Queensland’s Logan City Council is trialling a new asphalt technology that could help the city reduce its road maintenance and rehabilitation costs and extend pavement life.
With more than 2000 kilometres of sealed roads throughout its district, Logan City Council has its work cut out for it in maintaining its diverse network, especially when those roads are susceptible to the extremes.
From the harsh Queensland heat through to intense flooding, Logan’s roads are regularly subjected to both ends of the weather spectrum.
While the majority of asphalt surfaces on the city’s roads are built with a design life of between 10 and 25 years before they need replacing, the impact of these weather events and the rate at which its network is expanding means maintenance and renewals costs are adding up and the magnitude of the task at hand is increasing.
The city currently spends nearly $30 million a year on road rehabilitation across its network, but Logan City Council is exploring unique ways to reduce that cost and extend pavement life. One such avenue being pursued is the trial of fibre-reinforced asphalt on its roads.
“One of the important things we do at the council is encourage our staff and our engineers to innovate. This new kind of asphalt came to our attention through our employees and is now being taken to the next stage,” City of Logan Councillor Phil Pidgeon explains.
The council identified an asphalt additive that can extend the life of the pavement, which has been used extensively in the United States but is also being trialled at an intersection in Canning, Western Australia.
The fibre-reinforced asphalt product – Forta-Fi Fibre – is a heat-resistant blend of aramid and polyolefin fibres mixed into asphalt during manufacture. It is intended to strengthen the road surface and reduce the asphalt’s potential for cracking and rutting – extending pavement life.
Logan City Council has traditionally used dense-graded asphalt of varying depths and compositions on its urban network, and one of the main benefits of the fibre reinforced asphalt, according to Cr. Pidgeon, is the potential to reduce the thickness and amount of asphalt required by up to 35 per cent.
Fibres are added at about 0.5 kilograms per tonne of asphalt, meaning the minimal additional cost of the product is offset by the reduced need for asphalt.
The product also aims to delay road surface cracking by intercepting cracking propagation, which is partly achieved by reducing the amount of water ingress through cracks in the surface.
This August, Logan City Council’s Road Infrastructure Planning and Road Infrastructure Delivery branches collaborated to conduct a trial of the asphalt on a suburban road in Windaroo, which the council understands to be a Queensland-first.
For the trial council’s Road Infrastructure Delivery team constructed the fibre reinforced trial pavement alongside a more traditional geo-grid reinforced asphalt treatment to enable direct comparison of performance. The 150-millimetre-thick trial pavement consisted of 100 millimetres of AC20 with a 50-millimetre AC10 wearing course, each dosed with the Forta-Fi Fibre reinforcement. The control pavement consisted of 100 millimetres of geogrid reinforced AC20 with a 50-millimetre AC10 wearing course.
Cr. Pidgeon says the test area is highly trafficked and can accommodate a range of different types of vehicles in a given day.
With the fibre-reinforced additive on the ground, council engineers are keenly observing how the test site handles the area’s regular thoroughfare, with structural testing data likely to be available within 12 months.
He says the first trial will be followed by a second at Teviot Road in Carbrook later this year. If both trials are successful, the council plans to adopt the asphalt technology into its current practices.
“A lot of the road projects we undertake in Logan are large for a local government area and sometimes we do struggle to keep pace with infrastructure that we need to deliver,” Cr. Pidgeon says.
“We’re really at the cutting edge of things – if the trial is successful, and based on what we’re seeing already, we could end up using 35 per cent per cent less asphalt on any given project.
“It would also save our road projects a significant amount of money, which we can then use to deliver even more infrastructure – sooner and quicker. If this works it will take those shackles off and help to bring forward projects in our infrastructure program.”
Having such technology available in the market may have the potential to help Logan City Council achieve a more cost-effective approach to the rollout of its road rehabilitation activities and Cr. Pidgeon anticipates it may have wider implications for the pavement sector itself.
“We had quite a number of other councils observing the laying of this technology so it seems everyone is looking at this very closely with increasing interest because this could mean a big revolution for the industry,” he says.
“Logan always seems to lead the way in that technology space and it’s great to see we’re leading things on the front foot with something so innovative.”