The paving of enrobé à module élevé class 2 (EME2) asphalt on the GUN project in Brisbane is the culmination of many years of development work to transfer this new high modulus asphalt technology into Australia.
The paving of 10,000 tonnes on the GUN Project for Queensland’s Transport and Main Roads (QTMR) in March this year has been the single largest EME2 project in Australia to date.
This achievement came about as a consequence of the collective effort of many stakeholders who realised the benefits that EME2 asphalt will bring to the Australian road network.
“The prime benefit of EME2 is that it can potentially reduce the layer thickness of the base course for a heavily trafficked pavement by up to 30 per cent depending on climatic and traffic conditions,” explains Trevor Distin, Colas/SAMI Bitumen Technical and Marketing Manager.
“Alternatively it can be used to design and build stronger and longer lasting pavements. Either way, this has major cost benefits to road, airport and container terminal asset owners.”
Colas, the parent company of SAMI Bitumen Technologies (SAMI), has been closely associated with the development of EME2 since its inception in France in the 1980s.
The company has been involved in the manufacture and paving of EME2 asphalt technology across Europe and the United Kingdom, with the product now included in British Highway specifications
More recently Colas has constructed highway, airport and industrial pavements using EME2 in New Caledonia and the Indian Ocean islands of Reunion and Mauritius.
“With Colas’ acquisition of SAMI Bitumen Technologies in 2008, SAMI has been working closely with the local industry on transferring this technology over to Australia,” explains Mr. Distin.
“Key to designing and producing EME2 is the access to the special hard grade of bitumen. Since the construction of the first EME2 demonstration project in Brisbane in February 2014, SAMI has been supplying 15/25 penetration grade bitumen for EME2 trials across Australia out of its Port of Brisbane facility.”
With the support of Colas’ central laboratory in Paris, the company has been able to validate the mix designs using SAMI bitumen and local aggregates to ensure that the mix design meets the French performance-based specifications.
“This has been crucial in providing the local practitioners with the confidence that the Australian based EME2 specifications will render the desired outcomes. So much so that Main Roads Western Australia (MRWA) in April incorporated a 1200-tonne section of EME2 on one of their road projects in Perth,” says Mr. Distin.
The implementation of EME2 in Western Australia is a key example of just how far the pavement technology has come in Australia, and how it is becoming a sought after product nationally.
The Western Australian road authority established a joint research program with the Australian Road Research Board (ARRB) in 2016 called the Western Australian Road Research and Innovation Program (WARRIP). The program includes a number of projects to deliver over a four-year timeline, one of which is the use of EME2 on road projects in the state.
Steve Halligan, Bituminous Products Consultant from MRWA’s Materials Engineering Branch, says the project builds on work already done by Austroads, Australian Asphalt Pavement Association (AAPA) and Queensland’s National Asset Centre of Expertise to develop design and specification documents, along with a guide, on the use of EME2.
“For this project, we have partnered with Downer Australia in association with SAMI/Colas as the supplier of the special bitumen,” he says.
“During 2016, Downer developed an EME2 mix design using SAMI bitumen from its Brisbane plant, the mix design criteria of which came from an Austroads project to implement the use of EME2 in Australia.”
Mr. Halligan says MRWA required Downer send its raw materials to France where the Colas team from its campus for science and techniques (CST) combined the material to manufacture the EME2 mix in its laboratory and test it with equivalent European testing methods.
This validated the Australian mix design methods, and was delivered with positive results.
Following validation of the material, MRWA and Downer undertook the first placement of EME2 on a MRWA project at the intersection of Tonkin Highway and Kelvin Road at the end of April this year.
One of Colas’ project engineers from the Reunion EME2 Highway project – Pierrick Dupuy – assisted MRWA in an advisory capacity in order to help the authority’s own team capture best practice around the manufacture and paving of EME2.
Downer and SAMI worked closely to ensure the timely arrival of the bitumen from Brisbane and to keep it in good condition ready for use.
