Application Study Of Cold Recycled Mixture For Chang-jin Expressway Asphalt Pavement

With the rapid development of national economy in the past decade and the increasing of expressway mileage,most of the pavement forms are asphalt mixture pavement,which leads to the sharp increase of asphalt mixture aggregate.However,because of the construction quality,overloading and environmental factors,the asphalt pavement has been damaged too fast,so the maintenance and maintenance of asphalt pavement has become a major problem in highway construction.The maintenance and maintenance of asphalt pavement is bound to produce a lot of old asphalt mixture waste,the traditional practice is to directly abandon the waste,so as to pollute the environment and waste resources.Therefore,this article insists on the concept of sustainable development,aiming at the special maintenance project of the high speed pavement of Chang-jin,using the cold recycling method to recycle the old asphalt mixture.Based on the special maintenance project of Chang-jin High speed pavement,this paper makes an applied study on the whole process technology of old asphalt pavement.And five aspects of Pavement condition Damage Index,road running quality,rut depth,pavement structure strength and skid resistance of old asphalt pavement were investigated and analyzed comprehensively and statistically.In this paper,the cold recycling technology is used in the maintenance project,through a lot of experiments and the experience of the existing engineering,the article makes a comprehensive and meticulous evaluation on the items needing attention in the process of milling,stacking and sieving of the old asphalt pavement material(RAP)of Chang-Jin Expressway.Using emulsified asphalt and cement as recycled material,the compatibility of different emulsified asphalt and old asphalt pavement material(RAP)was compared in laboratory test,and the effect of different emulsified asphalt on the performance of cold recycled mixture was found.On the basis of comparative analysis of domestic and international gradation range and technical performance index,combined with previous engineering experience,the gradation curve and control index of cold recycled mixture were determined.In the best emulsified asphalt oil asphalt and the best water content,the best emulsified asphalt oil-stone ratio is determined by means of the method which differs from the ministerial criterion,and the maximum value of the splitting strength,the maximum value of the water immersion splitting strength and the asphalt of the emulsified asphalt oil with the maximum value of wet and dry splitting strength ratio.Moreover,it is believed that there is a best water content in different emulsified asphalt content,so the optimum water content of emulsified asphalt oil asphalt is used in determining the optimum emulsified asphalt oil-stone ratio.Through the test analysis of the relationship between cement content and the performance of emulsified asphalt mixture,it is found that a certain amount of cement must be added in emulsified asphalt mixture.But the cement content is not the higher the better,the cement content of more than 1.5%when the resistance to rut performance and low-temperature anti-cracking performance have decreased,the final determination of cement content of 1.5%.Finally,several specific requirements for field control and construction management of cold recycled mixture are put forward,including on-site material management,mixing mixing,compaction process and compaction equipment combination,engineering quality acceptance and so on.And through the test found that mixture from mixing to paving time interval within 2 hours,road performance can meet the specification requirements.