The effect of runoff acidity on fatigue cracking of hot mix asphalt using thermodynamic concepts

This study examined the fatigue performance of hot mix asphalt (HMA) under the influence of runoffs entering the pavement with different acidity degrees. Based on the fatigue test results, changing the runoff acidity and increasing the temperature decreased the number of cycles leading to HMA fracture (fatigue life) and accelerated the damage. The results of the surface free energy (SFE) method were aligned with the fatigue test results, indicating that changing the runoff acidity increased the bitumen-water adhesion SFE, aggregate-water adhesion SFE, and bitumen-aggregate debonding SFE. These changes diminished the fatigue cracking resistance of HMA. According to the Pull-Off test results, altering the runoff acidity and increasing the temperature reduced the adhesion and cohesion strength. According to the two principal factors in fatigue cracking (fracture adhesion and cohesion), the reduced fatigue life of the samples due to variations in the runoff acidity and temperature increase was acceptable according to the SFE and Pull-Off test results. The independent samples t test revealed that changing the runoff acidity led to a significant decline in the asphalt samples' performance parameters compared to neutral conditions.