SAYKEE Enterprise, Inc

II Congreso Internacional de la Construcción Argos Panamá
October 3rd, 2013

　

Trends in Waste Concrete
Recycling in Japan
Shinichi SUZUKI
EX Research Institute Ltd.

Contents
1. Waste Concrete Recycling Trends in Japan
2. Development of Recycled Aggregate
Concrete
3. Technology of Recycled Aggregate
Concrete
4. Management of Manufacturing Recycled
Aggregate Concrete
5. Challenges to the Expansion of the Use of
Recycled Aggregate Concrete
6. Conclusion


Unit: 10,000 tons

Shipping Amount Recycling
From Demolition Amount
Sites

Disposal
Amount

Recycling
Rate

1995

3,650

2,359

1,288

64.6%

2000
2002

3,530

3,394

133

3,510

3,425

87

96.2%
97.6%

2005

3,220

3,155

60

2008

3,130

3,043

84

Source: Ministry of Land, Infrastructure and Transport(MLIT)

98.0%
97.3%
1



Mass balance

Unit: million tons

Recycled Stones
Slag 8.18
from Waste
Asphalt 4.05
6%

Generation

To
Discharge
Amount
Recycling Recycling Recycle Recycled
Amount
32.01

31.27

Plant
30.62

30.43

Plant

Stones
(Crushing) 37.20

29%

Usage of
On Site Use
Crushed
Recycled Sand
0.74
Stones,
2.94
Disposal Disposal
gravel etc
Crushed
0.65
0.19 For Size ControlStones(virgin)65%129.95
5.65
84.57
Disposal Site
Source: Ministry of Land, Infrastructure and Transport(MLIT)

2

1.Waste Concrete Recycling Trends in Japan





Current Major Recycling Methods

Most waste concrete was used for base course material
and back-filling material
After finishing the standardization of all three types of
recycled aggregate in 2007, the resulting use of recycled
aggregate was about 15,000 tons (simple tabulation)
according to a survey in 2008.

Photos: Takenaka Corporation

3



Waste Concrete Generation in the Future
Unit: million m3
Shipping Volume of Ready-Mixed Concrete 1962-1998

150
100
50

Year
Source: http://www.kkr.mlit.go.jp/fukusan/topics/h23/kyouboshi.pdf

4










Waste Concrete Generation in the Future

The amount of waste concrete generated is predicted to
grow. An increase of 4 to 6 times is expected by 2050 due
to the lifetime of concrete structures which were built in
the past.
Reviewing trends in public works budgets, construction of
new roads has reduced. Budgets will be allocated more
for maintenance, rather than new construction.
Crushed stones have been collected by blasting
mountains while gravel has been collected from riversides,
which has been difficult. Both activities heavily impact the
environment.
Thus it is important in Japan that waste concrete
aggregate is used again and again for recycling.
5

Use of Waste Concrete
Aggregate has the
following two types:
(a) Opened-Loop
Concrete Recycling
System

Old building

Survey of
demolished
building

Concrete production

Test specimens
for confirmation
of concrete
properties

Demolition

(b) Closed-Loop
Concrete Recycling
System
Manufacture of recycled coarse and fine aggregates
6

2. Development of Recycled Aggregate Concrete


Background

•

1973: the building Contractors Society (BCS project) and the
Ministry of Construction (1st project) started research
1992: the Synthesis Technical Development Project(2nd
project) of the Ministry of Construction started to research a
more practical basis for recycled aggregate concrete.
2003: JASS 5 prescribed, based upon the above results, that
recycled aggregate may be treated as natural aggregate if it
achieves a quality equivalent to gravel and sand.
2005-2007: in 2005 the Japan Industrial Standard (JIS A
5021) for concrete-class H “high-quality recycled aggregate”,
in 2006 JIS A 5023 for concrete-class L “low-quality
aggregate” , and in 2007 JIS A 5022 for concrete-class M
“middle-quality aggregate” were enacted respectively .

•

•

•

7



Relations Between Recycled Aggregate H,M,L & Recycle Concrete

JIS A 5021
Recycled Aggregates H

JIS A 5308
Ready-Mixed
Concrete Factory

JIS A 5308
Ready-Mixed
Concrete

Natural Aggregates
Recycled Aggregates M

JIS A 5023
Ready-Mixed
Concrete Factory
Which Recycled
Aggregate L
Purpose-Built

JIS A 5023
Recycled
Aggregate
Concrete L

JIS A 5022
Recycled Aggregates M

JIS A 5022

Natural Aggregates
JIS A 5023
Recycled Aggregates L

Natural Aggregates

- Do for M -

JIS A 5022
Recycled
Aggregate
Concrete M

Source: Yukikazu Tsuji, “JIS Products of Recycled Concrete (Japanese), 2007

8



Major Use of Each Type of Recycled Aggregate
Concrete
H

Defined
Standard

Standard as
aggregate

M

L

Standard as concrete

Members/elements
which are not
Application Same as natural affected by drying
shrinkage, such as
aggregate
piles, footing
beams, steel tube
filled concrete, etc.

