Study On Viscosity Recovery Technology Of Aging Asphalt In RAP

In recent years,the research of asphalt pavement regeneration has become the research foc us.The plant-mixed heat regeneration is a widely used method.But the existing processing method of the plant-mixed heat regeneration does not guarantee the viscous recovery of the aged asphalt.Therefore,the aged asphalt is regenerated by self-made rejuvenator with different viscosity grades.By analyzing the performance of the reclaimed asphalt,the viscosity recovery degree of the aged asphalt is characterized,and the rejuvenator is preferred.Through the analysis of the mechanical properties of the w arm reclaimed asphalt rubber sand,the viscosity recovery of the aged asphalt is analyzed.And the road performance of the reclaimed asphalt pavement is verified by the high-temperature performance and the water stability of the reclaimed asphalt mixture.The conventional performance and aging resistance of recycled asphalt are studied.The results show that the penetration,softening point and viscosity of reclaimed asphalt meet the requirements of regeneration,but the ductility of reclaimed asphalt is worse.The low temperature performance of rubber oil type reclaimed asphalt is better than that of reducing line oil type reclaimed asphalt.That indicates that rubber oil type rejuvenator has better regeneration effect than reducing line oil type rejuvenator.Rejuvenators can significantly reduce the viscosity of aging asphalt.After short aging and long aging,the ductility of reclaimed asphalt is poor,only reclaimed asphalt A-X3 can achieve the performance of the base asphalt AH-70.The rheological properties and low temperature stiffness of reclaimed asphalt were studied.Compared with aging asphalt,the storage modulus G′,loss modulus G′′and rutting factor G*/sin δ of recycled asphalt decrease,and the phase angle δ increases.The results show that the addition of rejuvenator can restore the viscosity of aging asphalt.Compared with base asphalt AH-70,the viscoelastic parameters of reclaimed asphalt are similar to those of AH-70 asphalt.However,the phase angle δ results show that the addition of rejuvenator has the effect of viscosity recovery,but it can not completely restore to the level of base asphalt.Except reclaimed asphalt A-J5 and A-X4,the high temperature grade of reclaimed asphalt can reach the high temperature grade of base asphalt AH-70.The low temperature grade of all reclaimed asphalt is-22 ℃,which is the same as that of base asphalt AH-70.From the test results analysis,the rejuvenator X3 has better effect on the extraction of asphalt from RAP.The conventional properties,rheological properties and aging properties of reclaimed asphalt can meet the requirements of base asphalt.In the process of curing,the rejuvenator is well compatible with the aging asphalt,and the aging asphalt is restored to a certain viscosity.And the mechanical strength of the asphalt mortar is guaranteed.Finally,the curing condition of reclaimed asphalt mortar was defined,curing time is 2h and curing tempervation is 150℃.Reclaimed asphalt mixture has good high temperature performance and water stability.