1 Annual production of plantations for producing wood and bamboo (Janssen, 2002; Sundquist, 2002)

Furthermore, the environmental assessment was based on the use of bamboo (products) in the Netherlands. When used in the country that produces the bamboo (in this case Costa Rica), the environmental costs of bamboo will be considerably lower due to absence of sea transport.

3.3 Functional unit

In the study presented, bamboo in its natural form (culm) and in an industrial form (panel) were environmentally assessed. Before an environmental assessment can be executed, a general basis for the alternatives compared needs to be defined. This basis is called the ‘functional unit’ (Arets, Dobbelsteen, 2002). For a correct comparison, the functional unit is of vital importance: measurements of the alternatives are determined by its technical and functional requirements (e.g. strength and stiffness). It means that weaker alternatives require more material, and that alternatives with a shorter life span need to be maintained or replaced more often (both leading to higher annual environmental costs).

For the bamboo culm, the chosen functional unit was a column, beam and rail as used in the walking bridge in the 'Cherry blossom garden' in the Amsterdam Woods (see Figure 1), each one with its original technical requirements. Bamboo was compared with the building materials most commonly used in this application: steel, sustainably produced wood (species: azobé and robinia), and concrete. Concrete was only assessed in the function as column because concrete is not normally used as a line element like the other functions and therefore incomparable.

Figure 1 Bamboo bridge in the Amsterdam Woods (photo: Pablo van der Lugt)

3.4 Results

In order to obtain the environmental score of bamboo, all steps in the production process and life span of the bamboo culm needed to be analysed. For instance, for the culm this meant analysing the amount of boron used in preservation using the Boucherie method (Janssen, 2000), the amount of gasoline used for the chainsaws, the number of kilometres of transport, etc. After processing these data in the TWIN²⁰⁰² model, the environmental costs of 1 kg bamboo culm over the production process could be analysed (see Figure 2, an adaptation of the original output). The results are given in micro-points (mPt), equal to environmental euros (e€). Figure 2 shows that almost all environmental costs originate from the (sea) transport from Costa Rica to the Netherlands.

Figure 2 Environmental costs (in mPt) of 1 kg bamboo culm including transport to the Netherlands per part of the production process.

In order to obtain the annual environmental costs, the environmental costs of each alternative (bamboo, wood, steel, and concrete) were divided by the life span. Also other aspects (e.g. the amount of waste, recycling of the material) needed to be integrated in the assessment. Figure 3 presents the final results. Note that the numbers are not absolute environmental costs, however represent an index. For the index, the score of the alternative with the lowest environmental impact (in all cases: bamboo) was divided by the score of the alternative compared.

Figure 3 Index of the annual environmental costs of the different elements of the bamboo bridge in the Amsterdam Woods.

The graphic of Figure 3 demonstrates that the bamboo culm, even when used in Western Europe, can be considered the most sustainable alternative by far in all functions. In some applications the earlier mentioned factor 20 ‘environmental improvement’ is achieved. The difference in environmental performance of the longitudinal beam and the transversal beam is due to the fact that four bamboo beams instead of one are needed for the longitudinal beam to bear the loads. Note that the assessed timber species are sustainably produced, timber from regular, non-sustainable woods will have an environmental impact considerably worse (NIBE, 2003).

The good environmental performance of the bamboo culm has two distinct causes. First, its natural hollow design is structurally far more efficient than a rectangular massive section e.g. in case of timber (Janssen, 2000). This means that bamboo contains far less material mass in a certain function, compared to steel, concrete, and timber. The second cause is the simple, short production process (sawing, removal of branches, preservation, drying). Note that the assessed bamboo culm is dried in the open air without the use of a drying chamber (which would cost relatively more energy).

4. ENVIRONMENTAL COSTS OF THE BAMBOO PANEL

As an industrial bamboo product example, a bamboo panel was also assessed by environmental criteria using TWIN²⁰⁰². Bamboo panels are mainly used as parquet but can also be used in other applications like veneer or covering material. In the study presented the panel was compared with wood-based panels, applied as non-bearing internal wall covering.

Just as for the bamboo culm, the complete production process with corresponding environmental effects was analysed for the bamboo panel. However, the production process of the panel is far more complex. The bamboo culm needs to be sawn, smoothed, bleached, sandpapered, glued, pressed, etc., in order to obtain the required characteristics. Therefore, the environmental costs of 1 kg of bamboo panel are considerably higher than those of the culm. Figure 4 shows that the bleaching and preserving process by means of H₂O₂has a great share in the environmental impact of this product. Again, (sea) transport has a great share in the total environmental impact of this bamboo product.

Figure 4 Environmental costs (in mPt) of 1 kg bamboo panel per part of the production process, including transport from China to the Netherlands.

If other life cycle aspects, e.g. the life span and waste, are added, the bamboo panel can be compared with other materials (see Figure 5). In this figure a theoretical version is also added in which the panel is not bleached but only preserved with boron, using the Boucherie method.

Figure 5 Environmental costs of wood-based panels for internal walls including the bamboo panel (NIBE, 2003).

The graphic of Figure 5 indicates that the environmental performance of the bamboo panel is slightly less favourable than most wood-based panels for non-bearing internal walls. However, the theoretical non-bleached version of the bamboo panel scores significantly better. Only panels with wooden material originating from sustainably maintained forests or panels made from 100% waste environmentally perform better than the theoretical bamboo panel. Concerning the limited availability of these products, the theoretical bamboo panel can be defined as a relatively sustainable alternative[2]. Note that panels based on metal and synthetic material were not included in Figure 5. The environmental costs of these alternatives are expected to be higher than those of wood- and bamboo-based panels.

Nevertheless, especially compared to the relatively sustainable bamboo culm, the bleached bamboo panel cannot be considered a sustainable alternative. This is due to the disposal of features that made the bamboo culm a sustainable alternative: the efficient structural natural design of the culm is deteriorated through the laminating process. The intersection becomes solid, meaning more material mass is needed to fulfil the required function. Furthermore, the process to make a rectangular massive product of the bamboo culm is far more energy-intensive and complex, leading to considerably higher environmental costs.

