Roads and airport pavement infrastructure, such as runways, are under increasing strain from ever-growing road and air traffic. However, traditional asphalt surfaces are not designed to withstand the surge in loads, making them more susceptible to damage and less carbon-friendly due to the need for repeated maintenance.
Traffic and thermal loading impact the quality and durability of asphalt pavement surfacing for roads. This increased pressure on pavement infrastructure is not just a maintenance issue but also a sustainability challenge. Traditional asphalt surfacing on our existing pavement network with underlying cracks or joints is carbon-intensive, in large part because of the need for frequent repairs associated with reflective cracking.
“The traffic volumes and loading on our infrastructure have increased significantly, but are our existing pavements built for it? No,” said Zehra Kaya, Director of Civil at HUESKER Australia.
Advanced geogrids extend pavement life and cut emissions
Asphalt reinforcement geogrids are engineered to combine durability with sustainability. Independent studies revealed advanced geogrids can cut carbon emissions by up to 62 per cent a year through more efficient manufacture, the use of recycled materials and by extending the life of pavement and road surfaces.
Well-engineered geogrids extend the service life of asphalt pavements by up to four times by shielding them from reflective cracking and delaying the deterioration of pavements.
The technology absorbs and distributes stresses above weak points in the asphalt. This makes the asphalt more resilient to reflective cracking from underlying cracks or joints in the pavement. This increased resilience to reflective cracking prevents water intrusion into the pavement, thereby protecting not only the surface but also the underlying high-value pavement asset.
“Shrinkage and fatigue cracks as well as joints in our pavement infrastructure present weak points, which experience peak stress concentrations under loading and develop into cracks in the new asphalt surfacing that is meant to protect the pavement from moisture intrusion.” Kaya said. “Thus, addressing reflective cracking is essential to effective pavement maintenance and construction.”
Perth Airport free of reflective cracking after 15 years
At Perth Airport, Runway 06 threshold surfacing reinforced with HUESKER’s HaTelit C asphalt reinforcement geogrid more than 15 years ago is still free of reflective cracks, despite the underlying 20-30 mm-wide extensive cracks in the pavement. Unreinforced asphalt surfacing typically shows cracking within one to four years in similar conditions.
The pavement consisted of 300-mm concrete slabs constructed in 1960, which were later surfaced with asphalt that experienced consistent reflective cracking and additionally presented widespread fatigue cracking. Despite being old and cracked, in 2009, the existing pavement was overlaid with new asphalt reinforced with the HaTelit C geogrid that has extended the service life of a critical airfield pavement while increasing operational productivity.
This also reduced maintenance costs and achieved carbon savings of more than 60 per cent.
Condition in 2009 prior to asphalt overlay with HaTelit C:
15 years after the HaTelit C reinforced asphalt-overlay treatment (2024):
In another example, HaTelit C geogrid reinforced asphalt saved Brisbane City Council 62 per cent in maintenance costs per annum and 54 per cent in construction costs while reducing carbon emissions.
The material’s eco-friendly version is manufactured from recycled post-consumer PET water bottles, transformed into polyester yarns and engineered into the HaTelit C eco geogrid, which provides additional carbon savings of over five tonnes per kilometre of a two-lane road.
The applications are widespread across local councils, main roads, ports and airport pavement infrastructure, including busy road intersections, airport runways and rapid exit taxiways.
Kaya said HaTelit geogrids are highly engineered and effective in absorbing the stresses even in high-shear applications, such as airport runway turning areas and road intersections, due to the mechanical interlocking enabled by the ultralight temporary backing of the geogrid. The ultralight backing is necessary for ease of installation and is engineered to support aggregate penetration through the geogrid during asphalt compaction.
The technology has been successfully implemented at every major Australian airport along with larger international airports, numerous defence airbases and by road authorities along with local councils across the country, mostly under the wearing course.
However, Kaya cautioned that using the right geogrid material and a well-informed specification process ensures the technology’s benefits are transferred to infrastructure projects.
“There are various geogrid types available in the industry,” she said. “While these materials have different functions and benefits in different engineering applications, only specialised geogrids should be considered for asphalt reinforcement.
“This is because both the asphalt material and the asphalt paving technology have unique demands that must be met. These include mechanical and chemical compatibility between asphalt and the geogrid material, along with the geogrid allowing a good adhesion and the necessary interlocking between adjacent asphalt layers without a separation.”
Kaya said when geogrids with heavier or permanent geotextile backing are used between asphalt layers, this introduces a separation function that does not serve the reinforcement function.
“Reinforcement comes from well-engineered geogrids that allow mechanical interlocking between adjacent asphalt layers and achieve required tensile strain development, through which the load is transferred to the geogrid instead of the asphalt taking all the loads.”
Not all geogrid solutions are created equal. Kaya highlighted that selecting the right type of geogrid will impact both performance and sustainability.
To maximise not only performance but also sustainability, HUESKER engineers its HaTelit asphalt reinforcement geogrids with an ultralight geotextile backing that uses less material, requires less bitumen to install and produces much less residual material to recycle compared to heavier or permanent geotextile backing types.
“Getting more with less is the critical part, both in performance and in sustainability,” Kaya said.
The ultralight backing inherently provides much higher shear-bonding strength between asphalt layers due to mechanical interlocking. It is also more suitable and safer to use when applied with warm mix asphalt technology, where the mechanical interlocking becomes even more important in reinforced asphalt. Warm mix asphalt technology is an emerging trend in Australia that reduces carbon emissions during asphalt production by lowering mixing and placement temperatures.
Moreover, HUESKER’s specialised HaTelit geogrids can be milled and recycled back into the recycled asphalt pavement, with demonstrated experience after prolonged service life.
HaTelit geogrids are flexible and resistant to construction damage during asphalt paving and compaction. While HaTelit C is used on asphalt surfaces, HUESKER’s HaTelit XP geogrid is specifically engineered with additional alkali resistance for applications on concrete pavement surfaces.
For infrastructure asset owners and managers facing the twin pressures of maintaining performance while reducing environmental impact, well-engineered asphalt reinforcement geogrids help them achieve both sustainability and durability with cost savings.
“We need to engineer the decarbonisation outcomes we all want as an industry and a community,” Kaya said. “Delivering higher performance with less quantity of materials, especially non-renewables, is true sustainability that will have a real impact across the infrastructure sector.”
Don’t miss out the upcoming webinar on 19 March 2025, focused on Sustainable Asphalt Reinforcement and Material Selection. Register now to secure your spot and stay ahead in the industry!
