Study On The Performance Of Cement Emulsified Asphalt Binder And The Mix Proportion Design Method Of Mixture

The traffic opening time is delayed and late strength of emulsified asphalt mixture is also not ideal due to the low initial strength,poor temperature stability and large void ratio of emulsified asphalt mixture.To solve this problem,a new semi-flexible pavement material-cement emulsion asphalt mixture came into being.This article is based on comprehensive research at home and abroad,the macroscopic and microscopic properties of cement emulsified asphalt binder were studied through laboratory tests.Finally,the mix proportion design of the mixture is carried out on the basis of the performance of the cement emulsified asphalt mixture.Firstly,the optimum emulsified asphalt preparation scheme was determined based on the storage stability of emulsified asphalt and performance of three indicators for evaporation residue.Secondly,Through the DSR test results of cement emulsified asphalt binder found high temperature performance was related to curing period of the specimen.Moreover,the high temperature performance of cement emulsified asphalt binder has been greatly improved from one day to three day,however,after three day,the lifting range basically tends to be stable.The results of DSR and BBR tests for cement emulsified asphalt binder at 7d curing age showed that with the increase of cement content,the high temperature performance of cement emulsified asphalt binder became better,and the low temperature performance and fatigue performance became worse.Nextly,generation of cement emulsified asphalt binder was studied by Fourier transform infrared spectrometer(FTIR).It was found that the blend of cement and emulsified asphalt was only physically blended.By scanning electron microscopy(SEM),Microstructure of cement emulsified asphalt binder was observed.The results showed that the density of cement emulsified asphalt binder was closely related to curing period,and the surface morphology of cement emulsified asphalt binder became more dense with the increase of curing age.Moreover,the hydration products of cement was interwoven and form a network structure with the asphalt film.The melting zone of cement emulsified asphalt binder was tested by differential scanning calorimetry(DSC).It was found that the DSC absorption curve of emulsified asphalt residue was smooth and flat.Moreover,the obvious endothermic peak appeared after the addition of cement,and cement improved the thermal stability of cement emulsified asphalt binder obviously.Subsequently,mortar-to-aggregate interface zone structure of cement emulsified asphalt concrete was studied by SEM.The mortar-to-aggregate interface spacing of cement emulsified asphalt concrete was larger,and structural compactness of cement emulsified asphalt concrete was poor.However,compared with emulsified asphalt concrete,the interface spacing between mortar and aggregate of cement emulsified asphalt concrete decreases,and the structure was relatively compact.Finally,through orthogonal test,the optimum mix ratio of cement emulsified asphalt mixture was obtained by synthesizing the performance of various aspects,and the balance of road performance was realized.