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 be fully
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 structures were 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 Government reports 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 landfill waste decreased significantly in these 5 years and
the amount of waste that has been recycled increased in this 5 years.
Enginnering
Works
Buildings &
Houses
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
D em olition W aste
1996
2001
C onstruction/R enovation
W aste
P rivate Engineering
W orks
P ublic Engineering W orks
0
20
30
40
50
Totalam ount (m illion tons)
60
Landfill
Waste generated from the construction industry in Japan – in the year 1996
and 2001.
Recycled
Figure 1.
10
B uildings &
H ouses
1996
2001
Engineering
W orks
B uildings &
H ouses
Engineering
W orks
0
10
20
30
40
50
Totalam ount (m illion tons)
Figure 2. Amount of the waste landfilled and recycled.
Note: Recycle includes reduction by the methods of burning.
60
70
2 point less than the recycle ratio in 1996.
still less than 10%.
And the recycle ratio of the mixed waste was
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
1991
1996
Weight Recycle Weight
Type of waste
(million ratio
(million
tons)
(%)
tons)
Construction waste
42
99
Asphalt
50
36
Concrete
48
36
Mixed
31
10
Wood
56
6
Soil and rock
21
10
Recycle
ratio
(%)
57
81
65
6
40
6
2001
Weight
(million
tons)
85
30
35
5
5
8
Recycle
ratio
(%)
81
98
96
7
38
30
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 was improperly 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
Type of waste
Weight (tons)
Ratio (%)
Concrete
107,729.6
25%
Wood
108,233.3
25%
Other construction waste
88,034.9
20%
Plastics
76,961.4
18%
Steel
7,925.6
2%
Ash
9,458.9
2%
Mud waste
13,932.0
3%
Glass/Ceramic
2,582.8
1%
Organic waste
2,050.5
1%
Other
16,383.6
4%
Total
433,292.5
100%
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 land fill
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.
Photo 1. C&D waste carried into the
recycle center.
Photo 2.
C&D waste.
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 chips are
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.
Photo 3.
Wood waste.
Photo 4.
Wood chips.
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.
Photo 5.
Plastic waste .
Photo 6.
Paper waste.
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.
Photo 7.
Steel waste.
Photo 8.
Concrete waste.
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).
Photo 9. Mixed waste.
Photo 10.
Rough separation process of
the mixed waste.
Photo 11.
Line separation process of
the mixed waste.
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 necessary
technologies 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.
Development of low environmental
impact building materials
-
Environmental impact evaluation of the preserved wood.
Environmental impact evaluation of wooden composite materials.
Environmental impact evaluation of finishing materials.
Development of design and construction methods for
recyclable wooden buildings
-
103ｙｒ
98yr
Structural design of the joints and the structure.
Design and evaluation of the structural members.
Design and evaluation of the wooden materials and components.
Development of design and construction methods for
sustainable wooden buildings
78yr
100yr
-
Designing and construction methods to construct long service life
wooden buildings.
69yr
87yr
Figure 3.
Outline of the research program - develop of design and
construction methods.
Development of the technologies for the reuse of
dismantled timber materials
-
Reuse of beam and columns.
Reuse of finishing materials.
Development of the technologies for the recycling the
waste materials at materials level
-
Development and evaluation of structural building materials made
of wooden waste.
Evaluation of dismantled finishing materials for recycle.
Conversion into fuel
?
Recycle
Forms
Boards
Development of the technologies
for the recycling the waste
materials at the raw material level
-
Conversion into charcoal
Figure 4.
Technologies to convert waste into
charcoal.
Outline of the research program – recycle and reuse
technology.
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 developing new 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. The data will give basic
information 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
(a) Elevation.
Figure 5.
(b) Floor plan.
Elevation and floor plan of
the house.
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.
dismantling process.
(1) Remove the window glass by hand
(2) Remove the joiners by hand
(3) Remove the wallpaper and gypsum board by hand
(4) Remove the roofing materials by hand
(5) Remove the insulation materials by hand
(6) Remove the steel materials by hand
(7) Dismantle the structure by machine
Photo 12.
Outside view of the house.
