DECONSTRUCTION PROJECT TO EVALUATE THE RECYCLABILITY/REUSABILITY OF THE COMPONENTS AND MATERIALS IN WOODEN HOUSES

Transcription

1 DECONSTRUCTION PROJECT TO EVALUATE THE RECYCLABILITY/REUSABILITY OF THE COMPONENTS AND MATERIALS IN WOODEN HOUSES PART1. THE STATE OF DEMOLITION OF WOODEN HOUSES IN JAPAN AND OUTLINE OF THE PROJECT Tsuyoshi SEIKE Ph.D 1 Kanako SUZUKI 2 Takahiro TSUCHIMOTO Ph.D 3 Junko IDOGAWA KOGA Ph.D 4 1 Graduate School of Frontier Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo , Japan, seike@k.u-tokyo.ac.jp 2 Graduate School of Frontier Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo , Japan, muno.kanako@jcom.home.ne.jp 3 Building Department, National Institute for Land and Infrastructure Management, 1 Tachihara Tsukuba-shi, Ibaraki , Japan, tsuchimoto-t92ta@nilim.go.jp 4 Housing Department, National Institute for Land and Infrastructure Management, 1 Tachihara Tsukuba-shi, Ibaraki , Japan, koga-j2kn@nilim.go.jp Keywords: demolition, deconstruction, wooden house, waste, recycle, reuse, component, material Summary This paper describes the state of demolition and its demolition work flow of wooden houses in Japan. Then reports demolition and waste based on field investigation. The Building Research Institute, the University of Tokyo and 12 industrial corporations joined the deconstruction project to evaluate the possibility of recycling and reuse of components and materials in wooden houses in The objectives of this joint research were to get basic information for investigation into improvement of construction, recyclability, and reusability of components, along with materials which were not recycled. The examined house was dismantled by two methods; Deconstruction the selective dismantlement of materials in detail, and Demolition the conventional demolition. Research team recorded each worker s labor, the quantity and the quality of each component and their material to compare the effects of these methods. Deconstruction in almost all cases requires significantly more time than demolition. On the other hand, considerable improvements in the quality of waste arising can be achieved by the deconstruction. To determine labor requirements for specific deconstruction activities, research team documented the time required to manually disassemble of each component and material. The size, weight and quality were recorded to investigate recyclability and reusability of components and materials. 1. Present Situation of Demolition in Japan The demolition industry produces enormous amounts of waste components and materials, which are becoming unacceptable for their environmental and social impacts. In Japan, there are growing interests for demolition related issues, and demolition industry has been under mandatory control since the Construction Materials Recycling Act was enforced in Construction Materials Recycling Act (2002) The objectives of the act are to reduce, reuse and recycle wasted produced during building demolition and to ensure appropriate waste disposal, and to compensate for disposal cost. The act intended to encourage the sorting of construction waste by material type during demolition of structures and the recycling of waste for designated construction materials. It stipulates the following major obligations; Waste concrete, asphalt and timber should be sorted at the construction and demolition site for recycling (as materials or for combustion) during the construction work of a scale larger than designated

