Avaliação do impacto da metodologia FAD-CI de seleção granulométrica na vida de fadiga de misturas asfálticas

Abstract

Fatigue in asphalt mixtures is one of the most common causes of premature pavement failure. Such mixtures are usually designed by framing aggregate particle sizes into predetermined sieve sizes, with no other step in the methodology used in Brazil aiming to attend aspects such as fatigue resistance. In this context, the aggregate gradation selection methodology called the Dominant Aggregate Size Range (DASR) can help to produce mixtures with improved fatigue and rutting performance. National specifications related to mixture design indicate laboratory mechanical tests, not specifically to evaluate fatigue resistance. In an attempt to address this shortcoming, the National Department of Transport Infrastructure standardized in 2018 a test to evaluate mixture fatigue. Another recent advance has been the development of the mechanistic empirical National Design Method, which makes use of the referred test. Like other existing methods, it simulates the development and the evolution of pavement distresses, while calculating layer thicknesses to mitigate them. Therefore, there is great importance in seeking techniques able to accurately characterize distresses. In this scenario, the tensilecompression fatigue test is today considered the most fundamental and mechanically consistent laboratory test to characterize asphalt mixture fatigue. Its details and reach are still not widespread in the state of practice or even in the national academia. The objective of the present research is to evaluate the fatigue susceptibility of asphaltic mixtures with different particle sizes. A database of the Asphalt Technology Network was used. Mixtures with conventional asphalt binders and different stone skeletons were evaluated. Fatigue resistance was simulated at the material level of the mixture, and also as part of a pavement structure. There is a tutorial aspect in the present document, which contains details of the tensile-compression fatigue test, since its popularization is considered to represent an important improvement for the national pavement community. In addition to the DASR methodology, other criteria associated with mixture fatigue were evaluated, such as binder and mixture fatigue factors, and also fatigue classes. The latter proved to be promising and such classes may be adopted as part of an acceptance parameter for asphalt mixtures to be used in the field.