Members/elements
which do not
require intensity
and durability, such
as back filling,
leveling concrete,
etc.
9



Standardized Recycled Aggregate Concrete (JIS)

Coarse Aggregate
H
Oven-dry density
(g/cm3)
Water absorption
(%)
Fine material
content (%)
percentage of wear
and abrasion
resistance (%)

M

L

Crushed Stone
for concrete

≥2.5

≥ 2.3

ー

≥ 2.5

3.0≥

5.0 ≥

7.0 ≥

≥ 3.0

1.0 ≥

1.5 ≥

2.0 ≥

1.0 ≥

35 ≥

ー

ー

40 ≥

10



Standardized Recycled Aggregate Concrete (JIS)

Fine Aggregate
H
Oven-dry density
≥ 2.5
(g/cm3)
Water absorption
3.5 ≥
(%)
Fine material
7.0 ≥
content (%)
percentage of wear
ー
and abrasion
resistance (%)

M

L

Crushed Sand
for Concrete

≥ 2.2

ー

≥ 2.5

7.0 ≥

13.0 ≥

3.0 ≥

7.0 ≥

10.0 ≥

7.0 ≥

ー

ー

ー

11

3. Technology of Recycled Aggregate Concrete


Two Basic Production-Method Concepts
Aggregate Refining
Method

Aggregate Replacing
Method

Removing the original
Reducing the influence of the
mortar contained in the
original mortar and producing
Basic recycled aggregate to
concrete with the required
Idea acquire quality equivalent performance capability by mixing
to natural aggregate such natural aggregate and recycled
as gravel and sand, and aggregate at the concrete
being used as a substitute manufacturing stage
E.g.

Office buildings,
Apartment House, etc

Biotope Soga symbiosis building,
Incinerator building in Yokohama
12

3.1 Aggregate Refining Method (Outline)
Screening Method

Crude Concrete after
Demolition

Crushing Method
Rubbing Method
H

Jaw crushers

Primarily Crushed
Materials

Primarily Treatment
Source: Japan Society of Civil Engineers

Wet Screening
Heating and Rubbing
Method
Others (Coating Method)
Secondary Treatment
13

3.1 Aggregate Refining Method (Outline)
(1) Crushing

Recycled Sand

　　　　　　

Crude Concrete
Concrete Lump
Crude Concrete

Screening
Apparatus

Impact crushers
(horizontal axis type)

Dust
removal
Screening
Apparatus

Recycled Gravel

Jaw crushers

Recycled Roadbed
Materials

Water
Washing

Rod Mill

Source: Japan Society of Civil Engineers

Screening
Apparatus

14

3.1 Aggregate Refining Method
(1) Crushing Method

　　　　　　
Recycled coarse aggregates

Crushing Method
(Grade M or L)

Recycled fine aggregates

Rubbing Method (Grade H)
Source: Kyoboshi Corporation

15



(2) Rubbing Method: Mechanical Grinding
If treated more than once

Concrete Lump
Lump
Concrete Lump
Concrete
Screen
Apparatus
eccentric-shaft
rotor device

70%
Screen
Apparatus

Jaw crusher

Rejected

Coarse Aggregates

Source: Japan Society of Civil Engineers(partially added)

30%
16




The eccentric-shaft
rotor device 　
Crushed concrete
Under 50mm
Vibrating sieve

Processing system with the eccentric-shaft rotor device 　

Source: Takenaka Corporation

The eccentric-shaft
rotor device 　

17


Actual Application Example

Old office building
7-stories
Concrete lump: 10,000t
Whole quantity: 80,000t

New office building
38-stories
Recycled coarse aggregate: 3,000 t
Recycled concrete volume: 5,000 m3
18
Used as BF-1F slab



