Why to assess gravel use and which gravel? Arthur Braunschweig, Dr. - - PowerPoint PPT Presentation

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40th LCA Discussion Forum

Why to assess gravel use – and which gravel?

Arthur Braunschweig, Dr. oec. HSG, E2

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Content

• The questions
• Results & Learnings from a new LCA study on recycled vs. natural

gravel / aggregate and concrete

• Thoughts on gravel assessment

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Starting points

• Gravel is a resource
• Gravel is in soil. Getting access needs machinery etc. Their effects are
• bviously included in LCAs
• But for the resource itself, nobody cared - neither NGOs nor in LCA.
• The Swiss BAFU, however, cares (as do other authorities): It asked to

include 'gravel use' into UBP'06

• What are the first learnings? What should stay, what should be

improved`?

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Experience with the 'gravel ecofactor': The aggregate LCA 2010

• LCA for Aggregate ('Gesteinskörnung'; Kies etc.) and Concrete (Kytzia

et al., 2010, publ. pend.; commissioned by Holcim (CH) AG)

• Question: Is it environmentally useful to use recycled aggregate in

concrete?

• 4 LCAs:

LCA for aggregate types LCA for concrete with & without recycled aggregate LCA for a generic building project LCA for a Swiss region

• Background of the study: Environmental building standard 'Minergie

P-Eco' asks for 25 % recycled aggregate in concrete, if available in the area. Holcim wanted a scientific basis for their internal further strategy discussion and for the public discussion on concrete recycling.

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The aggregate LCA 2010: Key results

• Basic results ("Ökobilanzen zum Einsatz rezyklierter

Gesteinskörnungen in Betonen"; Kytzia et al., 2010,

• publ. pend.)
• Using recycled aggregate
• - reduces 'gravel use' and 'ecosystem damage', as well as the waste

stream

• - for low quality concrete reduces the airborne impact categories

(GWP, AP, respiratory effects)

• - for high quality concrete does not influence to a relevant extent

energy use and airborne impact categories (GWP, AP, respirat. Damage)

• Reason for the latter: high quality concrete with recycled aggregate

needs a higher cement content.

• Transport of recycled aggregate becomes very relevant @ > 30 km

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The aggregate LCA 2010: Results on high quality concrete (1)

0% 25% 50% 75% 100% 125% 150%

C 30/37 C 30/37 C 30/37 C 30/37 C 30/37

Concrete C 30/37

Gravel use Land use Respiratory effects Acidification GWP

• Energet. Resource use

Gravel production Recycled aggregate production Concrete prod. Cement prod.

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The aggregate LCA 2010: Results on high quality concrete (2)

0% 25% 50% 75% 100% 125% 150%

C 30/37 C 30/37 C 30/37 C 30/37 C 30/37 RC

Concrete C 30/37 Concrete C 30/37 (25% recycled aggregate = "RC") Gravel use Land use Respiratory effects Acidification GWP

• Energet. Resource use

RC RC RC RC

Gravel production Recycled aggregate production Concrete prod. Cement prod.

Note: RC 30/37: 320 kg cement C 30/37: 303 kg cement

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The aggregate LCA 2010: Results on low quality concrete

Comparison for 0 et 100 % RC; both w/ 200 kg cement

0% 20% 40% 60% 80% 100% 120%

Lean Concrete 100% RC ('Magerbeton') Lean Concrete

Lean 100 % RC Lean 100 % RC Lean 100 % RC Lean 100 % RC Lean 100 % RC

Gravel use Land use Respiratory effects Acidification GWP

• Energet. Resource use

Gravel production Recycled aggregate production Concrete prod. Cement prod.

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Sensitivity Analysis: Cement content, Recycled aggreg. content

Recycled aggregate content: Effect on gravel use & land use (?) No effect on emissions

0%

1% 2% 3% 4% 5%

3 6 9 12 15

Increase in cement content (based on 303 kg = 100 %)

‐ 100% ‐ 90% ‐ 80% ‐ 70% ‐ 60% ‐ 50% ‐ 40% ‐ 30% ‐ 20% ‐ 10% 0%

Energieressourcen Treibhauseffekt Versauerung Atemwegserkrankungen Landnutzung Kiesabbau

0%

1% 2% 3% 4% 5%

3 6 9 12 15

GWP AP Respirat. Land use ecosys. dam. Gravel use Energy res.

‐ 100% ‐ 90% ‐ 80% ‐ 70% ‐ 60% ‐ 50% ‐ 40% ‐ 30% ‐ 20% ‐ 10% 0%

Recycled aggregate share of total aggregate

Cement content: Effect on emissions No effect on resource use

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Gravel / Aggregate production: New (ranges) and RC (generic)

0% 100% 200% 300% 400% 500% 600% 700% 800%

Site 2 Site 1 RC, fixed

Production Moving land and gravel Other transports

Gravel use Land use Respiratory effects Acidification GWP Energet. Resource use

Site 2 Site 1 RC, fixed Site 2 Site 1 RC, fixed

But what does a combined assessment look like?

