sustainable recycling of concrete with...

September 2013 – Surabaya

Sustainable Recycling

of Concrete with

Environmental Impact

Minimization

Takafumi Noguchi

The University of [email protected]


Content

• Background

Environmental Impact in Concrete-related Industries

• State-of-the-art of Concrete Recycling

Technologies and Standards

• Closed-loop Recycling System

Completely Recyclable Concrete

• Conclusions


Environmental Problems in Construction

• Materials flow, resource consumption and waste generation

• Greenhouse gas emissions

• Destruction of the ozone layer

• Acidification (Acid rain)

• Outdoor air pollution

• Water pollution and soil contamination

• Disruption of the ecosystem (Biodiversity)

• Heat island

• Noise and vibration

• Landscape destruction (Aesthetic degradation of the

landscape)

• Indoor air pollution


Environmental Problems in Concrete Industries

• Global warming

• Resource depletion

• Waste disposal


Building Related CO2 Emission

Japan’s total

CO2 emission

1.2 billion tons

Other

industries

64%

Housing

construction

5%

Commercial

building

construction

6%Building

repair

1%

Energy for

housing

operation

11%Energy for

commercial

building

operation

13%

36%


CO2 Emission from Concrete Industries

Concrete: 1 m3

CO2: 0.35 - 0.45 ton

Portland cement: 1 ton

CO2: 0.75 ton

Decarbonation of limestone (60 %)

Fossil fuel combustion (30 %)

Cement production (0.25 ton)

Others (0.1 – 0.2 ton)


Resource Input into Construction Industries

Total

Construction

1,000 (million t/year)

50% of total resources for industries

Total: 2,000 (million t/year)

Construction

Total: 1,000 (million t/year)

Concrete

500 (million t/year)

50% of resources for construction

Others

Steel

Wood

CONCRETE is the second most widely consumed

substances on Earth, after water !

“LIQUID STONE:NEW ARCHITECTURE IN CONCRETE”

(National Building Museum in Washington D.C.)


Waste Output from Construction Industries

Industrial Waste

Construction

79 (million t/year)

17% of total industrial waste

Total: 406 (million t/year)

Construction Waste

Total: 79 (million t/year)

Concrete

35 (million t/year)

42% of construction waste

Energy

Agriculture

Pulp

Steel

ChemicalOthers

Asphalt

concreteSludge

WoodOthers


Final Disposal Sites for Waste

120

140

160

180

200

220

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

Poss

ible

wast

e in

final dis

posa

l are

a

(million m

3)

General

Industrial

Industrial Waste: 412 (million t/year)

Scarcity of residual capacity

of final disposal areasResource-recycling society


Definition and Meaning of Resource Depletion

• Significant reduction in availability to the next generation

• Difficulty in acquiring resources as a vast amount of

energy is needed to do so

• Difficulty in carrying out life activities that depend on

resources

• Soaring resource price

• Increase in environmental destruction through acquisition

of a resource

• Loss of economic advantage regarding the use of a

resource


Forecast of Limestone Depletion in Japan


Change in Aggregate Consumption in Japan

0

100

200

300

400

500

600

700

800

900

1000

Pro

du

cti

on

(m

illi

on

t)

Year

Crushed River gravel

Hill gravel Pit gravel

Sea gravel Others

Crushed stone have become major.

Good quality river gravel have become depleted.

Causingexposure of bedrock on the bottom of the sea erosion of embankmentsendangering sand spits and fishing grounds


Content

• Background






• Conclusions


Recycling Ratio of Concrete

0 10 20 30 40

Emission of Concrete Lumps (million t)

2005

2000

1995

1990

Recycle

Disposal

For road subbase

For mechanical stabilization underground

Ministry of Construction

Action Plan for Construction By-

products ‘94

Promotion Plan for Construction

Waste Recycling ’97

Basic Law for Establishing a

Recycling-based Society

Construction Material Recycling Act

Law on Promoting Green Purchasing


Predicted Amount of Future Concrete Waste

Pro

ducti

on (

million t

)

600

500

400

300

200

100

01950 2000 2050

Year

Concrete production

Concrete

wasteDemand for

road subbase

Imbalance between

supply of concrete waste

demand for road subbase

Greatest part of

future aggregate

for concrete

RecyclingFrom Quantity-oriented

to Quality-oriented


Japan Industrial Standards (JIS) for

Recycled Aggregate

• JIS A 5021– Recycled aggregate for concrete - Class H

• JIS A 5022– Recycled concrete using recycled aggregate Class M

• JIS A 5023– Recycled concrete using recycled aggregate Class L

Coarse aggregate Fine aggregate

Density (g/cm3) Absorption (%) Density (g/cm3) Absorption (%)

