7th December 2006
Industry asks government to encourage contractors to use recycled aggregates such as glass in our roads
The Glass Packaging Forum has funded a cost benefit analysis which finds that the premium for processing aggregate with
glass cullet over conventional mineral aggregate is around $2 per tonne but this extra cost isn’t recognised in most
An amended Transit road specification introduced this year now allows for up to 5% of glass cullet to be used in the
base course for roading. This will help provide a local answer for many communities who find that the cost of sending
glass back to Auckland for processing is often too high.
However at present this isn’t economically viable unless councils also include the potential cost of landfilling the
glass into the equation. The introduction of sustainable construction targets could incentivise councils particularly on
South Island to use glass cullet in local roads.
With around 5% more glass packaging recovered from homes year on year, New Zealand needs to find sustainable alternative
recycling uses for its glass. To finance research and development into these, industry through the Glass Packaging Forum
has established a voluntary levy on all those making, using or selling glass containers in New Zealand.
John Webber, General Manager of the Glass Packaging Forum says that using glass in roads is common around the world but
in its infancy here and unless changes are made to the procurement practices, it will be difficult to encourage uptake.
“We have assisted two local communities in Palmerston North and Nelson with funds to trial crushing glass in a mix with
traditional mineral aggregate and have subsequently commissioned a report to analyse the different production process
and associated costs of each. This report shows that whether glass is crushed separately and mixed later with minerals
or crushed together with minerals, the costs are broadly similar.
“The problem is that the premium for the glass cullet/ aggregate blended product over a conventional mineral aggregate
is around $2 per tonne. This effectively means that using 5% glass cullet in the mix may cost up to 30% more if low cost
stone is available.”
“With the aggregate industry now reporting a scarcity of stone in the Auckland region in particular, we believe that
using glass from household recycling which cannot be used to make new glass because it has been contaminated during
collection would make good sense.”
“And using glass locally in roads is economically viable if a whole of life approach is adopted. Whilst it costs more to
use a glass blend rather than just minerals, if you factor in what it would cost to landfill recovered glass it is a
much cheaper option overall.”
However Mr Webber says that the big question is who pays this premium:
“Road construction projects are highly competitive and contractors will always use the lowest cost product that complies
with specification. We are encouraging the government to show leadership by placing a value on using sustainable
aggregates so that glass recovered locally is utilized in local infrastructure.”
“One option could be to introduce a sustainable procurement policy along the lines of that enacted in California. The
California Bill will require the California Department of Transportation to use recycled aggregates in state paving
projects unless it is economically unfeasible.”
The Glass Packaging Forum was established to support and deliver on the objective, commitments and targets of the New
Zealand Packaging Accord 2004. All members are levied according to how much glass they use making it the first large
scale product stewardship initiative. Funds raised are available to assist local councils, recycling operators and
communities develop commercially viable uses for recycled glass.