Study On Degree Of Interface Blending Of Virgin Asphalt And Aged Asphalt In Warm Recycled Asphalt Mixture

At precent,Warm-mix recycling only makes the mixing and compaction at low temperatures,leaves diffusion and blending of virgin-aged asphalt as well as mobilization of asphalt film in reclaimed asphalt pavement out of consideration,it is difficult to guarantee the performance of recycled mixture and improve the utilization rate of RAP.This Paper based on the National Nature Science Fund project of China(51508063),according to aging behavior and mechanism of asphalt,developing a rejuvenator with good permeability,utilizing atomic force microscope to research warm mixing agent and rejuvenator that impact on interface diffusion phase and time and space evolution characteristics of virgin-aged asphalt.Through molecular tracing,stratification extraction,gel permeation chromatography(GPC)and Fourier transform infrared spectroscopy(FTIR),to research the effect of diffusion time and mixing temperature on degree of blending of virgin-aged asphalt and migration depth of Virgin asphalt in RAP asphalt under warm mixing condition.First of all,the aging mode of thermal-oxidation and photo-oxidation was used to aging the base asphalt with corresponding time gradient.According to the analysis of the conventional indexes of aging asphalt,the three major performance indicators of 5hours aging in rolling thin-film oven test are close to those of 36 hours aging in non-standard thin-film oven,which provide sufficient aging asphalt for the subsequent preparation of rejuvenator and research of the blending of virgin-aged asphalt.With the help of dynamic shear rheometer,Fourier transform infrared spectroscopy and atomic force microscope,The aging behavior of asphalt was studied.The deeper the aging degree of asphalt is,the higher the high temperature performance is,the lower the fatigue life is,the higher the carbonyl index and sulfoxide index are,and the number and area of the bee structure in the phase diagram change.Secondly,based on the theory of component regulation,the compound rejuvenator with low viscosity and good permeability is optimized.The contact angle between rejuvenator and aging asphalt is 27.112 °,the soaking effect is good.The thermal stability of rejuvenator is evaluated by TGA,the rejuvenator will not decompose in373.8 ℃ and has good thermal stability.The impact of rejuvenator and warm-mixing agent on the interface morphology of virgin-aged asphalt is that the dispersed phase area of asphalt increases and the area of bee structure decreases.The detection method of vertical superposition and horizontal overlap is used to analyze the diffusion of virgin-aged asphalt,and the virgin-aged asphalt diffuses each other and there is a blending area.Finally,the contribution of diffusion stage to mixing efficiency was studied by gel permeation chromatography and stratified extraction technology.Compared with the non diffusion stage and 2 hours heat preservation in the warm mixing asphalt mixture of degree of blending of virgin-aged asphalt,the mixing efficiency of the virgin-aged asphalt was greatly improved during the diffusion stage,the mixing efficiency can reach26.5%.Based on molecular tracer technology and Fourier transform infrared spectroscopy,research the impact of rejuvenator on the migration depth of virgin asphalt in RAP asphalt,the rejuvenator penetrates into RAP aged asphalt film and reduces the concentration difference between virgin and aged asphalt,the easier diffusion between virgin and aged asphalt,the deeper migration depth of virgin asphalt.