Asphalt modification using acid treated waste oil fly ash

Abstract

Oil fly ash (OFA) is generated in large quantities from power generation plants through combustion of fuel oil. Waste OFA contains more than 80% carbon and can be used to improve asphalt performance. H2SO4 and HNO3 acids were used to functionalize OFA with carboxylic group (COOH) to improve its dispersion and chemical bonding with asphalt. Thermo gravimetric analysis (TGA), FTIR and combined SEM/EDS techniques were used to characterize as-received and treated OFA. Asphalt modification with treated OFA showed better results than that of untreated OFA. The treated OFA were blended with base asphalt and tested for rheological properties of pure and modified asphalt binders. OFA were used at 2–8% by weight of asphalt binder. Melt state rheology was investigated in ARES rheometer using temperature sweep, dynamic shear and steady shear rheological measurements. Incorporation of OFACOOH in the modified asphalt binders showed improvement in binder properties as investigated through steady and dynamic shear rheology. OFACOOH modification reduced temperature susceptibility of modified asphalt binder and increased the upper grading (performance) temperature. The rutting parameter G*/sinδ increased linearly with OFACOOH content of asphalt binder. Activation energy was found to decrease with OFACOOH content which indicated better resistance to low temperature cracking of the modified binder. Asphalt modification with treated OFA proved that acid treatment of OFA has enhanced the properties of asphalt mixes.