Study On Mix Design Of Semi-rigid Base For Concrete Pavemnt Based On Anti-erosion Performance

Pavement slab with cavity caused by poor anti-erosion performance of semi-rigid base material is the main reason lead to damage of cement concrete pavement. Although requirements of the anti-erosion performance and stiffness of the base material are put forward in the existing design specification of cement concrete pavement, it only limited to qualitative requirement. There is sill lack of quantitative index and standard in the existing design specification. The stress status of the base material in cement concrete pavement is different from the asphalt pavement, but the value selection method of base is exactly the same. In this study, design index of base material should be studied according to the property of cement concrete pavement. And the material composition design method for semi-rigid base should be researched too.Based on the investigation and analysis of the using condition of cement concrete pavement, the failure modes of semi-rigid base of cement concrete pavement are proposed. The main factors that affect the base erosion performance are analyzed. And three-stage erosion damage mechanism is put forward according to the analysis of base erosion damage. Based on Poro-elasticity theory, the pore water pressure of the semi-rigid base of cement concrete pavement is calculated using ABAQUS finite element method. The pore water pressure of the semi-rigid base under different conditions, such as external loads and pavement structure, are calculated. Based on the calculation results,existing literature research and experiment study, the value of dynamic water pressure which can be used on the anti-erosion test of base material is proposed.The influencing factors of the base anti-erosion properties are summarized in accordance with the design of the semi-rigid base materials. And the relationship of base anti-erosion properties and its influencing factors is drawn by experiment study. Gray sequencing results of erosion and strength are advanced by the gray relation analysis of the influencing factors. Gray system theory is used to establish erosion and strength predict model of semi-rigid base material, and several predict formula of erosion and strength are developed. From the requirement of cement concrete pavement, different structure type of semi-rigid base should to be selected according to different traffic grade. In addition, the design index and standard of semi-rigid base material are put forward according to the experiment resluts and literature research. Finally, the material composition design method of semi-rigid base that based on anti-erosion properties is proposed.