Study On The Hot In-place Recycling Technology And Its Application In Maintenance Of Chongqing Expressway

With the continuous development of highway maintenance and the deepening of the concept of green maintenance,in-situ thermal regeneration technology of asphalt pavement came into being.Compared with the traditional milling and re-laying process,the in-situ heat regeneration technology has many advantages such as high construction efficiency,good repair effect and less impact on traffic.The domestic application of in-situ heat regeneration technology started late,and the application level is uneven.Chongqing area is constantly exploring the technology of asphalt pavement regeneration,and in 2015 began to apply specific projects of in-situ heat regeneration technology.The application of in-situ thermal regeneration technology in Chongqing has the characteristics of late start and rapid development.As of the end of 2019,about 1.7million m² of asphalt pavement in-situ thermal regeneration construction has been implemented.In order to promote the further development of the in-situ thermal regeneration technology of Chongqing Expressway,it is of great practical significance to analyze and sort out the problems arising in the application of the technology and explore its development direction.This article first introduces the characteristics of common asphalt pavement regeneration technology and the differences between the technologies.Through comparative analysis,it focuses on the advantages and application value of in-situ thermal regeneration technology;secondly,from the in-situ thermal regeneration process,the aging and regeneration mechanism of asphalt Theoretical research,and introduces the process characteristics and applicability of two in-situ thermal regeneration processes（remix regeneration and remix overlay）.On this basis,through the analysis and research on the common diseases and causes of Chongqing Expressway,and the statistics of the common diseases,it is pointed out that the geothermal regeneration technology is feasible and applicable to deal with the main diseases of Chongqing Expressway.The key processes in the application of the technology in Chongqing,the problems and solutions in the construction,and the construction quality management are explained in detail.Finally,the actual case is used to analyze and evaluate the effect of the in-situ heat regeneration technology in Chongqing.The results show that the diseases of the asphalt pavement of Chongqing Expressway are mainly three categories:insufficient anti-skid,rut and crack.Diseases are mainly distributed on long downhill and curved road sections.In the main processes of in-situ thermal regeneration construction,construction preparation,excavation of lap joints,heating at the starting point of the construction,control of the level of the mixture at the lap joints,treatment of lack of material in the longitudinal joints,temperature of recycled asphalt Monitoring is a key construction process.It is necessary to grasp the construction details of each process to ensure full control of the key processes.Taking the road repairing project of Taiping Interchange to Liangping section of G42Expressway in 2016 as an example,the road driving quality index（RQI）evaluation levels before and after the implementation of in-situ heat regeneration technology are both excellent,and the index has slightly increased after construction.There is no obvious change in the index,and there are large fluctuations,but the overall driving quality is good and there is basically no attenuation.The evaluation level of the Rut Depth Index（RDI）after construction and within two years is excellent,and the index is increased by about 8%compared with before construction.Decreased year by year in the next two years,but the overall attenuation rate was slower,and the attenuation rate was about 3%in 18 years than in 16 years;the anti-slip performance index（SRI）of the pavement increased by about 12%after construction,but the anti-slip performance declined faster in two years after construction,18 years Compared with 16 years,the attenuation is about7%,and the evaluation level is good.If the level continues to drop to medium（<80）,you need to consider repairing maintenance;in-situ heat regeneration technology has a significant effect on repairing the pavement anti-skid performance,but there is also a problem that the anti-slip performance declines quickly after construction;in-situ heat regeneration Has good economic,social and environmental benefits.Compared with milling and resurfacing,the in-situ thermal regeneration technology can save about 23.50yuan per square meter;the road occupation time during construction can be saved by 50%.Compared with the milling and resurfacing construction technology,the traffic pressure is greatly reduced,and the safety of traffic accidents is reduced.Hidden dangers and significant social benefits;compared with traditional processes,the in-situ heat regeneration technology can reduce CO₂ emissions by 9.02kg/m²,and the environmental protection benefits are better.