The port of Durban is one of Africa’s largest ports, and high volumes of trucks and heavy vehicles use its roads every day.
In 2011, a demonstration was undertaken to test a high modulus asphalt technology on a section of the South Coast road leading to the South African port. Reports to date show the asphalt is performing well, and Dr. Erik Denneman, Team Leader Pavement Technology at ARRB, says this technology is now being used in major projects in South Africa.
Dr. Denneman was involved in these successful South African demonstrations of enrobés à module élevé (EME): a French high modulus hot mix asphalt technology. He is now part of the team bringing EME to Australia.
EME has a long and proved history in its native France. Developed in the early 1990s, EME is a methodology that has been adopted and extensively used on France’s main routes and airports. Dr. Denneman says that EME is now a proved method close to what can be classed as the country’s national standard for asphalt technology.
This “technology transfer” to Australia, as Dr. Denneman puts it, comes off the back of international study tours involving ARRB, Austroads and Australian Asphalt Pavement Association (AAPA) in 2012. These organisations and asphalt suppliers collaborated in the preliminary testing for EME mixes in Australia. In this case, it was EME2 (or class 2) that was developed for use in Australia. In the first year of the three-year project, French counterparts sent materials for a proved French EME2 mix design to Australia to be tested in ARRB’s own facilities. The group then developed a specification for EME2 mixes in Australia, and requirements for its manufacturing, paving and compliance on the country’s roads.
EME2 pavements are thinner than those with conventional asphalt due to its hard grade bitumen applied at a high binder content. In some cases, its use has reduced the asphalt base layer thickness by 30 per cent. Its qualities make it the ideal candidate for roads designed for heavy traffic. “The main difference in this technology is the performance parameters,” says Dr. Denneman. EME2 is characterised by high stiffness, durability, and rut and fatigue resistance. But, it is the performance-based design philosophy behind the technology that makes it unique.
Dr. Laszlo Petho, ARRB Principal Engineer Pavement Technology and Project Leader for the EME technology transfer, explains that EME is tested in five areas to ensure its success. Workability, durability (including water resistance), rut resistance, stiffness and fatigue are tested in that order, following the French design philosophy. The idea is to make the pavement thinner, but not to compromise the performance.
He says that Australian asphalt suppliers have been active in following this methodology, and have sent their own EME2 mixes to France to ensure it adheres to French performance testing. “The requirements for aggregate quality are similar to normal asphalt mixes, therefore you can make this mix anywhere,” he says. Dr. Petho adds that the binder suppliers play a vital role in the implementation by producing a suitable binder locally.
The validation of the technology’s French performance-based philosophy has been vital to its implementation in Australia. “Comparing it to the French limits means we are designing an EME to the proved French method, but using Australian test methods and equipment,” says Dr. Denneman. “We don’t need to do 20 years of validation because if we’re sure we’re designing mixes to the French philosophy, we can be sure it will work.”
AAPA, ARRB, Austroads and industry and road agencies in relevant states have taken part in state-by-state demonstrations of the EME technology on Australia’s roads. Boral undertook the first demonstration at Eagle Farm in Brisbane in February last year. “And today, there is zero deterioration on this road,” says Dr. Petho. “EME is very rut resistant and this is the best I’ve ever seen in Australia.” Downer Group conducted the Victorian EME demonstration on the South Gippsland Highway in the first week of June. Fulton Hogan will lay EME in New South Wales later this year.
Dr. Denneman says that there’s only one specification for the EME technology currently in Australia. “We see it as a prelude to introducing more performance-based designs.”
AAPA is exploring the idea of having one national EME specification across the country. AAPA Chief Executive Officer Michael Caltabiano says the initiative to bring EME technology to Australia has been a bid to establish a national industry standard for asphalt technology: “AAPA is very keen to harmonise the [EME] specification across the country.”
He says that the state-by-state demonstrations of EME are helping the asphalt industry look beyond its borders.
As a high-strength product, EME can be laid thinner and quicker. This means cheaper production and reduced traffic delays during construction. “Like the consumers and tax payers using it, we’re focused on the end product,” he says. “In a macro sense, [EME] is the forerunner for future AAPA [asphalt] recipes. The outcome will be the best option for many pavements, ports, freeways and airports.”