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ASHTRANS Conference 7. September 2015 Claus Pade, Danish Technological Institute – Concrete Centre; [email protected]; +45 7220 2183
Carbon Footprint of Fly Ash
Hirtshals
Aarhus
Odense
Sønder Stenderup Taastrup
Warsaw
Gothenburg
Stockholm
Stavanger
Danish Technological Institute
Self-owned and not-for-profit
More than 1,000 innovative employees, state of the art equipment and facilities as well as a strong global network.
Content
Fly ash used for concrete production – benefits
Carbon Footprint of Fly Ash Concrete
Centre for Green Concrete (1998-2002)
Carbon Footprint of Fly Ash
Environmental Product Declaration of Fly Ash
All experience presented is based on data from Danish fly ash !
Lower cost at equivalent performance
Fly ash is cheaper per unit volume than cement
Better performance – (at equivalent cost or even at lower cost)
Lower heat development
Reduced shrinkage
Better flow properties (incl. stability)
Improved durability, e.g. resistance to chloride ingress
Fly ash in concrete – why?
Exposure class X0: no requirements to composition only strength (low)
50% or more fly ash
Slabs on ground (SCC)
Blinding layers
Etc.
Lower cost
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Vo
lum
en
Vand
Flyveaske
Cement
v/c = 0.50
k-faktor = 0.4
Fly ash concrete PC concrete
Vo
lum
e in
pas
te
cccccccccccccccccccccccc
Exposure class e.g. XS3: requirements to composition (max. fly ash)
Max 25% fly ash in powder (FA/CEM = 1/3) in DS 2426
Highway bridges
Marine structures
Deep foundation
Better performance
Center for Green Concrete 1998-2002
Carbon Footprint of fly ash concrete - DK
Environmental screening of ”Green” concrete highway bridge (in Danish)
Life cycle (50 years) CO2 inventory
http://www.gronbeton.dk/tidligere-projekter/groen-beton-i.aspx
From a concrete composition point of view the carbon footprint of concrete is dominated by the carbon footprint of the cement.
For severe exposure classes 1/3 of the cement may be replaced by fly ash according to DS 2426. From a performance based point of view higher replacement rates could probably be allowed.
For non-severe exposure classes higher replacement rates are allowed; in X0 no limit exist.
Carbon Footprint of fly ash concrete
Significant carbon footprint improvement is achieved from replacing cement by fly ash
In practice fly ash is in competition with other additions/powder (e.g. slag, limestone)
Started to see carbon footprint in concrete specifications
e.g. 400 kg CO2/m3 for the Copenhagen Metro extention ”Cityringen”
(2010)
18-34% fly ash in the concrete – most in deep foundation structures
Carbon footprint in specifications
Environmental Product Declaration
Sustainability in construction works R
EGU
LATE
D
Product level CPR (DoP, CE-marking)
Building level CPR and Eurocodes
VO
LEN
TAR
Y
Product level e.g. Nordic Swan, EEC Flower, EPD …
Building level e.g. DGNB, Bream …
Environmental
Product
Declaration
Declaration of
Performance
Construction
Product
Regulation
Environmental Product Declaration
Sustainability in construction works R
EGU
LATE
D
Product level CPR (DoP, CE-marking)
Building level CPR and Eurocodes
VO
LEN
TAR
Y
Product level e.g. Nordic Swan, EEC Flower, EPD …
Building level e.g. DGNB, Bream …
Environmental Product Declaration
Standards and PCR
Technical standards:
ISO 14044 (LCA)
ISO 14025 (EPD) (2006)
EN 15804 (EPD for construction products)
(2012)
Product Core Rules (PCR)
Product unit
Service life
Allocation procedures
And a lot more …
Environmental Product Declaration
LCA (Life Cycle Assessment – ISO 14044)
Production Transport and construction
Use End of use
Extraction and/or production of raw
material Transport Production process + +
Waste management
EPD in the Danish Concrete Industry
Cradle to gate approach
Included Excluded
Construction site
Concrete plant
EPD in the Danish Concrete Industry
Published EPD’s
Ready Mix Concrete Industry – average EPD’s for 5 typical concrete mix designs can be seen on the website based on specific data and generic data (GaBI) – ”Cradle to gate” www.danskbeton.dk
Prefab industry – average EPD’s for 6 typical prefabricated walls based on specific data and generic data (GaBI) – ”Cradle to gate” www.danskbeton.dk
The EPD’s for Danish Concrete Products are using a Danish EPD for Fly Ash in the calculations
Environmental Product Declaration for Fly Ash – DK – Carbon Footprint
Declared Unit = One tons of Fly Ash
Cement: 800 kg CO2-ækv.
Environmental Product Declaration for Fly Ash – DK
EPD Calculations based on:
Fly Ash is a co-product according to the definition in the waste Directive from 22.11.2008 (2008/98/EC) article 5, which means
The impact from production of fly ash shall be allocated, but can be neglected if processes is generating a very low contribution
Environmental Product Declaration for Fly Ash – Gabi Data
Declared Unit in the table = One kg of Fly Ash
Allocation has been done – makes a huge difference
Carbon Footprint = 201 [kg CO2-Equiv]/[tons Fly Ahs]
Environmental Product Declaration
Standardisation work in CEN TC/350 CENSustainability of construction works — Guidance for the implementation of EN
A guidance to EN 15804 is under development
Allocation rules are discussed
The 1,0 % cutt of rule is probably being changed