Characterization of Asphalt Mixes Behaviour from Dynamic Tests and Comparison with Conventional Cyclic Tension–Compression Tests

Abstract

In the presented research, conventional cyclic tension–compression tests and dynamic tests were performed on two types of asphalt mixes (AM). For the tension–compression tests, the complex modulus was obtained from the measurements of the axial stress and axial strain. For the dynamic tests, an automated impact hammer equipped with a load cell and an accelerometer were used to obtain the frequency response functions (FRFs) of the specimens at different temperatures. Two methods were proposed to back-calculate the complex modulus from the FRFs at each temperature: one using the 2S2P1D (two springs, two parabolic elements and one dashpot) model and the other considering a constant complex modulus. Then, a 2S2P1D linear viscoelastic model was calibrated to simulate the global linear viscoelastic behaviour back calculated from each of the proposed methods of analysis for the dynamic tests, and obtained from the tension–compression test results. The two methods of analysis of dynamic tests gave similar results. Calibrations from the tension–compression and dynamic tests also show an overall good agreement. However, the dynamic tests back analysis gave a slightly higher value of the norm of the complex modulus and a lower value of the phase angle compared to the tension–compression test data. This result may be explained by the nonlinearity of AM (strain amplitude is at least 100 times smaller for dynamic tests) and/or by ageing of the materials during the period between the tension–compression and the dynamic tests.

Dynamic testing of asphalt mixes

“…The impact hammer was automated to improve the repeatability of the test and to allow measurements directly inside the thermal chamber. The order of magnitude of the maximum strain induced in the specimen by the impact is about 0.1 μm/m [8][9][10]. The response of the material was recorded with an accelerometer (PCB model 353B15) glued in the middle of the opposite short side of the specimen (see Fig.…”

“…Carret et al [10] showed that the value of the Poisson's ratio has a very small influence on the FRFs calculation and that the norm and phase angle of the complex modulus can be determined from FRFs measurement at each temperature with a simple process described in Fig. 7.…”

“…Recently, measurement of frequency response functions (FRFs) have been performed on AM [6][7][8][9][10][11]. Gudmarsson et al [7,8] and Carret et al [9,10] showed that using FRFs measurements to obtain the LVE properties of AM is a very promising approach. In this paper, the possibility of using a simple approach using finite element calculations to obtain the complex modulus of the material at each temperature from FRFs measurements is studied.…”

Modeling the Dynamic Properties of the Polyurethane Mixture with Dense Gradation Using the 2S2P1D Model

“…By utilizing the 2S2P1D model, the master curve for the dynamic modulus of HMA can be established in the frequency domain [47,48]. Compared to the traditional complex modulus test, a new method that uses an automatic impact hammer, a load cell, and an accelerometer, is employed to measure the frequency response functions (FRFs) of HMA at various temperatures [49]. The complex modulus is then back-calculated from the measured FRFs, employing the 2S2P1D model and Williams-Landel-Ferry (WLF) function.…”