Window glass removed.
Photo 14.
Dismantling the structure.
Photo 13.
Photo 15.
Photos 12 to 15 show the
Inside view of the house.
Gypsum board removed.
Salvaged lumbers.
Investigation
Four faces and two ends of every piece of lumber were investigated. The size, weight and
existence of damage were recorded for all lumbers salvaged from the house. And the type
and location of the attached materials such as nails, bolts, metals, plastics, etc. were also
recorded. Figure 6 shows one example of the recorded test results.
Results
Figure 6.
An example of the test result - test results of the beam
shown in photo 16.
The results are summarized in table 3. 1860
pieces of lumbers and boards were investigated.
The total weight of the lumbers and boards was
around 8540kg and almost one-third of them
were posts and beams. The total volume of the
lumbers was around 13m3.
Discussion
To discuss the possibility of recycle of these
lumbers the salvaged lumbers were assorted into
Photo 16. Test specimen – beam.
several levels. Each level has different recycle
possibility. The criteria to evaluate the recycle
potential of the salvaged lumber for reuse is summarized in table 4 and that for material
recycle are summarized in table 5.
Table 4.
Level
L1
Criteria to evaluate the recycle potential of salvaged lumber for reused.
Criteria
Recycled products
Lumbers with large cross section. Lumbers that have Structural lumber.
less than three mortises. Lumbers with almost no
damage. Lumbers with less than 30 nails. Lumbers
with almost no other materials attached.
L2
Lumbers with almost no damage excluding the notches. Lamella of glulam.
Lumbers with one or two materials attached.
L3
Lumbers not categorized in level L1 and L2.
-
Table 3. The type, amount and condition of the lumbers salvaged.
Member type
Weight
(kg)
Volume
(m3)
Amount
Column
1203
2.52
91
Average
number of
the
nails
attached to
the lumber
29.5
Beam
1589
2.9
99
5.4
Girder
63
Sill
183
Purlin
377
Small sized lumber
842
Floor post
202
Number of
the lumbers
with no nail
attached
5
Number of
Number of
the lumbers
the lumbers
with more
with certain
than
10
damages
notches
29
29
(5.5%)
0.1
0.83
2.76
1.75
4
25
47
1129
20
6
6.7
7.6
(31.9%)
(42.9%)
26
25
10
9
(26.3%)
(25.3%)
(10.1%)
(9.1%)
0
1
0
0
(0%)
(25.0%)
(0%)
(0%)
1
9
1
5
(4.0%)
(36.0%)
(4.0%)
(20.0%)
8
18
10
3
(17.0%)
(38.3%)
(21.3%)
(6.4%)
46
176
-
74
(8.0%)
58
0.45
-
71
32
3.2
3.2
470
Finishing materials
510
0.83
175
7.6
Roof board
864
Plywood
905
Floor board
685
Small piece of wood
589
Total
8540
12.99
Note: Figures in the parentheses show the occurrence ratio.
185
1860
8.5
-
(6.5%)
0
0
3
(26.8%)
(0%)
(0%)
(4.2%)
1
7
38
1
(18.4%)
(100%)
(2.6%)
55
-
19
6
(4.6%)
0.85
(15.0%)
19
(3.2%)
Brace
(31.9%)
Number of
the lumbers
with other
materials
attached
39
(31.4%)
17.9
91
(9.1%)
(48.7%)
-
-
(10.9%)
-
55
(29.4%)
-
-
Table 5.
Level
C1
Criteria to evaluate the recycle potential of salvaged lumber for material recycle.
Criteria
Recycled products
Lumbers with cross-section larger than 80x80mm. Pulp chips
Lumbers with no damage.
Lumbers not painted.
Lumbers attached with less than 20 other materials.
C2
Lumbers with cross-section smaller than 80x80mm. Pulp chips
Lumbers with no significant damage. Lumbers not Board chips
painted. Plywood 5mm or more in thickness.
C3
Lumbers with large cross-section and significant damage. Board chips
Plywood 5mm or less in thickness. Short lumbers with
small cross-section.
Lumbers attached with other
materials and dirt.
