National R&D Project to Promote Recycle and Reuse of Timber Constructions in Japan

NATIONAL R&D PROJECT TO PROMOTE RECYCLE AND REUSE OF TIMBER CONSTRUCTIONS IN JAPAN – THE SECOND YEAR’S RESULTS

Shiro Nakajima (Building Research Institute, Tsukuba, Ibaraki); Mikio Futaki (National Institute for Land and Infrastructure Management, Ministry of Land Infrastructure and Transport, Tsukuba, Ibaraki)

SUMMARY

The waste generated by the construction industry is a serious social problem in Japan. And several organization and groups have started new projects to reduce the production of waste and to promote the reuse and recycling of construction and demolition waste. The government announced a new recycle law in May 2000 and this new law will befully effective in May 2002.

A national R&D project to develop technologies to reduce the waste in the process of dismantling wooden buildings started in April 2000. The final targets of this project are (1) to develop demountable and recyclable wooden buildings, (2) to develop new technologies for recycling building waste and residue and (3) to develop information transfer systems to disseminate the developed technologies.

The outlines of the second year’s results of the project are reported in this paper

To develop demountable and recyclable wooden buildings, the current design of the two construction systems used in Japan, the post and beam construction system and the 2 by 4 construction system were analyzed. All of the connections and the materials and components used in the buildings were reviewed to give alternative designs to the two construction systems. And model structureswere constructed by the new design methods and deconstructed as a showcase.

To develop new technologies for recycling building waste and residue the recycle processes of the representative building materials and components were studied. And the recycle potential of each material was investigated. And particularly for wooden waste and residue some new recycle technologies were proposed and developed.

To transfer the technical information and to promote the waste reduction in local areas the environment impact evaluation tool is being developed. This tool can calculate CO2 emissions, resource consumption and waste production of wooden buildings. The program will also give a guide for the best practice in the local area. Two local areas in Japan are involved to develop this tool and case studies will be conducted in these two areas.

KEYWORDS: C&D Waste, Wooden Buildings, Dismantle, Recycle and Reuse, Construction Methods, Environmental Impact

INTRODUCTION

Each year, there is an increasing amount of wooden materials left behind from the renovation or dismantling of timber structures. A large portion of these wooden materials become waste, rather than being recycled, thereby damaging the local and global environment and creating a serious community issues. In order to sustain the timber construction business into the 21st century, including the construction of wooden houses, broad-ranging recycling technologies to reuse the dismantled materials that appear throughout the lifecycle of buildings should be developed above and beyond the construction industry.

On the other hand, great amounts of resources are consumed in the process of building wooden houses and as the life spans of these wooden houses are very short in Japan these resources are disposed of over a short period of time. There is a pressing need for the development of technologies to increase the life span of wooden houses and to create a large stock of wooden houses.

As the waste coming out from the construction industry is getting a serious social problem in Japan several organizations and groups have started new projects to reduce the production of waste and also to promote the reuse and recycle of construction and demolition waste. And in May 2000 the former Ministry of Construction (current Ministry of Land, Infrastructure and Transport) announced officially a new law that stipulates the deconstruction process and promotes the recycling of construction and demolition waste. The whole part of the law will be fully effective in May 2002.

The Building Research Institute and the National Institute for Land and Infrastructure Management started a joint national R&D projects to develop technologies to reduce waste and to promote reuse and recycle of building materials and components in 2000. The final target of this R&D projects is to reduce the amount of the waste and also to promote the recycle and reuse of construction and demolition waste in the whole life cycle of timber buildings.

CURRENT SITUATION OF C&D WASTE IN JAPAN

The Japanese Governmentreports every 5 years the status of waste generated from the building construction activities [1][2].

The total weight of the waste generated from the construction industries in 1996 was approximately 99 million tons and three fifth of the waste was from the civil engineering activities and the two fifth of the waste was from the building activities. And as to the waste from the building activities two fifth of the waste was construction waste and three fifth of the waste was demolition waste. The amount of the waste has been reduced for approximately 10% and the total weight of the waste generated in 2001 was around 85 million tons. As to the waste from the building activities 40% of the waste was the construction waste and 60% of the waste was the demolition waste in 2001 (See Figure 1).

Figure 2 shows the amount of waste landfill and recycled in the construction industries in 1996 and 2001. The amount of landfillwastedecreasedsignificantly in these 5 years and the amount of waste that has been recycled increased in this 5 years.

