Written by Ruth Callaghan Thursday, 03 June 2010 12:27
IT’S stronger. It’s cheaper. It may once have been someone’s kitchen. It is also the road surface of choice for the City of Canning — provided they can get enough of it.
Curtin University researchers have been working with recyclers and councils to turn rubble from construction and demolition into the base for roads.
Recycled material is already being used on Kwinana Freeway and in the cities of Canning and Gosnells, where it can make up 90 percent of the volume of a road surface.
Colin Leek, an adjunct professor with Curtin University and project engineer for the City of Canning, says researchers conducted performance tests to check the material could take heavy traffic and also monitored the product’s consistency.
“You can have varying qualities of materials depending on the traffic loading that the material is going to be subjected to,” he says.
“Speed on the granular pavements that we are building is not a critical issue – it is the number of trucks that is important. If it is a road like Welshpool Road it does carry a high number of heavy trucks.”
Mr Leek says results show recycled material perform better than new-quarried road base.
“The sheer strength we are getting out of this material gives it excellent properties.
“It is apparent early in the life of the product that it is performing better than virgin quarry products. We put that down to the high degree of angularity in the product and the high degree of internal friction.
“But durability is a longer-term issue and we haven’t had the material as a surface long enough to determine how it will be in to the future.”
The material has the advantage of reusing waste that would otherwise go to landfill, often from the same site.
“We are getting the recycled product cheaper than the aggregate but the other big saving is that in an urban area, we are usually doing some demolition before the construction — we are pulling out curbs, footpaths, and all of that we can take to a recycling yard,” Mr Leek says.
On a broader scale, the technology offers options for rural towns with enough construction material for recycling.
However, while the science of turning more waste into roads is sound, the economics are not — at least not yet.
Mr Leek says there is a general shortage of recycled construction material and for every tonne recycled, another five end up in landfill. Unless landfill costs rise, the incentive for developers to divert the waste isn’t there.
“Ideally, if I could get enough of it I would build everything out of it, but there is a shortage,” Mr Leek says.
“For now, I would rather conserve this material for heavy traffic roads and use the virgin quarry material for the lightly trafficked roads.”