5. CONCLUSIONS ON THE ENVIRONMENTAL ASSESSMENT

The environmental assessment of the bamboo culm yielded very positive results. In several functions the environmental performance of the culm is 20 times better than building materials more commonly used, e.g. steel, wood, and concrete. When laminating the bamboo culm for flat-shaped applications, i.e. panels, the environmental advantage is diminished. Nevertheless, with some adjustments in the production process, a non-bleached sustainable alternative of the bamboo panel is possible.

These results form a dilemma: a problem with the application of the bamboo culm in Western countries is the irregular, hollow, round form, leading to problems in joints. By laminating, a rectangular section can be created, making joints easier. However, from an environmental point of view, the bamboo culm should be chosen, accepting possible problems of its geometry during implementation in the building process. These problems were analysed in the second part of the study (Lugt, 2003), however not presented in this paper.

6. Financial assessment of bamboo

For the analysed project (the walking bridge in the Amsterdam Woods), also a cost comparison was executed. The cost comparison was done in accordance with the environmental assessment on the same functions (column, beam, rail) and materials (see figure 8). The graphic in Figure 8 shows the annual costs of the various elements. In order to obtain the annual costs, all costs (e.g. costs for assembling, maintenance, disassembling, dump) occurring during the life cycle of the product were added to the purchasing costs and divided by the life span. Considering purchasing costs, bamboo is by far the least expensive. However, because of the shorter life span and the higher labour costs of assembling and disassembling (as a result of the irregularity of bamboo), on an overall cost level, steel turns out to be the most economic building material, due to the long life span.

Figure 6 Annual costs of the various elements and materials of the bamboo bridge in the Amsterdam Woods.

7. OVERALL CONCLUSIONS

The environmental and financial comparison demonstrates that bamboo can compete with building materials more commonly used in Western countries.

Nevertheless, practical problems (failure factors) when using the bamboo culm in Western Europe are numerous and have a couple of bamboo-related main sources: the shape of the material, the irregularity of the material and the lack of knowledge and building codes.

While many of the failure factors can be avoided in the future, some of them will remain. Bamboo is a natural product and will therefore always have some extent of irregularity. It is therefore suggested that in Western countries the bamboo culm should be used in functions were the measurement requirements are not entirely precise or fixed, as in temporary buildings, see Figure 7 (e.g. pavilions and tents) or small civil projects (e.g. bridges). Furthermore, bamboo can play a role as a finishing material (see Figure 8).

Figure 7 Bamboo theatre during the Festival of Vision, Berlin, 2000 (photo: Norbert Stück).

Figure 8 The bamboo culm as a finishing material (photo: Hulshof architects).

8. RECOMMENDATIONS FOR FURTHER RESEARCH

The environmental and financial comparison has been done for bamboo in a very specific application (column, beam, and rail, as used in the walking bridge in the Amsterdam Woods). For a broader perspective of the environmental performance of bamboo (products), additional environmental assessments by LCA are needed:

· With data from more plantations, species, and manufacturers, in order to increase the reliability of the results;

· Based on use in different countries (including the native country of the used bamboo);

· On another scale (complete joints, complete buildings);

· In other applications (using the bamboo culm internally, using the panel as parquet, using bamboo strips, etc.);

· In non-building applications (e.g. as biotic fuel).

For a broader perspective of the costs of bamboo (products) used as building material in the West, additional cost comparisons are needed:

· Of joints with other building techniques (e.g. lashing, joints with concrete).

· In another application (using the bamboo culm internally results in a longer lifespan)

· In another product (e.g. bamboo strips, corrugated board)

REFERENCES

Arets, M.J.P., A.A.J.F. Dobbelsteen, van den, 2002. Sustainable bearing structures. In: Anson M, Ko JM & Lam ESS, editors. Advances in Building Technology, Volume II, p. 1449-1456. Oxford, UK: Elsevier Science.

Brundtland, G.H. (ed.) et al. (The World Commission on Environment and Development), 1987. Our Common Future, Oxford, UK: Oxford University Press.

Dethier, J., 2000. ‘The ZERI pavilion’, In: A. von Vegesack, M. Kries, Grow your own house. Balingen, Germany: Vitra Design Museum.

Dobbelsteen van den, A., 2002. 'Rekenprogramma’s voor duurzaam bouwen' (in Dutch), In: Praktijkhandboek duurzaam bouwen, Amsterdam, Netherlands: WEKA Publishers.

Ehrlich, P., A. Ehrlich, 1990. The population explosion, London, UK: Hutchinson.

Environmental Bamboo Foundation (EBF), May 2002. website, http://www.ebf-bamboo.org/

Heijungs R. (ed.), 1992. Milieugerichte levenscyclusanalyses van produkten - Handleiding en achtergronden (NOH rapport 9253 en 9254, in Dutch), Leiden, Netherlands: CML.

Janssen, J.J.A., 2000. Designing and building with bamboo, Beijing, China: INBAR.

Janssen, J.J.A., Various interviews in 2002 and 2003

Kries, M., 2000. ‘Sustainability’, In: A. von Vegesack, M. Kries, Grow your own house. Balingen, Germany: Vitra Design Museum.

Lugt, P. van der, 2003. Bamboe als alternatief bouwmateriaal in West-Europa? - Een studie van de duurzaamheid, kosten en bottlenecks van het gebruik van bamboe(producten) in West-Europa (in Dutch). Delft, Netherlands: Delft University of Technology, Faculty of Architecture.

NIBE, 2003. Basiswerk Duurzaam & Gezond Bouwen (in Dutch)- Dé leidraad bij het realiseren van duurzame en gezonde woning- en utiliteitsbouw (supplement 4); Naarden, Netherlands: NIBE Publishing.

Speth, J.G., 1990. ‘Can the world be saved?’, Ecological economics vol. 1, p. 289-302.

