Abstract
The interface between an asphalt binder and a calcium silicate hydrate (C-S-H) gel is a weak point of semi-flexible pavement material. In this study, the adhesion performance of asphalt-C-S-H gel interface in semi-flexible pavements at a molecular scale has been investigated. Molecular dynamics (MD) simulations were applied to establish three asphalt binders: 70# asphalt binder (the penetration is 70 mm), PG76-22 modified asphalt binder (a kind of asphalt binder that can adapt to the highest temperature of 76 °C and the lowest temperature of −22 °C), and S-HV asphalt binder (super high viscosity). The effects of different temperatures and SBS modifier contents on interfacial adhesion were explored. The obtained results showed that temperature variations had little effect on the adhesion work of the asphalt-C-S-H gel interface. It was also found that by increasing the content of SBS modifier, the adhesion work of the asphalt-C-S-H gel interface was increased. The molecular weight of each component was found to be an important factor affecting its molecular diffusion rate. The addition of SBS modifier could regulate the adsorption of aromatics by C-S-H gel in the four components of asphalt binder and improve the adsorption of resins by C-S-H gel.
Highlights
The addition of SBS modifier could regulate the adsorption of aromatics by calcium silicate hydrate (C-S-H) gel in the four components of asphalt binder and improve the adsorption of resins by C-S-H gel
C-S-H gel model established in this study proved to be more reasonable and could be applied for subsequent Molecular dynamics (MD) simulations
Regarding different bitumen types at the same temperature, the order of adhesion work was 70# asphalt < PG76-22 modified asphalt < S-HV modified asphalt, which was because the SBS modifier content affected adhesion such that higher SBS modifier contents resulted in greater adhesion between the asphalt and C-S-H gel
Summary
Methods properties of and asphalt binders and asphalt aging [22,23,24,25,26,27]. In this study, MD was applied to establish 70# asphalt-C-S-H gel, PG76-22 modified. Using this four-component asphalt model, researchers haveAsphalt evaluated the compatibility of asphalt and modifiers, adhesion between asphalt has very complex chemical compositions with athe variety of hydrocarbons and and aggregate, and the effect of oxidative aging on asphalt binders [29,30,31,32]. In this retheir non-metallic derivatives (a mixture of hydrocarbons and non-hydrocarbons). In order to obtain a reasonable four-component asphalt model, initial density was set to 1 g/cm and pre-equilibrium operation of 100ps was carried out under NPT ensemble (temperature and pressure were set to 298K and 1 atm, respectively).
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