چكيده به لاتين
Studies in recent years demonstrated that Warm Mix Asphalt (WMA) technology is a practical solution to face the high production temperature of Rubberized-Asphalt (RA) mixtures. RA mixtures containing WMA additives are considered as environmentally friendly technology, which decreases energy and land consumption and control emissions during construction. Moreover, this combined technology lead to performance optimization of mixtures and tire-road noise reduction. This study aims to introduce two organic WMA additives, namely, Slack wax (SW) and Polypropylene wax (PPW) which are used to reduce the viscosity of RA mixtures at lower production temperature. Common bitumen tests including Penetration Degree, Softening point and Rotational Viscosity (RV), as well as tests related to mixtures including Resilient modulus (M_r), IDT Fatigue, Dynamic Creep, and moisture susceptibility (TSR and MRR methods), were carried out on both binder and mixture specimens. According to results, both WMA additives reduced mixing and compaction temperatures of control bitumen and CRM binder in about 20 to 25°C, by reducing the viscosity at high temperatures. Also, CRM and both WMA additives increased the value of M_r in mixtures. The value of Flow Number (FN) has increased by adding CRM and both WMA additives, which is an indication of better rutting performance in modified mixtures. In term of moisture susceptibility, based on TSR results, although, nearly all the specimens could pass the minimum requirement of SCDOT, both WMA additives and CRM caused a reduction in ITS of wet mixtures and final TSR value. The results of the MRR test depicted a similar pattern in reduction rates, however, M_r value showed more sensitivity to moisture compared to tensile strength. Furthermore, IDT fatigue results showed a different pattern for SW and PPW, in which, SW increased the fatigue life, while PPW decreased the value of N_f (the number of load cycles to fracture) for asphalt mixtures. Finally, it must be noted that, The PPW additive was more influential in comparison to SW in affecting properties of asphalt mixtures and binders.
