Study On The Road Performance Of Asphalt Concrete In Ultra-thin Wearing Course

Since 80's in 20 centuries, along with the fast development of the economy, the construction of our country's highway gets fast development. Close till the end of 2004, the total mileage of highway of our country is up to 34000 kilometers, occupies the second of world. The fast development of highway, improves the travel condition, accelerates the development of the transportation, and pushes social progress.The high grade road of our country mainly adopts the structure of semi-rigid roadbase asphalt pavement, the asphalt pavement is not main bearing layer, but mainly takes as the function layer. In the recent years, along with the high-speed development of the transportation business of our country, the phenomenon of heavy transportation and heavy load is gradually serious. Various surface functions of asphalt pavement are decaying very quickly (the function such as anti-skid, noise, flatness etc. are descending), directly affect the safety and comfort of automobile's driving.The decay of surface function is a kind of form of the diseases of asphalt pavement, such as the descending of the anti-skid, noise, and flatnesss etc. If rut and water damage are the general quantity problems of the pavement, then the surface function is the problem what embody the humanities road, green road, is a higher request of quantity to the asphalt pavement, and is the trend of the future development.For the sake of improving the usage function of the surface layer of asphalt pavement, on the foundation of referring abroad researchresults, our country puts forward the AK anti-skid surface layer, SAC, SMA, the OGFC(Open-graded Friction Courses).But these anti-skid pavement gradation types just improve one or some few aspects of the road usage function, haven't really roundly improve usage function of road pavement.But adopting the ultra-thin bituminous concrete pavement is a valid measure to prolong the life span of pavement and improve the driving quantity, correct the surface blemish, raise the safety( including raise the anti- skid performance and drainage), minish the noise and increase the strength of pavement. So the research work of this paper is around the function of bituminous concrete ultra-thin wearing course.According to the definition of French criterion NF P98-137, the thickness of BBUM is 20～25 mm, and the thickness of BBUM is 15～25 mm. The BBUM that has the modern meaning was generated in 1987, and it adopts the technique measures of reducing the amount of sand, using modified asphalt and thick glue layer, has advantages of prolonging the life span of pavement, improving driving quantity, correcting surface blemish, raising safety etc. , and is mainly used as the cover of high grade road asphalt pavement.The industry criterion of our country's Ministry of Transportation & Communications ,《The Design Norm of Road Asphalt Pavement》( JTJ 014-2004)(draft asking for opinion )prescribes that, the ultra-thin wearing course is a kind of wearing course which has a large structure depth, good anti-skid performance, and is applicable to the road which has neat pavement, the depth of rut is small than l0mm, and hasn'tstructural breakage. It can be taken as maintenance measure to raise the service function surface layer, also can be applied as the wearing course of new road. The general thickness of wearing course is about 20 mms, and the mixture is properly choose to use gap gradation, modified asphalt or other additives, to raise the water stability of the ultra-thin wearing course. According to the thickness of bituminous concrete surface layer, it can be divided into three kinds, namely thin bituminous concrete surface layer 25 mm～30mm, very thin bituminous concrete surface layer 20 mm～25mm, the ultra-thin bituminous concrete surface layer 15 mm～20mm.This paper carries on experimental researches of the road performance of ultra-thin wearing course bituminous concrete on the foundation of deeply analyzing the related domestic and international research result. The concrete works of this paper are as follows:(1)Thoroughly analyzing the structure constitution and gradation theory of asphalt mixture, study the request to the material of ultra-thin wearing course, deciding a reasonable gradation of wearing course bituminous concrete.(2)Testing the high temperature stability of mixture by using rut experiment , and testing the water stability by using water Marshall experiment and frozen and melt split experiment , testing the anti-frozen performance by using frozen and melt cycle split experiment, thus evaluate the road performance of the ultra-thin wearing course bituminous concrete.(3)Finally applying the ultra-thin wearing course in the maintenance project of Chang-Ping freeway, and putting forward theconcrete requests to the construction of ultra-thin wearing course, then examining the application effect in actual project by experiments.