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Asphalt rejuvenation technology is an effective method to recycle reclaimed asphalt pavement (RAP) for the production of high-quality recycled asphalt mixtures. This approach contributes to mitigating environmental pollution and facilitating resource recycling. In this study, the impact of rejuvenator molecules on the rejuvenation process was explored by utilizing theoretical models and dynamics simulations. Free volume theory models were used to calculate the diffusion coefficient, while molecular dynamics (MD) simulations revealed the internal energy changes during diffusion. Molecules with high interaction with aged asphalt are easier to reach the homogeneous state in diffusion systems under higher temperatures. The quantification of blending by Fick's 2nd law suggests that the blending process consists of three stages: an intense diffusion phase, a stabilization phase, and a homogeneous state phase. The time taken to reach the homogeneous stage depends on the chemical structure of the rejuvenators and the temperature. This study elucidates the molecular-scale mechanism of RAP rejuvenation and provides a roadmap for improving environmentally friendly RAP rejuvenation technology. • Blending process consists of three phases. • Interactions and free volume control the diffusion process. • Saturated-based molecules is more susceptible to high-temperature excitation. [ABSTRACT FROM AUTHOR]

Dispose and utilization of municipal solid waste incinerator bottom ash (MWSIBA) is one of the imperative issues in environmental protection. The applicability of substitution for natural aggregate with MWSIBA in asphalt mixture was investigated by the performance and micro structure of asphalt mixtures with diverse porosity levels of MWSIBA (varying the replacement percentage). The effects of porosity of MWSIBA on asphalt mixture performance were captured by determination of Marshall stability, tensile strength, dynamic stability and the maximum flexural-tensile strain. The horizontal vibration extraction procedure test was implemented for the heavy metal leaching concentration to evaluate the environmental safety of MWSIBA asphalt mixture. Chemical and micro-morphologic characterization for MSWIBA were conducted to explore the mechanism of moisture damage resistance of asphalt mixture. Results indicated that porosity and replacement rate of MWSIBA exerted impacts on properties of asphalt mixture. The rutting resistance of asphalt mixture decreased due to the addition of MWSIBA, resulting in a reduction in high temperature performance. MWSIBA with porosity no less than 19% was beneficial to the improvement of moisture susceptibility and low temperature performance of asphalt mixture, while high mixing amount of MWSIBA was unfavorable to the properties of asphalt mixture. The water immersion stimulated the hydration reaction in MWSIBA, leading to the formation of C-(A)-S-H gel with strong cementation property, which enhanced the adhesion between MWSIBA and asphalt binder. MWSIBA asphalt mixture presented lower heavy metal concentration and better environmental safety than MSWIBA. • The applicability of substitution for natural aggregate with MWSIBA in asphalt mixture was investigated. • Both porosity and replacement rate of MWSIBA exerted impacts on properties of asphalt mixture. • The formation of C-(A)-S-H gel contributed to superior resistance to moisture damage of MWSIBA asphalt mixture. [ABSTRACT FROM AUTHOR]

Waste asphalt shingle (WAS) has traditionally been disposed of by landfilling due to environmental concerns surrounding Polycyclic aromatic hydrocarbons in WAS, which may potentially leach out, causing environmental pollution. However, this disposal method has been less environmentally acceptable and less cost effective than in the past due to concern on land resources. This study evaluates the potential of degradation of WAS, therefore reducing the polycyclic aromatic hydrocarbons (PAHs) content, by exploiting microbial biodegradation. The white rot fungus Phanerochaete chrysosporium was tested for its potential to degrade waste asphalt shingle binder. The biodegradation process was analyzed and quantified by both Fourier-transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Results illustrate that P. chrysosporium can degrade WAS binder. GPC analysis indicates that the small asphaltic molecules were biodegraded preferentially by P. chrysosporium. The PAHs content of the WAS binder increased initially during fungal biodegradation, but subsequently decreased with the progression in biodegradation to a level lower than that of the original shingle binder. Results from this study could be used to develop solutions to the sustainable management of waste asphalt shingles. [ABSTRACT FROM AUTHOR]

Bio asphalt is an organic polymer derived from biomass resources, which has the potential to partially or completely replace petroleum asphalt. This study used lignocellulose to prepare bio oil by hydrothermal liquefaction method. A mixed solvent of ethanol and ethylene glycol was introduced to increase the oil yield and decrease the reaction temperature. The oil yield reached the highest when solvent mixing ratio of 1:1, liquid-solid ratio of 6:1, catalyst dosage of 3%, and reaction temperature of 250 °C respectively. The bio oil and 50# asphalt were mixed in proportion sheared for 30 min (1000 rpm) under the condition of 135 °C to produce bio asphalt. The chemical structures and rheological properties of bio oil and bio asphalt were investigated and compared with petroleum asphalt. Fourier transform infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance analysis indicate that the bio oil expressed a lower H/C ratio, higher O content and more light components including liquid compounds comparing to the petroleum asphalt. The content of the polar group including O–H and C=O of bio oil was higher than that of petroleum asphalt. Gas Chromatography-Mass Spectrometry (GC-MS) was used to prove the presence of olefins and alcohols in bio oil. Thermogravimetric analysis showed that the bio oil expressed better thermal stability than that of petroleum asphalt, which expressed a potential of using as a pavement material. The dynamic shear rheometer (DSR) results showed that the complex shear modulus, G∗ decreased as the content of bio oil. The Glass transition temperature Tg indicated that the bio asphalt with 10% bio oil content showed similar performance with that of 70# asphalt. [ABSTRACT FROM AUTHOR]

The recycling of asphalt shingles in pavement construction is beneficial to the environment and industry by reducing the consumption of virgin materials. However, current approaches of utilizing recycled asphalt shingle (RAS) by mixing with soft asphalt or rejuvenator were questionable for the anti-aging problems. This study developed a new approach to recycle asphalt shingles, in which the RAS binder was dissolved and extracted by a mixed solvent of heptane and trichloroethylene (TCE). In the proposed process, the viscosity of the extracted RAS binder was controlled by the polarity and composition of the mixed solvent. Results indicate that heptane dissolved the soft part and trichloroethylene (TCE) could dissolve the stiff part of RAS binder. The use of the mixed solvent of heptane and TCE with a certain proportion through the proposed method could prepare asphalt binder with desired properties. The current approaches of utilizing RAS were compared with the proposed method. Results indicate that the anti-aging properties of extracted RAS binder using the proposed method were better since the soft asphalt could not dissolve RAS binder at 170 °C, and the binder blend of RAS binder and rejuvenator had a potential anti-aging problem because an obvious loss of rejuvenator existed during the aging process. The performance test suggests that the high and low temperature region of the extracted RAS binder was close to 75.2–28 °C, which could be used as a common asphalt in pavement engineering. • RAS binder was extracted and used as common asphalt. • Heptane and TCE were mixed to prepare the mixed solvent. • Soft asphalt could not dissolve RAS binder. • Rejuvenator was evaporated seriously during the short aging process. [ABSTRACT FROM AUTHOR]