| Survey shows that transverse cracks have become one of the major diseases of semi-rigid asphalt pavement. Currently, there is a lot of research on improving anti-crack performance of pavement from the perspective of material properties including improving low temperature performance of asphalt mixture and anti-shrinkage performance of semi-rigid material. However, the research on improving anti-crack performance from the perspective of optimizing structure combination is relevantly less. Thus, on basis of analyzing typical pavement structures of Jilin Province, the paper determined the contraction coefficient of base course specimen, surface course specimen and different structure combination specimens of base course and surface course. Then, the paper put forwards theoretical formula of temperature shrinkage coefficient. The paper also gave the method for calculating transverse temperature shrinkage crack spacing in consideration of restrictive relationship between base course and surface course. Next, the paper analyzed the impact of various relevant factors on transverse temperature shrinkage crack spacing. At last, measures to control transverse crack spacing and suitable pavement structure combinations in Jilin Province were given. The main contents are as follows:Firstly, the transverse cracking mechanism of asphalt pavement was analyzed. Combined with typical pavement structures and transverse cracking condition of Jilin Province, the paper determined material type and gradation design in the test. Then, the paper designed simple and reliable methods of temperature shrinkage coefficient test and drying shrinkage coefficient test based on previous studies. Then, the temperature shrinkage coefficient of surface course specimen and the temperature shrinkage coefficient and drying shrinkage coefficient of base course specimen were determined through the method. The paper also analyzed the impact of various relevant factors on temperature shrinkage coefficient and drying shrinkage coefficient of the specimens.Secondly, according to the temperature shrinkage coefficient test results of surface course specimen and base course specimen, the paper selected six typical combination specimens of base course and surface course and determined temperature shrinkage coefficient at their representative thickness. Through comparing theoretical temperature shrinkage coefficient with the measured one, the accuracy of the theoretical formula of temperature shrinkage coefficient of the combination specimen was verified.Finally, the paper established contraction model of combination structure and derived the formula of transverse crack spacing of surface course and base course in consideration of temperature shrinkage effect and drying shrinkage effect. Then the paper analyzed the impact of various relevant factors on transverse crack spacing and put forwards a series of measures to control transverse crack spacing. In the end, comparing average transverse crack spacing of different structure combinations, the paper gave suitable pavement structure combinations in Jilin Province. |
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