Class H 2.5 or more 3.0 or less 2.5 or more 3.5 or less

Class M 2.3 or more 5.0 or less 2.2 or more 7.0 or less

Class L - 7.0 or less - 13.0 or less


Scope of application

Class - H

No limitations for structural concrete with a nominal

strength of 45MPa or less

JIS A 5308 (Ready-mixed concrete) allowing to use

Class-H RA for normal strength concrete

Class - MMembers not subjected to drying, such as piles,

underground beam, and concrete filled in steel

tubes with a nominal strength of 36MPa or less

Class - LBackfill concrete, blinding concrete, and leveling

concrete with a nominal strength of 24MPa or less

Applications of Recycled Aggregate


Demolished Concrete Rubbles

Jaw Crusher

Impact Crusher

Vibratory Sieves

Road Subbase,

Backfill

Cone Crusher

Vibratory Sieves

Vibratory Sieves

Low Quality

Recycled

Coarse

Aggregates

Heating Tower

Coarse Aggregate Scrubber

Fine Aggregate Scrubber

Low Quality

Recycled

Fine

AggregatesHigh Quality

Recycled

Coarse

Aggregates

High Quality

Recycled

Fine

Aggregates

Powder

Vibratory Sieves

(a) Road Subbase (b) Low Quality

Recycled Aggregates

(c) High Quality

Recycled Aggregates

Recycling Process of Concrete Rubbles


Problems in Conventional Technology

to Produce High-quality Recycled Aggregate

5-10mmnot less than10mm

No 1st 2nd 3rd

Number of Crushing Treatment

Water Absorption (%)

Recovery Percentage (%)

Recycled Fine Aggregate

Recycled Coarse

Aggregate

Powder

Size of Supplied

Concrete Lumps

Fine Aggregate

Coarse Aggregate

Fine Powder

No 1st 2nd 3rd OriginalConcrete

Crushing Treatment

Repeated crushing

•Recovery percentage decreasing

•Fine aggregate and powder generation increasing


Mechanism of Heated Scrubbing

Heating at

300C

Rubbing

process

Concrete rubbleWeakening of

hardened cement paste

Removal of powdered

cement hydrate


Rotary Kiln

2nd Scrubbing MachineDust Chamber

Filler Tank

Recycled Fine Aggregate -5mm

1st Scrubbing Machine

Sieve

Hot Elevator

Recycled Coarse

Aggregate 5-20mm

Heated Scrubbing Equipment for

High-quality Recycled Aggregate

By-product Powder


Total volume of recycled

concrete: 10,000m3

Laboratory :

・Structure : Steel structure (7

Stories)

・Building area : 9,800m2

・Total floor area : 51,000m2

Application of Heated Scrubbing MethodF- Project Completed in 2003


Concrete

lumps

Eccentric

tubular mill

Motor

External

cylinder

Scrubbing

Transmission

gearRecovery

Mechanical Scrubbing Equipment for

High-quality Recycled Aggregate


Old apartment Houses

12 x 4-storied

Concrete lump: 11,500 t

New apartment Houses

7 x 9-19-storied

Recycled coarse aggregate: 3,000 t

Recycled concrete volume: 3,000 m3

( Total concrete volume:40,000 m3 )

Application of Mechanical Scrubbing Method


Utilization of By-product Powders

• Large amount of by-product powders generated– Possible uses

• Raw material for clinker

• Ground improving material

• Addition to road bottoming

• Concrete addition

• Asphalt filler

• Inorganic board material

– Demands• Quality stabilization

• Reduction of quality control cost


Content

• Background






• Conclusions


Existing technology

Problems in Current Recycling

• Nosotropic technology– No recycling-conscious design applied

– Materials diffused into a wide range of industries

– Finally disposed• Quality degradation, Unstable supply, Unstable price, Unstable

distribution, Increasing environmental impact

Forward-

process

production


New technology

Concept of Completely Recyclable Concrete

• Proactive Technology– Upstream (inverse) processes incorporated

– Components of concrete completely recycled into concrete

– Resource conserved

– Resource circulated in a closed system


Cement-recovery Type Completely Recyclable Concrete

• Concrete whose binders,

additives and aggregates

are all made of cement or

materials of cement, and

all of these materials can

be used as raw materials of

cement after hardening

Semi-closed-loop

Production

of CRC

Operation

Construction

DemolitionCrushing &

Milling

Calcination

Clinker

Aggregate

Gypsum

Recycled cement


Changes in CO2 Emissions and Dumped Concrete

0

50

100

150

200

0 50 100 150 200 250

Elapsed year(2) Production of CRC

0

50

100

150

200

0 50 100 150 200 250

Elapsed year

(1) As it is

CO2 EmissionDumped concrete

CO2 EmissionDumped concrete

Dumped Concrete

CO2 EmissionCalcined limestone

never emits CO2.

