Abstract
The interfacial adhesion between asphalt and steel slag aggregate is a decisive factor in the formation of an asphalt–steel slag mixture and significantly affects the quality stability of steel slag–asphalt mixtures. In this study, the adhesion between an asphalt and steel slag aggregate, the interfacial microstructure, the adsorption and desorption characteristics, and chemical reactions were, respectively, explored by a PosiTestAT–A adhesion puller, a scanning electron microscope, a net adsorption test, an infrared spectrometer, and a dynamic shear rheometer. The mechanism of adhesion between the asphalt and steel slag aggregate was analyzed from the perspectives of physical adsorption and chemical reactions. The results showed that different factors had different effects on the adhesion of asphalt–steel slag aggregate interface. The freeze–thaw cycle and steel slag aggregate particle size had significant effects on interfacial adhesion, while the asphalt heating temperature, water bath time, and stirring time had relatively weak effects on interfacial adhesion. Compared to a limestone aggregate, the steel slag–asphalt mixture had greater adhesion and better adhesion performance because the pits and textures on the surface of the steel slag aggregate produced a skeleton–like effect that strengthened the phase strength of the asphalt–slag aggregate interface, thereby improving the adhesion and increasing the physical adsorption between the asphalt and steel slag aggregate. In addition, due to the N–H stretching vibrations of the amines and amides, as well as SiO–H stretching vibrations, a chemical reaction occurred between the asphalt and steel slag aggregate, thus improving the adhesion performance between the asphalt and steel slag. Based on the shape of the adsorption isotherm, it was determined that the adsorption type was multi–molecular layer adsorption, indicating that the adhesion between the asphalt and steel slag mainly involved physical adsorption.
Highlights
The interactions between asphalt and the steel slag aggregate are important in the formation of an asphalt mixture’s structure and are directly related to the strength, temperature stability, water stability, and aging speed of an asphalt mixture [1,2,3,4,5]
The adhesion of asphalt mixtures increases with an increase in asphalt grade
Other researchers have indicated that the angularity coefficient and fractal dimension of the surface texture of a steel slag aggregate have a linear positive correlation with the phase strength of the asphalt–aggregate interface
Summary
The interactions between asphalt and the steel slag aggregate are important in the formation of an asphalt mixture’s structure and are directly related to the strength, temperature stability, water stability, and aging speed of an asphalt mixture [1,2,3,4,5]. Other researchers have indicated that the angularity coefficient and fractal dimension of the surface texture of a steel slag aggregate have a linear positive correlation with the phase strength of the asphalt–aggregate interface. Williams [22] analyzed the peeling of asphalt from its aggregate surface in an asphalt mixture with a scanning electron microscope after a freeze–thaw cycle test. In this study, the adhesion between the asphalt and steel slag aggregate, the interface microstructure, the adsorption and desorption characteristics, and chemical actions were, respectively, explored using a PosiTestAT–A adhesion puller, a scanning electron microscope, a net adsorption test, and an infrared spectrometer [24,25,26]
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