Study On Performance And Application Of Polyurethane Modified Asphalt Mixture

The development and application of the asphalt pavement which is often used in the road construction has been widely recognized by domestic and foreign experts and scholars.Polyurethane is a kind of thermosetting material,which has the advantages of wear resistance,high temperature resistance,aging resistance,impact resistance and excellent low temperature resistance.In this paper,that if polyurethane is used in the application of the road engineering,it will hold the advantages of both the material requirements of asphalt pavement under high temperature strength and low temperature flexibility is regarded as a starting point,in order to study that blending polyurethane prepolymer with asphalt,by transforming of the basic physical blending and chemical modifying,which is eventually forming a three-dimensional network structure,and improve the performance of the asphalt mixture.Comparing the polyurethane material,studying the preparation conditions of polyurethane modified asphalt,and analyzing the curing mechanism,so as to determine the optimum mixture gradation and asphalt aggregate ratio,and then discussed the affection of mixture performance in different curing temperature and curing time.The performance test and the commonly used modified asphalt were compared,the Marshall strength,high temperature rutting,low temperature crack resistance and water damage resistance can satisfy the demand in 60 C curing conditions,and some performance far exceeds the evaluation standard.When the splitting tensile strength reaches more than 3MPa,the power of the resistance to tensile stress is obviously higher than that of the common asphalt concrete.At 15?,the static modulus E of polyurethane modified asphalt reaches more than 3000MPa,which is much higher than that of conventional asphalt concrete in road construction.The dynamic modulus of the uniaxial compression test of polyurethane modified asphalt,SBS modified asphalt and asphalt,the test results were analyzed,at low temperature,polyurethane modified asphalt mainly manifest as elastic properties and better than SBS and ordinary asphalt,that plays a significant role in improving the resistance to crack under low temperature conditions.At high temperature,polyurethane modified asphalt still manifest as elastic and obviously better than SBS and ordinary asphalt,which indicates that the high temperature stability is obviously improved.From low temperature to high temperature,the material properties of polyurethane modified asphalt mixture are closer to the elasticity,and the polyurethane modified asphalt reflected the properties of the high temperature resistance and low temperature resistance of polyurethane well.By using of BISAR3.0 software model,selecting pavement structure parameters,calculating the stress,strain and deflection of the elastic layer system.In the same case,the polyurethane modified asphalt concrete pavement surface deflection,base bottom tensile stress,compressive strain on top of subgrade soil decreased obviously.When the base modulus is reduced,the affection of reduce the tensile strain of asphalt layer bottom is obvious.In the case of certain thickness,the fatigue life of polyurethane modified asphalt is about 3.8 times of that of SBS modified,and it is about 5 times that of ordinary asphalt.Polyurethane modified asphalt can increase the fatigue life of asphalt layer obviously.When the fatigue life is certain,the required thickness is about 2?3.5 times that of ordinary asphalt polyurethane modified asphalt,SBS modified is about 1.8-2.9 times of polyurethane modified.Using polyurethane modified asphalt can significantly reduce the required thickness of the layer structure,affection is obvious.To research the polyurethane modified asphalt is a great application value in the future construction of asphalt pavement.