Development And Performance Evaluation Method Research Of Recycled Cold Mix Asphalt Patch Material

With the rapid development of China’s economy,the traffic volume is increasing year by year.China’s highway maintenance mileage is 4.9531 million km,accounting for 98.8% of the total highway mileage.The highway has entered the maintenance and management stage in an all-round way.A large number of pavements milling materials are produced every year,which wastes resources and pollutes the environment.Potholes disease is one of the main forms of pavement damage in China,and it is also a common disease in road maintenance management,which poses a great hidden danger to road driving safety.Using hot mix asphalt mixture to repair potholes has higher requirements on construction environment,and there is a situation that can not be repaired in time in winter.One third of the time in the north of China is in winter low temperature climate every year,so the problem of pavement potholes can not be effectively solved.In order to solve the problem that the potholes can not be repaired in northern China in winter,and from the point of view of saving resources and protecting environment,this paper mainly studies the following aspects.(1)The recycled cold patch asphalt mixture was developed by using the recycle asphalt pavement.The diluents and additives were compared and the mixing proportion was determined.The performance change of cold patch asphalt mixture with different recycle asphalt pavement content is studied in detail,and the best old material proportion is determined.The cold patch asphalt fluid and recycled cold patch asphalt mixture with excellent performance was developed,which can be used for repairing potholes in winter in northern China.(2)The Rotary compaction method and Marshall compaction method are proposed to evaluate the workability of cold patch asphalt mixture.The workability of cold patch asphalt mixture is quantified,and the evaluation index of workability is put forward,which avoids the problem of subjective arbitrariness.(3)At present,there is a lack of a set of standard and reasonable evaluation system and index for the performance evaluation of cold patch asphalt mixture.Based on the existing evaluation methods of emulsified asphalt and ordinary hot mix asphalt mixture,this paper summarizes and improves the curing methods of initial Marshall stability,molding Marshall stability and final Marshall stability,and road performance tests such as water stability performance,high temperature performance and low temperature performance.According to the indoor test results of various performance tests,the relevant recommended indexes are given.(4)Through digital speckle image processing technology,the differences and similarities of displacement field between cold patch asphalt mixture and common hot mix asphalt mixture during splitting test are compared.The results show that common hot mix asphalt mixture only produces longitudinal displacement,while the lateral displacement of cold patch asphalt mixture is greater than longitudinal displacement,which proves that the bonding performance of binder of cold patch asphalt mixture is weaker than that of common hot mix asphalt mixture It is suggested that the cold patch material should be used only in the low temperature emergency maintenance in winter,and the "hot patching method" should be used in other cases.(5)The finite element software was used to compare the force characteristics around the pit when the cold repair material has different moduli.At the same time,the force characteristics of the square pits for daily cutting and maintenance and the circular pits and elliptical pits for do not cutting and emergency maintenance under the same area are analyzed.The results show that the stress of round and oval pits with the same modulus is less than that of square pits,which proves that the emergency maintenance measures without cutting pits are feasible.(6)The recycled cold patch asphalt mixture developed in this paper is verified by real engineering,and no secondary damage occurs after half a year of use,which proves that the recycled cold patch asphalt mixture developed in this paper is suitable for repairing pits in low temperature areas in winter in China.