Research On Thin Overlay And Interlayer Shear Performance Of Steel Slag Asphalt Mixture

The state puts forward that"Clear waters and green mountains are as good as mountains of gold and silver".In order to achieve the harmonious development between human and nature.The state imposes strict restrictions on the exploitation of natural resources.These measures will affect the supply of materials required for road construction in our country,resulting in a shortage of stone materials.It is urgent to find a new building material that can replace traditional materials.As a kind of industrial solid waste,steel slag has a low utilization rate in China.But its mechanical properties are better than traditional natural aggregates.It is an excellent choice to replace traditional aggregates.At present,a large number of new roads are being built in China.At the same time,as the service life of the roads and the increase in traffic.The road conditions are on a downward trend,with potholes,cracks,rutting and other diseases appearing,and most of the roads need to be maintained.Therefore,in order to alleviate the environmental problems caused by mountain rock mining and promote the application of steel slag solid waste in the road maintenance stage.A gradation suitable for road thin overlay maintenance is designed.At the same time,during the maintenance process.The interlayer performance is related to the combination of the new and old pavement and the durability of the maintenance pavement.Therefore,the interlaminar shear performance is also a problem that can not be ignored.In this paper,steel slag aggregate is used for the thin overlay of asphalt mixture,and two AC-13C-type limestone asphalt mixtures with different texture depths are designed to simulate the surface layer of asphalt pavement,and SBR modified emulsified asphalt is used as the adhesive layer.Study the road performance of steel slag asphalt mixture thin overlay and limestone asphalt mixture surface layer.The influence of different texture depth,temperature,modified emulsified asphalt dosage and stress ratio on the interlayer shear performance of the adhesive layer.Through Marshall stability test,freeze-thaw splitting test and dynamic stability test to evaluate the performance of thin layer overlay and surface layer asphalt mixture.Direct shear test and shear fatigue test to evaluate the shear performance of the adhesive layer.Based on discrete element the numerical simulation explained the mechanism of interlayer failure.The following conclusions were obtained through research:（1）The crushing value and abrasion value of steel slag aggregate are lower than limestone aggregate.The adhesion of steel slag coarse aggregate to asphalt is good.The road performance of DG-10 steel slag asphalt mixture better than traditional limestone asphalt mixture.（2）The optimal coating amount of the adhesive material with the surface layer texture depth of 0.92 mm and 0.71 mm is 650 g/m² and 560 g/m²,respectively.According to different road sections and different surface layer texture depths,the appropriate amount of adhesive material should be selected.To achieve better economy.（3）The dosage of styrene butadiene rubber modified emulsified asphalt decreases with the decrease of the texture.The amount of styrene butadiene rubber modified emulsified asphalt increased.The influence of the texture depth on the shearing effect between layers is weakened.Rise in temperature.The interlayer shear rapidly attenuates the strength and shear modulus,and the temperature has a great influence on the shear performance of the adhesive layer.（4）Through the discrete element simulation shear test.It is found that when the amount of adhesive material is small.The adhesive material cannot be well combined with the surface layer and the thin layer overlay.The adhesive ability between the layers is weak,and stress concentration will occur between the layers.When these stresses reach the maximum.They are suddenly released,and the specimen will undergo shear failure under the action of a small force.When the amount of adhesive material is large.The damage mainly occurs at the adhesive material.Due to the weak resistance of the adhesive material to shear.The damage will occur at a small strength.When the amount of adhesive material is appropriate.The surface layer and thin layer cover the adhesive material Form a whole under the action of.Enhance the shear strength between layers.The surface layer and the thin covering layer form a whole under the action of the adhesive material.Thereby enhancing the shearing strength between the layers.（5）Through the fatigue test.It is found that the shear fatigue life of the adhesive layer increases with the increase of stress ratio.The shear fatigue life and shear modulus decrease rapidly.The shear fatigue property of the adhesive layer is sensitive to stress.The texture depth 2 of the surface layer and the texture depth 1 of the surface layer,under the same stress ratio.The texture depth 1 of the surface layer has better interlayer shear fatigue resistance.The shear fatigue life equation for the texture depth of the surface layer of 0.92 mm is N_f=1279.676（1/σ₀）^2.3812.The shear fatigue life equation for the texture depth of the surface layer of 0.71 mm is N_f=427.9569（1/σ₀）^2.8176.