AfPA paves the way towards a more sustainable industry

The Australian Flexible Pavement Association has partnered with Fulton Hogan to launch a new project with the City of Gold Coast, aimed at increasing the sustainability of their road network through the uptake of Reclaimed Asphalt Pavement.

The project enables a higher content of RAP (Reclaimed Asphalt Pavement) to be used in road surfacing, supporting the conservation of natural resources and reductions in energy consumption, helping the industry meet 2030 and 2050 emissions reduction targets.

The use of a higher percentage of RAP content (40 per cent) is possible through the use of rejuvenators, which are proven to effectively ‘reverse’ the ageing of the oxidised RAP binder, creating a functional and sustainable surfacing.

The trial represents a way to reduce the carbon footprint of road construction and can provide guidance to other local governments and State Road Authorities in the delivery of sustainable infrastructure.

While trialling three different rejuvenators with 40 per cent RAP in the mixes, the trial also sought to evaluate the use of A15E, a polymer modified binder, in the asphalt mixes containing high RAP content.

Conducted by AfPA and Fulton Hogan with CoGC (City of Gold Coast), the project consisted of manufacturing and laying AC14 H mix and three test sections with 40 per cent RAP and three different rejuvenators. The trial took place on the Hymix Road in the Gold Coast, which sees a traffic makeup of approximately 90 per cent heavy vehicles.

The High RAP mix project started in October 2021 with a conversation between Fulton Hogan and Anna D’Angelo, AfPA’s Executive Director Technology and Leadership. Extensive planning ensued over the next seven months, which included approaching the CoGC to assist the project team with selecting a suitable trial site. After a series of discussions, site inspections and investigations, a detailed proposal was developed by the Fulton Hogan team for the rehabilitation of Hymix Road.

The original pavement design consisted of a lightly modified granular overlay with a chip seal and Fulton Hogan’s proposal included five costed options of a full depth asphalt pavement, with a recommendation for CoGC to accept the fifth suggestion. Specifically, the scope of work included: profiling 100 mm off the existing pavement, placement of Tensar ARG geogrid, 617 tonnes of EME2 high modulus asphalt and four sections of AC14(A15E) with the three rejuvenators and one reference section with only A15E binder.

The CoGC also collaborated earlier this year with AfPA, trialling the use of AfPA’s Sustainability Framework scorecard for Asphalt (SF4A) in a recent asphalt tender, putting the local government in pole position to implement this leading innovation.

Carlos Rial, CEO of AfPA says the trial would help to increase the use of sustainable products in construction.

“This is a fantastic project, one with the capability to affect the sustainability and operation of the whole industry. However, this means that we must adopt a whole of industry approach to be successful,” Rial says.

“We always welcome the opportunity to partner with organisations and councils who share our interest in creating a more sustainable industry and better-functioning roads. The CoGC is to be commended for their commitment to lead the way for other councils to be and think more sustainably for their communities.”

Alton Twine, Director Transport and Infrastructure of CoGC says the city were pleased to partner with associations such as AfPA to deliver sustainability outcomes

“We firmly believe that effective change comes through innovative and foundational adjustments,” Twine says. “Projects such as these, and indeed our adoption of SF4A, keep our city at the forefront of environmentally-friendly infrastructure.”

TCL Hofmann supplied VIATOP plus RC for the trial, which is produced by J.Rettenmaier & Sohne (JRS) of Germany, which is the home of many innovations in the Asphalt Industry. VIATOP plus RC, containing a sustainably effective rejuvenator, is presented as a pellet for ease of control and addition to the asphalt mixer and does not utilise vegetable oils as are commonly used as RAP rejuvenators and is measured to have a significant effect on the heavily oxidised portions of RAP.

Ravi Rajagopalan, General Manager, Sripath Asia-Pac, supplier of ReLIXER, says Sripath greatly appreciated the opportunity to showcase its ReLIXER rejuvenator at the AfPA high-RAP trial.

“ReLIXER rapidly penetrates RAP particles, rejuvenates the aged binder and delivers excellent roadway performance and durability. A blend of green bio-based oils, it helps lower carbon footprint and greenhouse gas emissions. In High-RAP Mixes, it helps reduce the need for virgin bitumen and lowers the overall cost of the mix. ReLIXER has been tested, vetted and adopted by experts from around the world, now also in Australia,” Rajagopalan says.

The third supplier, Ingevity, supplied Evoflex, which is derived from forestry products, providing an environmentally friendly, nontoxic solution to increasing the amount of RAP incorporated into mixes. Evoflex accomplishes this by effectively solubilising the bitumen in recycled materials, increasing the blending of the virgin and the oxidised binders. Mixes with high amounts of recycled content made with Evoflex have improved coating and workability with a wide variety of paving materials.

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