Far from being viewed as a second-rate material, trials during more than a decade have shown that recycled materials are a cost effective alternative to using virgin quarried material, and often a superior choice for major road and water infrastructure projects.
Nicola Thom is leading Sustainability Victoria’s (SV) Market Development Research and Development projects and will be presenting the business case for using recycled products in infrastructure projects at IPWEA’s August Sustainability in Public Works Conference 2016, to be held in Melbourne.
In Victoria, the inclusion of recycled asphalt, crushed rock and concrete, crushed brick and recycled rubber in road sealing in VicRoads specifications and mix registration processes following robust lab testing and field trials has created confidence in the civil construction sector that the materials are fit for purpose.
This work has encouraged councils to utilise recycled materials such as recycled crushed concrete, crushed brick, glass fines, Reclaimed Asphalt Pavement (RAP) and crumbed rubber to supplement or replace traditional virgin aggregate and sand extracted from quarries.
This work has led to the use of these materials in several major infrastructure projects and roads in Victoria including Webb Dock (Melbourne International RoRo Automotive Terminal), City Link Extension, M80 Upgrade, and East Link.
Environmental benefits
The long-term environmental benefits of using recycled products in pavement construction include a reduction in the impact on the environment through the efficient use of extractive industries and limiting the use of non-renewable quarried materials.
Secondly, it reduces the amount of waste sent to landfill as it is being recovered, reprocessed and reused, which in turn increases the life of local landfill facilities. And, recycled products are generally less energy intensive to produce than quarry materials.
Cost savings from reduced haulage
Shortages in quarry materials in the Sydney market has seen prices rise by up to 70% due to increased haulage distances and associated costs. Now, reports of similar challenges are emerging in Victorian markets.
According to the Recycled products in pavement construction business case published by Sustainability Victoria last year, every person in the state requires an average of eight tonnes per year of quarry material to support the building of roads, houses and other infrastructure to service their needs.
The business case found continued demand for pavement construction materials is set to exhaust the supply from some of Victoria’s 500 existing quarries in the next 10 to 40 years.
This will force the supply of Victorian quarry resources to move progressively further away from demand, which will have a marked impact on costs.
Although the production cost for recycled and quarry products are similar, the bulk and weight of the material make the cost of haulage a significant component of delivered cost. In areas where they are readily available, local recycled products are cost competitive with and often cheaper than quarry materials.
Performance
While the performance benefits vary from material to material, there are some common benefits across the range of recycled products available.
SV’s research has found that in a range of road applications using recycled materials can reduce the total volume of material required and lead to a reduction in reflective and fatigue cracking, increase longevity of the roads and a decrease traffic noise.
Mobile crushers
From a business case point of view, the limitation of recycled products lies in an area’s proximity to Construction and Demolition (C&D) recycling facilities.
In regional areas investing in mobile crushers can expand the reach of recycled products, making them a competitive option by reducing the cost of haulage associated with either transporting recovered C&D materials to a recycling plant (by moving the crusher to the source of the C&D activity) or by transporting recycled crushed product from the crusher to the project site.
What now?
As the availability of virgin quarry material declines and supply from recycled material facilities become more widely distributed, the business case for recycled road aggregates will only become clearer.
“As the sector becomes more familiar and confident with the recycled materials the cost and the performance benefits are becoming more widely understood, resulting in these products becoming the materials of choice,” Thom explains.
Research and trials of recycled materials are ongoing. Sustainability Victoria has commissioned research to investigate the feasibility of using tyre-derived aggregate in the construction of road subbase. Yarra Valley Water has
recently conducted trials and adopted new specifications for the use of glass fines in pipe embedment construction projects.
To hear Nicola Thom from Sustainability Victoria speak about the Business Case for Using Recycled Materials in Pavement and Road Construction,
register now for IPWEA’s Sustainability in Public Works 2016 Conference. Held in Melbourne, the conference will run from August 24 – 26.