Non Linearity in Bituminous Materials during Cyclic Tests

Abstract

In the recent years rheology has been taking an increasing importance in the characterization of bituminous materials. Rheological parameters are suggested by many studies as good indicators of the performance of these materials and tools to efficiently predict the performance and durability of asphalt pavements.Bituminous materials exhibit a non-linear mechanical response beyond a certain level of solicitation. This behaviour is important as it is a source of error in linear stiffness measurements. Fatigue tests on bituminous materials are typically performed in the non-linear region. In the present study, non-linearity of bituminous binders and mixtures was investigated through strain sweeps and fatigue tests. The development of non-linearity was described and quantified. It was found the strain level effect has the same impact on mechanical properties as the accumulation of cycles. A phenomenological description of this behaviour is proposed, based on the destruction of supra-molecular structures.

New bitumen performance indicators - A feasibility study

“…Further considerations on non-linearity testing and its relationship to fatigue are to be found in [8].…”

Curing and temperature sensitivity of cement–bitumen treated materials

“…From a phenomenological point of view, the effects of curing (stiffness increase, phase angle reduction) may be considered opposite to the effects of non-linearity (path N) that results in stiffness reduction and a phase angle increase (Gauthier et al 2010). Opposite effects can be explained by opposite physical phenomena: in the first case, curing leads to the formation of stable microstructural bonds through the hardening of the fresh bituminous phase and cement hydration; in the second case, non-linearity occurring with large and/or repeated strains, brings to a progressive destruction of supramolecular structures and networks (Gauthier et al 2010).…”

“…Opposite effects can be explained by opposite physical phenomena: in the first case, curing leads to the formation of stable microstructural bonds through the hardening of the fresh bituminous phase and cement hydration; in the second case, non-linearity occurring with large and/or repeated strains, brings to a progressive destruction of supramolecular structures and networks (Gauthier et al 2010). International Journal of Pavement Engineering 9…”

Quantification of different effects occurring during fatigue tests on bituminous mixtures

“…Between 2 consecutive fatigue lags, a 24 hour rest period was imposed (axial stress was maintained at 0 MPa). During each rest period, 16 measurements of E* were performed after, respectively, 10, 20, and 30 minutes and 1,2,4,6,8,10,12,14,16,18,20,22, and 24 hours. The duration of these measurements, for which only 100 cycles were applied at 10°C and 10 Hz, is insignificant about the global rest period duration.…”