Experimental Investigation And Numerical Analysis Of PET On Properties Of Asphalt Mixtures For Railways

The asphaltic track structure is superior to the track structure using traditional granular material sub-ballast in dealing with track deformation,subgrade settlement and maintenance costs.Equally important,it effectively balances ballasted track performance and economic investment.However,the cracking and durability of typical dense-graded asphalt mixtures(DGA)are two issues that need to be addressed in the asphaltic track structure.On the other hand,stone mastic asphalt(SMA)outperforms DGA in terms of crack resistance and durability,but the increased cost caused by the high asphalt binder content in SMA limits its large-scale application.Based on this,in this thesis,recycled polyethylene terephthalate(PET)plastic waste was used to replace a portion of the asphalt binder in the SMA mixture,and the effect of PET substitution rate on the performance of SMA was studied.Additionally,the influence of SMA with PET on the structural response of the track was studied.The main contents and key findings of the thesis are as follows;(1)The effect of PET replacing part of asphalt binder in SMA on the performance of SMA was studied experimentally.When the amount of PETsubstituting asphalt binder is not more than 10%,the stability and fluidity of the SMA mixture are not affected.The results of the temperature and moisture sensitivity test,dynamic modulus test and repeated indirect tensile test show that the SMA mixture with a 10% content of PET has good performance,the TSR value is 84.8%,and the number of tensile failure cycles is more than 12,000 times,indicating that the mixture has good fatigue resistance and less susceptible to water damage.(2)The effect of SMA on the structural response parameters of ballasted track under PET substituting the portion of asphalt binder is studied by numerical analysis and calculation.When the mass ratio of PET to replace asphalt is 10%,the calculation of parameters such as track deformation,subgrade settlement,subgrade compressive stress,and asphalt tensile strain shows that the mixture of SMA and PET can be used as an alternative to DGA and can improve the service life of the ballasted track.(3)Formulated charts that can guide the design process of the asphalt mixture ballast tracks.Using these charts can more accurately predict and quantify the necessary parameters of the load repetition required before the subgrade and asphalt layer fails,namely the subgrade stress and the asphalt tensile strain values.This thesis contains 61 figures,22 tables and is well documented by 100 references...