The Study Of Asphalt Migration Patterns And Its Effect On The Mechanical Properties Of Asphalt Mixture In Hot And Humid Environment

In southern China,the asphalt pavement is exposed to the high temperature and rainy natural environment,which leads to the serious problem of the cutting of asphalt pavement in hot and humid environment(such as rutting and passing),seriously affects the quality and safety of driving.This paper takes AC-13 asphalt mixture as the research object,carries out a hamburg rutting test under the coupling effect of different temperature,humidity and load,analyzes rutting depth,rut deformation rate and variation of various factors.On this basis,using bitumen migration as an entry point,the extraction test of asphalt mixture is carried out,the law of asphalt migration is analyzed and summarized.This paper conducts SPT dynamic modulus and repeated loading permanent deformation test of five kinds of asphalt mixture with different Asphalt content,analyzes the variation of temperature,frequency,dynamic modulus and phase angle and temperature,load and rheological times,summarizes and discovers the variation of mechanical properties of asphalt mixture after asphalt migration.The results show that water,raising temperature and increasing load can exacerbate rutting,the effect of four factors on rutting depth is as follows:temperature>humidity>load>speed.Under the coupling of temperature,humidity and load environment,asphalt has a general trend of moving from bottom up,the influence of various factors on asphalt rutting depth is as follows:temperature>humidity>speed>load;under humidity factors,the migration rate of bitumen in the water-saturated process is obviously higher than that in the dry-saturated process,the coupling of high temperature,water environment and heavy load can accelerate the upward migration of asphalt.The dynamic modulus of asphalt mixture magnifies with the increase of loading frequency and the rise of temperature;as the bitumen aggregate ratio between upper and lower layers becomes larger and larger,the dynamic modulus turns smaller and smaller,the dynamic modulus E*and the dynamic modulus combined parameter E*/sinφ also decrease gradually,asphalt migration significantly weakens the resistance to permanent deformation of the mixture.With the increase of temperature or load,rheological frequency decreases differently;as the bitumen aggregate ratio between upper and lower layers is larger and larger,rheological frequency becomes less and less,the asphalt mixture is easier to be destroyed.