Data sources: ‐ RC, fixed: adapted from ecoinvent ‐ Site 1, Site 2: Holcim

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Regional assessment

Assumptions:

• All torn down concrete is used for RC (except 5 % waste), ..
• .. either for direct (loose) application, e.g. as foundation, road bed, etc
• .. or in (RC-)concrete

Scenario:

Kies‐ werk

Deponie

Betonwerk

Beton/ Gebäude Schotter/ Strasse 2.2 Mio. m3Beton 3.6 Mio. t Gesteinskörnung Demand in the region Natural Aggregate Angebot in der Region

B) Recycled Aggregate

Concrete 1.079 Mio. t Betonabbruch

A) Recycled Aggregate

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Regional assessment (w/ all old concrete used)

Natural gravel production Recycled aggregate production (*) Concrete production Concrete production Transports new gravel Transports recycled aggregate Transports concrete

0% 25% 50% 75% 100% 125% 150% RC aggregate direct use RC into concrete RC aggregate direct use RC into concrete RC aggregate direct use RC into concrete Gravel use Land use Respiratory effects Acidification GWP Energet. Resource use

With these assumptions, it does not mat- ter a lot HOW recycled aggregate is used. As long as it IS used.

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UBP'06 results in gravel and concrete LCA (Kytzia, 2010; 1)

UBP for gravel and RC-aggregate

5 10 15 20 25 30 35 40

ecoinvent Site 1 Site 3 Site 4 Site 2 fixed installation mobile installation Natural Gravel Recycled aggregate UBP / kg

Aufbereitungs- anlage, inkl. Landnutzung Kiesabbau Baumaschinen andere Transporte

For aggregates, the gravel ecofactor dominates the assessment.

Gravel prod. Machinery Aggregate production Other transports

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UBP'06 results in gravel and concrete LCA (Kytzia, 2010; 2)

For concrete, the gravel effect is very relevant. Lean concrete with high RC-content creates less environ. impacts For high quality con- crete, the gravel ecofactor's contribu- tion is significant. But the overall result shows only small differences.

Gravel production Concrete production Cement production

0% 25% 50% 75% 100%

C30/37 RC‐Beton C30/37 Recycled aggregate production

0% 25% 50% 75% 100%

Lean concrete with 15 % recycled granulate Lean Concrete, 100 % RC granulate Lean concrete

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UBP'06 results in gravel and concrete LCA (Kytzia, 2010; 2)

On a regional scale: IF all waste concrete is used, it does not matter if it is used in concrete or as loose aggregate!

Vergleich UBP regionale Betrachtung 0% 25% 50% 75% 100% 125%

Szenario A: RC as loose aggregate Szenario B: RC into concrete

Transports natural aggreg. Transports recycled aggregates Transports concrete Gravel production Concrete production Cement production Recycled aggregate production

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Gravel in the UBP'06 method

New in UBP'06: Ecofactors (weighting factors) for:

• Fresh water
• Diesel soot ('Russ')
• Diocins and Furans
• Radioactive emissions to water
• PAK
• Benzo(a)pyrene
• Endocrine substances
• Land use
• Gravel use

Why an ecofactor for gravel in UBP'06?

• 'a resource sui generis, necessary

for most building processes

• 'not all gravel is accessible'
• 'is a specific case of land use'
• scarcity: current use = critical use

Is this a convincing case for inclusion into LCIA? What abouts other stones, gold, diamonds?

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WHY GRAVEL: WHAT SAFEGUARD SUBJECTS? 'resource sui generis' cleaning of rain water, ground water some land (shapes) used for gravel sites are protected HOW TO INCLUDE: as a spearate impact category? include the gravel (soil) functions in similar impact categories (double counting? No function – resource, landscape, ground water – is covered fully in existing impact categories)? leave out?

Why & how put 'gravel use' as an environm. impact category?

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WHICH MATERIAL SHOULD BE ASSESSED? Gravel is heavy. Transports and landscaptes are regional: regional assessment like with sweet water? Only assess gravel which performs the functions, e.g.

• only gravel over aquifers?
• only gravel in protected zones?
• only 'round' stones (natural), but not stones? (Künninger: 85 / 15 %)
• all other gravel to be left aside?

Becomes too complex, not helpful. Note: by defining an impact category, the overall weight of that imp.

• cat. in UBP only depends on the scarcity! Gravel (F = Fk) therefore has

similar weight as e.g. Pesticides, Cu in water, or toxid waste.

Why & how put 'gravel use' as an environm. impact category (2)

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Why & how put 'gravel use' as an environm. impact category (3)

Basic issue of a non-renewable resource:

• time horizon? (10 yrs? 100 yrs? 100 yrs?)
• current planning horizon? (10 – 20 yrs)
• any +/- legal resource use yields "F = Fk" (current flow = critical flow)

To what extent is gravel different to other soil materials, such as clay, sand or other stones? My opinion: IF there remains an impact category on gravel (etc.), it should cover all exploited soil materials, or at least all hard soil materials.