Table 1 shows the type, amount and recycle ratio of the waste discharged by the construction industries in 1991, 1996 and 2001. The main C&D waste was concrete aggregate, mixed waste and wooden waste. The recycle ratio has been improved for these five years but we still have to make efforts to increase the recycle ratio of some types of construction waste. For example the mixed waste and the wooden waste show lower recycle ratio than the concrete aggregates. The recycle ratio of the wooden waste was 38% in 2001 and this was 2 point less than the recycle ratio in 1996. And the recycle ratio of the mixed waste was still less than 10%.

The government announced that the targeted recycle portion of the wooden waste in the year 2010 as 95%. In the sense that thermal recovery or simple burning will reduce the amount of landfill waste, thermal recovery or reduction by burning are categorized as recycle. The total amount of the wooden waste that went to thermal recovery, simple burning and material recycle was 83% of the whole wooden waste discharged from construction activities in Japan. Recycle ratio 83% seems to be close to the targeted recycle ratio for the year 2010. But as the actual recycle ratio of the wooden waste is 40%, new technologies and policies are still required to improve this situation.

Table 1 Type, amount and recycle ratio of the waste

Illegal or improper disposal of waste is a social problem in Japan that should be immediately solved. Table 2 shows the types and amount of the improperly disposed waste reported by the Ministry of Environment in 2001[3]. 433,292.5tons of waste wasimproperly disposed of in 2000. The amount of the illegally disposed construction waste was 303,997.8tons and it was more than 70% of total amount of the illegally disposed waste. When we look at the type of the illegally disposed waste 25% is concrete, 25% is wood and 20% is other construction waste. Wood waste generated in the process of constructing and dismantling wooden houses is largely the cause of this situation.

Table 2. Type and weight of the improperly disposed waste

Other issue is the capacity of the landfill sites. It is estimated that the landfill sites have their capacities to accept waste no longer than 0.8 years in the Tokyo area and 3.3 years in the whole country.

To improve the current situation and to give a hopeful light to the next generation, the government worked on a new law that stipulates the deconstruction process and promotes the recycling of construction and demolition waste. The details of the law were officially announced in May 2000. The law is roughly composed of five items as follows:

(1)Requirement for selective dismantling and recycling.

(2)Action to promote recycling and demolition.

(3)Adjust the contract between the owner and the dealer.

(4)The establishment of registration system to demolition dealer.

(5)The settings of objective concerning recycle.

Requirement for selective dismantling and recycling

For buildings beyond a certain minimum size, selective dismantling to recover specific materials such as concrete, asphalt and wood is required. It is expected that these requirements will be expanded and increased in the future.

Action to promote recycling and demolition

The owner of the building scheduled for removal is required to report the removal prior to demolition and the results of dismantling and recycling of materials at the end of the process.

Adjust the contract between the owner and the dealer

The subcontractor undertaking deconstruction must provide a plan for selective dismantling to the owner. The method of selective dismantling and the expense must be specified for the demolition work.

The establishment of registration system to demolition dealer

The subcontractor undertaking demolition needs to register with the municipality and local district. The demolition subcontractor must engage an engineer who manages the various technologies for demolition. Because the budget for demolition is typically small, it is not necessary to get the permission of local government. Thus it is easy for an unqualified and unlicensed contractor to provide demolition services. This is one of the reasons why illegal dumping of waste occurs as well as indiscriminate dismantling of structures.

The settings of objective concerning recycle

As the basic policy, the recycling and the reuse of construction materials are promoted by creating an action plan. Getting the cooperation of the owner is very helpful in recycling and reuse.

ASSEMLE PROCESS IN THE RECYCLE CENTER [4]

Construction and demolition waste is carried into the recycle centers and sorted again to minimize the amount of waste that should be controlled when they are taken into the landfill facilities (see photo 1). Various types of waste are separated: steel waste, paper waste, plastic waste, wooden waste, concrete aggregates and mixed waste (see photo 2). The wastes roughly assorted on the construction sites are almost separated when they come into the recycle center.

Wooden waste

Photo 3 shows the wooden waste assembled in the recycle center. Most of this waste is produced in the process of constructing or dismantling wooden houses. Wood chipsare produced from good quality wooden waste such as large size lumbers (see photo 4). But as the virgin chip is cheaper than the recycled one, some of the particleboard producing companies and the pulp and paper producing companies are still using the virgin chip for their products.

