Three-Dimensional Meso-Structure-Based Model for Evaluating the Complex Permittivity of Asphalt Concrete.

Area of Science:

• Materials Science
• Civil Engineering
• Electromagnetics

Background:

• Microwave heating offers a novel approach for cold-season road maintenance.
• Asphalt pavement's thermal response to microwaves depends critically on its complex permittivity.
• Accurate complex permittivity data is essential for optimizing microwave heating applications.

Purpose of the Study:

• To develop and validate an innovative computational method for determining asphalt mixture complex permittivity.
• To investigate the influence of key physical parameters on complex permittivity.
• To analyze and modify classical dielectric models for asphalt mixtures.

Main Methods:

• Proposed a three-dimensional meso-scale heterogeneous structure model for complex permittivity calculation.
• Conducted experimental validation of the proposed computational approach.
• Performed computational analysis on the effects of porosity, void size, moisture, and aggregate gradation.
• Analyzed classical dielectric models and modified the Lichtenecker-Rother model.

Main Results:

• Complex permittivity is sensitive to porosity, void size, moisture content, and aggregate gradation.
• Real part of complex permittivity decreases with increased porosity.
• Imaginary part shows frequency-dependent changes, influenced by void size.
• Moisture content significantly increases both real and imaginary parts.
• Modified Brown model achieved high determination coefficients (R²=0.922 for real, R²=0.980 for imaginary parts).

Conclusions:

• The validated computational method accurately predicts asphalt complex permittivity.
• Understanding parameter effects allows for optimized microwave heating strategies.
• The modified dielectric model enhances prediction accuracy for asphalt mixtures under various conditions.
• This research provides valuable insights for transportation agencies implementing winter road maintenance using microwave technology.