Assessing the fatigue performance of buton rock asphalt modified mixtures

Abstract

The main objective of this research was to assess the effect of granular Buton Rock Asphalt (BRA) modifier binder on the fatigue life of asphalt mixtures. This involved the laboratory evaluation of fatigue strength on four-point bending equipment under repeated flexural bending test in accordance with Austroads AG: PT/T233. The beam test under the controlled-strain mode of loading was applied for a dense grading of 10 mm of unmodified and BRA modified asphalt mixtures at 20°C test temperature, three different peak tensile strain including 400, 600, and 800 µe, 10 Hz loading frequency, continuous haversine mode of loading, and 5% air void content. The results showed the number of cycles for BRA modified asphalt mixtures increased from 2.0 to 2.4 and 1.6 to 2.1 as observed with the classical and energy stiffness ratio approaches, respectively. According to the strain approach, the number of cycles to failure for BRA modified asphalt mixtures was higher when compared with unmodified ones. Meanwhile, the strain-stiffness approach showed the initial flexural stiffness (S0) affected the fatigue life for both mixtures. Furthermore, the regression equations model to predict the fatigue life based on the strain and strain-mix stiffness approaches were developed. It was discovered that using BRA modifier binder in asphalt mixtures had a significant effect on the relationship between intercept (k1) and slope (k2) variables while the damage rate was lower compared to the unmodified asphalt mixtures.