عنوان مقاله [English]
Bitumen and mastic (mixture of bitumen and filler) are one of the components of asphalt mixtures, which have great influence on their behavior and performance. In recent years, many studies have been carried out on the evaluation of rheological properties of bitumen. In the present study, rheological properties of bitumen and mastic modified with warm mix asphalt additive (Sasobit) have been evaluated. The neat bitumen had a performance grade of PG64-16 that was modified with 1.5% by weight of bitumen using Sasobit additive. To prepare the mastic, siliceous riverrine filler was added with equal ratio to the bitumen. The superpave experiments for bitumen using dynamic shear rheometer and bending beam rheometer were carried out on base and modified bitumen and mastic. The fatigue and rutting parameters of the materials were determined and compared and master curve of the materials was created for general presentation of the rheological behavior of bitumen and mastic. Results indicated that Sasobit significantly increased the bitumen and mastic dynamic modulus (up to 60 and 100 %, respectively) at high temperatures, and reduced their phase angle by 5%. Sasobit has doubled the rutting parameter of bitumen and mastic. The fatigue parameter in pure bitumen did not change significantly with addition of the Sasobit, while Sasobit increased the fatigue parameter in mastic (20-30 %) and reduced fatigue resistance. The master curve model was well-fitted on experimental bitumen and mastic data modified with Sasobit, which allows comprehensive examination of the material behavior over a wide range of temperature and frequency.