Yong Wen

Organic Montmorillonite Modified Asphalt Materials: Preparation and Characterization

Organic montmorillonite (OMMT) modified asphalt was prepared with the melting intercalation technology. The distribution of OMMT layers in matrix asphalt was characterized through x-ray diffraction (XRD) and transmission electron microscope (TEM), and the effect of OMMT on physical properties and dynamic rheology of matrix asphalt were studied as well. It was found that OMMT homogeneously dispersed in the modified asphalt and intercalated OMMT/asphalt nanocomposites were prepared by means of melt extrusion. Additionally, from the penetration, softening point, and dynamic shear rheometer (DSR) testing result, it was observed that the OMMT obviously improved the high-temperature stability, temperature serviceability, and rut resistance of the matrix asphalt. The bending beam rheometer (BBR) results indicated that the OMMT modified asphalt with OMMT dosage of 3 % exhibited the lowest stiffness and highest resistance to low temperature cracking, and had less effect on the relaxation of stress in low temperature in comparison with OMMT modified asphalt with OMMT dosage of 1 % and 5 %. Furthermore, it was found that the optimal dosage of OMMT was 3 %.

Characterization of the Distress Modes and In Situ Material Properties of Highway Asphalt Pavement with Long Service Life

AbstractA 36-year-old, heavily trafficked highway asphalt pavement was analyzed in detail. The variation in structural capacity was assessed by a falling-weight deflectometer (FWD). Trenches were cut to examine the distresses in the pavement structure. Sample cores were taken for the study of distress modes, volumetric characteristics, and mechanical properties of the asphalt mixtures. Asphalt binder was extracted from the cores for the study of rheological properties. Rutting, cracking, fracture at the pavement bottom, and debonding at the interfaces were found to be the major distress modes. Air voids (AVs) were found to vary greatly in the samples and to be particularly high at the construction joints and at the pavement bottom. The total AV contents are primarily attributed to a few large voids, not a large number of seemingly disconnected voids. The stiffness of the road samples was much higher than that of the new mixture of the same type, and the average stiffness of the samples from the wheel path...