Characterization of Interface Transition Zone in Asphalt Mixture Using Mechanical and Microscopic Methods

Area of Science:

• Materials Science
• Civil Engineering
• Pavement Engineering

Background:

• The pavement sector faces increasing demand, necessitating cost-effective solutions.
• Assessing interface bonding in asphalt composites is vital for durability and economic efficiency.
• Understanding the interface transition zone (ITZ) is key to predicting asphalt mixture performance.

Purpose of the Study:

• To investigate the interface transition zone (ITZ) in various asphalt mixtures.
• To correlate micro-scopic and macro-scopic properties with pavement performance.
• To evaluate the effectiveness of a novel pull-off method for interface bonding strength assessment.

Main Methods:

• Microscopic analysis using fluorescence microscopy and scanning electron microscopy (SEM).
• Mechanical testing including rutting tests, semi-circular bending tests, and a novel pull-off test.
• Characterization of ITZ using gray value change law and bitumen penetration tests.

Main Results:

• Distinct ITZ characteristics were observed across different asphalt mixture groups (virgin, recycled, rejuvenator-modified).
• A strong correlation was found between ITZ morphology and macro-level performance (high/low temperature, bonding strength).
• The developed pull-off method proved reliable for assessing aggregate-bitumen bond strength.

Conclusions:

• Micro-scopic and macro-scopic analyses provide comprehensive insights into asphalt mixture quality.
• The novel pull-off test offers a viable alternative for evaluating interface bonding.
• This research contributes to optimizing asphalt pavement design and performance prediction.