Study On The Mechanism Of Kinetic Energy Dissipation Of Asphalt Buffer Isolation Layer Of Cement Concrete Pavement

Although cement concrete pavement has the advantages of high strength and stiffness, phenomenon of early broken slab of pavement slab is common under the impact vibration load of vehicle wheel.However, by setting a asphalt buffer isolation layer between the lean concrete base and cement concrete slab, the surface course transfers the impact vibration load to the base through the flexible asphalt buffer isolation layer, which effectively alleviates the impact and vibration acting on pavement structure and dissipates vibration energy from pavement slab. Study on the mechanism of kinetic energy dissipation of asphalt buffer isolation layer of cement concrete pavement is very few at presentThis paper emphasizes on the study of the mechanism of kinetic energy dissipation and effects of different influencing factors of asphalt buffer isolation layer of cement concrete pavement.The self-developed ball dropping device is combined with the ball dropping method which is put forward by America ACI544 Commission applying impact and vibration to the pavement structure, to study the vibration response of pavement structure with and without asphalt buffer isolation layer and asphalt buffer isolation layer in different affecting factors on lean concrete base. Results show that under the impact load the slab vibration weakens gradually, with energy dissipation. Asphalt buffer isolation layer can effectively reduce vibration response amplitude of pavement slab, and significantly improve kinetic energy dissipation of pavement structure. Big porosity of asphalt buffer isolation layer can reduce vibration response amplitude and enhance buffer capacity. Asphalt 90# reduces more impact force than 70#.Asphalt buffer isolation layer added with rubber crumb has a better effect of vibration reduction and energy dissipation and mix amount of rubber crumb chosen from 15 to 20% is more suitable. As the value of thickness of asphalt buffer isolation layer is 3 to 4cm, effect of kinetic energy dissipation is more ideal.Electro-hydraulic servo loading system is employed to use different pavement structure to conduct fatigue failure experiments simulating the impact and vibration effect of vehicle wheel load, to analyze the relativity between dynamic response and fatigue life of pavement structure.It can be seen that, the asphalt buffer isolation layer has good effect on vibration attenuation, reduces the impact force acting on pavement structure, and significantly improves the fatigue life of the pavement structure.Compared with the buffer isolation layer of asphalt 70#, the vibration of buffer isolation layer of asphalt 90# is attenuated faster and dissipate more vibration energy of the pavement slab, prolonging the fatigue life of pavement structure. Asphalt buffer isolation layer mixed with rubber crumb effectively improves vibration response of pavement structure and obviously makes vibration attenuation faster, significantly absorbing impact energy from vehicle wheel acting on pavement slab, increasing fatigue life in large amplitude. With asphalt buffer isolation layer thickening, impact force acting on base course is relieved, but it goes against reducing effect of impact and vibration from vehicle wheel acting on pavement slab, fatigue life of pavement structure just increases slightly.According to the results of experimental research, it is suggested that the asphalt buffer isolation layer using asphalt 90#, big porosity gradation would be better.