C4
Painted lumber. Lumbers with significant decay and Fuel
termites attack. Small pieces of wood.
Figure 7 shows the result of the
analysis. Almost 9% of all lumber
salvaged
from
a
Japanese
conventional post and beam house
have the potential to be reused as
structural lumbers and 22% have the
potential to be reused as lamella of
glulams. And almost 73% of the
lumbers have the potential to be
recycled as chips and to be used as
the raw materials for pulp and boards.
When we look at the member types,
beams seem to have higher
possibility for reuse or recycle than
columns.
Beam
L1
L2
L3
Column
All lumbers
0%
20%
40%
60%
80%
100%
Beam
C1
C2
C3
C4
Column
All lumbers
0%
20%
40%
60%
80%
100%
Figure 7. Results of the analysis.
Lumbers with large cross section, no
damage, no notch and less attached
materials have high potential for reuse and recycle. This kind of information will be very
useful and important to improve the design of wooden houses. And recycle potential of the
lumbers also depends on the deconstruction method. Same kind of program is planed in the
spring of 2002. This time the tested house would be completely deconstructed by hand.
Building design for reuse and recycle
The designing philosophy and construction methods for buildings should be reviewed to
reduce the waste from the building activities. As buildings were designed and built to
satisfy the requirement of the customers their performance such as structural performance,
durability or indoor quality was only taken into account. The performance of the buildings
after their service life was seldom discussed in the process of building design. Recently as
the effective utilization of natural resources and the reduction of waste is the key issues in
Japan and probably in many countries buildings should be designed considering every aspect
through their lifecycle. So the possibility of recycle and reuse of the building itself should
also be taken into account in the process of initial design.
Alternative design methods for remountable wooden houses are discussed in the project. To
propose new designing ideas for remountable wooden houses the current design was
analyzed. Some examples of the summary sheet of the analysis are shown in figure 8. As
we have two major construction systems for wooden houses in Japan both construction
systems were analyzed. The detail design of the floors, walls, ceilings and roofs were
checked.
Taking into account of the results of the analysis some new ideas for design were proposed
by the member of the research group composed by BRI members, university staffs,
homebuilders and designers. Some examples of the ideas are as follows:
(1) Use double head nails to connect metal joints.
(2) Use wood screws to connect boards.
(3) Standardize the joints.
(4) Standardize the module of the
members.
(5) Use glulam structures for the post
and beam construction system.
(6) Utilization of massive-holz.
To verify the effect of the proposed ideas
a demonstrative test program will be
conducted in spring 2002. Three post
and beam model structures and two 2by4
construction models will be constructed
and deconstructed. The approximate
size and shape of the models are shown
in figure 9. The detail specifications of
the models are now in discussion.
The project will also correct widely the
new ideas for remountable wooden
buildings from designers, carpenters and
homebuilders.
A full-scale single
detached house will be designed based
on these new ideas and a demonstrative
construction and deconstruction test will
be conducted in the fiscal year 2002.
Figure 9.
Size and shape of the 2x4
Construction model structures.
Summary sheet of the analysis – example (1)
【Construction Method】
【Component】
Japanese Post and Beam Construction System
Sill - Joist
【Joint】
Sill
【Figure】
【Design】
Jointed with notch and two nails
(N90).
【Problem for recycling】
・ To separate sill and joist two N90
nails should be removed. These
nails are very difficult to remove
on site.
・ There is a notch on the sill and
this notch makes it difficult to
reuse the sill.
・ The sill is usually chemically
preserved and the preserved
lumbers are difficult to reuse and
recycle.
【Measurement】
・ Use wood screws instead of nails to joint the sill and the joist.
・ Use metal hanger to setup the joist.
・ Use durable materials for the sill and the joist.
・ Develop recycle methods for the chemically preserved lumbers.
・
【Others】
Summary sheet of the analysis – example (2)
【Construction Method】
【Component】
2 by 4 Construction System
【Joint】
Rafter /Ridge beam
【Figure】
Rafter – Ridge beam
【Design】
Rafters are connected to the ridge
beam by nail(CN75 or CN90) .
【Problem for recycling】
・ Roof structure is deconstructed in
the following order.
