Moisture susceptibility of asphalt mixtures: 2S2P1D rheological model approach and new index based on dynamic modulus master curve changes

A methodology is proposed for evaluating the induced moisture damage in asphalt mixtures via a new index called the dynamic modulus area ratio (DMAR), which is used to calculate the difference under the areas of the dynamic modulus master curves fitted by the 2S2P1D model before and after conditioning. Were evaluated 21 mixtures applied in the field by comparing data obtained via empirical tests, e.g., the tensile strength ratio and dynamic modulus ratio, using AASHTO T283. The behavior that moisture damage analysis based on stiffness loss measurements in modulus tests can lead to different conclusions than those based on damage resistance tests like TSR. The 2S2P1D model proved to be adequate to evaluate the changes promoted by the deleterious effect of water on the stiffness of the mixtures after the induced moisture damage cycle. For the DMAR, the results clearly differed according to the type of binder, indicating that the impact of water damage on the linear viscoelastic behavior depends on the type of binder used in the mixture. The estimation of susceptibility to moisture using the DMAR, which assesses broader temperature and frequency ranges, enables a stiffness evaluation that is closely related to the field impact on this property, making it possible to evaluate variations in the entire stiffness spectra of the mixtures; thus, it can be used in methods based on the performance for the selection of asphalt mixtures.