Fatigue Damage Evolution Mechanism of Asphalt Binder Under Variable Stress Repeated Loading

Area of Science:

• Materials Science
• Civil Engineering
• Pavement Engineering

Background:

• Asphalt pavement fatigue damage occurs at the binder-aggregate interface or within the binder.
• Understanding asphalt fatigue response is vital for extending pavement service life.

Purpose of the Study:

• To refine asphalt fatigue evaluation systems by introducing a variable stress time sweep test.
• To analyze asphalt fatigue performance and life under variable stress conditions.

Main Methods:

• Variable stress fatigue tests were conducted on asphalt binders, altering stress amplitude.
• Rheological analysis was used to assess modulus recovery and damage.
• Fracture surface analysis examined the impact of high-stress loadings.
• Statistical analysis identified the
• exercise effect
• and its impact on fatigue life.

Main Results:

• Rheological analysis indicated asphalt binder modulus recovery after stress changes, suggesting damage recovery.
• Fracture surface analysis revealed that increased high-stress loadings led to a narrower edge flow zone and a flatter fracture surface.
• Statistical analysis demonstrated an
• exercise effect
• , which enhanced fatigue life in the second loading stage.
• Stress transitions were found to alter fatigue crack paths, deviating from Miner's linear criterion predictions.

Conclusions:

• The developed variable stress time sweep test accurately fits the fatigue life curve using a two-stage life model.
• The study affirms the applicability of the two-stage life model for evaluating variable stress fatigue tests in asphalt pavements.