Aged Asphalt Binders Research Articles

Physical and Chemical Methods to Assess Performance of TPO-Modified Asphalt Binder

The demand for effective asphalt additives is growing as road infrastructure ages and more sustainable pavement solutions are needed. Tire pyrolysis oil (TPO) is an example material that has been gaining attention as a potential asphalt additive. While physical performance grade (PG) temperatures are the predominant performance requirements for asphalt binders, chemical properties are also significant in the evaluation of asphalt performance. There is a need to chemically characterize the aging of asphalt binders modified with TPO and link chemical changes in binder components to binder performance. This study compares 2%, 4%, and 8% TPO and asphalt binder blends via dynamic shear rheometry (DSR), Fourier-transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) relaxometry. The variability in the modified blends was seen by both physical and chemical testing during four different blending times (1, 60, 120, and 240 min). After blending, high and intermediate PGs were determined by physical testing. The 8% TPO blend reduced the high PG of the binder from 64 °C to 58 °C. This effect was confirmed by chemical testing through changes in carbonyl indices and NMR relaxation times. With more oil present in the binder matrix, the binder’s resistance to rutting was reduced. While the high PG was hindered, the intermediate PG remained unchanged for all TPO blends. This physical similarity was mirrored in chemical testing. The chemical and physical variability along with the hindrance of the high PG temperature indicate that more treatment may be needed before TPO can be effectively applied to asphalt binders. This study suggests a correlation between physical performance and key chemical indicators.

Evaluation of Cracking Resistance of SMA-13 Hot Recycling Asphalt Mixtures Reinforced by Basalt Fiber.

In the context of green and low-carbon development, energy saving, and emission reduction, hot recycling technology (RT) has been researched, which is divided into hot central plant RT and hot in-place RT. However, due to the aged asphalt binders, the shortcomings of hot recycled asphalt mixtures have become apparent, as in comparison to new asphalt mixtures, their resistance to cracking was inferior and the cracking resistance deteriorated more rapidly. Therefore, it was very necessary to focus on the improvement of crack resistance of hot recycled asphalt mixtures. Basalt fiber has been proved to be able to effectively improve the comprehensive road performance of new asphalt mixtures. Therefore, this paper introduced basalt fiber to hot central plant recycled and hot in-place recycled asphalt mixtures, in order to improve the crack resistance of asphalt as a new type of fiber stabilizer. Firstly, six types of SMA-13 fiber asphalt mixtures were designed and prepared, i.e., hot mixtures with basalt fiber or lignin fiber, hot central plant recycled mixtures with basalt fiber or lignin fiber, and hot in-place recycled mixtures with basalt fiber or lignin fiber. Secondly, the trabecular bending test, low-temperature creep test, semi-circular bending test, and IDEAL-CT were used to comparatively study the changing patterns of low and intermediate temperature cracking resistance of hot recycled mixtures with conventional lignin fibers or basalt fibers. Finally, Pearson's correlation coefficient was used to analyze the correlation of the different cracking resistance indicators. The results show that the low and intermediate temperature cracking resistance of hot central plant recycled mixtures increased by 45.6% (dissipative energy ratio, Wd/Ws) and 74.8% (flexibility index, FI), respectively. And the corresponding cracking resistance of hot in-place recycled mixture increased by 105.4% (Wd/Ws) and 55.7% (FI). The trabecular bending test was more suitable for testing the low-temperature cracking resistance of hot recycled asphalt mixtures, while the IDEAL-CT was more suitable for testing the intermediate-temperature cracking resistance. The results can provide useful references for the utilization of basalt fiber in the hot recycling of SMA-13 asphalt mixtures.