Sundquist, B., May 2002. website, http://www.alltel.net/~bsundquist1/index.html.

Vogtländer, J.G., 2001.The model of the Eco-costs/Value Ratio, a new LCA based decision support tool. Delft, Netherlands: Delft University of Technology, DfS.

Technology of Sawing Bamboo Veneer

LI Li¹，YANG Yongfu¹，GUO Jianfang²

1. College of Material Science and Technology, Beijing Forestry University Email: lili630425@sina.com

2. TCWOOD Email: gtcwood@163bj.com

(The original paper is with about 8 figures and 3 tables).

Abstract: This paper introduces the technology of sawing bamboo veneer and the mini-nice frame saw as the machine to saw the bamboo veneer. The technology of sawing bamboo veneer with the mini frame saw form the laminated block with bamboo strips is one of feasible ways, after comparing it with the slicing and peeling veneer. The technology of sawing bamboo veneer could simplify the processing of the bamboo veneers, and increase the quality of veneer and the utilizable rate of the bamboo industrial utility.

Key words: Bamboo wood, Bamboo veneer, Frame saw

Bamboo-wood laminated floor is a kind of multi-layer composite floor made of bamboo veneer, wood or MDF. In recent years, the internal decoration level of our country has been increased every year, the decoration engineering costs and wood floor consumptions are also in a trend of going up yearly. But with the increasing pressure of environmental protection worldwide, the decreasing supply of wood, and the growing shortage of precious wood resources, the high quality wood materials with beautiful grains and colors for solid wood floor are restricted by the resources and in shorter supply, while the composite wood floor occupies gradually a larger part of the market. With distinctive grains and colors, the bamboo material has hard surface and wear resisting. The production of bamboo material has certain area limitation, but as it has short production period and grows fast, although its processing technology is complicated while its processing property is rather good, the bamboo-wood composite floor becomes favorite in both domestic and world markets.

1. The processing property of bamboo material

Bamboo is situated in Bambusoideae Nees in the grass family that is wide spread in China. Bamboo has more than 200 kinds with more than 20 genera. Bamboo grows fast and becomes mature and useful early, when it grows up to mature timber, it will make profits for many years. Bamboo is grown widely in south China, and the output holds the first place in the world.

Bamboo material as processed industrial material is mainly the bamboo culm, in the longitudinal direction bamboo is composed of a section of thick bamboo、bamboo node and a septum of bamboo node. In the thickness, its has bamboo skin、bamboo wall and bamboo with its green covering from outside to the inside. In most of the situations, the industrial processing of bamboo material is the bamboo wall after the bamboo skin and bamboo with its green covering to be removed. The bamboo is mainly composed of cylinder shaped parenchyma cell, fiber cell and tracheid cell. All the tissues, except those curving around the septum of bamboo node, are spread lengthwise along the bamboo, the bamboo material lacks crosswise parenchyma, with straight grains, is easy to crack. As a result, it is easy to process bamboo such as bamboo strip、removed bamboo skin and green covering、determinate width and thickness processing. The sawing process of bamboo veneer is to saw lengthwise along the bamboo grains, while sawing, the saw tooth cuts the bamboo material with its three edges, and one stroke of the saw will make three cutting planes --- the bottom of the kerf and both sides of the kerf. It is the same for both frame saw and circular saw. The main edge of the saw tooth cuts nearly section, the side edges of the saw tooth cut nearly crosswise. The main edge of the saw tooth cuts the bamboo fiber in the bottom of the kerf, and at the same time, its front face of the sawing tooth contacts and presses the fiber. While the saw tooth cuts deeply, the pressure of the front face increases gradually, when the pressure is big enough, the lay of bamboo material pressed by the front face of the saw tooth will be cut broken along the both sides of the kerf. The lay of bamboo material cut off will become bamboo chips under the pressure of front face of the saw tooth and the main edge. As bamboo lacks crosswise parenchyma and the grains are straight, the tapering is small, and has not much differences in the tissue structures of bottom and top parts of the bamboo, the resistance to lengthwise sawing processing is rather even, the cutting surfaces are rather smooth.

2. Sawing technology of the bamboo veneer

Bamboo material has high strength and toughness, dense structure and straight grains, with pithy color and smooth quality, it is easy to be bleached and carbonized. Bamboo material also has good tensile strength and decorative results, thus bamboo-wood composite processing is a major way to make use of bamboo with high benefit and to increase extra product value. In recent years, the industrialized use of bamboo will process the bamboo by splitting the section of thick bamboo into the strips with fixed width and thickness, then gluing the strips together with different combination forms to make laminated blocks, and the laminated blocks will be processed for use.

Presently, the general method is to glue the bamboo strips with fixed width and thickness together side-wise to make thin and wide boards, and then to glue several boards together to make laminated bamboo blocks. Then, the bamboo blocks will be cut into bamboo veneer with various specifications by different processing methods with different technologies, such as slicing, peering and sawing. For slicing bamboo veneer method, the bamboo blocks should make with bamboo strips with high moisture content or be softened by water or steam processing. Thus, there are strict requirements on adhesive and gluing technique, and such bamboo blocks are only suitable for making very thin bamboo veneer. The sawing processing can make bamboo veneer with thickness of 3-4mm from the laminated bamboo blocks made of dry bamboo pieces without water or steam treating, such bamboo veneer has no opposite direction crooked stress and cracks on the back.

Fig. 1 Illustration of the laminated blocks with bamboo strips

General processing flow chart of bamboo veneer shows in Fig.2.

Fig. 2 Flowchart of the bamboo veneer processing

3. Sawing machine for bamboo veneer

Under present technical conditions, the veneer manufacturing methods mainly include peering, slicing and sawing. Peering and slicing can only make thin veneer. To be confined to the processing method and quality requirement on veneer, veneer thicker than 2mm will mainly processed by sawing, with mini frame saw and thin circular saw.

