Fatigue Properties of Bitumen, Bitumen-Filler Mastics and Bituminous Mixtures
Background
Fatigue damage is the main failure type at the ambient temperature in a flexible pavement. Fatigue cracking results from accumulative damage under repeated loads, which induce stresses below the tensile strength. It is believed that bituminous binders dominate this failure mechanism because the fatigue failure occurs either between binder and aggregate or within the binder itself.
Recent research reveals that fatigue behaviour of asphalt binders can be evaluated using a dynamic shear rheometer (DSR). According to SHRP (Strategic Highway Research Program) criterion, G*sinδ, measured from oscillation testing with frequency sweep, there is good correlation between pure bitumen and asphaltic mixtures. However, no satisfactory link can be found between polymer modified bitumen and their mixtures.
Therefore, the fatigue failure mechanism of asphaltic mixtures or asphaltic pavement might be controlled by bitumen-filler mastics, not by asphalt binders, where a mastic is an asphalt binder mixed with filler.
Objectives
This study investigates the correlation of fatigue behaviour between pure bitumens, bitumen-filler mastics and asphalt mixtures. One pure bitumen mixed with three types of fillers, of which 100% pass a 75µm sieve, and different filler concentrations to produce different bitumen-filler mastics. 10 mm DBM (Dense Bitumen Macadam) will be studied with a ratio of bitumen and filler, which corresponds to the previous mastics, will be produced to test the fatigue performance. There are three objectives in this research project:
- Study the fatigue properties of pure bitumen and bitumen-filler mastics using the Bohlin Gemeni 200 DSR.
- Investigate the fatigue behaviour of asphalt mixtures on elastic foundations using a wheel tracking machine.
- Determine the fatigue relationship between bitumen, mastics and mixtures.