Research On The Variation Of The Composite Pavement’s Permanent Deformation And Interlayer Cohesiveness

Composite pavement is one of the long-life pavements and the reflection of thesustainable development among the scientists, which can not only reduce the asphaltusage but also promote the stiffness of the pavement. This nature greatly enhances thepavement’s performance. However, the ever increasing traffic and the influence of theenvironment would never stop breaking it. Especially their combination brings theearly damage of the pavement structure to be obvious in the daily usage. Compositepavement fails to resist the reflection cracks, cutting slippage or present theanti-rutting ability of the surface layer in the high temperature, etc. They are the veryshortages of this kind of pavement, and we have enough necessity to overcome themby researching the variation of the composite pavement’s interlayer cohesiveness andasphalt surface’s anti-rutting ability in the high temperature. There are several issuescontained in this thesis, which will be shown in the following paragraphs.Firstly, this thesis surveyed the related researches that were both at home andabroad and analyzed the interlaminar stress of the composite pavement. Then it putforward the “shear angle” method, which is aiming at the influencing factors of themaximum shear stress and the shear angle of the interlayer. By using the BISARprogram to calculate those factors, this thesis presents the influence such as asphaltthickness and modulus, thickness and modulus of the bond layer traffic load,temperature, etc, and the sensitivity of them. The result is clear and simple. Themaximum shear angle is about35°, and the thickness of AC, modulus of the bondlayer, and the traffic load are the significant effect factors. The result also presents themultivariable function to reflect the sensitivity by using the nonlinear planningfunction of fminsearch to fit the maximum shear stress, shear angle and some othersensitive factors.Considering the traffic load and the environment effects, the experiment comparedthe composite pavement of rubber-asphalt-stone seal layer and slurry seal in differenttemperature(25℃,60℃) anddifferent humidity(immersed in water0h,12h,24h)named immersion rutting test, and has analyzed the law of rutting resistance that isaffected by those factors. It has established the rutting depth-driving load durationcurve, and tells the result that the rutting resistance of soaking specimens is strongerthan the control. This is because the effective stress principle which was proposed by Terzaghi that the rutting depth is not caused by the normal stress which is imposed onthe specimens but by the difference of total stress σ and the pore pressure u.It iscalled effective stress σ ’. This is the first time to put forward thewater-temperature-load coupling effect in the prediction model of rutting by usingleast square method to establish function and determining unknown parameters in themodel with the improved random walk method.The result tells that the correlationbetween the measured rutting and the prediction rutting is high up to0.98. This meansthe model is tally with the actual situation.Besides, the experiment adopted the orthogonal test to design, and did the indoorshear test. It used shear strength as index to evaluate the bond behavior of thecomposite pavement interface in different temperature, humidity, and the times oftraffic load, and analyzed the results’ variance. The research tells that the higher thetemperature is, the weaker the shear strength would be. The same situation appearswhen the soaking time is longer or the times of the traffic load is more.