Study on Water Damage of Asphalt-Aggregate Based on Molecular Dynamics

Area of Science:

• Materials Science
• Chemical Engineering
• Geotechnical Engineering

Background:

• Water damage at the emulsified asphalt-aggregate interface is a critical issue in pavement durability.
• Understanding the molecular interactions governing adhesion and failure is essential for improving asphalt mixture performance.

Purpose of the Study:

• To investigate the mechanisms of water damage at the emulsified asphalt-aggregate interface.
• To quantify the adhesion properties and failure modes under varying water content using molecular dynamics simulations.

Main Methods:

• Preparation and characterization of emulsified asphalt using cetyltrimethylammonium bromide.
• Construction of molecular dynamics models for emulsified asphalt-aggregate interfaces with different water contents.
• Calculation of adhesion work and analysis of interfacial forces (van der Waals and electrostatic).

Main Results:

• Simulated properties of emulsified asphalt (density, cohesive energy density, solubility) closely matched experimental values.
• Adhesion force order with oxides was CaO > Al2O3 > SiO2, indicating better bonding with alkaline aggregates.
• Van der Waals forces were dominant in adhesion, followed by electrostatic forces.

Conclusions:

• Water enrichment at the interface is the primary cause of water damage in emulsified asphalt-aggregate systems.
• Alkaline aggregates exhibit superior bonding with emulsified asphalt compared to acidic aggregates.
• The study provides molecular-level insights into the failure mechanisms of asphalt pavements susceptible to water damage.