Study On Characteristics Of High Performance Asphalt Mixture And The Construction Technology

Freeway development in China is in a high speed stage.However,early damage of asphalt pavement is still a serious problem due to the lack of reservation of related technologies,heavy traffic and the overweight vehicles.The investigation shows that causes which led to the early damage of asphalt pavement are complex problems which have much to do with the type of pavement structure,mixture proportion design,construction techniques and so on,besides the environment and the loading conditions.In recent years,studies have been made on asphalt pavement structure and the mixture proportion design,also laboratory tests showed good combination property,but the problems of the early damage of pavement still exist in the construction,design of pavements directly adopted advanced foreign technologies are not as good as expected.Engineering practice shows that factors such as construction property of mixture,equipment performance,match relations between equipments, interaction property between equipment and material are important to ensure and to improve pavement quality.The above mentioned issues based on systematic theory study and engineering application are concentrated in the paper.Different aggregate gradations form different organization structures in asphalt mixture,structure status of mixture,volume characteristics and construction characteristics.All of theses govern the functional performance of the pavement. Since the gradation and property of high performance asphalt mixture are different from the traditional mixture in terms of gradation and property,the author analyzed and studied many problems about high performance mixture,which include gradation feature parameter control,factors that impact the volume property,construction quality control and so on,proposes construction control scope to ensure excellent property of the mixture.The functions of the machinery equipment should be selected and the parameters should be set up according to the concrete operation object to meet the needs of various pavement structures,material composition and environment requirement and full play of operational characteristics also should be made.The author probed deeply into the structure principle operation characteristics of the main equipments and the factors impacting the equipment property of the key equipment in the construction of asphalt pavement,and put forward the main control indices.The interaction between mixing equipment,paving equipment,compaction equipment and materials were also studied.A uniformity mathematical model for the mixing equipment and kinematics model for the automatic leveling device of the paver is set up.Asphalt pavement construction is an organic whole consisting of a series of machinery equipments combined by individual machine,which run coordinately on a large scale to achieve the best working quality and efficiency.Therefore,a reasonable matching relation between different machines is expected.Based on mixture compaction resonance theory,the author explored the changing regularity of the material compaction degree and compaction times,and sets up a mathematics model for the vibration rammer of the multifunction paver.The model shows that compaction degree of pavement varies with the paving speed,determining the rational range of accommodation for the paver,and sets up the new matching relations for the key equipment,the auxiliary equipment and the core equipment so that they can match each other very well,thus to ensure the operation quality.High performance asphalt mixture is very sensitive to construction variability. Once changes happen to the asphalt pavement,it will seriously influence the durability and the service life.In recent years,although studies on the reason that caused pavement quality variability and the corresponding measures have been carried out,there is still a lack of researches which are studied in a systematic way, and the impact of equipment on construction variability is often neglected.This paper studied segregation phenomenon and its mechanism in the whole process including design,production,transportation,paving and compaction of asphalt mixture,and proposed technical approaches for preventing and controlling segregation and evaluation standard,on the basis of material property,mechanical performance and interaction characteristics.These results have been applied in practical engineering.The study team aims to combine the theory study with the engineering practice, and trial performance have been carried out in "Wuhan-Yichang "freeway and "Laoyemiao-Jining"freeways respectively.The study shows that the research results have a remarkable effect on the prevention and control of early disease of pavement, improvement of construction quality and pavement durability.