1) Rafter ?
2) Rafter
3) Ridge beam
・ Roof structure becomes unstable
when deconstruction proceeds.
・ Difficult to pull out nails in a high
place.
【Measurement】
・ Develop a cutting device.
・ Develop easy to remove roof boards.
【Others】
Figure 8.
Examples of the summary sheet of the analysis.
All these test results will be summarized and the design and construction manual for the
remountable wooden buildings will be published. The drafted contents of the design and
construction manual are shown in figure 10.
Chapter 1; Introduction
Chapter 2; Materials and components to be used
Chapter 3; Designing methods
3.1; How to design foundation
3.2; How to design members
3.3; How to design Joints
3.4; How to design structural components
3.5; How to design non-structural components
Chapter 4; Construction methods
Chapter 5; Evaluation of the recycle and reuse potential
Appendix; Examples
Figure 10.
The draft contents of the design manual.
Detail study of dismantle and deconstruction
The whole deconstruction process of one post and beam wooden house and the whole
dismantle process of one 2x4 wooden house was recorded. The recorded data are being
analyzed to present the guidelines for deconstruction or demolition. Another three post and
beam wooden houses will also be investigated to record their deconstruction process.
Recycle and reuse technologies for building materials and components
Wooden materials and components
New technologies that will promote the recycle and reuse of wooden building materials and
components are being developed in the project. The reuse and recycle categories for wood
materials can be summarized as shown in table 6. Recycled wood chips have been used as
the raw materials for pulp or particleboards. As pulp is produced only from the high quality
wood chips we have to find a place where we can consume middle or low quality wood chips.
Particleboard or fiberboard producers have played a very important role in consuming the
middle and low quality wood chips for these few decades. As it is estimated that the
particleboard and fiberboard industry can consume a maximum of one-third of the wood
waste generated from the construction industry we have to prepare other technologies that
can consume the rest two-third of the wood waste.
In the project the following technologies are being developed.
(1) Reuse technology for lumbers.
(2) Technologies to produce recycled lumbers.
(3) Technologies to produce high performance recycle wood boards.
(4) Technologies to use recycled charcoal as landfill material.
Table 6. The reuse and recycle categories for wooden materials.
Categories of recycle
Technologies
Reuse technologies for buildings
Reduce
Others
Reuse technologies for post and beams
Reuse
Reuse technologies for joiners
Others
Technologies to produce chip and fiber
Technologies to produce recycled lumbers
Recycle
Technologies to produce recycled panels
Others
Technologies to produce recycled insulation materials
Technologies to produce charcoal
Material recycle
Technologies to use charcoal as landfill material
Others
Technologies for thermal recycle
Thermal recycle
Technologies for adequate burn
Others
Technologies for adequate landfill
Landfill
Others
Usage of Charcoal to Ground Materials
It is very important to utilize dismantled wooden materials effectively to maintain the global
environment. To achieve this aim, the reuse of wooden materials as column, beam or fixtures
is an effective way to make use of used wooden materials. On the other hand the
carbonizing of the used wooden materials, may be one of the effective ways to fix the carbon
dioxide from the global environment, can create new problems such as a lot of unsuitable
charcoal as with harmful components.
This study tries to propose how to use the charcoal, which is made of carbonizing wooden
chips from demolished wooden houses as substitutes for earthen materials on the
construction site. Earthen materials are used for the various purposes as follows:
1) To support the structure
2) To improve the drainage
3) To raise the plant
4) To purify the groundwater
The usage of the charcoal will be investigated related as an energy source and for 1), 2)
above.
[Contents of investigations]
1) Thermal resources
The electricity production by coal is available to use a mount of low quality charcoal,
burning coal with wood chips together.
This method has some problems, such as decreased generating efficiency, and it needs the
crushing of wooden materials into small pieces. By using charcoal in place of wooden
materials, these problems will be resolved in future. The coal electricity production plant will
be able to produce a lot of charcoal by making use of own thermal effectiveness and can get
rid of harmful materials with the own filter in the production plant. On the other hand it is not
permitted for this plant to burn waste materials under the present law but it should be
improved soon, because of the possibility of refuse derived fuel (RDF).
