Investigation of fatigue and rutting performance of hot mix asphalt mixtures prepared by bentonite-modified bitumen

The objective of this study was to evaluate the fatigue and rutting performance of hot mix asphalt (HMA) mixtures prepared by bentonite-modified bitumen. As a modifier of bitumen, 10%, 15%, 20%, 25% and 30% bentonite (BT) content by weight of bitumen was used. Unmodified and modified asphalt binders were subjected to physical and conventional tests (penetration, softening point and ductility). In this research, performance tests, such as Marshall stability, resilient modulus, dynamic creep and wheel track tests, were conducted on the modified and unmodified mixtures. Also, the fatigue life of asphalt mixtures was evaluated through four-point bending test in strain-controlled mode at three microstrain levels (600–800–1000 lm/m) with sinusoidal loading. The fatigue life of mixtures has been evaluated based on the 50% reduction in the initial stiffness modulus. The results show that addition of BT improves the physical properties of bitumen and also can increase the rutting resistance and the shear strength of HMA. In addition, the fatigue life of asphalt mixtures prepared with bentonite-modified bitumen is longer than that of the conventional HMAs.