Study On The Regeneration Effect Of Aged SBS Modified Asphalt In Central Plant Hot Recycling Asphalt Pavement

Although the central plant hot recycling asphalt pavement technology has been widely used in road reconstruction and expansion,but recycling technology is not perfect,recycled asphalt pavement performance has yet to be further optimized.In this paper,the diffusion dffect of regenerator on old asphalt on new and old aggregate surface and the effect of asphalt regeneration on the interfacial strength were studied to evaluate the regeneration effect of old asphalt,which provided the basis for optimizing the performance of recycled asphalt.The contents of the study and the results are as follows:1.The extraction test and the rotary evaporation test was carried out,and the performance index of the old asphalt was tested.The new SBS modified asphalt was aged by the delayed film oven heating method to test the performance index of the asphalt under different aging time.The nonlinear relationship between the performance index and the aging time of simulated aging asphalt was fitted.Then,the old asphalt index is taken into the fitting equation to calculate the simulated aging time.Comprehensive comparison,the aging time was calculated as 32h,and the aging time were verified2.The self-made device was used to simulate the new and old aggregate surface asphalt recycling effect in the recycled asphalt mixture.The new aggregate surface is distributed from the inside to the outside was as follows:the new asphalt-the regenerant-the old asphalt;the old aggregate surface from the inside to the outside was old asphalt-renewable agent-new asphalt.Design test temperature is 25℃,60℃,120℃;test time is 1h,3h,5h.The results show that the diffusion temperature and diffusion time have great influences on the diffusion of asphalt.In the same environment,the diffusion process of the old asphalt on the new aggregate surface is slower than that of the old aggregate,but the change is not obvious.3.In the study of the effect of the regeneration degree of recycled bitumen on the interfacial strength,this paper designs the aggregate+recycled asphalt film+aggregate sandwich specimens.The shear strength and tensile strength of different loading rate,asphalt dosage,positive pressure(shear test)were measured by direct shear test and drawing test.The results showed that,the interfacial strength is gradually increased with the increase of the loading rate,the amount of asphalt and the horizontal pressure.When the amount of asphalt reaches a certain value,the shear strength increment decreases.When the temperature is 60℃,the shear strength between the aggregates is mainly determined by the horizontal pressure provide.The type of aggregate and the degree of regeneration of the old asphalt will have an effect on the interfacial strength.Under the same conditions,the interfacial strength of basalt is the largest,and the interfacial strength of perlite is the smallest.The lower degree of asphalt regeneration,the greater the viscosity,the better the resistance to deformation,the stronger the interface strength,destruction of the specimen more prone to brittle fracture.