Evaluation of Bio-Rejuvenator and Compaction Conditions on Stiffness Modulus and Indirect Tensile Strength of Recycled Hot Mix Asphalt

This study focuses on the investigation of the effect of a reclaimed asphalt material (RAP) and a bio-rejuvenator (mix of vegetable oils) on the stiffness modulus and indirect tensile strength (ITS) values of eight bituminous mixtures produced by using three types of compaction, with different RAP amounts (25% and 50%) and rejuvenator (0%, 0.20%, 0.40% and 0.60% by mass of RAP). A conventional hot mix asphalt was considered as the reference mix. All tests were performed on cylindrical samples produced using: Marshall compaction with 50 blows/side, cored cylindrical specimens from slabs compacted using a roller compactor (39 passes), and, respectively, gyratory compaction on 80 gyrations. Stiffness modulus and ITS values showed strong linear variation with the increase in rejuvenator content, independently of test temperature and type of compaction. The rejuvenating effect of the bio-rejuvenator was observed to counterbalance the impact of RAP. The results at 20 degrees C for gyratory specimens for the mix with 50% RAP and 0.40% bio-rejuvenator were comparable/closer (under 5% relative difference) to those obtained for the reference mix. A strong correlation between stiffness modulus values of mixes and penetration values of the corresponding binder blends was obtained (R2 >= 0.977).