Rheological properties and regeneration mechanisms of aged bitumen recycled from two-step chemical modification of used edible oil (UEO) with high acid value

Document Type

Article

Publication Date

1-10-2025

Abstract

The acid value of used edible oil (UEO) affects its regenerative capacity. Modification of UEOs to reduce their acidic compound content is receiving extensive attention. However, there have been fewer investigations on the rheological performance of modified UEO reclaimed asphalt binders and their regeneration mechanism. Therefore, a two-step catalytic process was first conducted on UEO with high acid value to minimize its free fatty acid content. Apparent viscosity, oscillation, multiple stress creep recovery, linear amplitude sweep, and bending beam rheometer experiments were carried out to survey the influence of modified UEO on the rheological properties of aged binders. In addition, the chemical components, functional groups, molecular weights, and their distributions of the rejuvenator and various binders were characterized by thin-layer chromatography, gas chromatography-mass spectrometry, infrared spectroscopy, and gel chromatography analyses to reveal the regeneration mechanism of modified UEO. The results demonstrated that modified UEO can restore the rheological properties of the aged binder. The high-temperature performance of aged binders gradually decreased with the addition of modified UEO, but the rutting resistance of rejuvenated binders was acceptable. In addition, rejuvenated binders exhibited better low-temperature performance and fatigue resistance. Chemical analyses showed that modified UEO was rich in methyl esters. The modified UEO improved the homogeneity of the aged binder, restored its colloidal structure, and reduced the sulfoxide and carbonyl indices. Moreover, there was no chemical reaction during rejuvenation. Overall, using modified UEO as an asphalt rejuvenator realizes the utilization of both wastes.

Publication Title

Construction and Building Materials

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