Study On The Reclaimed Effect And Pavement Structure Application Of Plant Mixed Hot Reclaimed Asphalt Mixture

Excavating and milling during the maintenance and reconstruction of asphalt pavement will generate a large amount of recycled asphalt pavement materials.If the recycled asphalt pavement material is not used appropriately,it will inevitably cause serious environmental pollution and waste of resources.However,asphalt pavement reclaimed technology solves this problem well.Plant-mixed hot reclaimed technology is an important reclaimed technology in asphalt pavement reclaimed technology.Because it can ensure the mix quality of the reclaimed asphalt mixture well,it is widely used in road reclaimed engineering.Therefore,in this subject,the research on the reclaimed effect and pavement structure combination design of plant-mixed hot reclaimed asphalt mixtures with different grading types and different amounts of RAP.It is of great significance to solve the problems of environmental protection and aggregate shortage faced by highway construction in Gansu Province,promote the recycling and reuse of road building mate rials,and reduce the cost of asphalt pavement maintenance and reconstruction.This paper first analyzed and tested the gradation and physical and mechanical properties of recycled asphalt pavement materials.Then,the mix ratio design of the plant-mixed hot reclaimed asphalt mixture with different gradation types and different RAP contents were completed.Based on laboratory tests,the road performance and mechanical properties of different gradation types and different RAP contents plant-mixed hot reclaimed asphalt mixtures were tested.Finally,the pavement structure combination design of plant-mixed hot reclaimed asphalt mixtures of different gradation types were completed.The main research conclusions of this paper are as follows:(1)Recycled asphalt pavement material gradation refinement are quite obvious.The penetration and ductility of the old asphalt significantly reduce,and the softening point increases.With the increase of RAP content,the stability of the plant-mixed hot reclaimed asphalt mixture with different gradation types and different RAP content s show a trend of increasing first and then decreasing.The peak value of the stability of different gradation types plant mixed hot reclaimed asphalt mixture is different.(2)With the increase of RAP content,the dynamic stability of different gradation types of plant-mixed hot reclaimed asphalt mixtures gradually increase,which shows that the high-temperature stability of different gradation types plant-mixed hot reclaimed asphalt mixtures is gradually improving.With the increase of RAP content,both its flexural tensile strength and failure strain show a gradual decrease trend,which shows that the low-temperature crack resistance of different gradation types plant-mixed hot reclaimed asphalt mixtures gradually decreases.The unfreeze-thaw split strength and freeze-thaw split strength of different gradation types plant-mixed hot reclaimed asphalt mixtures increase with the increase of RAP content.The splitting strength ratios can meet the requirements of the specification,and with the increase of RAP content,the splitting strength ratios all increase first and then decrease.(3)With the same RAP content,the dynamic modulus,fatigue factor,and anti-rut factor of different gradation types plant-mixed reclaimed asphalt mixtures increase with the increase of the loading frequency,while the phase angle decreases with the increase of the loading frequency.At the same loading frequency,with the increase of the RAP content,the dynamic modulus,fatigue factor and anti-rut factor of different gradation types of plant-mixed reclaimed asphalt mixtures increase.However,the phase angle of different gradation types plant-mixed hot reclaimed asphalt mixtures decrease with the increase of RAP content.It shows that different gradation types plant-mixed reclaimed asphalt mixtures gradually hardens with increasing RAP content,tends to be elasticity,its fatigue resistance gradually decreases,and its rutting resistance gradually increases.(4)According to the mix ratio design results,road performance and mechanical performance test results of the different gradation types plant-mixed reclaimed asphalt mixtures,and combing with the requirements of current specifications,four kinds of recommended plant-mixed hot reclaimed asphalt pavement structure combination design are calculated.The pavement structure calculation results show that: the four recommended plant-mixed hot reclaimed asphalt pavement structure design schemes can be used as the pavement structure combined design plan for the test section.