INFLUENCE OF MIXING TIME AND TEMPERATURE IN HOT MIX ASPHALT STIFFNESS DURING ASPHALT MODIFICATION

When an asphalt binder is modified through a wet process, high temperatures and long mixing times are used. In most research carried out on this subject, it has been concluded that, when modifying asphalts through a wet process, the base asphalt’s stiffness increases. However, the contribution the used modifier makes to this mechanical parameter is unclear, as well as what is the effect of elevated mix temperatures (T) and times (t). In order to evaluate the influence of T and t, this study designed an experimental phase that attempts to simulate within a laboratory, the wet modification process of an AC 60-70 asphalt binder. AC 60-70 was exposed to similar T and t to those found in several asphalt modification studies, in order to then manufacture with said asphalts, Hot Mix Asphalts (HMA). HMAs were subjected to Marshall Tests, Indirect Tensile Strength Tests (ITS), Cantabro Test, Resilient Modulus and Permanent Deformation Tests. Each of the test results were subjected to an Analysis of Variance (ANOVA) tests. As a general conclusion, we obtained that T and t have a significant influence in the asphalt binder response as well as in the response of HMAs, mainly in terms of stiffness and adherence.