Abstract
Moisture-induced damage due to stripping is one of the major concerns to the highway agencies in recent years. In this study, nanoscopic investigations were carried out to examine the effects of moisture in asphalt binders. An Atomic Force Microscope (AFM) was used to estimate the asphalt binder’s modulus and adhesion values, which were believed to be indicators of binder’s resistance to moisture damage. To this end, two Performance Grade (PG) binders and their modified counterparts using polyphosphoric acid (PPA), styrene-butadiene-styrene (SBS), and SBS plus PPA were tested in this study. Test results show significant reductions of adhesion and modulus values after water immersion of the asphalt binders. AFM data also reveals that SBS-modified binders exhibit better moisture resistance compared to the base binder. Findings of this study are expected to help transportation professionals to achieve a better understanding of moisture damage of asphalt binders at a molecular level and their suitability in pavements.
Highlights
Moisture damage is one of the distresses that prematurely deteriorates asphalt pavements
Previous studies concluded that resistance against moisture damage of asphalt mixtures depends on the adhesive bond strength of the asphalt binder-aggregate system in dry and wet conditions [3, 4]
This research aims at estimating the moisture damage of asphalt materials based on adhesion and modulus values obtained through the Atomic Force Microscope (AFM) tests methods
Summary
Moisture damage is one of the distresses that prematurely deteriorates asphalt pavements. Moisture damage can be defined as the loss of strength or stiffness due to the mechanical loading in the presence of moisture, and this phenomenon is known as stripping [1]. It has been found that moisture can accelerate damage in asphalt pavements as a combined effect of other types of distress [5]. Current laboratory test methods such as Tensile Strength Ratio, Immersion Marshall, and Hamburg Wheel Tracking are empirical in nature These macro-level tests focus only on the overall strength of a specimen without providing any result that describes the moisture damage phenomenon in the asphalt mixtures [2]. It is necessary to develop an effective and advanced tool to investigate and quantify the moisture susceptibility of asphalt materials at the atomic level
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