Applications And Researches Of High-performance Recycled Asphalt Pavement Materials For Flexible Base

High-performance RAP material refers to that which used the old asphalt pavement recycling material as the matrix material and improved gradation by adding new aggregates,and then mixed with imitation steel fibers(PPTF)and last formed a high-performance mixture with pellets class.In order to demonstrate the feasibility of using the high-performance RAP material as flexible base in the old asphalt pavement materials recycling and in this article we researched it from two aspects of laboratory tests and theoretical analysis.Through a detailed investigation and evaluation of the old road pavement,we established the relationships between particle compositions of RAP material and old road PQI evaluation levels,and used the gray theory to evaluate the gradations of RAP under different old road PQI evaluation levels,and compared the CBR and the maximum dry density of the test results and the gray theory of the evaluation results,and last found the feasibility of using grey theory to evaluate the gradation directly.The physical and mechanical properties of the RAP material were compared and analyzed in the vibration compaction and heavy hammer compaction and found that the method of vibration compaction was used to represent the actual compaction effect;we used the particle interference theory to optimize coarse aggregate gradation and used the maximum density curve theory I method to optimize fine aggregate gradation and then chose gradation with the maximum dry density and strength double optimization index by changing the ratio of coarse aggregate and fine aggregate and then proposed the gradations of excellent physical and mechanical properties preliminarily.On this basis,we further researched that regularity for the effect of the passing rate on the mechanical properties of gradation RAP material.According to the principle of the best mechanical properties,the skeleton dense gradation of gradation RAP material was put forward based on vibration molding.To split strength as index,we proposed that imitation steel fiber(PPTF)material with the length of 2.5cm and the content of 1 ‰ was added as the fiber in high-performance RAP material.The test specimens of high-performance RAP material with vibration molding were made to do mechanical properties tests of CBR,modulus of resilience,shear strength.The results revealed the rules of influence of various factors(compactness,moisture content,test conditions,etc.)on strength characteristics of high-performance RAP material and the design result of the compound ratio of high-performance RAP material was validated further and experience conversion relationships between various strength index value were established.Making wheel tracking tests indoors to research and test the high temperature stability.The results show that the high-performance RAP material as flexible base could meet the requirements of heavy traffic loads.The elastic-plastic finite element analysis of asphalt pavement structure with the high-performance RAP material base was carried out.The differences of pavement structure of high-performance RAP material flexible base and pavement structure of traditional flexible base and pavement structure of high-performance RAP material flexible base and the pavement structure of semi-rigid base were analyzed in the aspects of carrying capacity,anti-rutting aspects of performance,fatigue cracks and other differences exist.Construction process and quality control of high-performance RAP material flexible base were researched by paving test road and the direct economic benefits between high-performance RAP flexible base material,cement cold recycled base and cement stabilized macadam base from the composition of the materials was analyzed and contrasted;In addition,social benefit analysis from the aspects of whether to interrupt the traffic in the construction and environmental protection and post-maintenance were made.