Fatigue process analysis of aged asphalt concrete from two-point bending test using acoustic emission and curve fitting techniques
Résumé
This paper presents a new method for analysing of experimental data stemming from the Two-Point Bending (2PB) fatigue test conducted on French standardized trapezoidal specimens, in accordance with NF EN 12697-24. These tests were performed on an asphalt mix specimen sawn from an in-service road pavement, adopting a loading frequency of 25 Hz and a target temperature of 10°C. The Acoustic Emission (AE) technique was implemented to monitor the damage and failure processes during fatigue. The fatigue life, defined as the critical number of loading cycles inducing specimen failure, is investigated herein according to several methods, including normalized criterion, models proposed in the literature, experimental fitting and Acoustic Emission activity analysis. First, the mechanical behaviour is fitted, in terms of strain, force, stiffness modulus and phase angle obtained from the fatigue test, in accordance with four functions, namely: a polynomial function, a continuous Fourier series, a sum of sine functions, and a Gaussian function. In a second step, a new damage criterion is proposed and validated with AE results based on a Fourier series decomposition. Lastly, a phenomenological analysis is carried out in order to understand the damage and failure process stages.
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