Determinação do módulo dinâmico de misturas asfálticas por meio de testes ultrassônicos

Abstract

In the last decades, ultrasonic testing has been adapted to determine the dynamic modulus of asphalt mixtures. This technique is promising because strain levels during the test allow the characterization in the linear viscoelastic regime, in addition of being fast non-destructive tests. There may be differences between its results and those of classical tests, mainly due different data treatment, resulting from the adaptation of variables in behavior equations, as well as the complexity of the material, and of how the waves propagate within it. The present paper studies the influence of variables in the equation that describes the relationship between mechanical behavior parameters (modulus, Poisson’s ratio and phase angle) and the ultrasonic pulse velocity. Material parameters are obtained in an indirect manner. The ultrasonic test results were combined with the 2S2P1D rheological model to obtain those variables and were compared to the results from classical tests. Results show that the simplification in considering nil phase angle and a constant value of Poisson's ratio leads to errors of 8.6% for high temperatures and 3.4% for low temperatures. Despite limitations of access to only the high frequency range of master curves, the technique is promising because it allows an adequate, nondestructive and fast characterization in accordance to the characteristics of the material.