Research On Quality Control And Improvement Of Hot In Central Plant Recycling Modified Asphalt Pavement For Construction Process

The total amount of SBS modified RAP generated by maintenance and reconstruction throughout China exceeds 32 million tons,growing at a certain rate every year.Significant environmental benefits and economic value can be achieved with SBS modified RAP recycling through the hot central plant recycling technology.The current recycling specifications clearly specify that SBS modified RAP can be recycled,with no targeted clauses on how to use it better to construct high quality asphalt pavement.For giant SBS modified RAP recycling better and more efficiently,the research,which based on the technology project " Research on the Key Technology of Hot Recycled Modified Asphalt Mixture and Engineering Application " of Shandong transportation,was conducted on key programs and improvement measures such as RAP pretreatment,new asphalt screening,and mixture construction.RAP pretreatment is the most important program in quality control.By investigating and comparing the representative RAP pretreatment process and pretreatment effects,the results indicated that the separation efficiency of the counterattack-rotor centrifugal multi-stage combined screening pretreatment process exceeds 70%,laid the foundation for increasing the amount of recycled materials and strengthening the quality control of recycled mixtures.It is recommended to add rotor centrifugal crusher to the crushing equipment combination,and apply multi-stage combined screening operation to improve the pretreatment effect of SBS modified RAP.With applying performance index prediction equations,old SBS modified asphalt can be generated accurately by screening and customizing new asphalt according to key indexes including penetration,viscosity,softening point,and ductility.The key performance indexes of recycled modified asphalt meet the technical requirements,and it is recommended to use viscous toughness as the key index for evaluating the viscoelastic properties of recycled modified asphalt.Research on road performance has shown that compared with mixtures using raw aggregates,the dynamic modulus of modified reclaimed asphalt mixtures is increased,the bearing capacity and anti-deformation under high temperature are improved,the low temperature performance meets the requirements of the specifications,and the fatigue resistance decreased.Impact toughness can evaluate the fatigue performance of asphalt mixtures,and can be used as an evaluation index for material optimization and gradation optimization during mixture design.Quality control of recycling modified asphalt pavement can be strengthened with application of intelligent construction system.It is recommended to use non-destructive testing techniques such PQI to evaluate the uniformity of recycled asphalt pavement,quality improvement measures are proposed according to evaluation results.Field evaluation results show that the pavement smoothness,water stability,skid resistance and bearing capacity of the first project are qualified.The Marshall specimens produced by field mixture and the pavement specimens were tested in laboratory.The high temperature stability of the recycled asphalt mixture layer was significantly improved compared with layer of raw aggregates.Low temperature performance of recycled asphalt mixtures layer meets the requirements of technical specifications.