Rutting Resistance Evaluation And Structure Optimization Of Asphalt Pavement

Rutting is one of the damage forms of asphalt pavement, which appears as the concaveof the wheel tracks and some times accompanied by the bulge of the track edge. The cause ofrutting is the compaction and shear deformation of asphalt mixtures, and which mainlyappears in the surface layer of pavement. With the rapid development of expresswayconstruction in Guangdong Province, the trend of constructure is gradually being transferredfrom the Pearl River Delta to the mountainous and hilly areas. The aphalt pavement ruttingdamages in long-steep section of expressway in mountainous areas has become aunavoidableissues, and will also become more prominent. Due to the particularity of thelong-steep sections of expressway in mountainous areas, the pavement damage is moreserious than ordinary sections: the expressway has to take on the complex terraion of themountainous areas and to adopt long and steep slopes; overload and low-speed traffic areunfavor to asphalt pavements. As a result, the rutting damages appear in these sections underhigh temperature, which will be a serious impact on traffic safety.There has been being blank in the pavement design and construction specification (Guide)for pavement structure design in long-steep section. The aim of this study is to futherunderstand the rutting characteristics of asphalt pavement under the climate and trafficcondictions in Guangdong Province. By enriching the pavement diseases of the long-steepsections, the pavement structure design guide of Guangdong Province will be improved.These works is favor to improve the overall quality of asphalt pavement, and is of wellsignificance for to be built expressway in mountainous areas. Based on these backgrounds,this paper begins with the asphalt mixture design theory, and based on the digital imageprocessing technology and Granular Mechanics, tries to connect the macro-mechanicalproperties of asphalt mixtures to the microstructural characteristics. Based on a evaluationplatform, a new asphalt mixture evaluation method for heavy traffic is promoted to provideimportant guidance for solution to the rutting damage in long-steep section. The main workand innovations of this paper are as follows:1. By summarizing the existing mix design theories and volume design method, theMultilevel Mixing Method is optimizated based on particle interference ideological (fineaggregate interference and asphalt mastic interference) and volume filling ideological. At last,the design method for anti-rutting asphalt mixture is promoted.2. Through summarizing the specialtyies and advantages and disadvantages of rutting test devices at home and aborad, a fact is found that the existing rutting tests do not wellsimulate the stress state of pavement. The DWPA rutting test system is empoldered based on“Driving Wheel Pavement Analyzer”. The evaluation index for DWPA rutting test is set upaccording to the contrast of3different rutting test methods and Grey correlation analysis. Thedeformation slope in the creep deformation stage well reflects the high temperature stabilityof mixtures.3. The contact characteristic of coarse aggregates of mixtures is analyzed based onDigital Image Processing technology. Two kinds of fine to coarse aggregate divided methodsare promoted, one is based on Multi-point support theory and the other is Granular Mechanicstheory. The results of aggregate contact characteristics analysis show that, the mixturespecimen molding method affects the inclination of coarse aggregate. Gradations containedmore coarse aggregates form more contact points and large inclination in the same sectionarea. Considering that the compaction energy in the same the molding way is approximate,the inclination of coarse aggregate reflects the stable state in the molding process.4. Two rut depth prediction models is established adopting the initial amount of contactpoints and asphalt performance index as the input parameters. Indexes of optimal number ofcontact point Noptand minimum number of contact point Nminare defined, which are supposedto be applied into the mixture design as references for gradation selection.5. The shear modulus prediction models are established according to GranularMechanics theory. The reasonableness of amount of contact points as the evaluation index formaterial stability at high temperature is discussed. And the test results of uniaxial penetrationtests show that the models can well predict the shear modulus of asphalt mixtures.6. The main factors that influence the rutting damage is detailed discussed based on theliterature survey of the asphalt pavement rutting damage in long-steep section of expressway.Slow traffic speed is the important characteristics of the long-steep section traffic flow. A rutdepth prediction model for asphalt pavement is established based on large amount of indoorrutting tests and pavement survey data. The prediction model can well predict the rut depth,which indicates that the model is basically correct. Lastly,28pavement structures are taken inthe prediction model. According to the prediction results, pavement structure combinationssuitable for different traffic levels and speed are summaried.