Effect of emulsifier on the interface structure and performance of reclaimed asphalt pavement aggregate cement concrete

Road material recycling could be achieved by addressing low substitution and poor performance of reclaimed asphalt pavement (RAP) aggregate. The influences of emulsifier contents and treatment temperatures on the mechanical performance of RAP aggregate concrete were investigated in the study. The effects of pretreatment methods on the surface free energy of RAP aggregate and the cement-asphalt interfacial bond were determined by sessile drop method and pull-out test. Concrete containing RAP aggregate was tested for impermeability using the electric flux method. Microstructure and structural characteristics of cement-asphalt interface in pretreated RAP aggregate concrete were evaluated by using SEM and EDS. The findings demonstrated a 14 % increase in cement-asphalt interfacial bond strength, a rise in cohesiveness, and an elevation of surface free energy of pretreated asphalt. Hydration products and asphalt were invaded and interlaced with each other inside concrete. Asphalt particles appeared in the hydration products, and the density of concrete could be increased. The concrete impermeability grade could improve, and the flexural tensile strength could increase by 15 %.