2) The use as earthen materials
It needs the strength of soils to bear the structures like buildings on the ground. Soil strength
drives from the confined stress to the soils, because soil has little cohesive strength. To
increase the confined stress it is effective to use soil pack. Soil pack method is a way of
general reinforced soil techniques.
The investigation on the deformation characteristics of packed charcoal will be performed in
the study. Charcoal is less weak than soil particles and is deformable much more.
Assembled charcoal has a lot of void, which helps to drain water smoothly in the ground. In
construction site, for instance, gravel layers are installed behind the retaining wall to drain
water from the ground to the front. The retaining wall has some holes connected with the
gravel layer to drain water. Packed charcoal can be used in place of the gravel layer.
Charcoal
To thermal use in
future
Figure 11.
Usage to Ground Materials.
Reuse
as
column, beam,
and fixture
Carbonization is a way to use wooden chips
as ground material or thermal resources.
To use as ground material has a function of
buffer to supply charcoal stably.
It is a point whether charcoal from
dismantled houses is waste or not.
Wooden Waste
Wooden Waste
Merchandizing
With harmful
Materials
Yes
Reuse?
To Chip, Fiber,
Column,
Beam,
Fixture
Regulation of demand and
supply to Merchandize
Loss
No
Merchandizing
PlateWaste
Wooden
With harmful
Yes
Reuse?
To Materials
Heat
Insulating,
Charcoal, Fuel,
Wooden
Plastic,Waste
Resin
With harmful
Materials
Particleboard
etc.
Inventory Adjustment
Loss
Merchandizing
No
Yes
Reuse?
Charcoal,
RDF and etc.
Little Distribution quantity
Loss
Wooden
chips
Charcoal
No
Un-wooden
Waste
Vinyl chloride,
Roof tile
Concrete
Carbonization
Charcoal
Safe charcoal
Safe
Transportation
Charcoal
With harmful
Materials
Convert
Fuel
Stabilized
By Slag
to
Wooden
chips
Ash
Use into Ground
Burning with coal
Removal of
harmful material
With harmful
Materials
STOCK
Convert to Fuel
Fuel
Ash
Thermal Recycle
Charcoal
Decontamination
No
Restricted
FILL UP
Stable
Filling
Figure 12.
Recycle by Material
Constructed
Ground
The recycling flow of wooden chips
Mounts of charcoal are available to store under the ground like the park and they should be
used again as the thermal resources, if necessary. Charcoal also has a lot of small voids in
its particles and it is good medium in which to grow plants. Charcoal should be mixed into
the ground and help the transmission of air in the ground. This is well known in general.
Another case is that a lot of charcoals are laid at the bottom of water (like a river) to clean
water, because of the absorption of various materials and action by bacteria.
Finishing materials and components
Finishing materials waste such as gypsum boards, wallpaper, plastics materials from the
dismantle sites are not well recycled in Japan. As huge amounts of the demolition waste are
composed of finishing materials and we have to launch new projects to develop new recycle
technologies for these finishing materials. Some industries already have some technologies
to recycle their products. To promote their recycle programs adequate deconstruction
systems and delivery systems should also be proposed by the construction industry.
Production (ton)
800000
600000
400000
200000
0
1950
1960
1970
1980
1990
2000
2010
Year
Figure 13.
Production of the gypsum from 1950 to 2010.
Table 7.
State of the art of the gypsum board producing industry.
Current level of recycle
Annual
Annual
Discharged
Level
Recycle
production waste
Location
ratio
In the mills
Gypsum is material recycled and Almost
paper is thermal recycled.
100%
4,680,000
tons
1,739,000
tons
At
the Gypsum boards discharged from 38.3 %
construction sites the big construction site are being
collected
and
recycled
particularly in the urban area.
Gypsum boards discharged from
the small construction site are not
recycled at all.
At the
Not recycled.
dismantle sites
Note: The data shown in the table is that of the year 2000.
Under
1.0%
The production of gypsum board from 1950 to 2000 and the estimated production of the
gypsum board after 2001 are summarized in figure 13. More than 700 thousand tons of
gypsum boards will be installed in building in 2010 and the installed gypsum board will be
generated when the buildings are dismantled or renovated.
