Research On Fatigue Performance Deterioration Laws Of Dense Asphalt Mixture Under Freeze-thaw Action

Freeze-thaw damage is one of the common forms of the early damage of asphalt pavement.Repeated freeze-thaw actions make the pavement performance and the use of performance decrease seriously,and then service life is reduced.At the same time,the freeze-thaw action can cause the change of the mesoscopic structure,thus affecting the macro performance.But fatigue property is one of the most important indexes to measure the durability of pavement,and then there are a lot of research results.However,the study about the effects of freeze-thaw effect on the fatigue properties of asphalt mixtures has not been carried out.Based on the above situation,it is necessary to investigate the decay law of the fatigue properties of asphalt mixture under the condition of macroscopic and microscopical conditions.Based on the above situation,it is necessary to investigate the decay law of the fatigue properties of asphalt mixture under the condition of macroscopic and microscopical conditions.For this,the paper uses the method with the combination of macroscopic and mesoscopic measures,and the change laws of fatigue performance of asphalt mixture influence law of different factors under freeze-thaw action is studied.The change rule of the mesoscopic parameters under the freeze-thaw action is analyzed.The relationship between freeze-thaw damage and the sensitive parameter is established.The model of freeze-thaw damage which considering fatigue is set up.The specific research contents are as follows:First of all,based on the freeze-thaw cycle test and indirect tensile test method,the fatigue life of asphalt mixture under different cycles of freezing and thawing is tested,and the change rule of fatigue life of asphalt mixture is studied.T he influence law of different influence factors including the asphalt mixture type,freezing and thawing cycles,void fraction and full water rate on the fatigue life is explored.The decay law of asphalt mixture fatigue performance under the macro freeze-thaw action is illuminated.Secondly,combining freeze-thaw cycling test and mesoscopic detection means-CT scanning technology,the mesoscopic structure of asphalt mixture under different freezing and thawing is obtained,and the changing rules of the porosity,the number of void,average void diameter,the connected porosity are analyzed.The rule of the influence on esoscopic parameters under is explored.The sensitivity of mesoscopic parameters is compared,and the parameter which is the most sensitive is determined.The sensitivity of each parameter is compared through variance analysis,and the sensitive and parameter which is easy to extract is determined.This parameter is selected as the correction factor for fatigue prediction model.Finally,based on the splitting strength index,the freeze-thaw damage is defined,and the relationship between freeze-thaw damage and the sensitive parameter is established.The freeze-thaw damage is considered as the impact factor to revise the existing fatigue equation.The prediction model which considers freeze-thaw damage fatigue are established.The freeze-thaw damage effect on the fatigue life is independent.The effects of freeze-thaw on fatigue performance are determined,and a new model is obtained,which provides support for further study on the multi-factors and multi-parameters model modification under freeze-thaw action.