LCA of recycled concrete: Environmentally superior to virgin concrete?

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avniR 2013 – Nov 5

th

:

LCA of recycled concrete:

Environmentally superior to virgin concrete?

1. Why such a study, and how?

2. Results for (natural and/or recycled gravel):

-- concrete

-- a building

-- construction in a region

3. Conclusions

Discussion

by Dr. Arthur Braunschweig (E2), Prof. Susanne Kytzia (HSR), S. Bischof (Holcim)

H S R

H O CH S C H U LE F Ü R T E C HN I K

R A P P E R S W IL

(2)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 2

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

(3)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 3

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

Why such a study?

• Concrete is key for buildings and infrastructure

• CH is densly populated  gravel gets

un-attainable

• Growing consciousness  Recycle concrete! (

Minergy standard

)

• 2005 CH: Demolished concrete covers

1/8

of gravel

(9 of 70 mio t/a)

In city areas, e.g. Zürich,

1/3

(0.8 of 2.2 m t/a) !

• Recycled concrete can be used

- loosely, as gravel

- fixed, in lean concrete

- fixed, in high-quality ("construction") concrete

and in all situations

replaces virgin gravel

!

(4)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 4

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

Four LCA-studies on gravel and concrete

• a)

Gravel (virgin & recycled)

b)

Concrete (high-quality & lean)

c)

A construction project

d)

Construction in a Swiss region

• Key assumptions, e.g.:

• Team: Prof. S. Kytzia & team, HSR / Holcim / A. Braunschweig, E2

(5)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 5

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

LCA: Scope – Example 'concrete production'

1 m

3

Concrete of a certain quality (at plant)

P

roz

esse

z

ur

H

er

st

el

lung

von

B

et

on

in

der

S

chw

ei

z

Q

uel

le:

K

yt

z

ia

et

al

,

201

1

Concrete

Production

Mixing

Gravel production

Transport

Transport

Limestone, Clay

Water

prep.

Additives production

Ene

rgie

s

prod./

W

a

s

te

trea

tm't

Infra

s

tructu

re

Trsp. of

demolished

building material

(concrete, mixed)

Building demolition

Cement

Production

(6)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 6

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

System definition details – Example "High quality concretes"

Composition per m³ concrete "C30/37":

Other assumptions, e.g. :

-

Cement production w/ 40 % alternative fuels

-

Transport distances

-

Swiss grid electricity

100 % natural aggregate

with 25 % RC-granulate

Gravel

2000

kg

natural

1400 kg

natural

460 kg

recycled (RC) granulate

Cement

300 kg

Portland limestone

cement

(7)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 7

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

Granulate production

RC-Granulate production

Concrete production

Cement production

1

st

result: LCA of high quality concretes

0%

25%

50%

75%

100%

125%

150%

C 30/37

Beton C 30/37 (25% RC-Granulat)

C 30/37

Beton C 30/37 (25% RC-Granulat)

C 30/37

Beton C 30/37 (25% RC-Granulat)

C 30/37

Beton C 30/37 (25% RC-Granulat)

C 30/37

Beton C 30/37 (25% RC-Granulat)

C 30/37

Beton C 30/37 (25% RC-Granulat)

Gravel use

(t)

Land use

(m2-eq*a)

Respiratory damages

(PM10)

Acidification

(SO2eq)

Climate Change

(CO2eq)

(8)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 8

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

Lean Concrete w/ RC-content doesn't need more Cement

Composition of 1 m³ lean concrete:

additional assumptions, e.g. on transport distances

Lean concrete with 100%

natural gravel

… with 100 % RC-granulate

Gravel

1'895 kg

natural gravel

1'590 kg

mixed demolition

granulate, treated

(9)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 9

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

… with 0 and 100 % RC-granulate

0%

20%

40%

60%

80%

100%

120%

Lean Concr. 100% RC

Lean Concr.

Lean Concr. 100% RC

Lean Concr.

Lean Concr. 100% RC

Lean Concr.

Lean Concr. 100% RC

Lean Concr.

Lean Concr. 100% RC

Lean Concr.

Lean Concr. 100% RC

Lean Concr.

