| Recycling of pavement materials is the key work of energy-saving and emission-reduction in highway industry,and a very important content of transforming transportation developing mode as well.It is conducive to the development of transportation in both quality and efficiency,helping reduce resource utilization and consumption.Therefore,asphalt pavement recycling technology has been receiving more attention in maintenance project.Currently,due to the concern about feasibility and durability of hot in-plant recycling,the application of cold recycling technology is more common in China.According to this,the improvement in performance of hot-recycled asphalt mixtures caused by activated asphalt rubber was investigated in the research,and the performance of recycled asphalt pavement was evaluated by numerical simulation method.The properties of activated asphalt rubber and hot-recycled asphalt mixtures were studied based on extensive laboratory tests.Then the structure of recycled asphalt pavement was designed and its performance was evaluated by numerical simulation method.This paper aims to provide some meaningful references for development of advanced materials and the improvement of design system of recycled asphalt pavement.The properties of activated asphalt rubber were investigated.First,the elementary physical property of activated asphalt rubber was researched,which revealed the storage stability,construction workability and security of this special asphalt binder.Second,the road performance was studied based on dynamic shear rheology test(DSR)and bending beam rheology test(BBR).At last,in order to sum up the performance characteristics of activated asphalt rubber,the experimental results of activated asphalt rubber,matrix asphalt,SBS modified asphalt and ordinary asphalt rubber were compared and analyzed according to customary technology index and SHRP performance index.Hot-recycled asphalt mixture regenerated by activated asphalt rubber was designed.Firstly,adaptability of activated asphalt rubber in hot-recycled asphalt mixture was analyzed based on its composition characteristics.Then,asphalt-aggregate ratio and gradation of recycled asphalt pavement(RAP)were tested by extracting test,and the performance of aged SBS modified asphalt was investigated.According to the material composition properties of aged asphalt mixture,RAP were divided into four tranches,asphalt-aggregate ratio and gradation of each tranche were detected,respectively.Finally,to meet the functional requirement of different structural layers,the hot-recycled mixtures applied to anti-fatigue layer and anti-rutting layer of the recycled asphalt pavement were designed composed by four tranches of RAP.Improving the comprehensive road performance of hot-recycled asphalt mixtures is the main objective of utilizing activated asphalt rubber.Therefore,extensive laboratory tests were carried out to reveal the performance characteristics of hot-recycled mixtures regenerated by activated asphalt rubber.With regard to EME-20 and AC-10,the effect of RAP content on dynamic modulus,high temperature stability and low temperature stability of hot-recycled.mixture was studied.In order to better simulate the three-dimensional stress state in actual asphalt pavement,the annular load test(ALT)was proposed and rational experiment parametric selection was analyzed.Then,the crack resistance of hot-recycled asphalt mixtures was tested and evaluated using ALT and notched semi-circular bending test(NSCB).The crack resistance of AC-20 was also studied to compare with hot-recycled asphalt mixture EME-20 and AC-10.Multiple approaches to evaluate the water stability of hot-recycled asphalt mixtures are applied in order to reveal the influence of RAP content on water stability.The performance of recycled asphalt pavement is the key criterion for the design rationality of recycled asphalt mixture.Thus,rutting depth of recycled asphalt pavement was predicted in service life.First,transient temperature field of semi-rigid asphalt pavement was calculated by numerical simulation method according to meteorological data of different seasons.Laws of rutting development under transient temperature field were studied and summarized.Second,the relationship between pavement temperature and rutting depth was established.Based on the conversion relationship and the rutting equivalent principle,numerical computation method for rutting effective temperature was proposed.At last,supported by rutting effective temperature,rutting calculation model considering consecutive temperature variation was built.The rutting development of recycled asphalt pavement in service life was predicted based on the rutting calculation model,in which the high-temperature creep parameters of hot-recycled asphalt mixtures were obtained by dynamic creep experiment.Meteorological environment has significant effects on the performance of asphalt mixture.To incorporate climate factors into pavement structure design system,the fatigue life of recycled asphalt pavement was predicted considering consecutive temperature variation.On the basis of investigating the fatigue failure behavior of semi-rigid asphalt pavement,the fatigue damage calculation model was established by employing the continuum damage mechanics theory.The influence of structural design parameters on pavement fatigue life was also discussed.Then,numerical computation method for fatigue effective temperature was proposed according to the fatigue damage equivalent principle.Supported by fatigue effective temperature,fatigue life prediction model for semi-rigid asphalt pavement was established considering consecutive temperature variation.Finally,the fatigue damage development of recycled asphalt pavement in service life was predicted based on the built model,in which the characteristic parameters of hot-recycled asphalt mixtures were obtained through trabecular bending fatigue test. |
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