Study On The Diffusion And Regeneration Effect Of Regenerating Agent In Reclaimed Asphalt

In response to the national call for green,environmental,and intelligent construction,recycled asphalt mixture(RAP)has been increasing year by year,but the low amount of RAP reuse and poor regeneration effect are still the most severe challenges.The performance of RAP in the recycling process is good or bad,and the degree of miscibility between the rejuvenator and the aged asphalt plays a vital role in the mixing process.Therefore,in order to effectively improve the recycling rate of RAP materials,this paper conducts research on the diffusion rules and regeneration effects of rejuvenator in aged asphalt under different conditions,and provides a theoretical basis for the recovery and utilization of RAP in hot mix plant recling.The main research contents are as follows:First,the tracer carboxy-terminated liquid nitrile rubber(CTBN)and thermoplastic styrene-butadiene rubber(SBS)are used to mark the regenerating agent,and the Fourier infrared spectrometer(FTIR)and fluorescence microscope(FM)are used to test the regenerating agent.The characteristic peak height and fluorescence intensity changes to the applicability and dosing of CTBN and SBS tracers were carried out.It was found that CTBN and SBS can be used as tracer labeling regenerants for diffusion test,and the dosing of CTBN and SBS 10%and 3%have better tracing effects.Furthermore,Fourier Infrared Spectroscopy(FTIR)and Fluorescence Microscope(FM)were used to analyze the diffusion laws of rejuvenators marked with CTBN and SBS tracers in aged asphalt under different diffusion conditions,and based on Fick diffusion The law and composite material theory were used to fit the data in the test room,and the diffusion coefficient was used to evaluate the diffusion law of the rejuvenator in the aging asphalt.The research result shows that the longer the diffusion time and the higher the temperature,the better the diffusion effect of the rejuvenator in the aged asphalt.However,the greater the degree of asphalt aging,the greater the resistance to the rejuvenator,and the weaker the rejuvenator’s diffusion ability.Then,three major index tests and rotational viscosity test were used to analyze the changes in the conventional performance of recycled asphalt with different rejuvenator content;Fourier infrared spectroscopy was used to analyze the chemical composition changes of recycled asphalt and different degrees of aging asphalt.The test results show that with the increase of the regenerant content,the penetration,ductility,asymmetric aliphatic and aromatic functional group indexes of recycled asphalt gradually increase,and the softening point,viscosity,carbonyl and sulfoxide functional group indexes gradually decrease;as the degree of asphalt aging increases,the asphalt undergoes chemical reactions such as oxidation,dehydrogenation and polymerization,and aliphatic carboxylic acid C=O stretching vibration peaks and sulfoxide group S appear at 1075cm-1 and 1031cm-1 S=O,and the greater the degree of aging,the greater the peak of the carbonyl and sulfoxide functional groups.Finally,a dynamic shear rheometer was used to study the high temperature rheological properties of recycled asphalt under different rejuvenator content;a curved beam rheometer were used,based on the Burgers model,and the fitting parameters λ,m(t)/s(t)and Jc was used to determine the low temperature of recycled asphalt.The rheological properties was analyzed,and the results show that with the increase of the rejuvenator content,the complex shear modulus G*gradually decreased,the phase angle gradually increased,and the high temperature performance and fatigue performance of the asphalt are improved;And it is found that the more the amount of rejuvenator,the better the flexibility of the asphalt and the better the low-temperature performance of the asphalt.