Safer SMA bituminous binder wearing courses: UNIBAS M.P.T. performance characterisation

Road safety is one of the most common issues involving many countries worldwide, as for the increasing mobility demand. In order to guarantee safety for a long time, both quality and durability are to be achieved for flexible and semi-rigid pavements wearing courses. From this viewpoint this study proposes the use of splittmastixasphalt SMA bituminous layers, which are widely employed in the northern countries of Europe, where the severe winter climatic conditions as well as the heavy traffic of studded tyres vehicles magnify the good performances (strength, durability, noise reduction) of such materials. In order to get to an increased diffusion of SMA layers also in Italy, the structural response is thereby characterised in this paper, the specific climatic and environmental conditions of our country being obviously taken into account. For this purpose such characterisation should well get to a performance analysis based on traditional equipments (Marshall and Brazilian tests) as well as on innovative means, such as the UNIBAS M.P.T. apparatus (triaxial tests machine). In particular, the UNIBAS M.P.T. apparatus is fundamental for the scope, as the results allow to find, for each mixture and test temperature, the corresponding yielding/rupture domain, which is the indispensable surveying instrument for the rational design of both flexible and semi-rigid pavements. As a consequence, the Authors propose the implementation of a new system which could automate the M.P.T. output readings, the results being therefore independent of the particular experience and the subjectiveness of the user. In this way a new and powerful instrument is arranged, which can furnish specific information on the plastic field response of SMA bituminous concretes in a faster and more reliable manner.