چكيده به لاتين
Increased demand for transportation in the last two decades, budget constraints along with high costs of new pavement construction, and high costs of pavement maintenance courses have led road engineers to look for new solutions to reuse of destroyed pavement technology. The use of recycled asphalt pavement (RAP) as one of the ways to increase the efficiency of existing budget and capital in the field of maintenance and improvement of the road network, and on the other hand, saves costs and conserves natural resources. However, one of the main concerns of using it more is to create unwanted properties in asphalt mixtures such as bitumen aging and reduction of cracking resistance of asphalt mixtures. One way to improve the performance of asphalt mixes containing recycled materials is to use rejuvenators (recycling agents). However, the use of higher percentages of the high content of reclaimed asphalt pavements in hot mix asphalt (HMA) not only produces toxic gases and environmental pollutants but also increases the stiffness of the produced asphalt mixtures and leads to global warming. However, the use of warm mix asphalt (WMA) technology, by reducing the temperature of asphalt production, in addition to reducing environmental pollution and saving energy consumption, provides better conditions for workers in the workplace in terms of lower temperatures and fewer emissions. It also prevents bitumen from aging and hardening due to oxidation of bitumen by eliminating the secondary hardness of the asphalt mixture.
Therefore, in the present study, in order to evaluate the effect of rejuvenator and anti-stripping additives on warm mix asphalt (WMA) containing recycled asphalt pavement (RAP), three types of rejuvenators from different categories of rejuvenators including Aromatic extracts (R1), Triglycerides and fatty acids (R2) and Tall oils (R3) and from an amidoamine additive (PAWMA) as a WMA additive and from Zycotherm as an anti-stripping additive in asphalt mixtures containing 25% and 50% RAP are used. For this purpose, various mechanical tests such as dynamic creep test, resilient modulus (MR), indirect tension stress (ITS), semi-circular bending (SCB) were used. Also, by performing the contact angle test by sessile drop method and using the concept of surface free energy (SFE), the energy ratio parameters of bitumens were determined, and the effect of rejuvenating types on moisture sensitivity of recycled asphalt mixtures was evaluated. The obtained results indicate that the mechanical properties of asphalt mixtures containing rejuvenators depend on the type of rejuvenator used so that the use of Aromatic type rejuvenators and Tall oils has increased the resistance of asphalt mixtures to moisture sensitivity. Reduces asphalt against moisture sensitivity. The results also showed that, in general, the use of rejuvenator had reduced the amount of flow number and rutting resistance of asphalt mixtures. The results of the SCB test showed that the use of a rejuvenator increased the amount of ductility index of asphalt mixtures, which increased the amount of rejuvenator for triglycerides and fatty acids more than other recycling agents. Although the use of RAP and increasing the percentage of its use in asphalt mixtures reduces the value of flexibility index and cracking resistance index, but has increased their resistance to rutting and moisture susceptibility. The results also showed that the use of PAWMA and Zycotherm has a positive effect on the resistance to moisture susceptibility and has increased the amount of flow number and fracture energy of asphalt mixtures.
