Mechanical Behavior And Damage Mechanism Analysis Of Asphalt Chip Seals Based On The Microstructure

Asphalt chip seals is a technique of pavement preventive maintenance,which is generally used as the main form of low-grade asphalt pavement.The technique has been widely adopted all over the word.However,under the effect of traffic loads and environmental factors,the road surfacing seals prone to early appear the damage of loosing,rotation,falling of seal stone and bleeding after the short opening of transportation,which results in low skid resistance and durability,and seriously affects the performance of chip seals.Meanwhile,there is no a mature,complete chip seal design methods and construction specifications in China at present.Related research were about the performance of road surfacing seals at a macro perspective,ignoring the chip seal’s internal mechanical characteristics.That can not guarantee a good pavement performance and service life.Therefore,it is necessary to carry on the study of asphalt chip seal’s mechanical behavior and damage mechanism based on microstructure.Firstly,based on the field investigation on asphalt chip seals,this paper sorted out the common damages and influencing factors,and analyzed the possible causes of pavement damages.Secondly,a shear creep test was used to obtain asphalt visco-elastic parameters.A virtual load test was used to verify the accuracy of the result of shear creep test,Burgers model nonlinear fitting and the conversion process of prony series visco-elastic coefficients,which provided an accurate parameter characterization for the visco-elastic material.Thirdly,based on the microstructure and visco-elastic theory,a two-dimesional finite elment model for road surfacing seal was built to analyze the displacement and rotation angle of stone,and the stress,strain of asphalt binder,aggregate-asphalt interface,aggregate-base interface.It also analyzed the influences of different types of asphalt,stone shape,load(overloading ratio),temperature,interfacecontact factor and horizontal load on asphalt chip seal mechanical behavior,and then compared the various factors on the impac of mechanical indexes by variance analysis.Based on the above analysis,the paper put forward mechanical evaluation index of chip seals damages,and revealed the damage mechanism of chip seals.Some improvements were proposed to establish connect with the road surface performance and mesostructure.