Experimental investigation and modelling of the compaction process in bituminous mixtures

Compaction is a crucial topic for asphalt mixtures. In fact, the success of mix design depends on the effectiveness of compaction and its understanding is of paramount importance as part of the comparative assessment of different mixtures. Furthermore, mixtures with high compaction characteristics require lower energies to be employed during placement on site. The main objective of this thesis was to investigate polymer-modified asphalt (PMA) mixtures – obtained by using different additives and by conveniently varying binder content and aggregate skeleton – characterized with respect to their compaction characteristics. Several PMA samples were prepared by using three type of additives, two different binder content and two granulometric curves. The goal of this first phase was to evaluate the better combination that leads to high compaction. In the second phase, all the PMA specimens were subjected to Indirect Tensile Strength (ITS) tests. The results showed that the PMA mixtures containing the additives exhibited reduced values of ITS value due to reduction of internal friction. In addition to the mechanical performance evaluation, the compaction characteristics were deeply analysed by means of different analytical models. These were studied and developed starting from simple models and thereafter combining them to create more complex arrangements. The objective of this phase was to obtain a model that can simulate with high accuracy the compaction of all PMA mixtures, with the consequent identification of parameters that can highlight different aspects of the compaction phenomenon.