Fatigue characterization of bituminous mixes is often based on laboratory tests. However, fatigue lifetimes obtained from different types of tests are generally not comparable, even when these tests are carried out under identical conditions. This disparity can be attributed to several factors, including the approach to analyzing fatigue results, specific test conditions, and variations in the stress-strain distribution of different specimens. The aim of this thesis is to harmonize fatigue results, in particular Wöhler curve parameters, obtained from three families of tests, namely: the 2-point bending test (2PB - two point bending), integrated into the French dimensioning method and supported by the Alizé calculation tool, the 4-point bending test (4PB - four point bending), used in the American dimensioning approach and supported by the Pavement M-E calculation tool, and the tension-compression test (TC), commonly adopted in Canada. The main objective is to establish a correlation between these different fatigue test methods and to improve the classical approach to fatigue analysis in order to better reflect the actual fatigue characteristics of asphalt mixes.
To this end, an extensive literature search was undertaken to identify the main factors influencing the fatigue behavior of asphalt mixes, as well as to understand how these factors impact fatigue test results. This study also highlighted gaps in the literature concerning the correlation of fatigue results obtained from different types of tests.
To achieve the objectives of this thesis, a comprehensive experimental fatigue testing program was designed to evaluate the fatigue behavior of a high-modulus asphalt mix (EME-14) adapted to cold climates. The program included three types of fatigue tests: tensioncompression (TC), 2-point bending (2PB) in accordance with NF 12697-24, and 4-point bending (4PB) in accordance with AASHTO T 321. The TC test was carried out at three different frequencies (5, 10 and 25 Hz) and four different temperatures (-10, 0, 10 and 20°C), with the aim of analyzing the impact of test conditions on the fatigue behavior of EME-14. In order to simplify the test program, the tests were carried out in strain-control mode only.
The structure of this thesis is divided into three distinct parts, each with its own specific objectives. The first part focuses on the methodology adopted to characterize fatigue failure of specimens, taking into account different criteria, through the three types of tests selected (TC, 2PB and 4PB). Two sub-objectives are targeted: firstly, to determine the fatigue life (Nf) and the characteristic parameters of the fatigue curve (or Wöhler line), and secondly, to reduce the discrepancies observed in the fatigue curve parameters resulting from the three families of tests selected, by judiciously choosing the failure criterion. The second part of the thesis explores, in two distinct phases, the influence of test conditions on the fatigue behavior of EME-14. The first phase aims to validate the impact of loading temperature (θ) and frequency (fr), while the second phase aims to confirm the time-temperature equivalence principle (TTSP) in the fatigue domain for EME-14. Finally, the third part of the thesis is devoted to developing a method for correlating the parameters of the EME-14 fatigue line, obtained from the 4PB and TC tests. To achieve this objective, it is essential to develop a rigorous and efficient analytical method for interpreting the fatigue results of each test, in order to obtain accurate and consistent values of fatigue life (Nf), thus ensuring that the fatigue lines derived from these tests are comparable.
| Date | 26 Nov 2024 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Daniel Perraton (Supervisor) & Hervé Di Benedetto (Co-supervisor) |
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Boussabnia, M. M. (Author),
Perraton (Supervisor) & Di Benedetto (Co-supervisor),
26 Nov 2024Student thesis: Doctoral thesis › Doctorate in Engineering: Engineering