Fatigue performance of Buton rock asphalt modified mixtures

The main objective of this research is to assess the effect of granular Buton rock asphalt (BRA) modifier binder on the fatigue life of asphalt mixtures. Laboratory evaluation method of fatigue strength on four point bending equipment under repeated flexural bending test was done 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 the conditions: test temperature of 20°C, three different peak tensile strain (400, 600 and 800 µe), loading frequency of 10 Hz, mode of loading of continuous haversine, and air void content of 5%. It is shown that the number of cycles for BRA modified asphalt mixtures increased by 2.0-2.4, and 1.6-2.1 observed by the using 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 asphalt mixtures. Based on the strain-stiffness approach, the initial flexural stiffness (S0) affected the fatigue life of unmodified and BRA modified asphalt mixtures. Furthermore, the regression equations model used to predict the fatigue life of unmodified and BRA modified asphalt mixtures based on the strain approach and strain-mix stiffness approach were developed. The use of BRA modifier binder in asphalt mixtures had a significant effect on the relationship between intercept (k1) and slope (k2) variables. The damage rate for BRA modified asphalt mixtures was lower compared with the unmodified asphalt mixtures.