Valorization of petroleum sludge as rejuvenator for recycled asphalt binder and mixture

The production of new pavements involving recycled asphalt pavement (RAP) is beneficial for preserving petroleum asphalt and natural aggregates. However, increasing the RAP content raises performance concerns in new pavement, thus necessitating the use of rejuvenators. This research examined the potential of using petroleum sludge (PS) as a rejuvenator for RAP recycling. Gas chromatography-mass spectrometry (GCMS) detected the PS hydrocarbons involved in rejuvenation. The dynamic shear rheometer (DSR) provided the rheological data of rejuvenated binders. The rheological data were subsequently processed using response surface methodology (RSM) to develop rutting and fatigue models. RSM was also employed to model the Marshall and volumetric properties of the asphalt mixture. Atomic force microscopy (AFM) of PS rejuvenated RAP binder revealed a new microstructure containing protrusions that resembled the morphology of lightweight bitumen fractions. These rejuvenating effects were attributed to lightweight hydrocarbons of PS, which supplement the maltenes fractions in aged asphalt. The multi-objective optimization provided the RAP and bitumen content of 90% and 4.79% to meet the required PWD specifications.