Asphalt mixture multi-sequence local loading high temperature performance test method

Abstract

The invention provides an asphalt mixture multi-sequence local loading high temperature performance test method. the method includes the following steps: firstly, determining the number of stress levels and the magnitude of stress applied to a test piece in a test according to actual axle load spectrum distribution of an expressway, forming a large rotating compacted test piece and cutting the upper and lower end faces of the test piece, and determining a holding temperature of a material according to layers applied the material in practical engineering; secondly, determining the diameter of ametal indenter used in the teat according to the size of the test piece, and arranging preloaded stress levels and loading times and stress cycles and loading times in multi-sequence loading; and finally, calculating permanent strain rates under the sequences according to a creep curve after the test is finished. The relationship between the permanent strain rate of the material and the stress levels under more realistic conditions can be efficiently and accurately obtained by using the method, and the high temperature of different asphalt mixtures can be compared under the multiple stress levels.

Description

technical field [0001] The invention relates to a multi-sequence local loading high-temperature performance test method of asphalt mixture, which belongs to the field of road maintenance. Background technique [0002] The dynamic creep test recommended by the NCHRP research program in the United States is an indoor test widely used to explore the high-temperature performance of asphalt mixtures. The test adopts half-sine wave pulse loading, which is considered to be the closest to the actual road vehicle load. Based on the test, the rheological number and the permanent strain rate in the second stage of creep are widely used indexes to evaluate the high temperature performance of asphalt mixture. Because the traditional dynamic creep test uses a single level of stress, that is, one test can only obtain the permanent strain rate of the material under this stress level. However, the actual road surface has complex axle load conditions, and the relationship between the permanen...

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Problems solved by technology

[0004] In addition, it is common knowledge that asphalt pavement has obvious temperature gradient and stress attenuation along the depth direction. However, most studies on the high-temperature performance of asphalt mixtures have not tested asphalt mixtures of different application layers in the laboratory test. Differentiate between the test temperature and the applied stress

The most unfavorable temperature and the most unfavorable load used for the middle and lower layers are the same as the upper layer, which will lead to misjudgment of the high temperature performance of the middle and lower layers, and is not conducive to the prediction of road rutting

Although some researchers have developed an indoor creep test method for the overall specimen that simulates the actual temperature field of the pavement, this method can only produce the temperature field of the pavement at a certain moment, and it is difficult to monitor and verify the temperature rise process inside the specimen. The retention time of the temperature gradient along the depth direction of the specimen is relatively limited, the preparation process of the overall specimen is relatively cumbersome, and the thickness of the thermal insulation coating is difficult to control, etc.

Moreover, the cumulative deformation and permanent strain rate of the specimen obtained in this test are all based on the whole, and cannot be obtained for a single surface layer, which creates obstacles for the analysis of the permanent deformation contribution rate of each layer, and it is impossible to obtain The amount of deformation of each layer is used to improve the combined structure of the overall test piece in a targeted manner

[0005] To sum up, the existing technology can only roughly obtain the pros and cons of the high-temperature performance of the material, the test conditions are relatively single, and it is impossible to simulate the stress and temperature conditions close to the real road surface, and there is no correlation between the test results and the rutting growth of the actual road surface sex

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