Effect of Aggregate Type on Asphalt-Aggregate Adhesion and Its Quantitative Characterization

Area of Science:

• Materials Science
• Civil Engineering
• Geology

Background:

• Asphalt-aggregate adhesion is critical for pavement performance and longevity.
• Understanding the influence of aggregate mineralogy on adhesion is essential for optimizing asphalt mix designs.
• Existing methods for evaluating asphalt-aggregate interaction may not fully capture complex behaviors like flaking.

Purpose of the Study:

• To investigate the effect of different aggregate types (limestone, basalt, diabase) on asphalt adhesion.
• To quantitatively analyze the adhesion work and flaking behavior of asphalt on various aggregates.
• To establish a relationship between aggregate mineral composition and asphalt-aggregate bonding.

Main Methods:

• X-ray diffraction (XRD) for aggregate mineral phase composition analysis.
• Surface energy theory to calculate adhesion work and work of flaking.
• Modified water boiling method coupled with image processing for quantitative flaking assessment.
• Contact angle measurements to evaluate aggregate-asphalt wettability.

Main Results:

• Aggregate type is a key factor influencing asphalt-aggregate adhesion.
• Limestone, rich in calcium carbonate (CaCO3), demonstrated the strongest adhesion due to its alkaline nature.
• Adhesion strength followed the order: limestone > basalt > diabase.
• Image processing provided effective quantitative characterization of asphalt flaking.

Conclusions:

• The mineral composition and surface properties of aggregates significantly dictate asphalt adhesion.
• Limestone's alkaline nature promotes superior asphalt bonding, enhancing pavement durability.
• The modified water boiling method with image analysis is a reliable technique for quantifying asphalt-aggregate adhesion and flaking behavior.