Investigation into the effect of waste engine oil and vegetable oil recycling agents on the performance of laboratory-aged bitumen

The pavement recycling method is one of the practical ways to integrate sustainable development into transportation infrastructure, and it has been adopted worldwide. The use of reclaimed asphalt pavement (RAP) in new asphalt highways is limited due to the ageing effects caused by UV damage and weathering on the asphalt binder. To address this issue, waste vegetable oil (WVO) and waste engine oil (WEO) have been proposed as potential rejuvenating agents to enhance the recyclability of pavements containing RAP. This study evaluated the effectiveness of WEO and WVO as chemical rejuvenating agents through various tests on both aged and virgin asphalt binders. The tests included measurements of ductility, fire, and flash points, softening points, and penetration. The results indicate that the addition of WEO and WVO can improve the low-temperature properties of asphalt binders when mixed with RAP, resulting in reduced stiffness. The mixture containing WEO and WVO exhibited improved stability compared to the control, suggesting enhanced flow with increasing waste oil content in comparison to aged binder, albeit with slightly reduced flow compared to the virgin binder. This study demonstrates the potential of WEO and WVO as recycling agents to enhance the performance of bituminous mixes incorporating RAP.

Properties of waste vegetable oil recycled asphalt-binder: a molecular simulation study

ABSTRACT The aging of asphalt-binder during long-term use is an important reason for the decline in road performance of asphalt mixtures. In this study, waste vegetable oil (fried for 1-2h) was investigated as a rejuvenator of asphalt-binder. The optimisation effect of waste vegetable oil on the performance of asphalt-binder with different aging degrees (RTFOT, PAV15/20/48h) was evaluated by testing their conventional physical properties, high-temperature properties, and low-temperature properties. The molecular dynamics method was used to construct models, and the diffusion properties, solubility properties, adsorption energy, and asphaltene aggregation were calculated. The influences of linoelaidic acid and oleic acid molecules on aged asphalt-binder molecules were evaluated. The changes in the functional groups of the aged asphalt-binder after the addition of waste vegetable oil were analyzed by infrared spectrometry, and the changes in the microstructure of the aged asphalt-binder surface were observed by scanning electron microscopy. The results revealed that waste vegetable oil could regenerate aged asphalt-binder and significantly improve their physical and high-/low-temperature properties. Waste vegetable oil molecules are compatible with aged asphalt-binder molecules, improve their diffusion behaviour, enhance their adsorption capacity, and slightly reduce the aggregation of asphaltenes. Overall, waste vegetable oil shows great potential for the regeneration of aged asphalt-binder.

In-situ detection on near-infrared spectra fingerprints of asphalt mixture after laboratory short- and long-term aging

Although Fourier transform infrared spectroscopy has been widely used in research on the aging of asphalt binders, it is a cumbersome, time-consuming, and environmentally polluting process using toxic solvents to extract and recover asphalt binders from asphalt mixtures for spectral measurement and analysis. However, little effort has been devoted towards its non-destructive spectral measurement, which is important for intelligent monitoring of pavement deterioration conditions. This paper focused on the non-destructive investigation of comparative near-infrared spectra of asphalt mixture specimens designed using the Marshall method after laboratory short- and long-term aging with a portable near-infrared spectrometer. The near-infrared spectra showed that asphalt mixtures from different aging states appeared significantly different fingerprints. The near-infrared fingerprints and aging states were also statistically significantly different according to the analysis of one-way analysis of variance. These distinctive near-infrared fingerprints could be attributed to the varied amounts of chemical functional groups, mainly hydrogen-containing groups during oxidative aging. This study provided a non-destructive and in-situ detection of the aging of asphalt mixtures.

