Regeneration Technology And Application Research Of Hot Recycled Asphalt Mixture From Central Plant In Cold Region

In order to further promote the application of plant-mix hot recycling technology in highway field,this paper comprehensively studies the application of plant-mix hot recycled asphalt mixture in seasonal frozen zone.Relying on the expressway maintenance project from Changchun to Yingchengzi Town,the proportion design and performance verification of plant mixed hot recycled asphalt mixture with different RAP(Reclaimed Asphalt Pavement)content were carried out without regenerating agent.After the construction of the test road,the key process and special points for attention in the construction are summarized.The specific process is as follows:First,the asphalt content in old asphalt mixture,aggregate gradation and physical and mechanical properties of aggregate were determined by extractive distillation test,screening test,crushing value and abrasion test of old aggregate.The RAP fine material was tested for sand equivalent and water content,and the RAP was evaluated comprehensively.The asphalt was regenerated by mixing the old asphalt with the new asphalt.The penetration value was 65.53(0.1mm)and the ductility value was 21.24 cm at 15?,because of the light aging degree of the old asphalt.Therefore,when the ratio of SBS modified asphalt to old asphalt is 7:3,its performance index can reach SBS modified asphalt,and the ductility of recycled asphalt is greatly improved.Secondly,the traditional Marshall design method was used to design the target mix proportion of hot recycled asphalt mixture,and the gradation of recycled aggregate and the optimal asphalt content were determined.The gradation of recycled aggregate and the optimum asphalt content are given according to the different content of RAP.Through laboratory tests,the performance of recycled materials with two different dosages of RAP was evaluated and analyzed,including high temperature performance,low temperature crack resistance and water stability.The test data prove that the pavement performance of hot recycled asphalt mixturemeets the specification requirements.It provides a basis for determining the type of raw materials,feeding speed of cold storage bin and belt speed of mixing plant.Thirdly,through the screening test of the aggregate from hot aggregate bin,and referring to the design data of the target mix ratio,the production mix ratio of the recycled material with different dosage of the old asphalt pavement is finally determined,and the production mix ratio is determined by fine-tuning the recycled asphalt pavement ratio through the mixture performance check.Fourthly,through the performance verification of two different proportion of RAP from road paving site,the standard mix ratio which can be used in large-scale construction and production is finally determined.Fifthly,relying on the expressway maintenance project from Changchun to Yingchengzi Town,the production process and construction technology of hot recycled asphalt mixtures are summarized and summarized by paving test roads and studying the mixing process of hot recycled asphalt mixtures.After trial mixing,adjustment,trial paving and road performance test,the final mixing temperature is180?~190?,the total mixing time is 50s~60s,the discharging temperature of recycled materials is about 175?,the paving temperature ranges from 165?to175?.Finally,on the basis of referring to in-place hot regeneration,cold plant mixing regeneration and cold in-place regeneration of asphalt pavement regeneration technology,the advantages of hot plant mixing regeneration technology and some problems encountered in its application are put forward.