Experimental Methods for the Mechanical Characterization of Asphalt Concrete at Different Length Scales: Bitumen, Mastic, Mortar and Asphalt Mixture

This chapter presents a comprehensive characterization of asphalt concrete at different scales of observation. State-of-the-art characterization procedures for bitumen, mastic, mortar and asphalt are described in detail. The procedures were envisaged to provide experimental data for parameter identification and validation of constitutive numerical models. The validation of numerical models against experimental data is a prerequisite for the use in any application. The temperature-frequency dependency of the rheological properties of bitumen and mastic was characterized using temperature sweeps in the dynamic shear rheometer. The results showed that the bitumen provenance and the filler’s mineralogy have a major impact on the rheological response of the asphalt. A new rheometer, known as Dresden dynamic shear tester, was developed with the aim of characterizing the thermo-viscoelastic properties of mortar. This novel equipment was also used to identify the stiffening effect of the aggregates by comparing the results of bitumen, mortar and asphalt. Finally, the short and long term behavior of different asphalt mixtures were characterized with the repeated load triaxial tests and with the indirect tensile tests. The results showed that the performance of asphalt is highly affected by the bitumen type and the aggregate gradation.