A Study On Pavement Performance Of The Asphalt Mixture In Cold Area

With the asphalt roads for the volume of traffic increasing rapidly, the channeling running, and overloading seriously, etc. Particularly, in the seasonal freezen zone, the low temperature crack is very commonly. seriously affecting the use quality and lifespan of pavement, and increasing the expenditure of pavement maintain. So research and solve this problemJilin province is in the seasonal frost region. It locates in the most north end of the temperate, near the sub frigid zone. The climate is the significant temperate continental climate. The temperature in winter is low (which can reach -38℃), while the temperature in summer is high (which can reach 39℃). So the road design in this region not only requires considering the low temperature crack resistance, but also requires considering the high temperature stability.The paper is aimed at the main reason of the asphalt pavement'destruction in the frigid zone. From several aspect discussing the factors affect on the stability of low temperature and high temperature. Because there are so many factors affect on the low temperature crack, We must use systemic methods and consider the performance and structure of material and begin with choose of asphalt, the optimize and design of gradation, then find out the way to solve the low temperature crack. This paper just from the research of gradation optimizes to improve the crack-resistance performance,and at the same time improve the high temperature-stability.The choose of the asphalt is an important part of the asphalt pavement design. In the selection, it should consider the climate condition and the traffic situation, especially in the north seasonal frost region. This paper uses the Dalian western pacific AH-90# petroleum asphalt. The paper not only did the routine test, but reflected the viscoelastic properties scientifically.In the design methods of the asphalt mixture, we lead in the Superpave methods. Through at traditional Marshall design method and Superpae pitch that method compound mix materisl carry on way compares with and analyses with performance, and discussing the rationslity of design indexes and the restricted zone. Grading aggregate is the framework of mixture; it decides the weight and the quantity of asphalt in the mixture. Through choosing suitable aggregate gradation and deciding the optimum asphalt content to design the asphalt mixture and making the asphalt mixture has smaller shrinkage and better flexibility is the main content of the low temperature asphalt mixture design. We analyze five kinds of testing gradations'low temperature performance and find out the fourth one, which conforms to SHRP gradation idea, has perfect low temperature crack-resistance performance and high temperature-stability.The paper got the following conclusions:(1)The paper proved the design conceptions is same to the experiment result, and it compared the advantages and disadvantages among the design methods by laboratory test.(2)It is reasonable to comprehensive evaluate asphalt mixture low temperature crack resistance by low temperature trabecular bending experiment and low temperature contraction coefficient experiment. Asphalt mixture low temperature crack resistance relies on the flexibility of the asphalt in the mixture. The more asphalt amount is, the much flexible the mixture is in low temperature. And it can increase the stress relaxation. The contraction coefficient of the asphalt depends on the type of the mixture, the amount of the asphalt, porosity and etc. The contraction coefficient is different between the asphalt and the aggregate. The more the big mineral aggregate is, the small the whole contractility is. But when the amount of the asphalt is low, the flexibility of the mixture will become weak.(3)When the small feed is more, the asphalt is more. The flexibility and deformation are good, but the contraction coefficient is high.(4)When the amount of the asphalt is large ,or when the mineral powder is fine, the contraction coefficient is high.(5)When the porosity is high, the contraction coefficient is high too. But when the contraction coefficient increases, the stress relaxation ability will decrease.(6)This paper believes"S"gradation under SHRP gradation conception has a good stability both in high and low temperature by study five experiment gradation, and suggests use it widely in real project.