Research On Rheological Response And Mechanism Of Asphalt Disposal By Ultrasonic

Asphalt is a thermoplastic material,and its viscosity changes continuously with temperature.The warm-mix asphalt mixture technology can reduce the mixing temperature of the mixture,and the room temperature performance after the paving is cooled is not significantly affected.Its basic technical principle is to use chemical additives to make asphalt achieve the effect of high temperature viscosity reduction or interface lubrication.This has increased the complexity of asphalt components to a certain extent,which may make its long-term performance unpredictable;at the same time,additives generally increase the cost of materials and significantly increase the cost of large-scale road projects.Existing studies have shown that:ultrasonic treatment can change the chemical structure of the macromolecular clusters of viscous petroleum products,making the asphaltene aggregates more uniform and finer,and the viscosity is significantly reduced.With the help of ultrasonic viscosity reduction effect,power ultrasonic technology has been widely used in industrial processes such as heavy oil extraction and residual oil transportation.Petroleum bitumen is the product of further processing of residual oil,which is not essentially different from the residual oil in terms of chemical composition and structure.Therefore,the viscosity reduction effect of power ultrasound on the residual oil can theoretically be extended to the molten bitumen,which can then be used for adjustment.Viscosity of asphalt at high temperature and the possibility of warm mixing technology.At the same time,the impact of power ultrasound on asphalt viscosity is the result of ultrasound intervention on the chemical composition and chemical structure of asphalt.If this intervention has a favorable tendency,it also has a wide range of other technologies such as asphalt production,storage and transportation,modification,and regeneration.prospect.This article first explores the effect of ultrasonic treatment on the viscosity of molten asphalt.Based on the high-temperature viscosity influence law during construction period,combined with the evaluation of asphalt road performance,the performance of the asphalt after ultrasonic treatment in the service temperature section is analyzed in depth.And through the analysis of the microstructure and chemical composition of the asphalt,the hypothesis that the ultrasonic technology affects the chemical structure and chemical composition of the asphalt was verified,and the internal influence mechanism of the ultrasonic treatment on the macro performance of the asphalt was revealed.The specific content is as follows:Based on the viscosity test,the effect of treatment conditions such as ultrasonic treatment time and ultrasonic treatment temperature on the high-temperature viscosity of the two asphalts was explored.The study found that:at a certain treatment temperature,the viscosity reduction rate first increased and then decreased with the increase of the ultrasonic time,and a certain treatment time The viscosity reduction rate first increases and then decreases with the increase of the ultrasonic treatment temperature.Through the analysis of variance,it is found that the ultrasonic treatment time has the greatest contribution to the viscosity reduction rate of asphalt.In this study,under the conditions of 40kHz and 110℃,ultrasonic treatment with 0.78W/cm2 for 30min can reduce the viscosity of No.90 asphalt at 135℃ by 43%,and the viscosity of No.70 asphalt at 135℃ by 30%.The viscosity reduction effect is obvious..Based on the ultrasonic treatment conditions of the maximum viscosity reduction rate,the influence of ultrasonic on the empirical index and high and low temperature rheological properties of asphalt was explored.By simulating short-term asphalt aging,the rheological properties of the asphalt after ultrasonic treatment are analyzed.The results show that the penetration of the treated asphalt is slightly reduced,the softening point is slightly increased,and the rutting factor of the DSR test is basically unchanged.Ultrasonic treatment has no significant effect on the high temperature stability of the asphalt in service;the ductility at 15℃ after treatment is slightly The m value of the BBR test is basically unchanged,and the ultrasonic treatment has no significant effect on the low-tempcraturc crack resistance of the asphalt during the service period.Ultrasonic treatment has no significant effect on asphalt performance in the service temperature section.The results show that the viscosity reduction effect of the high temperature section does not extend to the normal temperature section.This result is inconsistent with the conventional thermoplastic change of asphalt,but it meets the technical requirements of warm mix asphalt.Ultrasonic treatment may be used in warm mixing technology.Finally,starting from the basic principle of ultrasonic action on liquid,the influence mechanism of ultrasonic on petroleum pitch was proposed,and the hypothesis of the proposed influence mechanism was verified by two test methods:component analysis and microanalysis.The four-component analysis results after the treatment show that the asphaltene and gum content in the asphalt are significantly reduced,and the aromatic and saturated components are significantly increased.Ultrasonic treatment has the effect of cracking and hydrogenation of the asphalt;observations with a 400x optical fluorescence microscope after the treament found A fter ultrasonic treatment,the asphaltene particles in the asphalt became uniform and refined,indicating that the ultrasonic treatment can break up or disassemble the associated macromolecules of the asphaltene micelles in the asphalt.The heavy components in the asphalt decrease and the light components increase.Conventionally,the viscosity or consistency of the service section at room temperature corresponding to the rheological test decreases,but the ultrasonic treatment makes the asphalt not follow this rule,or even the opposite(decreased penetration,slightly increased softening point).The above phenomenon shows that the impact of ultrasonic treatment on macroscopic performance may be more mainly from its chemical structure-the colloidal structure of the asphaltene macromolecular micelles is broken up and cooled and reorganized,which in turn reduces the heavy components in the asphalt.At the same time,its normal temperature viscosity or consistency increases instead.The laws discovered in this study indicate that ultrasonic treatment can cause specific changes in asphalt properties.This change may be used in road engineering fields such as warm-mix asphalt mixtures,and may also have other application prospects in asphalt modification and upgrading.