A Study On Permanent Deformation Prediction Model Of Asphalt Mixture And Flow Number

Asphalt Concrete Pavement is the main form of the highway in our country, which has been widely used in various regions. The existence of rutting of asphalt pavement, seriously affected its performance. Permanent deformation of asphalt pavement deformation is an important reason, therefore the study of permanent deformation of asphalt mixtures is of great significance.In the papers, the asphalt permanent deformation test scheme was developed. The diameter and height of specimen was 100 mm and 150 mm respectively; modified asphalt and ordinary asphalt are developed in the test, and the asphalt content was 4.4%,4.9% (OAC) and 5.4%; the type of loading was haversine, the frequency was 1 HZ, the loading time was 0.1s and the interval time was 0.9s, he number of load applications was 10000; the confining pressure was 138kPa, the deviator stress was400 kPa,600 kPa and 900 kPa.Repeated load triaxial tests were conducted to Aspalt mixture on a universal testing machine (UTM). The permanent deformation developmental curves of Aspalt mixture were got; the factors that affect asphalt pavement deformation are discussed. Whose factors contain different asphalt content, different temperatures, different asphalt specimens; the basic relationship between the plastic strain and the loading times was found, and the square of the correlative coefficient between the calculated and measured permanent deformation was higher than 0.75.The material damage process along with the Repeated load triaxial tests. The shear strength in the process of damage were studied by the principle of damage mechanics, and on the base of damage mechanics, thermodynamics of irreversible process, the relationship of the asphalt mixtures shear strength and load times is derived.Flow number is the points that the curvature increased rapidly,which is an important feature of asphalt permanent deformation, in the three-stage model of permanent deformation. On the point of the flow number, the repeated load is to be equivalent to shear strength, when the parameters of the prediction model are obtained.This article assumes that FN is the critical point that the asphalt mixture specimen will damage under the shear stress, derived this condition into the shear strength damage model, then the flow number prediction model are obtained. Conmbined With traditional flow number solving method, the method has the advantage of considering the material damage process.