Study On Structure And Material Of Compound Base Asphalt Pavement

At present, semi-rigid asphalt pavement structure still plays important role in high-grade highway in our country. However, its early damage has seriously affected the using character and service life of the highway. Especially, many expressway built in early years need to have a maintenance on large scale or reconstruction one by one. We have paid out enormous economic cost and social cost for the thoroughly reconstruction of the highway. So it's necessary to find out the new pavement structure which has good pavement performance and fits to the economic development level of our country. The technology has been studied by the expert all over the world, and some encouraging results have been obtained. However, in some aspects the researches are not substantially and systematical. Based on pavement structure durable design idea, further studies are carried out on compound base structure and materials by widely collecting the using actuality of semi-rigid asphalt pavement in our country and researching pavement structure at home and abroad.This dissertation has mainly researched nine aspects as follows:(1) As the characteristic of semi-rigid materials is easy to crack and be washed out. Systematic study are done from the aspects of mixture design, mechanical properties, crack resistance, anti-erosion property and fatigue characteristics, etc.. (2) Grey relational grade analysis for common evaluation indices of anti-cracking performance of semi-rigid materials is carried through by grey correlation analysis. The results indicate that the optimal evaluation index of anti-cracking performance for semi-rigid base course is anti-crack evaluation index. The anti-crack evaluation index is recommended as the control index during the mixture design. (3) Formula for shrinkage stress of semi-rigid base is derived. Influencing factors of the maximum shrinkage stress is analyzed, and the cracking law for semi-rigid base is proved. Temperature contraction cracks for semi-rigid base is predicted, and the approximate formula for the width and space between two Temperature contraction cracks is put forward. (4) Systematic study on asphalt treated base are carried out from mixture design and pavement performance, such as high temperature stability, low temperature crack resistance, water stability and fatigue characteristics etc.. (5) The simulated test of compound base fatigue life has been done applying ordinary rutting machine. Fatigue life of compound base is studied systematically by changing the loads, asphalt treated base thickness, crack depth in semi-rigid base. (6) According to the strength characteristics and stiffness characteristics of material, sensitivity analysis of the load inner force for compound base asphalt pavement is done by using calculation software. Mechanical analysis for the effect of anti-crack of asphalt treated base is done applying finite element software. (7) Fatigue life of compound base asphalt pavement, under different situations, is calculated. The determination method for asphalt treated base optimal thickness based on fatigue life of the whole pavement has been proposed. The effect of asphalt surface modulus, asphalt treated base modulus, semi-rigid base modulus and subgrade modulus on compound base asphalt pavement fatigue life is analyzed. Measures for improving fatigue life of compound base asphalt pavement are put forward. (8) The distribution rule of temperature stress for compound base asphalt pavement is studied under different situation. (9) Based on researching current asphalt pavement design problems and the design control indices of flexible asphalt pavement at home and abroad, the main and assistant control indices and standard for the design of compound base asphalt pavement are put forward combining with the mainly damage type of the structure. Then, the design method for compound base asphalt pavement is put forward.