2 Owners are obliged to notify in advance the construction and demolition work of building beyond the specified scale. Demolition contractors should be registered with contractors. The parties involved are required to fulfill the following obligations (Table 1). Owner Contractor Demolition contractor Table 1 Obligations of Construction Materials Recycling Act Notify the administrative authority concerned of the construction plan in advance Bear the demolition cost Sort and recycle the wastes produced by demolition The prime contractor is obliged to notify subcontractors of the plan Explain plans for sorting wastes during demolition and submit completion reports to the owner File applications for registration at prefectural governor s office Assign engineering supervisors and install signs at the site 1.2 Quantity of Wastes and Situation of Recycling in Japan As Figure 1 shows, construction and demolition wastes consist of about 20% of industrial wastes, constitutes about 40% of disposal volume in landfills. The annual production of wastes related construction and demolition work has been estimated to be 11 million tons from new construction and renovation, 16 million tons from demolition, and 55 million tons from the construction of road, bridges, ports etc. as Figure 2 shows. The quantity of construction wastes decreased from 99 million tons (1995) to 83 million tons (2002), do to the reduction of public works, decrease in housing starts, etc. However, the quantity of construction wastes is expected to increase gradually and reach 100 million tons per year by Construction wastes through demolition of buildings will increase rapidly in the future, and top 34 million tons by 2020 (2.1 times as much as in 2002). Foods 3% Ceramics, clay & stone products 3% Mining 3% Chemistry 4% Beverage, cigarette & feed 1% Others 7% Iron & steel 7% Construction Pulp paper & 19% paper products 8% Agriculture 22% Electric power, gas, heat & water supply 23% New construction / Renovation 11 million t 13% Private civil work 3 million t 4% Demolition 16 million t 20% Architecture 27 million t 33% Civil work 55 million t 67% Public civil work 52 million t 63% Figure 1 Quantity of industrial wastes by industry classification in Japan (2002) Figure 2 Quantity of construction wastes for each work division in Japan (2002) The quantity of construction wastes by waste classification is presented in Figure 3, and the situation of recycling for each type of construction waste presented in Figure 4. The recycle ratio of waste has been improved but we still have to make efforts to increase the recycle ratio of some types of waste. At present, bitumen / concrete block, concrete block and metal are almost recycled, but only 61% of wooden construction waste is recycled. On the other hand, the recycle ratio of the mixed waste is still less than 20%, and most of mixed waste is discarded directly to landfills for reasons of technical difficulties.

3 Wooden Mixed waste from construction 3 million t 4% Construction sludge 8 million t 10% construction waste 5 million t 6% Concrete waste 35 million t 42% Others 1 million t 1% Bitumen / concrete waste 30 million t 37% Bitumen / concrete waste Concrete waste Construction sludge Mixed waste from construction Wooden construction waste Total % 20% 40% 60% 80% 100% Recycling Reduction Final disposal Figure 3 Quantity of construction wastes by waste classification Figure 4 Situation of recycling, etc. for each type of construction waste The demolition for small-sized detached wooden houses is quite different from large-sized buildings, as to demolition method, waste quantities and types, state of storage on site and carrying out of waste, etc. There are various types of interior and exterior components in wooden houses. Therefore, the quantity of each component and material is considerably small that most of demolition waste is mixed (except timber, wood, concrete, and metal). The quantity of waste from demolition of wooden houses is increasing, bringing new need for technologies and systems to promote recycling and reuse. 2. Demolition Work in Japan 2.1 Demolition Flow The procedure for demolition of buildings and housings is explained in Figure 5. There are some important steps before starting the dismantling work execution. Particular accounts of each step are as follows; Preliminary survey The first step investigates the conditions of the building or house to be dismantled, including the surrounding area with regard to existence of harmful substances, assortment and Preliminary survey quantity of expected wastes from dismantling, etc. Quantity survey and cost estimate The second step estimates for the costs of temporary work, Quantity survey and cost estimate dismantling work, collection and transport, disposal, etc. Work planning The third step planes of temporary work schedule, selection of Work planning dismantling methods and procedure, selection of carrying-out routes, plan for treatment and disposal, etc. Preliminary measures Preliminary measures The fourth step provides preliminary explanation to the owner, arrangement and application for various approvals, reservation of carrying-out routes, contracting on waste treatment, etc. Dismantling work execution Dismantling work execution This step includes work management, safety management, environmental maintenance, preparations, dismantling, separation, collection, loading and carrying-out of dismantled construction materials. Figure 5 Demolition flow

