The use of the gyratory compactor in the design of portuguese bituminous mixtures

The volumetric design of bituminous mixtures has been adopted in several countries with success, and it is expected to gradually replace the traditional methods based on the Marshall test or the Hveem test. The Marshall method is commonly used in Portugal for bituminous mixture design. However, this method has serious drawbacks and a more effective design method is required. The adoption of a volumetric design can contribute to overcoming these questions. However, this type of design method must be carefully carried out because it can lead to the rejection of mixtures known to have a good behaviour in practice. It is important to define design values which can simulate the field behaviour of bituminous mixtures. However, the definition of those design values has to take into account the bituminous mixtures' properties, traffic levels, the in-service temperatures and the bituminous mixtures' mechanical behaviour observed in the past. The adoption of the gyratory compactor will lead to new limit-values for the design parameters. The goal of this project is to study the application of the gyratory compactor to common Portuguese bituminous mixtures, taking into account the experience of other countries, the current Portuguese practice and the capability of this equipment as a base to perform the volumetric design. The required bituminous mixtures' volumetric properties based on the Marshall method and the volumetric design method are analyzed. The compaction effort applied throughout the mixtures' volumetric design is also discussed. Suggestions are made for the adjustment of the design values for Portuguese mixtures and issues such as the resistance to fatigue and permanent deformation are addressed. Guidelines are drawn regarding the application of volumetric design to bituminous mixtures commonly used in Portugal. For the covering abstract see ITRD E144473.