PAVEMENTS – Introducing EME2 to Queensland: Reducing the thickness of full-depth asphalt pavements

Enrobé à Module Élevé (EME), or high modulus asphalt, was developed in France in the late 1980s in response to the need to build stronger and longer lasting pavements.  With further development, EME use was extended to airport pavements and major highways, and the second generation (EME2) is extensively used across France and elsewhere in Europe. 

EME2 is a structural asphalt which offers increased stiffness, fatigue and rut resistance properties over conventional unmodified asphalt base course mixes. To achieve these performance enhancements, a very hard grade of bitumen is used in the asphalt mixture at a high binder content, which along with some changes to the grading of the mix, leads to improved outcomes for Queensland through: 

• a reduction in the pavement thickness to achieve the same design life, resulting in reduced costs, reduced construction time and reduced use of scare resources 
• alternatively, a substantial increase in the service life of the pavement if the equivalent layer thickness is used, and 
• a reduction in time required for pavement construction, reducing delays to road users.  

The early work toward the introduction of EME2 into Australia was undertaken by Austroads, TMR, ARRB, AAPA and its members.  In 2014 this culminated in the first EME2 trial project in Australia in Eagle Farm (Brisbane) where 315 tonnes of EME2 was laid.  This trial proved that locally procured aggregates and bitumen could produce EME2 asphalt consistent with French specifications, which had been adapted to Australian conditions and practices. 

To facilitate its broad scale introduction into Queensland, a procedure for the design of EME2 pavements was developed and included in the TMR Pavement Design Supplement.  TMR also created a new specification, MRTS32 High Modulus Asphalt (EME2), which was the first EME2 specification in Australia.  To complement this research, another related initiative was the development and publication of TMR Technical Note 167 which related to the procedures to test modulus and fatigue properties of asphalt mixes during pavement design. 

Since the initial work under Austroads and NACOE, a series of further demonstration projects have taken place in Queensland and around Australia, and EME2 has now been utilised as a pavement base layer across several recent and ongoing major projects in south east Queensland.