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Environmental Performances of Bricks made from Stainless Steel Slag: A Life Cycle Assessment Approach
Andrea Di Maria 1
Outlines
Ø Bricks from Stainless Steel Slag (SSS) • Stainless steel slag • Unfired Bricks from SSS
Ø Environmental evaluation: Life Cycle Assessment (LCA)
• Methodology overview • Results of assessment for SSS bricks
Ø Comparison of results with previous LCA Ø Conclusions
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Ø Masonry and facade bricks developed from Stainless Steel Slag (SSS)
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SSS bricks
Stainless Steel Slag
The StainlessSteelSlag (SSS) bricks
Chemical treatments
Technical aspect Is it possible to make bricks from slags which fulfil the current normative requirements in terms of shear stress and bearing capacity? Environmental Aspect Looking at the whole life cycle, what are the environmental benefits of using these new bricks compared to traditional bricks? Economic aspect What is the economic potential for such technologies and their strong and weak points in a view of a possible market introduction?
Stainless Steel Slag (SSS) • Stainless steel production by-products • 300 Kg of SSS each tonne of steel produced • 8,7 Mtons of SSS produced in 2011
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Industrial Product
Industrial By-product
SS Slag
Stainless Steel
The Stainless Steel Slag (SSS)
Stainless Steel Slag (SSS) • SSS contains high quality oxides (CaO,SiO2,Al2O3,MgO) • Hazardous compounds (Cr, Pb, Ni, Cd ). Borates or cement
addition to stabilised the slag
Landfilling
Recycling Aggregates and filling material in road construction
Stabilization required!
Low value application
(downcycling)
The Stainless Steel Slag (SSS)
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reactor
chamber
Carbonation
Alkali activation
Perforated SSS bricks
Solid SSS bricks
Aerated SSS bricks
Stainless Steel Slag
Ø Unfired Bricks • Alternative brick production using Industrial by-products (Fly
ashes from MSW incineration, Granulated blast furnace slag, etc.) • Findings to date demonstrated that unfired bricks can be
used as base for construction materials
The StainlessSteelSlag (SSS) bricks
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Perforated SSS bricks
Solid SSS bricks
Aerated SSS bricks
Ø Carbonation • Method of carbon capture that accelerates the natural weathering of
calcium, magnesium and silicon oxides, allowing them to react with CO2 to form stable carbonate
𝐶𝑎(𝑂𝐻)↓2 + 𝐶𝑂↓2 =𝐶𝑎𝐶𝑂↓3 + 𝐻↓2 𝑂 Oxides Carbonates (Solid)
Ø Alkali Activation • Chemical process that transforms glassy structures into compact and
well cemented composites, through chemical activation with alkali compounds
The StainlessSteelSlag (SSS) bricks
RESEARCH QUESTION Ø Looking at the whole life cycle, what are the environmental
benefits of using these new bricks compared to traditional bricks?
Life Cycle Assessment (LCA) Methodology allowing to assess environmental impacts associated with all the stages of a product's life from-cradle-to-grave
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The StainlessSteelSlag (SSS) bricks
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Goal and
Scope
Inventory Analysis
Impact Assessment
Inte
rpre
tatio
n
The
LCA
fram
ewor
k • Functional unit
• System boundaries
• Data collection
• Data treatment
• Calculation method
• Results analysis
Life Cycle Assessment
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Goal and
Scope
Inventory Analysis
Impact Assessment The
LCA
fram
ewor
k • Functional unit
• System boundaries
• Data collection
• Data treatment
Life Cycle Assessment
Comparison S-2 bricks to traditional bricks with similar properties (substitutes) that are already available in European markets
§ Perforated and solid S-2 bricks→ fired clay bricks § Aerated S-2 brick → Autoclaved brick (ytong)
Functional unit Impacts related to the production of 1m³ of bricks Avoided impact It refers to the impact of virgin material production that is avoided by the use of recycled material. In LCA it accounts as a value to be subtracted to the total impact (negative value)
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Life Cycle Assessment
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Systems analysis
SSS Bricks vs Traditional bricks
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Systems analysis
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Goal and
Scope
Inventory Analysis
Impact Assessment The
LCA
fram
ewor
k
• Calculation method
• Results analysis
Impact Assessment
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Raw Materials Land use CO2
VOC P SO2
NOx CFC PAH DDT
Ozone depletion Human toxicity
Radiation Ozoneformation Particules form. Climate change
Terr. ecotox Terr. acidif.
Agr. land occ. Urban. land occ. Nat. land transf Marine ecotox.
Marine eutr. Freshwater eutr. Freshw. Ecotox. Fossil fuel cons
Mineral cons. Water cons.
Damage
Damage
Damage
Human Health (Daily)
Ecosystems (Species yr.)
