Mohsen Ech

Behaviour of asphalt mixtures containing reclaimed asphalt pavement and asphalt shingle

This paper presents the results of laboratory research on asphalt mixtures containing reclaimed asphalt pavement (RAP) and asphalt shingle, including the study of their linear viscoelastic (LVE) behaviour and fatigue characteristics. Complex modulus measurements using the tension-compression test on cylindrical specimens were conducted to determine LVE behaviour. Sinusoidal cyclic loadings with a strain amplitude of approximately 50×10−6 were applied at several temperatures (from−30°C to+40°C) and frequencies (from 0.01 to 10 Hz). In addition to axial stresses and strains, radial strains were also measured. The complex modulus E* and complex Poissons ratio ν* were then obtained and the three-dimensional (3D) LVE behaviour (with isotropy hypothesis) was then completely described. The time–temperature superposition principle was verified with good approximation in uni-dimensional and 3D conditions for the same values of shift factor. Experimental results were modelled using the 2 springs, 2 parabolic creep elements and 1 dashpot model developed at University of Lyon/ENTPE. Fatigue properties were evaluated by tension-compression tests on cylindrical specimens using the same testing device used for complex modulus. Sinusoidal loading at 10 Hz in controlled axial strain mode was applied at 10°C. The variation of complex modulus E* and complex Poissons ratio ν* as a function of the number of cycles was obtained. The fatigue test results were analysed using six different fatigue life criteria. The analysis of the results provided a ranking of the tested materials. The influence of RAP and asphalt shingle contents was quantified.

Low-Temperature Cracking of Recycled Asphalt Mixtures

The thermo-mechanical behavior of asphalt mixtures, with Recycled Asphalt Pavement (RAP) and other recycled materials was investigated. The cracking behavior at low temperature was studied considering Thermal Stress Restrained Specimen Tests (TSRST). The experimental setup was improved as the radial strains were measured during the performed TSRST. Tri-dimensional behavior could thus be investigated. Mixes made with different RAP content (up to 25%) and manufacturing-waste asphalt roofing shingle content (up to 10%) were studied. The influence of the content of RAP and shingle was analysed. A ranking of the different mixes was proposed based on the classical TSRST outputs, stress and temperature at failure.