The technical levels of the industries for recycling their products are discussed in the project
and the states of the art are reported. For example table 7 shows the state of the art of the
gypsum board production industry. Approximately one-third of the gypsum board waste
from the construction sites are recycled and that from the dismantle sites are actually not
recycled at all.
Evaluation
Service Life
The evaluation method to evaluate
Summary
the sustainability of wooden
Table of the
buildings is under development. Calculation
And the evaluation tool is under
development by revising the
building design and assessment
Construction
Results
Service
tool developed in 1996 [6][7].
The database of the tool would be
Renovation
of
Dismantle/
revised and new inventories would Production
Building
Demolition
Components
be included. The tool would be
designed so that the life cycle Figure 14. The design and assessment tool released
resource consumption and waste
in 1996.
production of wooden buildings
could be calculated. Data was collected in 2001 and the tool will be fully revised in autumn
2002 with an English version.
CONCLUSION
In this paper the current situation of the C&D waste was reported base on the statistical data
provided by the government. 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.
And the total amount of the illegally disposed construction waste in 2000 was 303,997.8tons
and it was more than 70% of total amount of the illegally disposed waste. It is considered
that wooden waste generated in the process of constructing and dismantling wooden houses
are very responsible for this situation. On the other hand it is estimated that the landfill
sites have their capacities to accept waste for no longer than 0.8 years in the Tokyo area and
3.3 years in the whole country. Another issue for C&D waste in Japan is the capacity of the
landfill sites.
The second year results of the joint national R&D projects with The Building Research
Institute and the National Institute for Land and Infrastructure Management was reported in
this paper.
The results of the investigation of the lumbers from the dismantled post and beam house
shows that lumbers with large cross section, no damage, no notch and less attached materials
have high potential for reuse and recycle. This kind of information will be very useful and
important to improve the design of wooden houses. And recycle potential of the lumbers
also depends on the deconstruction method.
Alternative design methods for remountable wooden houses were discussed in the project.
To propose new designing ideas for remountable wooden houses the current design was
analyzed. Based on the ideas for alternative design for remountable wooden houses three
post and beam demonstrative houses and two 2by4 demonstrative houses are going to be
constructed and deconstructed.
New technologies that will promote the recycle and reuse of wooden building materials and
components were in studied in the project. Such technologies as reuse technology for
lumbers, technologies to produce recycled lumbers, technologies to produce high
performance recycle wooden boards and technologies to use recycled charcoal as landfill
material are being developed. The technical levels of the industries for recycling finishing
materials were also discussed in the project and the states of the art of some products were
reported.
Data that compose the evaluation tool was collected.
autumn 2002 with an English version.
The tool will be fully revised in
All the programs are on going and the final output of the project will be prepared in spring
2003.
REFERENCE
(Reports)
1 Sakamoto I. Present condition and problems of dismantled materials of wooden houses.
Wood Industry, Vol.54, No.11, Tokyo, 1999.
2 Nakajima S. Research program to promote recycle and reuse of houses. A monthly of the
housing, Japan housing association, pp.13-17, Tokyo, 2001.
3 Ministry of Environment. Annual national report for of the sustainable society,
pp.144-147, Tokyo, 2001.
4 Dismantle and recycling system research committee. Report of dismantle and
recycling system research committee, Building Center Japan, Tokyo, 1998.
5 Building Research Institute, Building Center Japan. Annual report of the general
technology development project “C&D Waste reduction technologies for wooden
buildings”, Tsukuba, 2001.
(Proceedings)
6 Nakajima,S, Miyamura,M, Arima,T. Energy Consumption and Environmental Impact
Due to Producing Wood Based Materials, Proceedings of CIB W70 Helsinki ’96
Symposium, pp.185-188, Helsinki, 1996.
7 Kodama,Y, Nakajima,S, et.al. Life Cycle Energy and CO2 Analysis Program, CIB TG8
Building and the Environment Second International Conference Proceedings Vol.1,
pp.493-500, Paris, 1997.