Research On The Bonding Behavior Between Graded Crushed Stone And Asphalt Layer And The Impact Of Road Performance

The asphalt pavement flexible base which uses graded crushed stone as base not only has the advantage of low cost, but also performs well in low temperature cracking resistance and water stability. But the strength of graded crushed stone is usually not high, and the cohesive force with layer and seal is low, which lead to poor performance in high temperature and can easily be broken between layers, and is restricted in practical application. Therefore, depending on the project “ Study on the bonding behavior between graded crushed stone base and asphalt layer based on meso mechanics”, relied on that the strength of graded crushed stone base was improved, this paper carried out the research about the bonding behavior between graded crushed stone flexible base and asphalt layer and it’s high temperature performance based on indoor full-scale direct shear test and rutting test.Firstly, this paper was based on the strength theory, the graded broken stone strength is mainly reflected by the shear strength. By controlling the key sieve and aggregate ratio, it designed A、B and C three different kinds of skeleton dense type’s graded crushed stone. On this basis, through the CBR, modulus and dynamic CBR test, it took a comprehensive evaluation on the mechanical properties of graded crushed stone flexible base, and got the order of graded crushed stone with different thickness which was: gradation B> C> A.Secondly, to research the bonding behavior, shear strength as evaluation index, it evaluated the shear performance between graded crushed stone base and asphalt layer by the self-made direct shear apparatus. First, it screened the materials such as aggregates, and asphalt by performance testing. On this basis, it completed the design of flexible base pavement structure. Then, it selected base gradation, seal thickness and prime coat as main factors, and carried out the orthogonal test of three factor and three levels. The result showed that the influence of base gradation to the bonding behavior is most distinct, seal thickness was worse and prime coat nearly had no influence.Based on the test above, this paper used the discrete method to simulate the direct shear test by PFC2 d numerical software. In the first step, it began to simulate penetration test, and obtained the micro performance parameters of graded crushed stone. In the next step, it began to simulate the direct shear test, and described the related mechanical behavior of graded crushed stone from micro perspective, which showed that graded crushed stone reflected the typical granular property, namely the unity of the overall consistency and the individual inconsistency. On this basis, it furtherly adjusted the parameter of the model, and obtain the simulation model which highly fit the indoor direct shear test.Finally, this paper carried out the indoor evaluation about the high temperature stability of graded crushed stone base asphalt pavement. Using rutting test which was consistent with the direct shear test, choosing base gradation, seal thickness and prime coat as main factors, and carried out the orthogonal test of three factor and three levels. The result show that: the factor influenced the high temperature stability was as follows: base gradation> seal thickness > prime coat. The result was consistent with the direct shear test and simulation; and through the comparison of test results, the bonding behavior between graded crushed stone base and asphalt layer and it’s high temperature stability had a positive correlation.