Mechanical Properties of Various Paving Mixtures (Part 5)

Dynamic Properties and Fatigue Properties of Mixtures

Abstract

The surface course in the pavement structures must carry varying wheel loads and spread loads to the lower courses. Concerning the material properties, the main factors that effect the above behavior are the modulus and fatigue properties of the paving materials.
In this research, two kinds of testing methods, dynamic loading testing and fatigue testing, were used to compare the mechanical properties of the various paving materials. The former testing was employed to evaluate the dynamic properties of the paving materials and the latter testing was employed to evaluate fatigue behavior-mainly the resistance to repetitions of loading-of the materials.
In this experiment, four kinds of binders, straight asphalt cement, modified asphalt cement, epoxy asphalt cement and epoxy resin, were used by mixing each of them with dense graded aggregates. Conclusions drawn from this experiment are as follows:
1. Epoxy resin system mixtures (epoxy resin mixtures and epoxy asphalt mixtures) showed less temperature and time susceptibility than that of the asphaltic mixtures. They also showed lower limits of complex modulus that mean descending limits of load spreading effects (Figs. 1-10).
2. The upper limit of the loss tangent was found in the epoxy resin system mixtures at a certain specified loading time, and a greater time susceptibility of the complex modulus was found at the same loading time (Figs. 5, 7).
3. Specific temperatures T_c, of paving mixtures used in this experiment were obtained from the reduced variable method and they were about 45-50°C higher than the glass transition point of the same paving mixtures (Figs. 2, 4, 6, 8, 9).
4. The fatigue resistance of the epoxy resin system mixtures to load repetitions was greater than that of the asphaltic mixture; moreover, the former mixtures also showed a smaller strain susceptibility to fatigue life than the latter ones (Fig. 14).