The combined effects of magnesium chloride (MgCl2) deicer and freeze-thaw (F-T) accelerate the progression of moisture-induced damage in asphalt pavements. A multiscale approach was employed to evaluate adhesion and debonding mechanisms in systems of a polymer-modified asphalt binder and different aggregates subjected to various concentrations of aqueous MgCl2 solutions and F-T cycles. Pull-off tests conducted on binder-aggregate samples revealed that the pull-off strength and failure mechanism were affected by the salt concentrations and aggregates’ mineralogies. Investigating the adhesion and debonding using the surface free energy, a thermodynamic approach, showed that depending on the aggregate type, lower salt concentrations could accelerate adhesion decay at a higher rate compared to higher salt concentrations. Atomic force microscopy study revealed that salt concentration and F-T cycles significantly affected the microstructure, morphology, and micromechanical characteristics of the asphalt binder, contributing to an accelerated loss of adhesion in asphalt binder-aggregate systems.
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