Oil extracts from spent coffee grounds and waste cooking oil to modify the physical properties of recycled asphalt binder -

Abstract

Interest in recycling has been on the rise in the past decades accompanied with research for sustainable practices to mitigate the negative impact of various wastes on the environment. Accordingly, this study explores the use of spent coffee grounds (SCG) and waste cooking oil (WCO) as rejuvenators for reclaimed asphalt pavements (RAP). The food wastes, SCG and WCO, were collected from local catering establishments and used either as is or after further oxidation-modification. The extracted SCG oil and WCO were further oxidized by heating to 150oC accompanied by pumping air into the samples for 6, 9, 12, 24 and 48 hours. The oxidized oils were then physically and chemically characterized. Consequently, the modified oils were mixed at different percentages with PG 58-XX (unaged) and artificially aged PG 76-XX binders. The rheological properties of the blends were studied using dynamic shear testing and multiple stress creep and recovery testing according to ASTM and AASHTO standards. The addition of the oils to the asphalt binders restored the linear viscoelastic behavior of the binders which was lost during the artificial aging process. This addition has softened rejuvenated binder thus decreasing its high temperature PG grade. Finally, compared to the control unaged binder, oil-rejuvenated artificially aged asphalt shows higher strain recovery at low stress levels, i.e. showing lower susceptibility to permanent deformation.