Research On Anti-cracking Characteristics Of Frame-densed Cement Stabilized Graded Crushed Stone

The semi-rigid base asphalt pavement, as a main-stream structure type, plays an important role in our country's road construction. However, the problems such as cracking and its decline of strength and rigid become an important ingredient which confine the long term durability of the semi-rigid base asphalt pavement structure. Thus, based on the Mohr-Coulomb strength theory, much attention was paid to the structure constitute and characters of the gravels in semi-rigid materials. Utilizing the design theory of the frame-densed cement stabilized graded crushed stone, the mechanical character of the semi-rigid base layer and the character of the anti-cracking was co-ordinated. Taking systematic experimental researches as a main method and assisted by the theoretical analysis concentrating on specific problems, the design method, index system and pavement performance of this kind of semi-rigid base materials were studied. So that, a solid foundation was set for the improvement of the technical system of the semi-rigid base asphalt pavement, the elongation of the pavement structure using life and the enhancement of the using quality. It has a vital significance for the improvement of the comprehensive benefit of the traffic transportation.First of all, based on the north-east areas, surveys are made on the transverse cracks of the high-grade highway asphalt pavement and analyzed main reasons of cracking and technical countermeasures. For example, since the flexible base and semi-rigid base has the most obvious performance differences, with the survey results of the western-ring highway of Harbin in the past years the developing discipline of the cracking in a low temperature was analyzed. So that, it is clear that one important point in cracking researches is anti-cracking character of the base layer and the semi-rigid material design according to the anti-cracking requirement.Furthermore, the frame, flow path and basic principles of the crushed stone gradation volume method are put forward. Forming methods of the graded crushed stone were compared and a proper parameters'combination was determined. Then, the material-technique integrated design method was realized. Through the typical frame design and the comparison of fine aggregate constitute, taking the filling parameter as a technical index, the influence of this index to the structure constitution characteristics of the graded crushed stone was deeply analyzed, from which the design method based on the mechanical characteristics was concluded. With the static tri-axial tests, dynamic tri-axial tests and the MTS cycling loading tests, the structure of the graded crushed stone was evaluated, and the structural variability, stability and integrated structure was used to guide the design of the graded crushed stone and to determine the design index and its technical criteria.On this basis, with the vibration forming methods and lots of experiments, the dry and temperature shrinkage of frame-densed structure cement stabilized graded crushed stone was systematically studied. Besides, based on the analysis of main factors, the relationship between the filling parameter and the dry shrinkage was understood, which could guide the material design and the construction operation.Based on the elastic-plastic damage theory, using the ABAQUS finite element software, coupling analysis between the pavement structure temperature field and the dry shrinkage field was made, and the specific conditions that would appear cracks in the curing period was found, which could guide the field construction organization.Based on the above researches, the research results of cement stabilized graded crushed stone was integrated, the decline of the strength, the character of dry shrinkage and the character of the temperature shrinkage. Then, a proper range of the filling parameter was put forward and the design principles were deduced. What's more, an improved volume design method was proposed to guide the construction application. In the end, the main results into the Qitai highway construction were applied to validate the application and effects of this technology, as a foundation for the following improved technology system. Through the combination of theory and construction practice, a performance design and optimization of the semi-rigid base layer was primarily realized, and a series of cement stabilized graded crushed stone technology was set up.