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Opportunities, Benefits & Barriers Associated With The Use of Glass Waste as Aggregate in Coated Roadstone

This project studied the use of glass as an aggregate in roadbuilding material (coated roadstone). It looked at:

  • the scale and need for this management option for waste glass
  • barriers embedded in technical requirements and standards
  • the associated environmental benefits and disbenefits
  • attitudes and actions in Local Authorities

The project consisted of

  • Life-cycle assessment to compare the environmental impact of producing coated roadstone using only virgin aggregate with the environmental impact of producing coated roadstone using a mixture of glass and virgin aggregate
  • Telephone survey of Local Authorities' Recycling and Highways Officers in Wales
  • desk research into; road construction - technical and legal requirements, standards and specification; glass processing & re-processing and the glass waste market

THE PROJECT REPORT

LTCS
the-environment-council
RMS

This project has been awarded Beacon status

Beacon status is awarded to RMC projects that are deemed forward thinking and whose deliverables far exceed the funding criteria and the objectives of the Landfill Tax Credit Scheme.

SUMMARY FINDINGS

  • there are no technical or standards-related barriers to the use of waste glass as a aggregate in coated roadstone up to a certain proportion;
  • formal "HAPAS" approval of products such as "Glasphalt®" would help to overcome the natural reluctance to change that comes from unfamiliarity;
  • the surplus of available waste glass over thermal recycling capacity makes this additional outlet valuable, particularly since it can absorb low-quality material and green glass

ENVIRONMENTAL TRADE-OFFS

An environmental life-cycle assessment showed that the obvious benefits of reduced landfill and quarrying activity come at a cost in increased greenhouse gas emissions when waste glass travels more than 40km or so.

A CRACK IN THE "MARKET"?

The market survey showed that:

  • within Local Authorities, the efforts of recycling officers to increase recycling rates are hampered by a perceived lack of outlets for recyclates, with rather low awareness of the potential for glass use as aggregate.
  • highway maintenance officers are more keenly aware of the opportunity that exists to use roadbase materials containing waste glass

CONCLUSIONS

  • Although, in environmental terms, it is worthwhile transporting glass waste some distance for thermal recycling, glass waste destined for aggregate use shouldn't travel very far. An ideal glass waste management system would therefore look like this.
  • There is a need to raise awareness in Local Authorities about glass recycling into aggregate as a practical option for this waste stream
  • There is also a need to develop practical arrangements to return low-quality glass waste to aggregate use close to where it arises

DOWNLOAD THE FULL PROJECT REPORT