The £320 million M80 motorway project between Stepps and Haggs, along one of Scotland’s busier road corridors, is one of the largest uses of the EME2 (Enrobé à Module Élevé) to date.

EME2 is a closely graded material that is binder rich and utilises a very stiff binder. This makeup ensures a material with a high stiffness, low air voids, which results in increased durability compared to more traditional asphalts.

Grontmij designed the EME2 with a Class 3 Foundation. The stiffer foundation allowed the asphalt thickness to be reduced. Two foundations options were designed:

• a cement bound granular sub-base material
• a composite unbound sub-base overlaid with a high stone content HRA

The Asphalt composite foundation option was developed by Grontmij to enable online widening sections of the works to be constructed rapidly without waiting for cement bound materials to cure.

Overlay / Inlay treatments

Where the new alignment closely matched existing over lengths of asymmetric widening and tie-in locations, analytical designs were used to allow the incorporation of the existing pavement into the new works. This resulted in:

• a substantial reduction of carbon footprint of the works
• time and cost savings to the project