Fig. 3 Figuration of the frame saw

1. Working table 2. Feeding system 3. Sawing unit 4. Base

3.1 The basic structure of the frame saw

Figure 3 is the contour of the mini frame saw machine. The sawing and outlet unit 3 is fixed on the base 4. For the convenience of changing frame, checking, and maintenance, the working table is driven by an open/close motor that can be opened along the guide on the base relative to 3. There are gates all have joins with hinges in front and back part of the opening and the fixed sections.

3.2 The transmission system of frame saw machine

Fig. 4 is the mechanical transmission system of frame saw machine. The main sawing unit is composed of motor 1, transmission belt 2, and crank connecting rods unit (main crank 3, main connecting rods 4, saw frame 5 and base). The saw blades will be tensioned on the saw frame 5 that moves up and down repeatedly to saw the work-piece.

The feed unit is mainly composed of automatic ratchet wheels and feed system to realize interval feeding. The saw blades cut when the work-piece feeds and cut free when the work-piece stops to feed. To increase productivity, the feed in advance before the saw blades reach the upper stop point, that is feed in advance before the saw blade cut to compensate the clearance and increase the productivity. The advanced angel is 17⁰~25⁰。^.

Fig. 4 The Transmission System of Precision Frame Saw Machine

1. Main motor 2. Transmission belt 3. Main crank 4. Main connecting rod 5. Saw frame 6. Sub crank 7. Feed connecting rod 8. Rocker 9. Feed ratchet wheel 10. Clutch 11. Counter reverse ratchet wheel 12. Connecting rod – chain combination unit 13. Transmission chain 14. Pressure roller 15. Cylinder 16. Movable working table 17. Upper feed roller 18. Lower feed roller 19. Driven motor for table movement 20. Worm 21. Worm gear 22. Guide screw for working table movement 23. Pressure roller 24. Output roller 25. Taper bearing

The work-piece feeds with rolling driven from the top and bottom. To guarantee that the work-piece stops feeding when the frame cuts free, the feed mechanism adopts interval feeding. The feed unit uses sub crank 6, sub connecting rod 7 and swing rod 8 to drive feed ratchet wheel 9 to make interval swings thus to transfer the movement to the connecting rod-chain combination unit 12, and then the chain transmission 13 drives upper and lower rollers 17 and 18 to make interval revolutions. There are two groups of upper feed rollers pressed by cylinder 15 that are controlled by the photoelectric sensors to press down firmly the work-piece according to its feeding position. Besides, there are a group of elastic pressure rollers 14 after these two groups of feed rollers to press down the work-piece. The upper and lower feed rollers are droved by transmission chain to guarantee them to make movements synchronously. When the upper driven rollers move up and down by the cylinder. The driving chain is tensioned by the chain wheel installed on the swing rod 26.

To prevent the work-piece reverse while the frame 5 cuts free, there is a counter reverse ratchet wheel 11 installed on the same axle with the feed ratchet wheel 9. It is installed in the opposite direction with the feed ratchet wheel to guarantee that the work-piece will not reverse under opposite pulling.

The adjustment of feed speed is made by adjusting the position of the guide screw nut on the rocker 8. When adjusting the length of the swing rod, the auxiliary crank turns a circuit then the turning angle of rocker 8 is adjusted. The adjustment is made through the hand wheel and the soft axle of steel wire to drive the guide screw on the rocker.

The outlet is composed of a group of driven rollers 24. The rear rollers and the feed rollers connected by the clutch 10 move synchronously. When the work-piece comes out, a group of rear pressure rollers 23 will press it, and the pressure valve in the compress air system to adjust the pressure will guarantee to give relatively little pressure to prevent the veneer from splitting.

For the maintenance and frame changing, the power of the outlet should be cut out by the clutch 10, the motor 19 will drive the worm mechanism (20, 21) to move away the feed mechanism and working table from the cutting and outlet facilities through guide screw 22, and open the machine. The connecting rods – chain combination unit 12 will adapt the position changes of the moving and the fixed parts of the machine automatically.

To minimize the wear and tear by friction between the clearance face of the sawing tooth and the bottoms of the kerfs in idle cutting stroke, and to increase the service life of the saw blades, the frame saw machine adopts oblique installation to make the saws keep off, so that the frame will keep out of the way in the idle cutting stroke to guarantee the spaces between the saws and the bottoms of the kerfs. The oblique installation structure is illustrated in Fig. 5, the oblique degree can be adjusted by adjusting screw.

3.3 Tensioning the sawblade

The saw blades require to be tensioned by rolling, the purpose is to introduce tensioning stress in the saw blades. When the saw blades are drew, the stress on the back of the saw blade changes to the tensioning stress at the teeth edge, so that the stability of the saw blade is increased and the kerf loss is minimized. After rolling tension, the back of the saw blade will have a certain bend. Table 1 shows detailed requirements.

3.4 Drawing of sawblade

As illustrated in Fig. 5, the saw blades are pressed firmly by spacers and drawn by friction. After side pressing, three M20 bolts are used to pull them tightly. When cutting in groups, the tightening force of each bolt is M=10Nm.

The pulling force of a single bolt Q can reach 40000N.

Adjusting bolt

Changing frame

Positioning pin

Fig. 5 Sketch map of sawing frame inclining setting

Fig. 6 Back curve of sawbalde

Tab. 1 Measuring amount of back curve of sawbalde

4. Comparison of Mini-nice Frame Saw Cutting with Other Processing Methods

In wood processing, it is also possible to use slicing and peeling methods to process veneer with thickness of 3-4mm. Such methods will make high rate of utility of wood, but they damage the structure of the wood and make breaks on the back of the veneer as the veneer bends in opposite direction while being sliced or peeled. The bamboo material has its specific characteristics, the bamboo fiber mainly arranges in order along the direction of the length of the bamboo, there is little fiber in crosswise direction, so that slicing and peeling will always make crosswise cracks and breaks. Besides, with slicing and peeling methods, the bamboo blocks should be glued with high moisture content or the bamboo blocks should be sliced or peeled after hot water process that requires the glue to be used to be highly water-proof and to have high gluey strength. Frame saw cuts with multi saw blades to avoid structure damage of the work-piece that usually happens with slicing and peeling. There is no need of hot water process of the blocks so that the requirements to the glue and block gluing technology are lowered and the quality of the finished products are increased.

