Research On The Fatigue Properties Of Asphalt Mixture Under Heavy Load

Semi-rigid pavement structure was usually used in China's highway asphalt pavement structure. The pavement damage accelerates with the increase of traffic, which leads to the pavement maintenance costs dramatically increase and the influence to the traffic has become more obviously. The recent research results showed that the fatigue damage of pavement structure is one of the main failure phenomenon of the pavement damage. Because the increase of modern traffic volume, speed, axle load, the pavement structure was in the state of overlapping change of flexural stress for a long-term, which cause the fatigue damage occur in early time. In order to reduce the pavement maintenance and exert the economic and social benefits of road, in the existing road traffic environment, choosing durable pavement structure and pavement materials which is suitable for heavy-load and heavy traffic is a inevitable trend to improve the pavement life. In this paper, the test on the fatigue of the mixture of the following layers was conducted, and finite element modeling calculation and the fatigue software calculation was used to study the fatigue of semi-rigid pavement structure. The main achievements were summarized in detail as follows:(1) Bi-logarithm fatigue equations were obtained through fatigue test of the asphalt mixture of seven gradations. Based on the fatigue equations of gradations, the recommended gradations of the middle layer and the below layer was proposed.(2) The test were analyzed by ABAQUS, and the calculation results were imported into nSoft to carry out fatigue analysis. It was found out that the three gradations of AC20, LAC25 and SAC25 can also satisfy the traffic volume of the heavy traffic demand in pavement structure with 1.5 MPa wheel pressing. So this paper recommends the three gradation as the following layers of pavement structure under heavy traffic.(3) Multiple semi-rigid pavement structure were modeled, the grey relational between the design parameters and anti-fatigue properties of pavement structure analyzed by ABAQUS. Considering the factors of thickness of each layer, material modulus of each layer in semi-rigid pavement structure and so on, the influence of semi-rigid base thickness to the anti-fatigue performance of semi-rigid pavement structure is particularly important, followed by the below layer modulus, semi-rigid modulus and top layer modulus.The relationship sequence between the factors and the fatigue life of semi-rigid pavement structure indicates that the relationship between each pavement structure design parameters and the fatigue of semi-rigid pavement structure can playing a guiding role in pavement structure design with index of fatigue.The result of this paper provides a reference for semi-rigid pavement structure design and further research, and lays foundation for popularizing and applying the gradations with good performance of anti-fatigue.