Correlation between stiffness and fatigue behavior at asphalt mastic and asphalt mixture level

Performance-based tests on asphalt mix level to assess performance behavior are already state of the art, including the fatigue test with the 4-point bending beam. However, this test method requires high effort in material, time, and manpower, making it less practical for routine quality control. This study aims to partially substitute the performance-based tests on asphalt mix level with a practical test method on asphalt mastic level. The tests on asphalt mastic level were carried out with a dynamic shear rheometer (DSR) by time sweep tests on hyperbolic specimens. Fourteen different asphalt mixtures and the corresponding asphalt mastic mixtures were tested. We used a wide range of different asphalt binders and types of aggregates to extend the validity range of the developed model. Correlations between the asphalt mastic performance and asphalt mix performance were investigated using simple and multiple linear regression models. The correlations show that the dynamic modulus |E∗|30Hz at asphalt mix level can be linked to the complex shear modulus |G∗|initial at mastic level by a simple linear regression model. On the other hand, no correlation could be found between the phase angles of both mix levels. However, the characteristic fatigue value of the asphalt mix ϵ6 can be linked with high accuracy (R2 = 0.92) to the characteristic fatigue value τ6 and complex shear modulus |G∗|initial of the asphalt mastic using a multiple linear regression model. In summary, a reliable prediction of the fatigue behavior and stiffness of an asphalt mixture through simple fatigue tests with the DSR on asphalt mastic is feasible. Copyright © 2021 by ASTM International.