Chemical characterizations and molecular dynamics simulations on different rejuvenators for aged bitumen recycling

Molecular dynamics simulation and experimental validation on the interfacial diffusion behaviors of rejuvenators in aged bitumen

“…As a result, the intermolecular interactions between engine-oil and aged bitumen molecules are much lower than bio-oil, and that's why the engine-oil molecules exhibit a higher diffusion coefficient than the bio-oil at low temperatures. However, bio-oil molecules' molecular mobility and self-diffusion capacity are more significant than the engine-oil molecules at high temperatures, as reported in our previous work [45]. Therefore, the bio-oil rejuvenator shows a faster diffusion rate than the engine-oil at high temperatures.…”

“…In this study, the average molecular structures of four rejuvenators are determined based on their chemical characteristics of elemental analysis, functional group distribution, and average molecular weight. Our previous paper described how to construct the average molecular structures of these rejuvenators [45], as illustrated in Fig. 4.…”

“…Interestingly, no aromatic-oil molecule compasses to the underside of the aged bitumen layer even though the diffusion time is at 10 ns. It implies that the diffusion rate of aromatic-oil molecules is the lowest among these four rejuvenators, which is related to its highest molecular weight, polarity, and intermolecular interaction with aged bitumen molecules [45]. Moreover, the amount of aged bitumen molecules in the aromatic-oil layer is the least; thus, a long blending time is required to obtain a homogeneous aromatic-oil rejuvenated bitumen.…”

“…It means that adding these four rejuvenators can enhance the fatigue resistance of aged bitumen. However, the enhancement effect of the aromatic-oil rejuvenator is limited due to its large molecular weight and viscosity [39,45]. The bio-oil rejuvenated binders show the highest N f values, followed by the engine-oil and naphthenic-oil rejuvenated bitumen.…”

Effect of Oils on SBS Modified Asphalt: Rheological Characteristics and Oxidation Aging

“…A number of studies showed that the bio-based oils exhibited superior properties as a recycling agent regarding improving internal stress relaxation ability, reducing stiffness, long-term rejuvenating effectiveness, etc. [18][19][20][21]. Another challenge concerning the use of recycling oils is the oil dosage determination.…”