Avaliação do comportamento mecânico e autorregenerativo de misturas asfálticas recicladas.

Abstract

After a lifetime of service exposed to bad weather and various traffic conditions, the pavement quality declines until it becomes unsatisfactory. To rebuild a new pavement, it is necessary to remove the old one using milling techniques. Milling the pavement generates, as a byproduct, the milled asphalt. The inappropriate disposal of this material causes a relevant environmental liability, in addition to representing a waste of potentially reusable good quality material. When used in new mixtures, this material is called Reclaimed Asphalt Pavement (RAP). Research involving the use of RAP in asphalt mixtures has expanded, but knowledge of the behavior of a recycled coating in the long term is still incipient, if not nonexistent. In this sense, this research aimed to evaluate the mechanical performance and selfregeneration capacity of recycled asphalt mixtures with the incorporation of milled asphalt at levels of 0%, 10%, 30% and 50% by weight, before and after ageing. The study has four stages: the first, when the mechanical properties of the recycled mixtures were evaluated through the Tensile Strength by Diametral Compression (RT), Resilience Modulus (MR), Induced Moisture Damage (DUI), Resistant to Permanent Deformation (Flow Number) and Fatigue Resistance (RF); the second phase consisted of the study of the selfhealing using the fatigue life test; in the third and fourth phases, the same tests were made on mixtures subjected to longterm oven ageing. The MR, RT and Flow Number tests indicated an increase in stiffness and a decrease in deformability as the RAP content in the mixture composition increases, and the ageing accentuate these properties. The moisture damage susceptibility was not affected for the inserted RAP contents, neither in the aged condition. Fatigue resistance increased as the RAP content increased and the behavior of the reference mixtures (0% RAP) and 10% RAP were similar, as well as the mixtures with 30% and 50% of RAP. The aged mixtures were more resistant to fatigue. They presented an increase in the number of cycles until failure, as well as a decrease in deformability compared to the mixtures in the nonaged condition, due to the observed increase in stiffness. Therefore, the results shows that the use of RAP makes the asphalt mixtures more rigid, and strongly affected by ageing. The addition of RAP negatively affects the selfhealing index of the coating layer. Due to what has been observed, it is necessary to pay attention to the rigidity compatibility of the pavement's constituent layers so that the use of recycled asphalt mixture is satisfactory.