Study On Application Of Hot In-Place Recycling Technology In SMA-13 Pavement

Hot in-place recycling technology of asphalt pavement can treat waste asphalt mixture,save energy and environmental protection,reduce the cost of road construction,thus bringing higher environmental and economic benefits.At present,the research on In-situ thermal regeneration technology has become mature,but the mix design of hot in-place recycling mixtures and the influence of related factors,energy consumption and emission in construction projects and benefit analysis need to be further studied.The main conclusions of this paper are as follows.Therefore,this paper systematically studies the hot in-place recycling technology of Asphalt Pavement Based on the SMA-13 asphalt pavement thermal recycling project from Laibai Road Jiepai to PetroChina Gas Station of X308 Line in Jiulongpo District.Firstly,the recycled asphalt binder is prepared by extracting the old asphalt from the waste asphalt mixture originating from the project section.Then,the optimum dosage of recycling agent is determined by testing the basic physical properties of recycled asphalt binder,and the high temperature,fatigue and low temperature properties of recycled asphalt binder are further evaluated.Then,according to the determined amount of recycling agent and the proportion of used materials,the mix proportion of hot recycling mixture is designed and its pavement performance is verified.Finally,the whole process and benefits of hot in-place recycling are comprehensively analyzed.（1）The physical and chemical properties of the old asphalt in RAP of the project section are analyzed.The results show that compared with the modified asphalt used in the construction period,the penetration,ductility and softening point of the old asphalt decrease obviously,and the chemical structure of the old asphalt is affected by aging.The C=C double bond of the PB section of SBS in the asphalt is broken,and the carbon and sulfur elements in the asphalt react with oxygen.Compounds with carbonyl and sulfoxide groups are formed.（2）Select specific regenerant and aging asphalt to prepare regenerated asphalt binder.Through comprehensive comparison with penetration,ductility,softening point and viscosity index of the original asphalt,the optimum content of regenerant is determined to be 6%.The rheological properties of recycled asphalt binder with optimum content were analyzed.Compared with old asphalt,its fatigue properties and low temperature properties were significantly improved,and its high temperature properties were slightly decreased.（3）The mix design of SMA-13 hot recycled asphalt mixture is completed by Marshall design method.The mix content of recycling agent is 6%,and the optimum asphalt-stone ratio is 6%.SMA-13 hot recycled asphalt mixture has good high temperature performance and impermeability,low temperature performance and water stability basically meet the requirements of specifications.（4）By verifying the test section,its pavement smoothness,construction thickness,compactness and surface seepage coefficient all meet the requirements of relevant specifications.Through the analysis of the total cost of the whole hot in-place recycling construction,it is 36.2%lower than that of the ordinary HMA.At the same time,the environmental benefits of hot in-place recycling mixtures are analyzed based on the LCD China Life Cycle Basic Database.The energy consumption is 35.1%less than that of HMA,and the CO₂ reduction rate is 24.8%.The hot in-place recycling technology has superior economic and environmental benefits.