An investigation was carried out into the properties and performance of a high modulus asphalt material designed using the French design method with ingredients readily available in the UK. The asphalt material, known as Enrobé à Module Élevé (EME) Class 2, was evaluated under full-scale loading in the Pavement Test Facility (PTF) at TRL. Two test sections were constructed using full-scale plant to provide a direct comparison of the performance of an EME binder course with that of a heavy duty macadam (HDM) binder course. This direct comparison allowed the performance of the 'new' material to be calibrated against a material that experience has shown to perform well in service. Two additional test sections were used to test a one metre wide (wheel-track) trench inlay to confirm that it could be included as a realistic and sustainable alternative maintenance treatment for surface rutting on heavily trafficked roads. The EME Class 2 material deformed less than the HDM and no cracking was observed along the joints adjacent to the trench. Indirect Tensile Fatigue Testing (ITFT) and Indirect Stiffness Modulus (ITSM) stiffness testing before and after saturation with water, and permeability measurements indicated that EME would be durable and would act as an impermeable layer beneath a thin surface course. No reduction in stiffness was measured after 50 days of soaking, and the cracking resistance of the richer EME Class 2 was superior to that of HDM. The very low air voids obtained in both the HDM and the EME binder courses using conventional plant, confirmed that the laying and compaction of EME Class 2 layers does not require special measures. As a consequence of this work an interim specification for EME Class 2 has been developed and specification trials under contractual conditions are planned for the near future. These will provide confirmation of the material's structural properties and mixing, laying and compacting characteristics. (Author/publisher)
Samenvatting