(3) Gravity Concentration by Wet Screening Method
10%
Fine Powder

Concrete Lump
Concrete Lump
Screen

2%

Impact crushers
Rubbing Apparatus

Screen

Wet Screen

Rejected

Jaw crusher
15%
45%

28%

Rubbing Apparatus

Back-filling Materials,etc
Recycled Fine Aggregate


Light
Recycled
Materials Aggregates

19


Photos: Kyoboshi Corporation

20




Recycled Aggregate
Low density area

Surface
Water
Lever

High density area

Low Density
Recycled
Aggregate

High Density Recycled Aggregate


21


(4)Heating and Rubbing Method

Recycled coarse
aggregate

Heating
treatment

Rubbing
treatment

Recycled fine
aggregate

Disintegration of
cement paste
by dehydration

Selective
separation of
cement paste

Source: Mitsubishi Materials

Powder

22


(4)Heating and Rubbing Method

44%

Concrete Lump
Concrete Lump

Fine Powder

Coarse aggregate
recovering equipment
(Ball Mill)

Jaw crusher

Fine aggregate
recovering equipment
(Secondary Mill)

Screen

Packed bed
heater
(300℃ ）

Fine Aggregate Coarse Aggregate


21%

35%

23


(4) Heating and Rubbing Method

Whole View of the Aggregate Recycling Plant
Source: Shimizu Corporation

24


(1)Effect of Recycling

The recycling rate of “Heating and rubbing” and “Mechanical
grinding” are reported to be as high as about 56% and about
30% respectively.
However, the recycling manufacturers use byproducts of
recycled aggregate such as fine powders for their other
businesses such as the manufacture of roadbed materials.
Thus it is believed that the recycling rate of the recycling
manufactures are more than 95%, otherwise their recycling
business can not be continued.

25

(2)Unit Price

According to a survey by ACRAC of its members in 2011,
the average unit price by spot delivery is as follows.
Type
Coarse Aggregate
Fine Aggregate

L
$10.9/t
$7.9/t

M
$12.0/t
$17.5/t

H
$22.0/t
$25.0/t

(3) CO2 Emission
The CO2
emissions from
recovering recycled
aggregate are high,
yet total emissions
can be reduced.
26

3.2 Aggregate Replacing Method
(1) Outline
Crushed

200m3 (2002)

Recycled concrete
manufacturing

concrete

Demolition

1,000m3 (2005)

600m3 (2008)

11,00m3 (2009-2010)

Precast concrete
product

Recycled roadbed gravel
27-45%
Mixed with natural
spray concrete
aggregate which is
replaced

Approved by MLIT
as structural
55-73%
Block type
concrete
Source: Y.Dosho, “Development of a Sustainable Concrete Waste Recycling System laying member
27
http://www.aij.or.jp/jpn/design/2013/date/32_2013award_dohshoY_dtd.pdf

(2)Blending Planning




Method that decides the mixing ratio of natural aggregate
to recycled aggregate to assure the performance of
concrete
The value of relative quality is an index used for assessing
aggregate quality and is given by the following equation.
QCt=

QCvG x a + QCvS x b + QCrG x c + QCrS x d
a+b+c+d

Where;
QCt(%): Relative absorption rate;
QCvG(%): Absorption rate of natural coarse aggregates in recycled aggregate concrete
QCvS(%): Absorption rate of natural fine aggregates in recycled aggregate concrete
QCrG(%): Absorption rate of recycled coarse aggregates in recycled aggregate concrete
QCrS(%): Absorption rate of recycled fine aggregates in recycled aggregate concrete
A,b,c,d(L/m3): Absolute volume of natural coarse aggregate, natural fine aggregate,
recycled coarse aggregate, and recycled fine aggregate, respectively

28

(1) Effect of Recycling
A simulation was carried out by TEPCO based upon a case
study in which a current thermal power plant (350,000kW) is
to be replaced with a 1.5MW facility.
 The amount of waste concrete generated would be about
9,700m3, all of which could be confirmed for use at the
present site as recycled aggregate concrete (about 11,000m3)
and recycled crushed stones (about 6,500m3).

(2)Cost
Relative to the current use for back-filling and roadbed
materials, the cost would be reduced by about 41% because
of savings in waste disposal fees and in material for aggregate
and crushed stones.
29

Aggregate 　 Concrete
(1) Receiving Inspection
　 A. Reaction rims surrounding aggregate
and/or cracks in the aggregate must
not be observed.
B. Fractured surfaces of aggregate
must not be covered with crystallined
materials, nor colored white.
C. On the surface of concrete, white
deposits must not be observed.


30

(2)Product Inspection
　 A.

Monthly chemical analysis is conducted based
upon the JIS A 5308 appendix 7.
B. The Fresh-Con GBRC Rapid Method* is
conducted with lot inspection time.

