Study on the effect of using reclaimed asphalt pavement and rejuvenator on the fracture behavior of warm mix asphalt

Asphalt recycling or, in other words, reuse of pavement is one of the latest technologies in the field of road construction that is now more accepted than other pavement construction methods. In addition to better environmental protection, this technology results in significant cost savings. Still, one of the major concerns of its use is the creation of undesirable properties in asphalt mix, such as bitumen aging and reduced cracking resistance. The use of rejuvenation agent and WMA (warm mix asphalt) additive are of the solutions to improve the performance of asphalt mixers containing RAP (reclaimed asphalt pavement) materials. Hence, in this research, in order to evaluate the effect of using RAP on the fracture resistance of WMA mixtures, the RAP materials with two dosages of 25% and 50%, one type of rejuvenation agent and Sasobit, as a WMA additive, were employed. To study the fracture resistance of the mixtures at the temperatures of -15 C and 25 C under mode I loading, semi-circular bending test was selected, and different fracture parameters including critical fracture load, fracture energy, flexibility index, cracking resistance index and fracture toughness were calculated. The results exhibited that the addition of RAP material to the mixture had negative effect on the fracture parameters at different temperatures, and resulted in the reduction of these parameters. While, the mixtures containing rejuvenator showed more elastic behavior than those without rejuvenator. Therefore, the use of rejuvenator led to the improvement of the fracture parameters.