Plastic waste

Photo 5 shows the plastic waste assembled in the recycle center. Plastic waste goes to the landfill site. Plastic waste shown in photo 5 travels to the landfill site located 1000km away from the recycle center.

Paper waste

Photo 6 shows the paper waste assembled in the recycle center. Paper materials are selected from the paper waste and non-paper materials are taken away by hand.

Steel waste

Photo 7 shows the steel waste assembled in the recycle center. Steel is the one of the materials that is well-recycled in Japan. Steel materials are collect by a magnetic device and separated from the non-steel waste.

Concrete waste.

Photo 8 shows the concrete waste assembled in the recycle center. Concrete wastes are also well-recycled in Japan and most of them are used as road construction materials.

Mixed waste

Photo 9 shows the waste that was not sorted on the construction site. The mixed waste is separated into wooden waste, steel waste, plastic waste, etc.to maximize the recycle ratio and to minimize the amount of landfill waste. The sorting process will start from separating the waste roughly to several types. The waste are spread on the ground of the recycle center and four or five workers pick up big size steel, wood, plastic, concrete and others, and put them into the rooms that are prepared for each type of waste (see photo 10). And the small size waste goes to a line separation process. And here again 10 or 11 workers separate the waste into several types (see photo 11).

OUTLINE OF THE R&D PROJECT

The volume of the waste generated in the process of dismantling wooden buildings is increasing yearly. It is quite necessary to promote the recycle and reuse of the resources consumed in the process of constructing wooden structures. And new systems and technologies that enable the reduction of the volume of the waste generated in the building activities are also strongly required. A national research project [5] is ongoing from the fiscal year 2000 to 2002. In this project we are developing new construction methods, formulating technical guidelines and compiling design and construction manual for remountable wooden constructions. And we are also developing recycle and reuse technologies to reduce the waste produced in the process of dismantling wooden buildings.

The project is composed of three research subjects. The research subjects are as follows:

(1)Development of the design and construction methods to reduce the waste products in the wooden building activities.

(2)Development of the recycling technologies for building materials and components.

(3)Development of the evaluation technologies.

Development of the design and construction methods

Figure 3 shows the outline of the research program to develop the design and construction methods to reduce the waste generated in the process of constructing and dismantling wooden building. The current design and construction methods for the 2 by 4 construction system and the post and beam construction system were reviewed to develop the necessarytechnologies to design and construct recyclable and remountable wooden constructions. In detail we are developing the following three new technologies.

-Technologies to design and evaluate low environmental impact building materials.

-Technologies to design and construct recyclable and remountable wooden buildings.

-Technologies to design and construct sustainable wooden buildings.

Recycle and reuse technology

Figure 4 shows the outline of the research program to develop recycle and reuse technology. In this research program we are developingnew technologies to promote reuse and recycle of the wooden waste and the other waste generated. In detail we developed the following three new technologies.

-Technologies to reuse the dismantled timber materials.

-Technologies to recycle the waste at the materials level.

-Technologies to recycle the waste at the raw materials level.

And we will also propose reuse and recycle systems that will work well to reduce the amount of waste that goes to the landfill site.

Evaluation technology

To develop the evaluation system we are collecting data for evaluation and discussing the inventories that should be considered. We will propose some simulation model and estimate the waste produced in the future. And we will do some case studies to estimate the efficiency of the newly developed technologies.

RESULTS

Analysis of the wooden waste

Lumbers salvaged from one single detached wooden house were investigated to make a database of the lumbers salvaged from wooden houses. 10 university students joined the project. Approximately 2000 pieces of large and small lumbers and boards were investigated. Thedata will give basicinformation that will be useful to discuss the remountable and recyclable design of wooden buildings and it will also show the possibility of recycle for each lumber according to its size and condition.

Materials

Almost all of the lumbers salvage from one single detached wooden house were collected and investigated. The house was built by the Japanese conventional post and beam construction system in 1974 and dismantled in 2000. The house had two stories and the total floor area was 144m2. Machine dismantle was used to dismantle the wooden structure of the house. With the aid of one dismantling machine, 4 carpenters dismantled the whole house in 8 days. Figure 5 shows the elevation and the floor plan of the house.

The house was dismantled following the process shown below. Photos 12 to 15 show the dismantling process.

(1)Remove the window glass by hand

(2)Remove the joiners by hand

(3)Remove the wallpaper and gypsum board by hand