Analysis Of Adhesion Characteristics Of Base-Surface Rubber Powder Modified Asphalt Adhesive Layer

As the semi-rigid base asphalt pavement has the advantages of high strength,good stability and low cost,it is widely used in our country.However,the modulus of the semi-rigid base course and the asphalt surface course is quite different.If the interlayer treatment is not in place,it will become a weak link in the road structure layer,unable to withstand the shearing force caused by the vehicle load,so that the surface course and the base course Relative slip occurs between.At the same time,in my country’s current pavement structure design theory,the asphalt pavement structure layer is assumed to be in complete continuous contact,and the influence of the actual contact state between the structure layers on the road is ignored.In view of the above problems,this paper proposes to set up a rubber powder modified asphalt bonding layer between the semi-rigid base layer and the asphalt surface layer,and through the oblique shear test and torsion shear test,to study the different bonding layer setting schemes to bond the base layer and the surface layer Performance impact.In addition,a finite element model of the contact between the base and the surface layer was established to analyze its mechanical properties.The specific research content is as follows:First,the oblique shear test is used to detemine the best bonding layer among the 48 bonding layer setting schemes considering the four influencing factors:the amount of crushed stone,the particle size of the crushed stone,the amount of rubber powder,the amount of rubber powder,and the number of rubber powder meshes.Design plan,and analyze the influence of four factors on the interlayer shear strength.The results show that the best design plan for the base-surface bonding layer is that the rubber powder mesh number is 40 meshes,and the rubber powder asphalt distribution amount is 0.9L/m,80%of the crushed stone distribution,and a combination of crushed stone particle size of 5～10mm,and the order of the four factors affecting the shear strength of the base-surface bonding layer is as follows:crushed stone particle size>crushed stone Spreading amount>rubber powder asphalt sprinkling amount>rubber powder mesh number.Secondly,through the oblique shear test and torsion shear test at three different temperatures of-10℃,25℃and 45℃,the influence of temperature on the shear strength of the base-surface bonding layer is explored.The results show that:The inter-layer shear strength has a greater impact.The shear strength is the largest at low temperatures,and the shear strength decreases significantly with the increase of temperature,indicating that the weak interface between the base-surface bonding layer is more likely to be sheared under high-temperature environments.,Produce the phenomenon of slip between the base and the surface layer.Through the force-displacement curve,we can get the change law of the shear dissipated energy density in the oblique shear test at different temperatures,and it is concluded that the shear dissipated energy density decreases continuously with the increase of temperature.Finally,based on the finite element theory,a mechanical response model of the contact properties between the substrate and the surface layer is established based on the indoor shear test to verify the feasibility of the cohesive contact to simulate the contact state between the layers.The results show that the numerical simulation results are generally similar to the experimental results,indicating that the interlayer shear can be simulated by setting the cohesive contact attributes.In addition,based on the cohesive simulation of the contact between the base and the surface layer,a three-dimensional finite element model of the asphalt pavement is established to analyze the change law of the interlayer shear stress under different vehicle loads.It is found that the interlayer shear stress increases as the vehicle load increases.It also keeps increasing.When the vehicle is turning,the interlaminar shear stress is much greater than when driving in a straight line.It is also found that whether the vehicle is driving in a straight line or turning,the base-surface interlaminar shear stress is less than the shear strength obtained in the test.Therefore,setting the rubber powder modified asphalt macadam bonding layer between the base layer and the surface layer can ensure that the road surface will not be sheared under the action of the vehicle load.