“A total of 1200 tonnes of EME2 was manufactured and placed in two layers of 105 millimetres each which was covered by a 50-millimetre layer of 14-millimetre dense graded asphalt as the wearing course,” explains Mr. Halligan.
“This included 100 tonnes placed at Downer’s plant as a pre-trial to adjust processes to the special asphalt.”
Mr. Halligan says the results from the trial found that EME2 was easy to handle and compact with low in-situ air voids, making the product impermeable in the mat.
“Learnings from this first application are being compiled in a WARRIP report which will be presented to industry in a knowledge transfer workshop in Perth in late June,” he says, adding that another knowledge transfer workshop is also planned where EME2 is to be placed on another project.
“The first use in WA was at a higher temperature than necessary so Downer was comfortable with making it and placing the EME2. Therefore, we are yet to place it in summer but the process will be to manufacture EME2 over a range of temperatures to suit the time of year, thus at a lower temperature in summer,” explains Mr. Halligan.
He says the bitumen used for the manufacture of EME2 is not yet available in WA and the first two applications of the asphalt technology in the state will be supplied from Brisbane.
“Colas and SAMI have seen the potential for the ongoing use of EME2 in WA and are in the process of building infrastructure to manufacture the bitumen in WA, which will make the use of EME2 in WA commercially viable in conventional full depth asphalt pavement,” explains Mr. Halligan.
He says the shared knowledge and collaboration around the development of EME2 in Australia is crucial to its implementation in WA.
“It has been vital to get the assistance of people who have knowledge of the product and its use in Europe. This project included Laszlo Petho, who was working for ARRB at the time under WARRIP, Trevor Distin from Colas, Warren Carter and other key people from Downer.”
This September, MRWA is set to lay a further 12,000 tonnes of EME2, which will be placed on the Tonkin Highway as part of the NorthLink Stage 1 project.
The EME2, with bitumen sourced from SAMI in Brisbane, will be applied to demonstrate and confirm the viability of the manufacture and use of EME2 in the state, which Mr. Halligan says will lead to the publication of guidelines and specifications for the pavement technology.
“With a successful outcome, the use of EME2 should become a standard option for inclusion in future construction contracts when the special bitumen is produced in WA,” he says.
Mr. Halligan surmises that EME2 will have an important role to play in the state’s road network.
“An advantage of EME2 being compacted to low air voids in the pavement is that it should eliminate Main Roads’ concerns of moisture ingress into the asphalt in comparison to standard asphalt pavements, and therefore increase opportunities for more paving in small windows of dry days in winter,” he explains.
“A successful implementation of EME2 into WA will result in a reduction in the thickness of asphalt pavements and an expected significant cost saving that is a key aspect of the WARRIP project.
“This will enable more road construction for the available budget.”
Given the interest shown in EME2 in Perth, SAMI has plans in place to build a new processing facility at its new Kwinana bitumen terminal, which will allow the company to produce EME2 bitumen for the local market.
Mr. Distin say as the demand for EME2 increases, SAMI will increase its manufacturing capabilities in Australia to be able to supply the special hard bitumen out of their various facilities.
“AAPA has released a model specification to allow road authorities to make greater use of EME2. The model specification includes two grades of hard bitumen which can be used, namely 10/20 and 15/25,” says Mr. Distin. SAMI is able to supply both grades, with the 10/20 rendering a higher modulus value to the asphalt. Additionally, he says, ARRB has developed a pavement design method for QTMR, which allows the engineer to utilise the actual modulus and fatigue properties of the mix to design the pavement to meet the actual anticipated loading and climatic conditions. He says the Australian industry is well ahead of the curve, with many industry stakeholders making such progress in the implementation of EME2 on the nation’s roads.
“Colas and SAMI, through their association with the other industry stakeholders, are proud to be a key player in delivering a new technology to Australia,” states Mr. Distin.
“This will result in more sustainable use of our natural resources and to provide roads which will be able to carry heavier loads at a reduced cost to the taxpayer.”