Abstract
The fatigue properties of asphalt mixtures are important inputs for mechanistic-empirical pavement design. To understand the fatigue properties of asphalt mixtures better and to predict the fatigue life of asphalt mixtures more precisely, the energy-controlled test mode was introduced. Based on the implementation theory, the laboratory practice for the energy-controlled mode was realized using a four-point-bending fatigue test with multiple-step loading. In this mode, the fatigue performance of typical AC-20 asphalt specimens with various reclaimed asphalt pavement (RAP) contents was tested and evaluated. Results show that the variation regulation of the dissipated energy and accumulative energy is compatible with the loading control principle, which proves the feasibility of the method. In addition, the fatigue life of the asphalt mixture in the energy-controlled mode was between that for the stress-controlled and strain-controlled modes. The specimen with a higher RAP content has a longer fatigue life and better fatigue performance.
Highlights
With the service life of asphalt pavement increasing, maintenance and rehabilitation are inevitable
Referring to (3) and the theory of the strain-controlled mode, we propose a laboratory operational method, based on a 4PB device, called multiple-step loading: according to the modulus Sn at Cycle N, shift the bottom tensile strain of the beam εn to √S0/Sn × ε0 and shift the force applied to the beam Fn to √S0/Sn × F0
Results showed that AC-20 with 25% reclaimed asphalt pavement (RAP) content had the longest fatigue life, 0% RAP content was second, and 50% had the shortest life
Summary
With the service life of asphalt pavement increasing, maintenance and rehabilitation are inevitable. Many researchers are still focusing on how to evaluate and improve performance, especially the fatigue durability of the recycled asphalt mixture. In the strain-controlled mode, fatigue life increases as the initial modulus decreases. Advances in Materials Science and Engineering use one control mode to evaluate asphalt mixture properties and construct fatigue damage models considering modulus, dissipated energy, and accumulative energy [13,14,15,16]. Previous research [22,23,24,25,26] has shown that the fatigue process of the bottom surface layer of the asphalt pavement is more related to the energy than to the stress in the stresscontrolled and the strain in the strain-controlled modes. The test results could contribute to the establishment of a new estimation index for fatigue properties of asphalt mixtures
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