Abstract
Epoxidized soybean oil (ESO) was employed as a novel penetrant cooperating with a conventional rejuvenator (CR) for the recycling of reclaimed asphalt pavement (RAP). The influence of ESO on the diffusibility and the regenerating effects of CR on RAP were investigated. The diffusibility testing result shows that the diffusibility of CR is enhanced by the addition of ESO because the epoxy group in ESO can facilitate asphaltene dispersion due to its high polarity, which simultaneously reduces the viscosity and improves the fluidity of aged bitumen so as to allow diffusion of the rejuvenator into the aged bitumen. Road performance testing of a recycled hot mix asphalt mixture (RHMA) indicates that the fatigue and cracking resistance properties as well as the water stability of RHMA containing CR can be improved by the addition of ESO due to the diffusibility enhancement of CR, which boosts the regenerating effect of CR on aged bitumen in RAP. The fatigue and cracking resistance properties as well as the water stability of the recycled hot mix asphalt mixture containing CR with 7 wt % ESO approximate those of the hot mix asphalt mixture composed of the same virgin aggregates and bitumen. Taking into account the rutting resistance decline versus the addition of ESO, the content of ESO should not exceed 7 wt % of the conventional rejuvenator.
Highlights
In the recycling of reclaimed asphalt pavement (RAP), the RAP is blended with virgin aggregate, virgin bitumen as well as a rejuvenator to fabricate recycled hot mix asphalt (RHMA), which can conserve natural resources and reduce environmental pollution [1,2,3].RAP usually has lower road performance due to the aging of bitumen [4,5,6]
It was reported that the rejuvenator and aged bitumen were initially blended evenly, and a series of testing, including the physical properties, rheological properties and chemical components, was conducted on the blends to investigate the influence of the rejuvenator on aged bitumen; the results indicate that the aged bitumen can reach the target performance grade if the appropriate amount of the rejuvenator is determined and added [9,10,11,12]
Epoxidized soybean oil (ESO) has been used for the modification of oxidized bitumen; the results indicate that ESO displays good compatibility with the oxidized bitumen due to the polar epoxy group in ESO [21] and can facilitate asphaltene dispersion [22], which benefits the colloidal structure transformation of the oxidized bitumen from gel to sol-gel; the fluidity of oxidized bitumen can be enhanced and the viscosity can be reduced [23]
Summary
In the recycling of reclaimed asphalt pavement (RAP), the RAP is blended with virgin aggregate, virgin bitumen as well as a rejuvenator to fabricate recycled hot mix asphalt (RHMA), which can conserve natural resources and reduce environmental pollution [1,2,3]. A rejuvenator that can reconstitute the chemical component and colloidal structure of aged bitumen to regenerate its performance [7,8] is crucial for the recycling of RAP. The diffusibility of the rejuvenator can be enhanced by simultaneously reducing the asphaltene content and by increasing the fluidity of the aged bitumen. ESO has been used for the modification of oxidized bitumen; the results indicate that ESO displays good compatibility with the oxidized bitumen due to the polar epoxy group in ESO [21] and can facilitate asphaltene dispersion [22], which benefits the colloidal structure transformation of the oxidized bitumen from gel to sol-gel; the fluidity of oxidized bitumen can be enhanced and the viscosity can be reduced [23]. The effects of ESO on the diffusibility and regenerating effects of the conventional rejuvenator were investigated
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