Estudo laboratorial das propriedades mecânicas de misturas com diferentes cimentos asfálticos de petróleo produzidos no Brasil

Abstract

The evaluation of the behavior that different petroleum asphalt cements (CAP) give to the mixtures becomes important due to the direct relationship between the quality of the pavement and the performance of the binder. The objective of this research is to evaluate the mechanical behavior of mixtures originated from six CAPs representing Brazilian production, produced in refineries REFAP (RS), REPAR (PR), REGAP (MG), LUBNOR (CE) and REVAP (SP). For this, the influence of these CAPs on the dosage properties, stiffness, fatigue damage and permanent deformation in the asphalt mixtures was verified in the laboratory. The CAPs used in paving change their properties and chemical constitution, because they come from different oils or mixtures of oils and from different production routes. To develop the knowledge of the influence of the binders on the properties of the asphalt mixtures it is essential to know the stiffness of the asphalt mixture when subjected to different loads, temperatures and loading frequencies and their resistance to permanent deformation and fatigue. The six asphalt mixtures produced from different CAPs and the same aggregates (as DNIT C range), dosed by the Superpave methodology, were submitted to the following tests: Resilience Module and Complex Module to evaluate the stiffness of the mixtures; Diametral Tensile Strength, Flow Number (FN) and Direct Tension Cyclic Fatigue test to evaluate the damage. The analyzes of the Complex Modulus results were performed by the 2S2P1D modeling and the results obtained for the mixtures with CAPs 50/70 were similar while the mixture with CAP 30/45 showed to be stiffer and less susceptible to temperature. In addition to the classical Wöhler curves approach, S-VECD was used as testing and analysis premise of Direct Tension Cyclic Fatigue test results, where the supremacy of the mixture with CAP 30/45 is remarkable compared to mixtures with 50/70 CAPs, which are arranged in three resistance levels: the CAP 50/70 of REFAP being the strongest and the least resistant were the CAP 50/70 mixtures of LUBNOR, REVAP and REGAP. In the FN results, the mixture with CAP 30/45 supported a greater number of cycles when compared to CAP 50/70, which presented different levels of behavior among them, where the mixtures with CAP 50/70 of REFAP and REVAP which had the highest FN and the mixture with CAP 50/70 from REPAR which have the lowest FN. It is evident that, from the point of view of stiffness, all mixtures with CAP 50/70 have similar behaviors. However, from the point of view of damage there are differences between the mixtures with CAPs 50/70, showing that even with similar stiffness they present different behavior to the damage due to fatigue and permanent deformation.