Research On Evaluation Indexes And Characteristics Of Segregation In Asphalt Mixture

Segregation makes the quality of asphalt pavement can not meet the design requirements and cause the early damage of asphalt pavement easily.The effects of segregation on the road has already attracted the attention of a great road workers at home and abroad.The gradation segregation,temperature segregation and compaction segregation are studied in this paper on the basis of research results at home and abroad for reference.This paper expounds the reasons of the gradation segregation and then drills cores from the pavement area with segregation,gradation segregation is divided into pavement without segregation,mild segregation,moderate segregation and severe segregation with reference to American Segregation Evaluation Standard and use structural depth as index.The grading,asphalt content and air voids of the segregation parts are obtained by indoor test,and then use structural depth ratio as well as the changes of grading,asphalt content,void fraction as the evaluation index of segregation.Different degrees of gradation segregation are imitated indoor in this article to study the effect of gradation segregation on asphalt mixture.Temperature segregation is studied on the basis of real engineering and analyzes the causes of temperature segregation in the process of production,transportation and paving of asphalt mixture.The changes of void fraction and temperature are put forward to be the evaluation index of temperature segregation through the study of pavement void ratio under different temperature change.And finally the effects of temperature segregation on the performance of asphalt mixture are studied by the indoor simulation of different degrees of temperature segregation.Compaction segregation has relation to construction machinery,compaction scheme,layer thickness and so on;This article analyzes the effect of compaction segregation on pavement void fraction based on test way and proposes to use the change of void fraction as the compaction segregation evaluation index.At last,the unity relationship of the gradation segregation,temperature segregation and compaction segregation is discussed in this paper.After getting the evaluation standards of segregation,it need to study how to apply evaluation criteria to construction process to control the segregation.The application of infrared camera and non-nuclear density gauge in pavement segregation control are discussed in this paper.With the use of this two kinds of equipment,the sites that form segregation can be found in time during construction and we can find the causes of segregation easily.The article expounds the concrete control measures for segregation during construction process at last.