Research On Application Of Hot In-place Recycling Technology Of Asphalt Pavement In Changjiu Expressway

Expressway industry in China has gradually stepped into the stage of transformation from construction to maintenance,and the task of road maintenance is arduous.As an effective preventive maintenance measures,the asphalt pavement Hot In-place Recycling technology has significant economic and social benefits.Compared with the theoretical system,design system and application of asphalt pavement Hot in-place recycling technology in abroad,the application and research in our country started relatively late and the engineering application experience is insufficient.In recent years,a large number of expressway in Jiangxi Province appears early disease,and preventive maintenance is urgently needed.The Hot In-place Recycling technology is suitable for the maintenance in Jiangxi Province because of its unique advantages,such as economy,energy saving and opening up traffic.Therefore,this paper studies the application of Hot In-place Recycling technology of asphalt pavement on the basis of the project of "K598+300~K603+700" section of the asphalt pavement on Nanchang-Jiujiang Expressway.The main research results include:(1)Comparison and selection of preventive maintenance schemes for asphalt pavement.Based on the project of HIR(Hot In-place Recycling)of asphalt pavement on Nanchang-Jiujiang Expressway,some field investigation about the old road was done,and traffic conditions,main diseases in the road and route longitudinal distribution characteristics were analysed.Combined with the pavement core samples,the development situation and position of diseases were also analysed.Meanwhile,the stability of the pavement structure is evaluated by deflection test.Integrating road traffic conditions,disease characteristics,structural features,the causes of pavement diseases were studied,and the advantages and disadvantages of several common conservation measures were also compared in this paper.(2)Analysis of HIR technology of asphalt pavement.The characteristics of HIR of asphalt pavement were analysed,and the applicable conditions were determined by referring the specification.The disease characteristics,asphalt aging degree and pavement structural strength of the two sections of Nanchang-Jiujiang Expressway were compared,and A section(K598+300~K603+700)was finally chosen to used HIR technology.At the same time,the instructions of the HIR scheme design were simply introduced from the aspects of structure,material and technology.(3)Design of HIR mixture proportion.The main methods and steps of recycled asphalt mixture design were determined by material characteristics of recycled asphalt mixture.We also designed three different recycled asphalt mixture gradation by analyzing old asphalt and aggregate performance of RAP.The content of recycling agent was determined by performance of asphalt and practical experience.Finally,the optimum asphalt content was determined by Marshall test.(4)Construction process and key technology of HIR were provided.The detailed elaboration of the HIR construction scheme and construction technology were carried,and the quality problems of the HIR construction process were analyzed.Meanwhile,the construction temperature control and uniformity control were the key points in the quality control of the construction of the HIR technology.(5)The long-term performance of HIR asphalt pavement was tracked.The effect of HIR technology in practical engineering was analysed by the comprehensive evaluation of field test and laboratory test.