4 2.2 Demolition Methods There are two methods of demolition in Japan; by hand and by composite way with machine and hand. The indiscriminate demolition method by machine is prohibited by Construction Materials Recycling Act. Demolition is in-effect the reverse of construction; remove hazardous materials, soft strip, and then main frame and finally the foundations Procedure for demolition of wooden houses Figure 6 shows the common procedure for demolition of wooden houses in Japan. Particular accounts of each dismantling step are as follows; Dismantling of building equipment Preparations Lighting fixtures, unit bath, kitchen cabinets, etc. Check of removal of residual objects are dismantled. Building equipment consisted in many cases of complex materials includes woods, Check of removal of hazardous materials metals and plastics. This brings extra complication Dismantling of building equipment to sort its component parts after dismantling. The Construction Material Recycling Act makes it mandatory to dismantle building equipment by hand (except when difficult for structural or technical reasons). Dismantling of interior finishing materials Fittings, interior wall materials, ceiling materials, floor materials, etc. are dismantled. The Dismantling of interior finishing materials Construction Material Recycling Act makes it mandatory to dismantle interior finishing materials by hand (except when difficult for structural or technical reasons). Among other wastes, the quantity of plaster board is especially large among other wastes. As a result of the revision of the Waste Disposal Law, plaster board has to be disposed at controlled type landfill sites. It tends to be fully separated from others due to high cost of its Dismantling of installations on the roof disposal at controlled type landfill sites. Dismantling of roofing materials Dismantling of installations on the roof and roofing materials Roof tiles and slates are removed. The Construction Material Recycling Act makes it mandatory to remove roofing materials by hand (except when difficult for structural or technical reasons). For some kinds of roofing materials, removal by machine also allows sorting so that it can be more efficient and safe as a matter of fact. Dismantling of exterior walls and timbers Namely, removal by hand cannot always be said to be adequate. Waterproofing materials are separated after removal by machine in many cases because they serve as hindrance for concrete regeneration. Dismantling of exterior walls and timbers Exterior walls and superstructure are often dismantled by means of heavy machinery. Where Demolition of foundation etc. site is not wide enough to admit heavy machinery, dismantling by hand is also employed. In case of dismantling by machine, water is sprinkled for dust prevention. Demolition of foundation Foundation is demolished by heavy machinery as shown in the pictures. Concrete lumps are further divided to separate reinforcing bars which are carried out as needed. Ground leveling and cleaning Figure 6 Procedure for demolition of wooden houses

5 2.2.2 Storage and carrying-out of dismounted construction wastes Dismounted construction wastes are sorted and stored in parking or in other outside space available, if any, within the site of the dismantled building (Figure 7: left). Containers or the like may be provided. If no space is available for storage on site, dismounted wastes are carried out of each room to trucks (Figure 7: right). In the latter case, dismounted wastes are temporarily placed on the dismounting spots to lower the working efficiency or to lead to increase of mixed dismounted wastes due to unfavorable sorting conditions or finally to any problem of working safety. Figure Disposal and Recycling of dismounted construction wastes Dismounted construction wastes are carried into the recycle centers and sorted again (Figure 8). Various types of waste are separated: concrete aggregates, metals, timbers, organic waste, plastics, gypsum board, glass and ceramics. Concrete aggregates are used as road construction materials. Metals are well-recycled. Wood chips are produced from good quality wooden wastes. Most of other wastes go to the landfill site. Storage and carrying-out of dismounted construction wastes Figure 8 Recycling of construction wastes 3. Objectives and Outline of the Project The Building Research Institute, the University of Tokyo and 12 industrial corporations joined the deconstruction project to evaluate the possibility of recycling and reuse of components and materials in wooden houses (Table 2). The Building Research Institute Table 2 Organization of the project Graduate School of Frontier Science., The Univ. of Tokyo The Japan Federation of Housing Organization Japan Fiberboard and Particleboard Manufacturers Association Plastic Waste Management Institute Flat Glass Manufacturers Association in Japan Vinyl Environmental Council Interior Floor Manufacturers Association Graduate School of Engineering., The Univ. of Tokyo Housing and Demolition Processing Industry Council Gypsum Board Manufacturers Association Glass Fiber Manufacturers Association Japan Sash Manufacturers Association Japan Vinyl Goods Manufacturers Association Japan PVC Pipe and Fittings Association The objectives of this joint research were to get basic information for investigation into improvement of construction and recyclability and reusability of components and materials which were not recycled. To clarify the present state of art on recycling of the construction wastes through demolition work, we interviewed and sent questionnaires to manufacturers associations of the materials and components before the investigation. This survey was carried out from July 2001 to March in 2002, and the current situations problems were identified and discussed. The following points were decided from this survey. - For developing new technologies to recycle and reuse the dismantled timbers, it is necessary to record the size, weight and existence of damage of all timbers dismantled from the house. - For evaluating the possibility of recycling and reuse of components and materials, it is important to compare between deconstruction (the selective dismantlement in detail) and conventional demolition. The tested wooden house (S-house) was dismantled and recorded from February to March in Other two houses were dismantled from June to July in 2002 for comparison. Research team recorded each worker s labor and quantity and quality of each component and material.