Table 2 Specification of Saw Blade and the Width of Kerf

Compared with the gang circular saw, the frame saw machine seems to have low productivity. The feed speed of frame saw machine is generally 0.5 – 1.5m/min, and the feed speed of the circular saw is generally 10 – 20m/min that is more than 20 times faster than frame saw machine. But the gang circular saw machine installed saw blades number is less than frame saw and cutting height is lower. If the cutting height of frame saw machine is 200mm, the saw frame installs 40 saw blades, and the feed speed is 1m/min, to calculate the area of the products per minute, the productivity of the frame saw machine is 8m²/min. The kerf is only 0.7 – 1mm. If cutting the work-piece with the thickness of 200mm, the twin-shaft gang circular saw machine must be required to cut from opposite directions, the kerf is generally 2.6- 3.2mm, for the errors caused by position error of the twin saw blades and the transverse vibration of the saw blades, more processing tolerance is required for the later process, the rate of bamboo utilization is lowered. The comparison of kerfs of these two kinds of machines is illustrated in Fig. 7. Theoretically the kerf of frame saw machine is less than half of that of the circular saw. Compared with the circular saw and the band saw, the saw blades of frame saw machine has the highest stability. Based on the differences of the thickness of the veneer cut, generally the rate of bamboo utilization with frame saw machine is 15 – 50% higher than that with circular saw. Presently, the frame saw machine and its saw blades producers in Europe supply saw blades with cutting height of 80 – 250mm, thickness 0.8 – 1.1mm, and kerf 1.2 – 1.7mm. Table 2 is the specification and kerf of saw blades at different cutting heights. According to the statistic information, when cutting veneer with the thickness of 2mm, the of rate of material utilization with frame saw machine is 1.6 times more than the circular saw machine; Fig. 8 is the comparison of theoretical rate of material utilization of these two kinds of saw machines while cutting veneer with different thickness.

Fig. 7 Comparison of the kerf loss between the frame saw and the circular saw

Fig. 8 Comparison of the bamboo utility rate between the frame saw and the circular saw

In addition, if only judging productivity from the feed speed, the frame saw machine is much lower than the gang circular saw machine, but the processing precision of frame saw machine is high that the circular saw cannot compare with it. Take for example the mini-nice frame saw machine model Clasic, its feed speed is 0.2 – 2.0mm/min with step-less adjusting, the cutting frequency of the saw blades is 450 times/min, and the feed per teeth is rather small. The thickness of sawing chip is 0.15 – 0.25mm (rough cutting), 0.07 – 0.1mm (medium cutting), and 0.03 – 0.05mm (precise cutting). Table 3 shows the thickness of sawing chip at different feed speed. As the tension of the saw blades of frame saw machine is rather high and the stability of the saw blades during cutting is high, the height of sawing trace on the cutting surface caused by the transverse vibration of the saw blades are very small, the cutting surface is smooth and straight. The production of solid wood laminated floor indicates that the veneer cut at the feed speed of 0.6- 0.7m/min can be glued directly without any follow-up process, or glued after sanding processing, thus the processing costs and the material consumptions are reduced.

To consider comprehensively the complicacy of the processing technology, the specific characteristics of the work-piece to be processed, the productivity, the rate of material utilization, the processing quality and etc., in bamboo veneer processing, the min-nice frame saw machine has high superiority that reflects highly in respects bamboo laminated block no need softening, rate of material utilization and cutting quality.

Table 3 The thickness of sawing chip at different feed speed

5. Conclusion

To produce laminated bamboo blocks by gluing and laminating, and then to cut the laminated bamboo blocks into bamboo veneer with different specifications is one of the ideal ways to use the bamboo resources of our country with high effects, and to increase the utility of the bamboo material and the added value of the products. The min-nice frame saw machine is the most ideal equipment to cut the bamboo veneer. The superiority of the machine mainly reflects in its simplified processing technology, increased rate of material utilization and product quality.

The frame saw uses tension processed thin saw blades which have high tensioning and stability, so that the kerf loss is reduced and the rate of material utilization is increased, it is specially suitable for thin veneer cutting process.

Compared with slicing and peeling, the frame saw cutting has no need to make softening process for the laminated bamboo blocks, so that the requirements to adhesives and gluing technology are lowered. Compared with the circular saw processing, frame saw processing has increased the material utility and product quality.

China has rich resources of the bamboo wood. The demand for furniture, laminated floor and other decoration materials is rather great. In recent years, the demand for bamboo material in decoration material markets in China and abroad is in the trend of increasing each year. Some solid wood laminated floor and pencil board producers in China have imported min-nice frame saw machines made by Neva of Czech and Winterseiger of Austria, their production practice has proved that frame saw cutting is an effective and practical way to process veneer. It is an effective way to increase product quality and reduce kerf loss. The practice has proved that frame saw cutting is a feasible technology in laminated bamboo blocks cutting, under the condition that the productivity is guaranteed, the processing technology can be largely simplified, the utilizing rate of bamboo material, the precision of finished products and quality of the sawing surface can be increased.

References

Bao Yipei, The Technology, Equipment and Economic Analysis of Laminated Bamboo Floor, 2001, Construction Wood-based Panel (2001) 3:27 – 30.

Cheng Ruixiang, Xu Bin, Zhang Qisheng, Study on Gluing Technology of Laminated Bamboo Blocks for Veneer Slicing, 2003, Wood-based Panel Report, (2003) 7:5-7.

Hu Changlong, Bamboo Furniture and Weaved Bamboo Utensils, 1983, Jiangsu Science and Technique Publisher.

Jiang Shenxue, Zhang Qisheng, The Status Quo of Bamboo Material Process and Application in China, 2002, International Wood Technology (2002): 10-16.

