Performance Analysis Of Hot Recycled Asphalt Mixture In West Sichuan Basin

The asphalt mixture pavement structure has basically become the main pavement structure of highways and other grades of highways.However,with the construction of larger-scale highways,the problem of waste caused by maintenance and repairs has gradually increased.Therefore,in recent years,more and more attention has been paid to the recycling technology of asphalt mixtures,and the pavement of recycled roads has been carried out in actual engineering.Based on theoretical and laboratory experiments,the regeneration technology has been further applied in practice.The gradation design for recycling old asphalt and RAP materials has been relatively mature,so it is extremely important for the performance of the recycling technology in actual engineering.Recycled asphalt mixture is made from old pavement materials,new asphalt,new aggregates,and regenerant.Compared with the original mixture,the performance is different.This paper focuses on the road performance of recycled asphalt mixtures,and studies the recycling method of old asphalt,the road performance of recycled asphalt mixtures,and simulates the pavement structure.The main contents of the research are as follows:(1)Conducting a road survey of the project,and analyzing the causes of major diseases such as ruts and cracks.(2)The advantages and disadvantages of the two asphalt recovery methods,the Absen method and the Rotary Evaporator method,were compared and analyzed.Finally,the Rotary Evaporator method was selected to recover the asphalt of the RAP material.The using of the Rotary Evaporator method is introduced,and the test parameters of the rotary evaporator are calibrated.The recovery control parameters that meet the test conditions are obtained,and the secondary aging problem of the asphalt in the RAP material during the recovery process is avoided to a greater extent.In addition,the effects of trichloroethylene and mineral powder on the performance of the recovered asphalt during the recovery process were studied,and the 0.5% content was determined as the influence limit,which provided an effective theoretical reference for the test of the recovered asphalt by the Rotary Evaporator method.(3)Asphalt recovery of RAP material was carried out based on the Rotary Evaporator method.A number of tests were tested on the recovered asphalt: three major indicators of asphalt,viscosity,dynamic viscosity,SHRP index,etc.,and the performance was compared with with new asphalt.The analysis of results shows that as the aging degree increases,the asphalt becomes harder,the high temperature performance is better,and the low temperature performance is worse.For old asphalt,a comparison test of different mixing ratios of regenerants was also carried out.The regenerants can improve the low-temperature performance of the original asphalt to a certain extent.Screening tests of recycled materials at various stages were also conducted.The original asphalt pavement was found that the mixture has been refined to some extent.(4)Based on the Hamburg Wheel Tracking test(HWTD),rutting tests were performed on the core samples of the project under the high temperature test environment of water bath and air bath,and the test phenomena under two high temperature(55 °C,65 ° C)environments were observed respectively.Analyzing the test data,performance of recycled asphalt concrete pavement was compared with two ways,high temperature environment and water environment,from various aspects such as rut depth and peeling inflection point.(5)Based on the BISAR elastic layer system theoretical calculation software,referring to the relevant modulus of each layer of the pavement structural layer and the calculation theory of the continuous elastic layer system,the asphalt mixture pavement structure model is established.Based on the maximum tensile stress at the bottom of the layer,the fatigue cracking life of the fresh asphalt pavement structure,the aged pavement structure,and the recycled pavement structure were calculated and analyzed.Based on the BISAR elastic layered system theory calculation software,referring to the relevant modulus of each layer of the pavement structure layer and the calculation theory of the continuous elastic layered system structure,the asphalt mixture pavement structure model was established.Based on the maximum tensile stress and the vertical compressive stress at the top of the layer,the fatigue cracking life,the permanent deformation and its influence of the recycled asphalt mixture pavement structure under different working conditions were calculated and analyzed.