Research On Design Method And Performance Of RSAM Mixture Of Bridge Seamless Expansion Joints

The ideal expansion joints for bridges are seamless expansion joints,which are widely used throughout the world due to their advantages such as easy installation and maintenance,low traffic noise,and good driving comfort.But seamless expansion joints have poor durability and relatively short service life.Therefore,in this paper,the joint filling material of bridge seamless expansion joints is taken as the research object.Based on the refined analysis results of the seamless expansion joints structure of the bridge,and taking the performance index of the joint filler as the starting point,the interaction surface method was used to analyze the interaction of various factors,and a new RSAM mixture and its design method were proposed.Then test and analyze the material properties of the mixture and its main structural properties.The main research contents are as follows:(1)At the stage of fine structure analysis,combined with the structural form of the bridge seamless expansion joint,the displacement is calculated to determine the expansion and contraction range of the seamless expansion joint,which provides an evaluation standard for the performance test described later.Then use the ABAQUS finite element software to establish a full bridge structure model,simulate the vehicle static load and dynamic load,analyze the mechanical response distribution law of the weak position of the seamless expansion joint,and provide a reference for the design of the RSAM mixture later.(2)During the determination of raw materials,dynamic shear rheology tests are used to analyze the performance changes of the four modified asphalts before and after aging.One is selected as the asphalt binder,and then the aggregate composition is calculated and determined based on the Belay method Gradation.(3)In the mix design phase,based on the response surface method,the void value(VV),stability(MS),and flow value(FL)of the Marshall test pieces are used as the evaluation values.As the three influencing factors,a three-factor three-level three-response design was carried out,and then the statistical analysis software Design-Expert 11 was used to determine the optimal mix ratio.(4)During the performance verification phase,the RSAM mixture is poured to form the mixture ratio designed above,and the rutting test,immersion Marshall test,direct tensile test,full-scale simulation test,etc.are performed to evaluate the high-temperature stability of the RSAM mixture,Water stability,deformation and durability.The research results show that the new mixture RSAM designed in this paper has good performance,has better viscoelastic performance and is less prone to rutting and cracks than existing seamless expansion joints,and can meet the deformation requirements of small and medium expansion joints of beam bridges.