6 3.1 Survey of the tested wooden house The summary of the tested house (S-house) is as follows; built by Japanese conventional post and beam construction system in 1980, renovated in 1990 and deconstructed in The house had 2 stories and the total floor area was square meters. Figure 9 shows the elevations of the tested wooden house. South elevation North elevation Figure 9 East elevation Elevations of the tested wooden house (S-house) West elevation To compare the result with the conventional demolition, other two houses (C-house and H-house) were dismantled and recorded. Table 3 shows the survey of three wooden houses. Table 3 Survey of three wooden houses Name S-house C-house H-house Picture Site area m m m2 Total floor area m m m2 Construction year Number of floors 2 floors 2 floors 2 floors Structure system Japanese conventional post and beam construction system Japanese conventional post and beam construction system Address Urawa Koshigaya Kawagoe Japanese conventional post and beam construction system

7 3.2 Research Method The tested wooden house (S-house) was dismantled by two methods; Deconstruction the selective dismantlement of materials in detail (Figure 10: left) Demolition the conventional demolition (Figure 10: right) Figure 10 Deconstruction Pictures of deconstruction and demolition Demolition Research team recorded each worker s labor and quantity and quality of each component and material to compare the effects of these methods. The tested wooden house was divided in half. The southern part was deconstructed (dismantled and sorted out components and materials in detail), while northern part was demolished in a conventional way. As Figure 11 shows, Seven rooms were deconstructed (1F: living room, dining room, kitchen, extension room, 2F: Japanese-style room, Western-style room B&C), while other seven rooms and stairs were demolished (1F: hall, Japanese-style room, lavatory, utility room, bathroom, 2F: Western-style room A, lavatory). N Demolition Japanesestyle room Westernstyle room A Bathroom Utility room Hall Kitchen Lavatory Lavatory Dining room Japanesestyle room Deconstruction Living room Extension room Westernstyle room B Westernstyle room C 1F 2F Figure 11 Floor plans of deconstructed parts and demolished parts in the tested house (S-house)

8 Table 4 Materials and dismantling methods of each component in the tested wooden house Deconstructioon Demoliti- Material Component Surface Timber or Foundation Wallpaper Gypsum board Wood tile Gypsum board Interior wall Ceramic tile Gypsum board Furring strip Plaster Gypsum plaster Insulation board Wallpaper Gypsum board Plywood Ceiling Ceiling board Zincing iron plate Insulation board Carpet Carpet Heating board Tatami Wood sleeper Floor Wood flooring PVC sheet Heating board Plywood Ceramic tile Mortar setting bed Concrete sub-floor Exterior wall Stucco Mortar Wire lath Asphalt waterproof paper Furring strip Roof Slate Roofing felt Roof sheathing Insulator Glass fiber Foundation Concrete Table 4 shows materials and dismantling methods of each component in the tested wooden house. There are various types of materials. It is characteristic of wooden houses constructed in the last few decades. Figure 12 shows the structure system of tested wooden house. It is Japanese conventional post and beam construction system. Most of deconstruction cases requires considerably more time than demolition. On the other hand, significant improvements in the quality of waste arising can be achieved by the deconstruction. To determine labor requirements for specific deconstruction activities, research team documented the time required to disassemble manually each component and material. Simultaneously, the size, weight and quality were recorded to investigate recyclability and reusability of components and materials. Part2 describes the result of case study, the need for further research to develop recycling and reuse, and gives an overview of issues relating to demolition of wooden houses. Figure 12 Structure system of tested wooden house References Suzuki, K. 2004, Study on recycling building components and materials in view of demolition, Proceedings of twentieth symposium on organization and management of building construction, pp Koga, I.J. 2003, A state of art report on recycling of finishing materials, AIJ Journal of Technology and Design, NO.17, pp Charles, J.K. & Abdol, R.C. 2000, Overview of deconstruction in selected countries, CIB Report, Publication 252