Study On The Performance Of Modified Asphalt Mixture In The Alpine Region

The asphalt mixture pavement occupies a considerable proportion with the rapid development of Chinese highways.However,the asphalt pavement is prone to appear low temperature deformation cracks in winter and ruts in summer due to extremely high or very low temperatures.Therefore,it is crucial to study the high and low temperature performance of an asphalt mixture.Currently commonly used SBS modified asphalt exists many problems such as complex preparation,storage and transportation,and high cost and energy consumption.In view of the above problems,combined with the actual environment in the alpine region,we should explore a simple and fast modification method that can achieve both green and low-carbon development and ensure the quality of the mixture under the premise of construction.In this thesis,asphalt mixtures with direct-throw modifier LM-S were studied.High temperature performance of mixtures at different temperatures and loads is analyzed by high temperature triaxial repetitive creep test;The low temperature performance of the mixture under different freeze-thaw cycle conditions was analyzed by low temperature bending creep test.Obtained the creep deformation curve of 110# asphalt mixture and LM-S modified asphalt mixture by using the triaxial repetitive creep test.Then analyze the influence of temperature and load conditions on the high temperature deformation of the two asphalt mixtures.Last,the creep curves of the 110# asphalt mixture and the LM-S modified asphalt mixture under two factor conditions were fitted to obtain the high-temperature viscoelastic parameters by using the four-element and five-parameter viscoelastic mechanical model,and then the high-temperature stability of the two asphalt mixtures was analyzed from the perspective of viscoelasticity.The results show that the temperature has a great influence on the LM-S modified asphalt,the LM-S modified asphalt mixture is more resistant to loads at 40℃,and 110# asphalt mixture is more resistant to loads at 60℃.The two steps secant slope method was proposed.The data of each group of the high-temperature triaxial repetitive creep test in this study were calculated for the rheological times,and the ability of the LM-S modified asphalt mixture to resist the load at 40℃ was further analyzed.The data analysis of the creep rate of the low temperature bending creep test of two asphalt mixtures with different freeze-thaw times was analyzed linearly,and further analyzed by the four-element and five-parameter viscoelastic mechanical model,the parameters of the model were fitted,and the low temperature performance indicators were analyzed.The results show that the increase in the number of freeze-thaw cycles will seriously reduce the low temperature performance of the asphalt mixture,but the low temperature crack resistance of the asphalt mixture with LM-S modifier is better.And stress relaxation time τ and dissipation energy ratio can be a comprehensive analysis of the change of low temperature performance of asphalt mixture under freeze-thaw cycle.The results indicate that an increase in the number of freeze-thaw cycles will seriously reduce the low-temperature performance of asphalt mixtures.There is no significant difference in low-temperature performance between the two types of asphalt mixtures during 0-15 freeze-thaw cycles.After 20 freeze-thaw cycles,the asphalt mixture with LM-S modifier has better low-temperature crack resistance performance.The four-unit five-parameter model was improved and the high and low temperature performance test data under certain conditions were unified and analyzed,and it was obtained that the viscous flow strain of the asphalt mixture has a good linear correlation with the total strain of the asphalt mixture.It is also shown that the model can simultaneously characterize the high-temperature performance and low-temperature performance of the asphalt mixture to a certain extent.