Effects of WMA additives and hydrated lime on high-stress and high-temperature performance of Elvaloy®- and PPA-modified asphalt binder

Addition of Poly Phosphoric Acid (PPA) and polymer modifiers such as Elvaloy (R) found to improve the rheological performance of asphalt binders. However, such modification has also shown an increase in mixing and compaction temperature. Use of Warm Mix Asphalt (WMA) additives has shown a reduction in construction temperature, hence making such modification environmentally sustainable. Therefore, a control binder (an AC-30 asphalt binder modified with PPA and Elvaloy (R)) was modified using three different types of WMA additives: Sasobit (R), Evotherm (R) and Advera (R). In addition, considering moisture susceptibility of WMA-modified control binders additives, hydrated lime was further added to asphalt binder combinations. The current study involves the performance evaluation of different asphalt binder combinations using (a) Superpave rutting parameter, (b) time-temperature superposition data of complex modulus over a wide range of frequency and (c) multiple stress creep recovery test with application of different stress levels (0.1, 3.2, 6.4, 12.8 and 25.6 kPa). The addition of Sasobit (R) observed to enhance stiffness, rut resistant and recovery characteristics, whereas, Advera (R) and Evotherm (R) addition led to degrade the stiffness, rut resistant and recovery characteristics of a control binder. HL addition to control binder and control binder containing Advera (R) were observed to have an undesirable effect on rutting resistive performance. However, HL addition to control binder containing Evotherm (R) and Sasobit (R) showed improvement in rutting resistivity potential. Overall, high stress levels observed to have a significant effect on all asphalt binder combinations; hence, consideration of higher stresses can play a vital role in binder selection process.