| Segregation is an important factor in causing early disease on asphalt pavement.Diseases such as pits,flaking,looseness,cracks and unstable ruts on asphalt pavements are likely to occur in areas where coarse aggregates are isolated;oily roads such as asphalt pavement and structural ruts are prone to occur in areas where fine aggregates are isolated.It is of great significance and practical value to analyze and isolate the causes of segregation to study the effects of road performance.In this paper,the indoor and outdoor test methods are used to analyze and study the causes of segregation,the gradation composition of asphalt mixture,the evaluation index and evaluation criteria of segregation and the influence of segregation on asphalt pavement performance.In this paper,the cause of the segregation of asphalt mixture was studied by analyzing the contact and contact moment of the particles under self-weight and the motion characteristics and mechanical characteristics of the particles under the action of external force.Poor gradation composition of asphalt mixture,excessive discharge opening of the mixing building,excessive inclination of the compartment when unloading,unreasonable rotation speed of the auger,and excessive spacing between the auger and the ground may lead to segregation.The gradation composition of the isolated asphalt mixture was simulated.By comparing the structural parameters of the asphalt mixture with different degrees of segregation,the evaluation method of the asphalt mixture segregation with the void ratio evaluation index was proposed,and the asphalt was determined according to the proposed standard.The degree of separation of the mixture is divided into fine aggregate separation,no segregation,slight segregation,medium segregation and severe segregation.Through laboratory tests,the effects of segregation on the road performance of asphalt mixture such as water stability,high temperature stability,low temperature crack resistance,permanent deformation resistance and fatigue resistance were studied.The results show that the coarse aggregate segregation makes the water stability of the asphalt mixture significantly lower;the fine aggregate segregation reduces the high temperature stability of the asphalt mixture,and the slight segregation makes the high temperature stability of the asphalt mixture slightly improved,medium segregation and Severe segregation significantly reduced the high temperature stability of the asphalt mixture;the fine aggregate segregation resulted in a slight decrease in the low temperature crack resistance of the asphalt mixture,and the coarse aggregate segregation resulted in a significant decrease in the low temperature crack resistance of the asphalt mixture;fine aggregate segregation The anti-permanent deformation ability of the asphalt mixture is reduced,and the coarse aggregate segregation significantly reduces the anti-permanent deformation ability of the asphalt mixture;the coarse aggregate segregation causes the anti-fatigue property of the asphalt mixture to be significantly reduced. |
