Study On The Formation Of Wheel Ruts In Heavy-traffic Asphalt Pavement And Component Design Of Mixture

With the development of the transportation economy, heavily-loaded transportation has been widely spread. Guangdong province is in the south pat of China and the temperature here is quite high all over the year, thus, with the impact of high temperature and heavy traffic, asphalt pavement is facing a series of severe problems and wheel ruts are the most typical and destructive way to bring damage to roads. Meanwhile, wheel ruts are also one of the problems which are at present difficult to be controlled by the design method of asphalt mixture. The appearance of wheel ruts not only will shorten the lifespan of the road, affect the comfort of traveling on it but also endanger the safety of driving, which will bring great financial damage and negative effect to the society. Since there is a high tide of transportation construction in Guangdong province, even all over the country but exists widely-spread wheel ruts problem which bring damage to the built highways, a thorough research into the anti-rutting asphalt mixture under heavily traffic as to prevent or decrease the occurrence of wheel ruts in the asphalt road will have great practical significance in the transportation construction not only in Guangdong province but also in the whole China.Firstly, with the back of several asphalt roads in Guangdong province where exist typical destructive wheel ruts, by the on-the–spot detailed survey and combined with the demonstration analysis of interior high-temperature performance tests, this paper explores the formation mechanism of wheel ruts in the heavily-load asphalt pavement at the angle of performances against high-temperature of the asphalt mixture and finds out the use condition of ruts in different states, which provides beneficial reference for the design and quality control in construction of asphalt mixture. Secondly, by adopting GTM and Marshall Process, this paper carries out gradation design of several common types of asphalt surface mixture in Guangdong province, makes comparative experiments of performances of asphalt mixture at high temperature and other use performances, finds out differences between two methods and put forwards the gradation design of anti-rutting asphalt mixture on the basis of combining the merits of the two methods. Thirdly, based on the application of Bailey method in classifying the composition according to thickness and adopting the gradation design of GTM, by the research method of AHP it analyzes the proportionality of the neighboring particle size aggregate and Bailey parameters which effect the property of skeleton denseness of AC-16 bituminous mixture and also explores the proportional factors of types of materials (e.g. grade-parameter, asphalt-stone ratio, volumetric index ), which will have an impact on the performances of asphalt mixture at high temperature. On the basis of linear regression analysis, this paper provides the criteria of inspection and optimization in gradation design of asphalt mixture. Lastly, by adopting triaxial repeated load creep tests and GTM gyratory compaction test and analysis on high temperature properties of different asphalt mixture by wheel-rutting experiment, this paper put forwards the reasonable test criteria for experimental methods of high temperature properties of different asphalt mixture. Based on this, this paper builds the rutting prediction model.The results of experiments show that wheel ruts are mainly produced in the middle and surface courses and the main reason for this is the imprecise command of asphalt-stone ratio in the construction of asphalt mixture, undemanding control or unreasonable design in mineral gradation design, poor interlayer adhesion, inadequate degree of Compaction, and low homogeneity. They lead to weak strength of shear resistance of road mixture and roads are easily rolled and impacted, which make the road produce great lateral flow and deformation of compaction and condensing when vehicles are on it. If combining the GTM mechanics design of asphalt mixture with the traditional volumetric one and making full use of the advantages of two methods, the high temperature stability will be improved twice compared with the result in Marshall Process, and the water stability will also been improved due to the decrease of void. According to the variation-curve regression formula of void in mineral mixture under ramming, it is possible to find out the bound-filling proportionality between aggregate of neighboring particle size. This proportionality is the cut-off point which the aggregate particles of neighboring particle size interfere with each other. Thus, this can be a basis for the inspection of gradation design of skeleton-dense state. At the angle of anti-rutting, the void of heavy-traffic road should be over 3%, But the saturation should be less than 72%. The order contact of skeleton is similar to that of common traffic and is suitable to be kept between 1.07 and 1.15. When adopting dynamic stability index to evaluate the high temperature performance of asphalt mixture, it is likely to stretch the work of modified asphalt and there is a discrepancy between the capacity to evaluate different gradation designs and the practical facts. In the late process of creep, stiffness module index can evaluate the high temperature performance of asphalt mixture which is relatively objective. The rutting prediction model based on this is relatively reliable.