Tu Maoqing, To Develop Jiangxi Solid Wood Laminated and Bamboo Laminated Floor Production by Using Faster Growing Wood, 2000, Jiangxi Forestry Science and Technology (2002)2:42-45.

Yang Rongfu, The Performance Analysis of Mini-nice Frame Saw Machines,2003, Wood Processing Machinery (2003) 2:5-9.

Zhao Renjie, Du Chungui, Long Strip Bamboo Laminated Floor, 1999, Forestry Science and Technology Development (1999) 6:10-11

Zhang Qisheng, Sun Fengwen, The Prospects for the Development of Bamboo Industry in Our Country, 1999, Forest Industry (26) 4:3-5.

Technological Innovative Course and Prospect of Bamboo-based Panel of China

Zhao Renjie Chen Zhe Zhang Jianhui

Central-south Forestry University, Zhuzhou 412006, Hunan Province, P. R. China.

Phone: +86-733- 8700032

Abstract: Based on the technology and facility of modern wood industry and rich bamboo resources in China and excellent characteristics of bamboo, bamboo-based panel series were developed, the course of which was summarized in this paper. And it elaborated technological innovations in improvement of structure, in craft and technology, in modification of adhesive and in development of special equipment for bamboo processing and the historical course of bamboo industrialized utilization. In addition, the developmental prospect of bamboo-based panel was also discussed in this paper.

Key words: Bamboo-based panel Technological innovation Industrialized utilization

1. Preface

Bamboo resource is very rich in China. According to the fifth investigation of forestry resource (1994—1995), there was 4,210,000 hectare bamboo forest and the total store is 110,870,000t, of which the area of mao bamboo reached to 69%. There are 2000 mao bamboo per hectare^[1]. Compared with timber, bamboo is high in strength, toughness and rigidity and easy of be cut lengthways. Utilizing rich bamboo resources and excellent characteristics of bamboo, based on the technology and facility of modern wood industry, through proper process, bamboo-based panel serials such as bamboo mat plywood, bamboo curtain plywood, bamboo plate plywood, bamboo stripe laminated material, bamboo particleboard and so on were developed successively. The production of this series has the history of more than 20 years. Because of the structure rationality of bamboo-based panel, the shape and structure of bamboo has been changed greatly, the physical and mechanical properties of bamboo has been improved. The application scope of bamboo has been enlarged. Therefore, the production of bamboo-based panel is an important aspect that using bamboo sufficiently and improving bamboo properties. Nowadays, the development of bamboo-based panel is very fast and it has many species. The output in 2001 of all kinds of bamboo-based panel was about 2,000,000m³, which was 9% of the annual output of domestic wood-based panel. And the industry basement of bamboo-based panel has been set up preliminarily. The new era of bamboo industrialized utilization in China has been inaugurated. The product history of bamboo-based panel is more than 20 years. Whether the improvement of structure, the innovation of process, the modification of adhesive or the development of special equipment for bamboo was a history of scientific innovation, which includes intelligence and painstaking efforts of a generation of experts. Technological innovative course of all the kinds of bamboo-based panel was reviewed in this paper, based on which its developmental prospect was prospected.

2. Technological innovative course of all kinds of bamboo-based panel

2.1 Bamboo mat plywood

Bamboo mat, waved vertically and horizontally with bamboo strips, as the component of bamboo mat plywood, after added UF or PF resin, it is pressed into bamboo mat plywood with the “hot-hot “process. Some people call bamboo plywood as bamboo waving plywood. UF bamboo mat plywood, when thickness ranges from 2 to 6mm is also called thin bamboo mat plywood, which is mainly used as decorative and packing material. PF bamboo mat plywood, whose thickness generally is over 7mm, is also called thick bamboo mat plywood and mainly used as structural material. Bamboo mat plywood is the earliest product among bamboo-based panel series and at one time or another, it developed fast in some sort, and the national quality inspecting department published national standard of bamboo mat plywood GB13123---91and national standard of experimental methods of bamboo mat plywood GB13124---91in 1991. But now, on the one hand, its workload is very great and it consumes too much adhesive, furthermore, whether the usual adhesive spreading or glue dipping does not achieve the satisfying effect. As structural material, it has no advantages compared with other materials because of its low p/p (performance/price). On the other hand, it has clear surface roughness and the texture of bamboo mat also confines its utilization, so as the decorative material, it could not achieve ideal decorative effect. So because of the two above reasons, it is in the atrophic situation now. For the sake of improving decorative effect, Professor Zhao Li in Beijing Forestry University once made research of cover wood veneer on the surface of bamboo mat plywood, after sanding, painting, and its decorative effect increased greatly. But because this process was very complex and cost was very high it also had no advantages compared with the usual wood based plywood, so it was ignored by the market. So although bamboo mat plywood was the first to come out, technological innovation walked with difficulty and got little effect because of its disadvantages.

2.2 Bamboo curtain plywood

Bamboo curtain plywood was a scientific research fruit of Central South Forestry University in 1991. Although came out late, its technological innovation is very effective and has gotten many innovative fruits. So bamboo curtain plywood develops the fast, has the most output and the widest use among all the bamboo based panel serials.

Bamboo curtain plywood, a kind of structural material, is obtained by hot-pressing to bamboo curtains which have been dipped into PF resin and long and short curtains are assembled in crossing method. And its advantage is that lengthwise and transverse intensity can be adjusted by change the quantity ratio of long bamboo curtain to short bamboo curtain. Compared with bamboo mat, bamboo curtain is easy of being processed and being dried, and less adhesive consumed, so it has low cost and high mechanical capability. It can be used as bottom board of train and template for concrete-form.

Because of the great amount of demand for template for concrete-form in market, scientific research innovation of bamboo curtain plywood has been closely to the requirement of satisfying the capability of template for concrete-form. These innovations that aim to decrease energy consumption, to increase bamboo utilization ratio and to decrease cost consist in improvement of structure, in craft and technology, in modification of adhesive, in development of special equipment for processing bamboo curtain and in improvement of its capability.

