Effect of Evaporation Methods on Modified Emulsified Asphalt Residues from Rheological and Chemical Characteristics

Abstract

Accurately evaluating and characterizing the performance of emulsified asphalt is the basis of its application. The rheological properties of modified emulsified asphalt residues and its material action mechanism were studied. To achieve this goal, styrene butadiene styrene (SBS)- and styrene butadiene rubber (SBR)-modified emulsified asphalt were prepared, and modified emulsified asphalt residues were prepared by the direct heating method (DHM) and two low-temperature evaporation methods (EN13074 and ASTM D7497-09). Then, the rheological properties and fatigue resistance of the modified emulsified asphalt residues were characterized through dynamic shear rheometry tests. Finally, Fourier transform infrared spectroscopy and elemental analysis were conducted to monitor the curing behavior of modified emulsified asphalt residues. The results indicated that the incorporation of SBS and SBR latex into emulsified asphalt significantly improved its viscoelastic properties, high-temperature properties, and fatigue life, and reduced its temperature sensitivity. Under different evaporation conditions, the unmodified emulsified asphalt residues and SBS-modified emulsified asphalt residues obtained by the ASTM D7497-09 evaporation method had the best rutting resistance and recovery percentage, followed by the emulsified asphalt residues obtained by EN13074 and DHM. However, the rutting resistance of SBR-modified emulsified asphalt residues was not greatly affected by the evaporation method. Though prepared with different evaporation methods, unmodified emulsified asphalt residues had similar fatigue life, and the fatigue life of modified emulsified asphalt residues were ranked as Nf (ASTM D7497-09) >Nf (EN13074) >Nf (DHM). The emulsified asphalt residues obtained by DHM and EN13074 still contain moisture, and it is recommended to use the ASTM D7497-09 evaporation method to obtain emulsified asphalt residues for performance evaluation.