Research On Degradation Regularity Of Rubber Powder In Asphalt

The application of polymer modified asphalt is more and more widely,rubber asphalt has gradually been taken seriously,the performance of rubber asphalt is affected by powder degradation degree,dispersion status and other factors.However,the degradation law and modification mechanism of the powder in the asphalt have not yet formed a unified understanding.In this paper,three kinds asphalt were used to analyze the degradation of the powder in the asphalt by analyzing the change of the viscosity and the solubility in the degradation process.The gel permeation chromatography and the infrared absorption spectroscopy were used to explore the modification mechanism of the modified Asphalt.The viscosity of the rubber asphalt during the degradation was found to be increasing first,then decreasing and then increasing again when the experimental temperature was first-level,When the experimental temperature was second-level and third-level,the viscosity of the rubber asphalt showed a first decrease,then increase.This is because the rubber swelling process makes the viscosity increases,the degradation process makes the viscosity decreases,the asphalt phase of the aging process makes the viscosity increases.Temperature higher,the reaction speed faster,the swelling process is not reflected.By studying the conversion rate of the powder,it can be found that the longer the development time,the deeper the degradation degree and the higher the solubility.Under the same conditions,the higher the experimental temperature,the greater the solubility,and the higher the light component content in the matrix asphalt,the greater the solubility.The content of large molecule size(LMS)increases first and then decreases,while the content of medial molecule size(MMS)and small molecule size(SMS)decreases and then increases.This is due to the degradation of polymer powder produces polymer macromolecules so that the LMS content increases,the MMS and SMS content decreases,while the macromolecule?s decomposition makes the LMS content decreases,the MMS and SMS content increases.The experimental temperature and the type of asphalt have no effect on the change of molecular weight distribution,but the higher the asphaltene content,the higher MMS content.By analyzing the infrared absorption spectrum of rubber asphalt,we can see that the rubber asphalt contains methyl,methylene,double bond,hydroxyl,carbonyl and other functional groups,the longer the development time,the higher content of the double bonds and hydroxyl,indicating that the more powder degradation products.The higher the temperature,the higher the solubility of the powder,the more obvious the absorption peak in the infrared absorption spectrum.The more light components in the matrix asphalt,the more obvious the absorption peak.By analyzing the fluorescence microscopy of rubber asphalt,it can be seen that the powder particles are dispersed in the asphalt by the rod-like structure.The longer the development time,the smaller the particles and the more loose the dispersion.Under the same conditions,the higher the experimental temperature,the more the lighter component content in the matrix asphalt,the better the dispersion of the powder.