Measuring method for asphalt mixture cryogenic fatigue performance test

Abstract

The present invention discloses a method for testing a low-temperature fatigue performance of an asphalt mixture. Before the test of the method, the heat preserving time of the hemi-spherical test piece in the temperature-controlled box is kept more than 6hours. The temperature of the inner part of the temperature-controlled box is in the range of from -20 DEG C to 20 DEG C. A loading device which is provided with an upper squeeze head and a lower squeeze head is adopted for loading the hemi-spherical test piece. The loading device is totally placed in the temperature-controlled box. The distance between the supports of the lower squeeze head is in the range from 50mm to 120mm. The evaluation index of the low-temperature fatigue test is 0.2 times of stress ratio. The loading speed to the hemi-spherical test piece is 50mm / min. The fatigue loading frequency is 10Hz. The fatigue number under state of sinusoidal wave is read out thereby checking the low-temperature fatigue performance of the asphalt mixture. The test piece which has fatigue number larger than 100 thousand is qualified in low-temperature fatigue performance. The method of the invention is simple and easy for application.

Description

technical field [0001] The invention relates to a test method for low-temperature fatigue performance, which belongs to the field of road engineering, in particular to a test method for low-temperature fatigue performance of asphalt mixture. Background technique [0002] At present, many scholars at home and abroad have carried out many indoor tests on asphalt pavement cracks, such as direct tensile fatigue test, splitting test, bending tensile fatigue test, etc., but most of them are tests for ordinary asphalt mixture, and for low temperature These methods have certain limitations for stress-absorbing layer mixtures that still have outstanding deformability under certain conditions. In the direct tensile fatigue test, the connection between the specimen and the tensile indenter is difficult, and it is difficult to ensure that the axis of the specimen is consistent with the centerline of the test without distortion; The low-temperature bending test is difficult to implement...

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Problems solved by technology

[0002] At present, many scholars at home and abroad have carried out many indoor tests on asphalt pavement cracks, such as direct tensile fatigue test, splitting test, bending tensile fatigue test, etc., but most of them are tests for ordinary asphalt mixture, and for low temperature These methods have certain limitations for the stress-absorbing layer mixture that still has outstanding deformability under certain conditions.

In the direct tensile fatigue test, the connection between the specimen and the tensile indenter is difficult, and it is difficult to ensure that the axis of the specimen is consistent with the centerline of the test without distortion; The low-temperature bending test is difficult to implement due to the large bending and tensile strain at the bottom of the beam bottom of the stress-absorbing layer mixture, and it cannot reflect the fatigue characteristics of the mixture

Although other large-scale plate reflective crack fatigue test benches can better simulate the generation and development process of asphalt overlay reflective cracks, large-scale fatigue tests consume a lot of materials, high costs, and long test periods, and it is impossible to do it for the same structure. Multiple groups of parallel experiments may lead to deviations in the conclusions of the experiments

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