2.2.1 Improvement of product structure

Used as template for concrete-form, groove in the surface of bamboo curtain plywood must be gotten rid of. In order to do that, instead of bamboo curtain, bamboo mat who have dipped into PF resin can be used as surface layer. Although its surface also has roughness bamboo mat took, it can be used as low-grade template. And it has still been used in the field of architecture so far. On this basement, in order to improve surface smoothness more and to increase water resistance and abrasion resistance, multi-plastics bamboo curtain plywood was obtained by the “cold–hot –cold” hot-pressing process to mat which had been assembled by adding PF or MF dipping paper to the surface of bamboo curtain. The improvement of structure boosted the grade of product and made this product has the most quantity and the widest using among bamboo based panel for template. Because of the using of bamboo mat, the surface of this kind of panel also exists roughness in some degree, and it only could be used as concrete template for houses. Later, inner bamboo curtain was replaced by cross grain wood veneer to promote its surface smoothness, thus boosted the level of product once more. It could be used as template for clear water concrete for bridge building of motorway and railway, so it was called bridge template.

Adopting radical cutting bamboo strips and radical bonding instead of the ordinary chordwise cutting bamboo strips and bonding, radical bamboo strips curtain composite panel was developed in Central-south Forestry University in 1999. This craft need not get rid of bamboo yellow and bamboo cyan, thus could improve bamboo utilization ratio and bamboo strips processing efficiency and decrease cost greatly. The potent number of processing of radical bamboo strips curtain composite panel is CN131251. Through the improvement of aspects above, bamboo curtain has formed reasonable structure basically.

2.2.2 Improvement of hot-pressing craft

Nowadays, one time hot-pressing process is mainly adopted to make multi-plastics bamboo curtain plywood and its hot-pressing craft is “cold-hot-cold”, which does not lead distortion and blister, but it also has some disadvantages, such as long hot-pressing time, low output, much energy consumption and water consumption, low thickness precision and uneven surface color, etc. In order to get over these disadvantages, some factories replaced one time hot-pressing forming process with double processing. First, base board was made by “hot-hot” craft, then base board sanded, and then dipping paper overlaying “hot-hot” pressing or film “hot-hot” pressing. Products made by double processing has high thickness precision and little surface abrasion, thus creates good conditions for export. The improving processing method of multi-plastics bamboo curtain plywood has gotten invention potent (potent number: 97 107942.0).

2.2.3 Modification of adhesive

Adhesive is the main raw material of bamboo curtain plywood, the properties of adhesive affects the quality and cost of product greatly, it also has a important effect on the making-board craft. Nowadays, bamboo curtain plywood mainly adopts high temperature (150±5℃) curing and water-soluble phenol-formaldehyde resin, if adopting “cold-hot-cold” hot-pressing process, more hot steam will be consumed and hot-pressing cycle will be too long. if “hot-hot” hot-pressing craft is adopted, it will easily result in the mat＇s blow, warp, distortion and so on. Therefore, we developed moderate temperature (120±5℃) curing phenol-formaldehyde resin through modification, which could have high curing speed under low temperature. At present, some of factories have used this new type of glue, and they gained favorable economic benefit. In addition, in double processing mode to overlay dipping paper, low-pressure and short -cycle MF resin which could satisfy the demand of rapid overlaying has already replaced high- pressure MF resin as the adhesive to dip raw paper through modification. The modification research of these two types of glue above have already achieved success and applied to production.

2.2.4 Innovation of special equipment for bamboo processing

The industrialized utilization of bamboo, which must be provided with bamboo specific machining equipment, can satisfy the demand for the quantity and quality of semi-finished goods. Bamboo stripe is the raw material of weaving bamboo curtain and bamboo mat, which are the semi-finished products of bamboo curtain plywood. The demand for the bamboo curtain and bamboo mat is enormous. On the early part of 1990s, all these mats and curtains were waved by hand, which would not only result in inefficiency, but also could not insure the quality of products. Therefore, bamboo-knot removing machine, bamboo-culms cutting machine and bamboo stripes-cutting machine and so on were developed one after another, they all greatly improved the machining efficiency of bamboo stripes. At the same time, several kinds of length feeding bamboo-curtain weaving machines which had different structure came out in succession. Because of length feeding, the length of work distance restricted work efficiency of bamboo curtain weaving machine. Recently, cross-feed bamboo stripes weaving machine was developed, which improved the produce efficiency greatly.

The weaving of bamboo mat, not only handwork but also machining needs more time and labour force compared with weaving of bamboo curtain. It is especially difficult to develop bamboo mat weaving machine. Up to now, weaving of bamboo mat entirely is in handwork. It is delightful that two kinds of bamboo mat weaving machine with different structure have been produced recently from Hunan, one is hand-swinging sample bamboo mat-weaving machine, and the other is linkage-working bamboo mat-weaving machine. It can be forecasted that these two machines will be put into application before long.

In a word, on the improvement of structure, modification of glue and development of bamboo special machining equipment, bamboo curtain plywood came through continuous innovation, which has achieved great achievement and accelerated the development of bamboo curtain plywood. These innovations not only upgraded products many times, but also expanded the realm of application, especially increased output greatly. The annual capacity of bamboo curtain plywood reached 70,000,000 m², which was paid attention to by people in the world. The department of construction of China published the standard of bamboo plywood for template JG/T3026-1995 in 1995. As building template with Chinese characteristics, bamboo curtain plywood is one of the three main building templates in China, bamboo curtain plywood, together with steel template and wood-based plywood template constitutes the huge template market in China.

In conclusion, for the sake of satisfying the demand for application of template for concrete-form, the structure of bamboo curtain plywood went through three stages which include bamboo curtain plywood, multi-plastics bamboo curtain plywood, radical bamboo strips curtain plywood respectively; the process of bamboo curtain plywood developed from one time hot-pressing forming to double processing; The grade of product developed from ordinary concrete template to rinsing concrete template for roadway and bridge, and even aim to template for export. At the same time, modification of glue and development of special bamboo processing equipment made great achievements.