5% of concrete replaced with

cement-recovery type CRC every year


Closed Recycle of

Concrete Pole

Remove and

Transportation

Use and

Operation

Supply of

Pole

Limestone

Supply

Limestone

Mining

Circulation of

CementManufacture of

Cement

Manufacture

of Pole Crushing and

Classifying

Raw Material

for Cement

Steel

Recycling

Cement

Supply

Application of Cement Recovery Type CRC for “Eco-Pole”

Placing of concrete

Steam cured

Removal of form


Aggregate-recovery Type Completely Recyclable Concrete

• Concrete which is designed to

reduce the adhesion between

aggregate and the matrix to

an extent that does not

adversely affect the

mechanical properties of

concrete by modifying the

aggregate surfaces

beforehand, thereby

facilitating recovery of

original aggregate

Closed-loop

Production

of CRC

Operation

Construction

DemolitionCrushing &

Sieving

Calcination

Clinker

Surface modified

aggregate

Recycled cement

Recycled

aggregate


Mechanism of Aggregate-recovery Type CRC

Chemical treatment

Physical treatment

The principal ingredient of the coating agent is mineral

oil. The agent hydrolyzes in alkali conditions of fresh

concrete, forming acidic matter and indissoluble amalgam

on the surface of the aggregate. The surface coating

results in decreased amounts of cement hydrate, and

leads to decreased adhesive strength between aggregate

and paste matrix, allowing easy recovery of the original

aggregate.

The coating agent is a water-soluble synthetic resin

emulsion, which is applied in process of abrasion, and

which is chemically stable in fresh concrete. The uneven

surfaces of virgin aggregate become smoother, the shape

of the aggregate being roughly maintained. This decreases

adhesive strength between aggregate and paste matrix ,

allowing easy recovery of the original aggregate.


Recovery and Mechanical Property of

Aggregate-recovery Type CRC

W/C=60%

40

50

60

70

80

90

Crushed stone Gravel

Recovery

rati

o (

%)

No treatment Chemical Physical

W/C=40%

10

20

30

40

50

60

Crushed stone Gravel

Str

ength

(M

Pa)

No treatment Chemical Physical

• Trade-off relationship remained

– Aggregate recoverability increased

– Mechanical properties of concrete decreased


< After microwave heating >< Microwave heating >

Surface modification treatment

Aggregate

Mortar

Advanced Aggregate Recovery-type CRC• Concrete strength enhancement

– Aggregate surface modification

– Increase bonding force between

coarse aggregate and mortar

• Fine SCM: pozzolanic reaction

• Mineral powder: mechanical

friction

• Aggregate recoverability– Inclusion of dielectric material

– Selective heating by microwave

– Weakening aggregate surface

– Recovery of aggregate with low

energy

330C at 10sec610C at 30sec


Mechanical Properties in Advanced

Aggregate Recovery-type CRC

Increase


Aggregate Recovery Ratio in Advanced

Aggregate Recovery-type CRC

0

20

40

60

80

100

120

O1 O2 O3 SP80

Recovery

rati

o (

%)

Original coarse aggregate Fine aggregate Paste

Decrease

Increase


CO2 Emission in Concrete Recycling Process

0

5

10

15

20

25

30

35

40

Heated-

scrubbing

Mechanical-

scrubbing

30sec 60sec 90sec

CO

2 e

mis

sion (

kg/t-

concre

te)

Others

Scrubbing

Microwave heatingDecrease


Coarse aggregate

By-product powder

Fineaggregate

Modifiedcoarse

aggregate

Fineaggregate

Cement

Modification

Sustainable Resource Recycling Concrete SocietyDemolition

and recovery

Recycled coarse aggregate

Recycled fine aggregate(under technology development)

High-purity Ca

Complete

separation

Microwave

heating

Concrete structure

Long-lived

Completely recyclable structure

Demolition and recovery

Cement factory

Use as raw material

of cement clinker Little CO2emission


Content

• Background






• Conclusions


Conclusion

• Toward sustainable resource-recycling society

– Concrete recycling in closed system

• Current method: Some technical and social problems

– Adoption of technology enhancing resource conservability

at the stage of design

• Completely recyclable concrete

• New technology with aggregate surface modification and

microwave radiation

– Overcoming inherent conflicting properties in concrete recycling

– Achieving high performance of concrete

– Energy saving and small CO2 emission in concrete recycling

– Fully recovering original aggregate

– Generating cement raw materials which never emit CO2


Thank you for your kind attention!

[email protected]

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