Resources (Cost)
Calculation methodology
Single Score
Substances Midpoints Endpoints
Uncertainty
ReCiPe
Impact Assessment
Results(1): Single Score (impact categories)
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-‐40
-‐30
-‐20
-‐10
0
10
20
30
40
50
60
Solid AA bricks Perforated bricks CC Perforatef bricks R Clay brick
Pt
Climate change Fossil deple;on Par;culate ma>er forma;on Metal deple;on Human toxicity others
Impact Assessment
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-40
-20
0
20
40
60
-60
-40
-20
0
20
40
60
80
100 100%
1.76%
-61.71%
Clay bricks
Perforated bricks R
Solid AA bricks
Perc
enta
ge
Perforated bricks CC
Total impact
Pt
31.39%
Clay bricksPerforated bricks R
Perforated bricks CCSolid AA
bricks
Disposal landfill (0.42) Disposal recycle (0.24) Landfill - avoided impact (-16.58) Steam (0.02) Sand mining (0.41) Alkali production (34.24)
Disposal landfill (0.41) Disposal recycle (0.24) Landfill - avoided impact (-42.95) CO2 production (10.13) CO2 uptake (-4.69)
Disposal landfill (0.41) Disposal recycle (0.24) Landfill - avoided impact (-42.96) Electricity (32.92) CO2 production (10.13) CO2 uptake (-4.69)
Disposal landfill (0.61) Disposal recycle (0.35) Process materials (2.44) Raw materials (3.76) Engergy consumption (29.54) Direct emission (23.04)
Results(1): Single Score (processes contribution)
Impact Assessment
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0
2
4
6
8
10
12
ytong Aerated AA bricks
Pt
Climate change Fossil deple;on Human toxicity Metal deple;on Others
Results(2): Single Score (impact categories)
Impact Assessment
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11.95 11.94
Aerated AA bricks
-10
-5
0
5
10
15
20
Pt
Disposal landfill (1.85%) Disposal recycle (1.08%) Landfill - avoided impact (-65.25%) Steam production (0.18%) Alkali production (160.56%) Sand mining (1.30%)
Ytong
Disposal landfill (0.95%) Disposal recycle (1.22%) Electricity (63.95%) Lime production (26.77%) Cement production (6.31%) Sand mining (0.74%)
Aerated AA bricks Ytong0
2
4
6
8
10
12
14
16
18
20
22
Pt
Total impact
Results(2): Single Score (processes contribution)
Impact Assessment
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11.95 11.94
Aerated AA bricks
-10
-5
0
5
10
15
20
Pt
Disposal landfill (1.85%) Disposal recycle (1.08%) Landfill - avoided impact (-65.25%) Steam production (0.18%) Alkali production (160.56%) Sand mining (1.30%)
Ytong
Disposal landfill (0.95%) Disposal recycle (1.22%) Electricity (63.95%) Lime production (26.77%) Cement production (6.31%) Sand mining (0.74%)
Aerated AA bricks Ytong0
2
4
6
8
10
12
14
16
18
20
22
Pt
Total impact
Results(2): Single Score (processes contribution)
Impact Assessment
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
Raw material Drying Baking Shaping of clay Distribu;on (diesel)
kWh
0 50 100 150 200 250
Global worming
Acidifica;on
Eutrophica;on
Solid waste
Ø Saving energy From (Koroneos et al. 2007)*: Emissions of CO2, SO2 and NOx , released during the baking stage, highly contribute to the total environmental impacts of clay brick production, and actions to reduce these emissions would affect significantly the final score
* Koroneos C and Dompros A. (2007); Environmental assessment of brick production in Greece. Building and Environment 42: 2114-2123.
Comparison with similar LCA
0
10
20
30
40
50
60
70
80
90
100
CEM I CEM III
0% recycled
10% recycled
20% recycled
30% recycled
40% recycled
Comparison with similar LCA
Ø Cement composition and aggregates recycling From (Blankendaal et al. 2014)*: Decrease up to 30% of the total impact could be achieved substituting Portland cement with slag cement, while increasing from 0% up to 40% the quantity of waste material replacing gravel as aggregate, the reduction of the total impact was negligible
CEM I= 100% Portland Cement
CEM III= 50% Portland Cement+ 50% slag
* Blankendaal T, Schuur P and Voordijk H. (2014) ; Reducing the environmental impact of concrete and asphalt: a scenario approach. Journal of Cleaner Production 66: 27-36.
Conclusions
Ø Saving energy Solid AAbricks and perforated carbonated bricks lower the energy consumption (electricity or fossil fuels), which is the highest impact for conventional clay bricks (during baking stage). Ø Cement production Aerated AAbricks decrease the impact of cement production in traditional autoclaved bricks. Ø Alkali production Alkali activation requires high quantity of alkali activators. Ø Avoided landfilling of slag Lower stress on the use of virgin materials but also to saved impacts arising from the handling of the slag in landfill Ø Disposal phase It seems not to account significantly on the final results, and the reuse of waste bricks as aggregates has little effect on decreasing the total impact.
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