2.3 bamboo plate plywood

Bamboo plate plywood is also named by bamboo plywood, which is a scientific research fruit of Academician Zhang Qisheng in Nanjing Forestry University. Its structure component is uniform thick bamboo plate with groove. Bamboo plate plywood, which has symmetry structure, can be obtained by hot-pressing to mat board in which close layers are assembled vertically. Bamboo plate is made by planishing and planing. Bamboo plate plywood can be used not only as common structure material but also as bottom board of motors through lengthening and surface processing. The National Forestry Department released the standard of bamboo plywood for bottom board of motorcar LY1055-91 in 1991. Bamboo plate plywood developed very fast and formed some scale at one time. but it have some disadvantages, such as complex process, low bamboo utilization ratio, big cavities in plywood＇s section. In order to overcome the above disadvantages and exert its predominance, bamboo plate was used as surface layer and fast-grow wood (as poplar) veneer was used as core layer, after roller coating PF resin, mat assembling and hot-pressing, coated bamboo plate plywood was obtained. The multilayer compound structure could make the best of respective merits through assembling them reasonably. The coated bamboo plate plywood has some advantages, such as high intensity and rigidity and preferable surface abrasion resistance. After strictly killing bug and immunity disposal, coated bamboo plate plywood could be used as the bottom board of container for dry cargo, which expanded the realm of its application. At the same time, technicians used the bamboo plate plywood which had sanded with uniform thickness as base board, and wood veneer, PF dipping paper and MF dipping paper in order on the two surfaces of the bamboo plate plywood, then assembled them into mat board of tectorial bamboo plate plywood, and then pressed it into finished product. Tectorial bamboo plate plywood which adopted double processing mode had some advantages, such as high intensity, high thickness precision, bright surface and uniform color and luster, excellent water resistance and abrasion resistance. It is a template for concrete form of high quality.

2.4 Bamboo laminated material

Bamboo laminated material, a kind of structural material, is obtained by laminating parallel all bamboo component having being dried and adding adhesive. It has high lengthways intensity and mainly used as bottom board of train and motorcar. It is a very excellent wood replacer.

Bamboo laminated material has two kinds at present: bamboo strips laminated material and bamboo strips curtain laminated material.

2.4.1 Bamboo strips laminated material

Bamboo strips laminated material has been produced since 1980s, and chordwise bamboo strips with uniform thickness are its components, after laminated along the grain, it can be obtained by “cold-hot-cold” craft. After bamboo strips laminated material is cut into thin strip and processed shiplapped groove in it, it can be used as bottom board of cargo train. The railway department published the technological standard of bamboo strips laminated material for cargo train “TB/T2412---93” in 1993. Because of the low transverse intensity, it more often is made into thick board and used as trip material after it has been cut lengthways. During production term, bamboo strips are long and thin, have poor rigidity, which lead much inconvenience to drying, glue application, spreading and the transportation and store among processes, also can't realize mechanization and serialization. In particular, it is hard to spread mat evenly, which leads to large deviation of thickness and density. If the deviation of the thickness is great panel must be planed with uniform thickness. The great deviation of the density results in bad unification of quality and density of panels, even affects its utilization. For overcoming defects of bamboo strips laminated material in process and quality, Professor Zhao Renjie of Central-south Forestry University substituted bamboo strips curtain laminated material, which used radical bamboo strips bound curtain as core layer and used chordwise single bamboo strips curtain as face layer, for bamboo strips laminated material. This technology has achieved great effects through extensive application.

2.4.2 Bamboo strips curtain laminated material

The component of the bamboo strips curtain laminated material is bamboo strips curtain. Radical bamboo strips bound curtain as core layer and chordwise single bamboo strips curtain as face layer, it has parallel laminated structure. Compared with bamboo strips laminated material, it is added a process of waving bamboo strips to bamboo curtain, but the process can bring much convenience to production and improved panel quality greatly. Using radical bamboo strips bound curtain as core layer not only improves efficiency of processing bamboo strips but improves efficiency of waving curtain. Using two layers of chordwise single strips curtain as surface layer of this kind of panel can improve surface quality. In addition, owning to special elastic press stop which works as forming block in lay-up process and can control both thickness and width of board in hot-pressing process, which makes product reach thickness accuracy demand without planning, remainder of edge trimming could be reduced from formal 7-8cm to about 1cm, thus can improve utilization efficiency of board edge trimming greatly, So it can be said that bamboo strips curtain laminated material was a great innovation for the bamboo strips laminated material, and it can also be regarded as the upgrade product of bamboo strips curtain laminated material. Methods of bamboo strips curtain laminated material has already applied for invention patent on June 2003 and its application number is 03124434.3.

2.5 Bamboo particleboard

Bamboo particleboard uses little diameter bamboo and remainder of bamboo processing as its raw materials. And particle is produced, through drying, glue application, forming and hot-pressing in order, it can be obtained. Bamboo particleboard is a good product which can made good use of small diameter bamboo and improve bamboo utilization ratio. Nowadays, ordinary bamboo particleboard is mainly produced and its property and function is similar to wood particleboard.

At present, few factories produces bamboo particleboard, because if this product is used for furniture and indoor decorative material to get good decorative effect, this kind of stuff must be overlaid, and ordinary painting effect is not very good; If bamboo particleboard is used as structural material, it's mechanical capability can not satisfy demand. Structure of particle sandwich composite board is obtained by using bamboo particle as core layer and strengthening stuff as surface layer in order to strengthen mechanical intensity of bamboo particleboard. Process is still one-time forming technology. First, put one or two layers of strengthening stuff on caul plate, then spread l bamboo particle, and then put one or two layers of strengthening stuff , last, they are formed by hot-pressing. There are two kinds of particle sandwich composite board with different structure and use. In the first structure, dipping paper is served as surface layer, bamboo curtain with adhesive dipping is served as inside layer and bamboo particle is used as core layer. Panel with this structure, whose property is closer to multi-plast