Study On Rheological Properties Of Evaporated Residue Of Emulsified Asphalt For Cold Recycling

Emulsified asphalt cold recycling mixture has the advantages of good pavement performance,low carbon,energy saving and environmental protection,and has become one of the most commonly used methods for asphalt pavement maintenance,repair and reinforcement.The performance of emulsified asphalt residues is closely related to the road performance during use,so it is used as the main quality control parameter in the production of emulsified asphalt.At present,the research on emulsified asphalt residues mainly focuses on the acquisition method and rheological properties.However,the differences between the properties of emulsified asphalt residues under different evaporation conditions and the changes in the microstructure and chemical composition of the residues during water evaporation are still unclear,which affects the accurate evaluation of the performance of emulsified asphalt residues.Based on rheological theory,the rheological characteristics of emulsified asphalt residues for cold recycling were analyzed in this paper.The microscopic characteristics of emulsified asphalt residues were studied by means of microscopic analysis methods.Combining the significance analysis method and grey entropy theory,the influencing factors of rheological properties of emulsified asphalt residues and the correlation between evaluation indexes were discussed.The main research results are as follows:1.The viscoelastic and anti-fatigue properties of emulsified asphalt residues were systematically studied by dynamic shear rheometer.The results showed that compared with the matrix asphalt,the emulsified asphalt residues had better high temperature deformation resistance and fatigue resistance,and the addition of modifiers can significantly improve the high temperature performance and fatigue resistance of ordinary emulsified asphalt residues.Under three different evaporation conditions,the high temperature performance and fatigue performance of the emulsified asphalt residues obtained by two low temperature evaporation methods of EN13074 and ASTM D7497-09 were better than those obtained by the direct heating method.2.The microstructure and chemical composition of emulsified asphalt residues were analyzed by scanning electron microscope,infrared spectroscopy and elemental analysis,and the microscopic characteristics of emulsified asphalt residues were explored.The results showed that during the evaporation process of emulsified asphalt,the distance between asphaltene particles widened and pore structure appeared due to the higher conversion rate of colloid than asphaltene.Under three different evaporation conditions,the emulsified asphalt residues suffered different degrees of thermal oxygen aging,the carbonyl functional group index and aromatic functional group index of the residues increased,the internal aromatic substances increased,the condensation degree deepened,and the cyclic structure was complex,which further led to the improvement of the high-temperature stability of the residues,and the decrease of the low-temperature performance.3.Different evaporation methods,emulsifier types and matrix asphalt have significant effects on the performance of emulsified asphalt residues.Rheological performance evaluation index rutting factors has good correlation with basic performance index and microscopic performance index,which can evaluate the performance of emulsified asphalt residues to a certain extent.