EXPERIENCES: ASSESSMENT OF ENVIRONMENTAL APPLICABILITY AND MATERIAL SPECIFIC CRITERIA

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EXPERIENCES ASSESSMENT OF ENVIRONMENTAL
APPLICABILITY AND MATERIAL SPECIFIC CRITERIA

• Margareta Wahlström, Jutta Laine-Ylijoki
  Ulla-Maija Mroueh
• VTT Processes

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EXPERIENCES ASSESSMENT OF ENVIRONMENTAL
APPLICABILITY AND MATERIAL SPECIFIC CRITERIA

• Background
• Critical properties in residues
• Case study risk assessment of coal fly ash
  utilisation
• Material specific criteria
• Future works

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Background

• In the 1970ies Coal fly and bottom ash
  largely used
• In 1980ies Lack of regulations limited the
  use. Low interest, because low price of
  natural materials.
• Interest for environmental rules started in
  late 1980ies
• In 1990ies Dutch system in use (problems
  with coal fly ash, e.g. Mo, Se critical)
• Standarized quality control system for
  reclaimed concrete (SFS 5884) now several
  years experience with the system
• Present situation a case by case evaluation
• For residues with a clear market value a need
  for a regulatory system (a decree, which
  defines the conditions on which the material may
  be used)

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Examples of critical components in some residues

• components remark
• Coal fly and bottom ash Mo, Se, Cr, V, Sulphate
  dust
• Peat/biomass fly and bottom ash Mo, Cr, Se, F,
  Pb, Sulphate dust
• Granulated blast-furnace slag Sulphate, V
• Steel slag(e.g. LD) V, Sulphate alkalinity
• Crushed concrete waste Sulphate, Cr only
  selective demolition
• Foundry sands PAH, phenols, organics
• Crushed tyres Zn? Organics?

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Case study Risk assessment of coal fly ash used
in earth constructions(1997-1999)

Exposure risks in different work phases
1. Storage
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2. Prehandling
Dust exposure, dermal exposure (workers)
3. Loading
Dust exposure, dermal exposure (workers)
4. Transport
Dust exposure (passers-by)
5. Temporary storage
Dust exposure, leaching, ingestion via mouth
6. Road construction
Dust exposure, leaching
7. Use and maintaince
Leaching
8. Dismantling, reuse
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Case study Risk assessment of coal fly ash used
in earth constructions - Conclusions

• Paved construction
• low leachant quantities during the lifetime of
  the construction
• risks not significant
• Non-paved construction
• leached compounds cause some risks
• risks dependent on site conditions (e.g. urban
  areas)
• site specific assessment needed for sensitive
  areas (e.g. country side)

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Case study Risk assessment of coal fly ash used
in earth constructions - Experiences

• Easily managed
• Steps to be included, critical parameters,
  exposure pathways (references to soil risk
  assessments)
• Definition of a typical construction and
  utilisation scenario
• Selection on acceptable risk level (comparison to
  reference values for water)

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Case study Risk assessment of coal fly ash used
in earth constructions - Experiences

• Demanding
• Definition of site specific conditions (urban
  respective country side environment)
• Need for numerous assumptions in modelling !
• Conclusions
• Not all impacts can be modelled or assessed. Need
  for political decision for promotion of
  utilisation!

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MATERIAL SPECIFIC CRITERIA

• Basic requirements
• Significant amounts, residue fullfilling
  technical requirements
• Clear market for the specific residue
• Focus on inorganic residues
• Content of harmful compounds must be low
• Selection of parameters for total composition
  (material classification), basic characterization
  and compliance testing (key parameters for
  quality control)

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MATERIAL SPECIFIC CRITERIA (CONT.)

• Baseline
• Limit values for inert waste (direct exposure to
  plants, animal species and human not regarded)
• In paved constructions three times higher values
  accepted (not for Cd, Hg)
• Increase of values for specific materials based
  on results from TAC-modelling
• Rationale for increase (also analytical
  requirements)

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MATERIAL SPECIFIC CRITERIA (CONT.)
Reclaimed concrete
Coal, peat, wood ash
Blast furnace slag

• Inert waste criteria
• Cr and sulphate critical
• No need for increased
• values!
• Remarks
• SFS standard stricter
• values
• several year experience
• of a quality control
• system

• Inert waste criteria
• V and Sulphate critical
• No need for increased values

• Critical elements
• Mo, Cr, S, Sulphate
• Need for increased
• values!
• Remarks
• Bottom ash OK!
• Fly ash only in paved constructions

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Summary and Future works

• Summary
• Needs for both general criteria and
  material-specific criteria
• Utilisation also possible through case by
  case evaluation!
• Future work
• new candidate materials foundry sand,
  metallurgical slags
• quality variation data essential
• technical suitability