*Test for alkali-aggregate reactivity of ready-mixed concrete

(3) Implementation of control measures to
total alkali
•The amount of the total alkali of recycled
aggregate concrete is not more than
3.0kg/m3 even though the recycle
aggregate is judged as harmless.

31



Quality Control (On-site for refining method)

Investigation of structure to be demolished
and aggregate used in the structure
Quality control of concrete lump; mainly
impurity
Processing for recycling
Inspection of the quality of recycled
aggregate
Quality control of recycled aggregate
Manufacturing of concrete using recycled
aggregate
Inspection of concrete using recycled
aggregate

Check Items
Alkali-Aggregate
Reaction (AAR) *
*if necessary

Impurity
Density,
Water absorption,
Grading curves,
Chlorides content,
Impurity
Slump and flow
Compressive strength
AAR*

32




Quality Control (On-site for replacing method)
Demolition

Physical & Chemical Survey
conformity

Recycled Aggregate Production
Quality Survey
conformity

Blending Planning

nonconformity

nonconformity

Re-inspection
or
Disabled

Recycled Aggregate Concrete Production
Quality Survey
conformity

Apply

nonconformity

Source:http://www.aij.or.jp/jpn/design/2013/date/32_2013award_dohshoY_dtd.pdf

33



Quality Control (On-site for replacing method)
Survey

Checked Items
Intensity of original concrete, chloride
Physical & chemical survey
content, alkali-silica reaction, with or
on original concrete which
without deterioration symptoms
is planned to be demolished
Quality control/inspection ofMajor physical property of aggregate,
manufactured recycled
amount of impurity, alkali-silica
aggregate
reaction, chloride content
Quality control/inspection of Slump, air capacity, chloride content,
alkali-silica reaction, intensity
manufactured recycled
aggregate concrete
Source:http://www.aij.or.jp/jpn/design/2013/date/32_2013award_dohshoY_dtd.pdf

34








The “Law on Promoting Green Purchasing” has been
amended, but recycled aggregate is only on the
longlist. Why?
- Is it possible to procure all over the country?
- Can its durability be guaranteed?
It is not included in government project specifications.
(but the Tokyo metropolitan government has changed
after it was selected as the Olympic host)
Not enough capacity in urban areas
High costs, esp. when demolition site is 40 km+ away
35



The case of non-conforming melt slag aggregate
used for concrete in 2007-2008






A registered concrete manufacturer, namely
Mutuai Concrete Ltd., used non-conforming melt
slag as recycled aggregate.
“Pop-out” phenomena were observed in the
constructed concrete due to quicklime contained
in melt slag.
This case emphasized that recycled aggregate,
when applied to concrete, should be used with
caution.
36



Association

The Affairs Council of
Recycled-Aggregate Concrete
(ACRAC) is formed by voluntary
recycling manufacturers who
aim to include recycled
aggregate concrete in their
project specifications. As of
2013 there are 19 firms
participating in ACRAC.
ACRAC takes responsibility
for its own products.
Source: ACRAC

grade
grade
grade

37

6. Conclusion






Almost 40 years have past since recycled aggregate
concrete was first studied in Japan. JIS was enacted for
recycled aggregate, and stable manufacturing technologies
have been established.
Based upon the portion of civil engineering and construction
that uses concrete, the quality requirements of concrete will
change. It is necessary to secure a suitable balance
regarding 1) safety and quality, 2) cost and effectiveness,
and 3) environment impact.
There are two approaches to using recycled aggregate; (a)
the refining aggregate method, and (b) the replacing
aggregate method. There are merits and demerits of both
methods.
38

6. Conclusion








In the case of (b), applicable sites will be mostly limited to
massive building projects which have a record of using
aggregate and concrete, such as power plants.
Both methods require inspection for the purpose of
manufacturing safe concrete. It is important to prevent
recycled aggregate-manufactured devices from being
delivered in inappropriate concrete lumps, especially in the
case of (a).
To increase recycled aggregate concrete use, the role of
government is very important: to standardize recycled
aggregate, promote green procurement, and punish
companies who break the law.
For the success of recycled aggregate business, the
discarded byproducts should be minimized as much as
possible by excluding impurity at the beginning of recycling,
39
and by utilizing byproducts obtaining social credibility.

6. Conclusion


Waste concrete recycling is inevitable because of the
increasing use of concrete, especially after WWⅡ - a trend
which will discontinue in the near future. There is lots of
know-how regarding waste concrete recycling in Japan, so
we can share our experience.

40

Thank you very much
suzuki@exri.co.jp

SAYKEE Enterprise, Inc

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