2

nd

result: LCA of lean concretes

Granulat-Herstellung

Gravel use (t)

Land use (m2-eq * a)

Respiratory damages

(PM10)

Acidification (SO2eq)

Climate Change

(CO2eq)

Energy use (MJeq)

Granulate production

RC-Granulate production

Concrete production

(10)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 10

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL I B U IN S T I T U T F Ü R B A U U N D U M W EL T

Hochba

u

6 km

14 km

14 km

36 km

19 km

16 km

V2: pit +

recycling

C 30/37,

w/

25% RC

gravel

demolition

waste is

used

V1: Pit +

landfill

C 30/37,

100% new

gravel

demolition

waste

landfilled

(11)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 11

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL I B U IN S T I T U T F Ü R B A U U N D U M W EL T

25%

50%

75%

100%

125%

0%

Production: RC-gravel

Production: Cement

Transports: Granulates

Production: natural gravel

Production: Concrete

Waste treatment

Transports: Concrete

V1 (100 %Natural / Waste to landfill)

V2 (25 % RC / Waste to recycling)

V1

V2

V1

V2

V1

V2

V1

V2

2

nd

LCA: Results for the fictitious building project

Gravel use (t)

Land use (m2-eq * a)

Respiratory damages

(PM10)

Acidification (SO2eq)

Climate Change

(CO2eq)

Energy use (MJeq)

V1 (100 %Natural / Waste to landfill)

V2 (25 % RC / Waste to recycling)

(12)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 12

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

'Swiss Mittelland' (e.g. larger Zürich area)

Simplified calculations (e.g. no metals, wood)

Concrete waste = ca. 1/3 of Concrete demand

(1,1 vs. 3,6 mio tons p.a.)

Construction waste is treated: 15 % final waste to landfill,

85% are re-used –

either loosely

as granulate,

or in RC-concrete

(13)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 13

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL I B U IN S T I T U T F Ü R B A U U N D U M W EL T

Concrete

Plant

Regional Offer

1,1 m t

Concrete

waste

Regional Demand

2,2 m m3 Concrete

3,6 m t Granulate

Roads

Gravel

A) RC-

Granulate

Landfill

3

rd

LCA: Regional Building Scenario

B) RC-

Concrete

(14)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 14

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL I B U IN S T I T U T F Ü R B A U U N D U M W EL T

0%

25%

50%

75%

100%

A) loose RC-Granulate

B) RC-Concrete

A) loose RC-Granulate

B) RC-Concrete

3

rd

LCA results: CH Regional Construction Scenario

Use of construction waste for …:

Gravel use (t)

Land use (m2-eq * a)

Respiratory damages

(PM10)

Acidification (SO2eq)

Climate Change

(CO2eq)

Energy use (MJeq)

A) loose RC-Granulate

B) RC-Concrete

A) loose RC-Granulate

B) RC-Concrete

A) loose RC-Granulate

B) RC-Concrete

A) loose RC-Granulate

B) RC-Concrete

Production: natural gravel

Production: RC-Gravel

Production: Cement

Transports RC-Granulate

Production: Concrete

Transports Concrete

(15)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 15

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

Conclusions of this study

• Lean concrete made from recycled gravel is environmentally superior,

esp. for resource use (land, gravel).

• A

high-quality concrete

w/ recycled gravel has a similar environmental

effect as a concrete with natural gravel (except for gravel & land use).

• Knoeri et al (2013) add: Recycling of steel from reinforced steel makes RC

even more advantageous.

• Concrete using

recycled gravel is preferrable

if construction waste would

otherwise be

landfilled

.

• On regional scale it is

important that demolished concrete is used

– either

loosely or in new concrete –

and not landfilled

. How it is used is less

important.

• Key parameters:

Cement type and amount

, and

transport

means and

distances.

(16)

E2 A. Braunschweig / avniR 2013 / LCA Recycled Concrete? / p. 16

H S RH O CH S C H U LE F Ü R T E C HN I K R A P P E R S W IL

I B U IN S T I T U T F Ü R B A U U N D U M W EL T

Literature

• Study published in German by Holcim

(Switzerland)

• Article on this presentation on

avniR documentation

(publication pending)

Figure

Updating...

References

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