Study On Road Performance And Mechanism Of Dry Mix Rubber-plastic Composite Modified Asphalt Mixture

In wet polymer modified asphalt,modifier is easy to separate from asphalt,which leads to great variability of asphalt performance and poor storage stability.Because of the special process flow,using dry mix process to prepare asphalt mixture can effectively solve the poor storage stability of wet modified asphalt.The traditional preparation process of dry mix modified asphalt mixture is to improve its performance by adding polymer such as rubber powder or polyethylene plastic into the mixture separately.However,a single modifier is difficult to improve the comprehensive road performance of asphalt mixture.On this basis,this paper tries to add rubber powder and polyethylene composite modified particles into dry-mix direct-throw asphalt mixture,and analyzes the enhancing effect and modification mechanism of composite modified particles on asphalt mixture road performance.Firstly,use twin-screw extruder to desulfurize the rubber powder,and then put the blended LDPE particles and desulfurized rubber powder into the twin-screw extruder to make rubber plastic composite modified particles.Secondly,produce the asphalt mixture according to the best combination of parameters determined by orthogonal test,and then evaluate the performance of asphalt mixture from three aspects: high temperature resistance performance to deformation,low temperature performance and water stability performance.Finally,study the modification mechanism of composite particles from two aspects: the working state of composite particles in mixture and the improvement effect of composite particles on asphalt performance.the performance of rubber plastic composite modified asphalt mixture was analyzed the mechanism of composite particles was explored from two aspects: the working state of composite particles in mixture and the improvement degree of composite particles on asphalt performance.The conclusions of the experiments are as follows:(1)Using rubber and plastic composite modified particles in dry-mix asphalt mixture can effectively improve the high temperature deformation resistance of the mixture,and improve the low temperature cracking resistance and water stability to a certain extent.Compared with adding desulfurization activated rubber powder alone,the asphalt mixture modified by rubberplastic composite method can obviously improve the comprehensive road performance of the mixture.(2)Blending rubber powder with low density polyethylene by twin-screw extruder has no obvious effect on the improvement of rubber and plastic composite modification,but extrusion granulation can improve the preparation efficiency of dry-mix rubber and plastic composite modified asphalt mixture.(3)The rubber-plastic composite modified particles can not only enhance toughness,impingement and reinforcement in the structure of dry asphalt mixture,but also improve the bonding ability between asphalt film and aggregate as well as between aggregate and aggregate.(4)In the dry process,after the rubber and plastic composite modified particles are compatible with asphalt,they are uniformly dispersed in the asphaltene in the form of monomers.The interaction between particles can hinder the flow of asphalt at high temperature and effectively improve the high temperature performance of asphalt.(5)The main modification effect of rubber and plastic composite modified particles on asphalt in the dry process is physical modification.