Investigating the Potential of Untreated and Treated Waste Cooking Oil for Rejuvenation of Aged Asphalt Binder

Investigating the Potential of Untreated and Treated Waste Cooking Oil for Rejuvenation of Aged Asphalt Binder

Influence of Petroleum-Based and Bio-Derived Recycling Agents on High-RAP Asphalt Mixtures Performance

Reclaimed asphalt pavement (RAP) has been utilized as a potential partial substitute for virgin asphalt binder in asphalt mixtures. However, a primary concern with increasing RAP content in asphalt mixtures is the cracking potential, attributed to the aged RAP asphalt binder (RAP-binder). To address this, the use of petroleum-based and bio-derived recycling agents (RAs) in enhancing the cracking resistance of high-RAP asphalt mixtures has been explored. The objective of this study is to ascertain the effectiveness of six RAs in mitigating cracking in high-RAP asphalt mixtures. The RAs considered include petroleum-crude-oil-derived aromatic oil, soy oil, and four types of tall-oil-derived phytosterol (industrial by-product, intermediate, purified, and fatty acid-based). The RAs’ dosages were optimized, based on RAP-binder and unmodified asphalt binder properties, to produce target PG 70-22 asphalt binder when incorporated in asphalt mixtures containing 30% RAP. To assess the engineering performance of these 30%-RAP asphalt mixtures for each RA, a conventional asphalt mixture incorporating styrene-butadiene-styrene (SBS)-modified PG 70-22 asphalt binder without RAP or RAs was benchmarked for comparison. Mechanical tests performed included Hamburg wheel-track testing (HWTT), intermediate-temperature fracture tests (semi-circular bend, Illinois flexibility index, and IDEAL cracking tolerance), and thermal stress-restrained specimen tensile strength test to evaluate permanent deformation, intermediate-temperature cracking resistance, and low-temperature cracking resistance, respectively. Results showed that petroleum-crude-oil-derived aromatic oil and tall-oil-derived fatty-acid-based oil RAs were able to rejuvenate RAP-binder as measured by the cracking tests performed. Further, the use of these RAs did not adversely impact the asphalt mixtures’ permanent deformation performance.

Effect of SBS/SBR/component molecular compatibility on anti-aging properties for asphalt binder

To explain the effect of SBS/SBR/component molecular compatibility on anti-aging properties for asphalt binder, the micro-aging behavior of SBS/SBR composite modified asphalt binder was studied by molecular simulation, scanning electron microscopy (SEM) and infrared spectroscopy (IR). First, the micro-models of SBS molecule, SBR molecule and component molecule (asphaltene, resin, saturation, aromatic) were established, and the molecule number was determined by component test. Additionally, the characteristics of micro-model were analyzed, and the change characteristics of molecular compatibility for unaged asphalt binder and aged asphalt binder were obtained. Lastly, the rationality of molecular compatibility simulation results of SBS/SBR/component was demonstrated by SEM and IR tests, respectively. The results show that there is a close relationship between SBS/SBR/component molecular compatibility and asphalt binder anti-aging performance. The change of molecular space structure leads to the increase of asphalt binders density and the decrease of intermolecular distance. The study revealed the anti-aging properties of asphalt binder from the aspect of SBS/SBR/component molecular compatibility, which provided a theoretical foundation for the improvement of its aging resistance.

A molecular dynamics simulation study on the recovery performance of aged asphalt binder by waste vegetable oil rejuvenators

This study employed molecular dynamics to simulate the recovery performance of a waste vegetable oil rejuvenator on aged asphalt binder. The model's accuracy was verified through density and glass transition temperature (Tg) calculations. The Radial Distribution Function (RDF) was utilized to assess the aggregation state of different asphalt binder components. The impact of the waste vegetable oil rejuvenator on asphalt binder microstructure was evaluated using cohesive energy density (CED), relative concentration, mean square displacement (MSD), radius of gyration (Rg), and free volume amount. Changes in functional groups of the aged and recycled asphalt binder samples were analyzed using Fourier transform infrared spectroscopy (FT-IR). Results indicate that the rejuvenator significantly influences the dispersion of SARA components. Improved compatibility between aged and virgin asphalt binders is achieved through increased activity of asphaltenes and resins. The incorporation of rejuvenators into asphalt binder mildly counters the aggregation of asphalt binder molecular structure, mitigates the negative effects of aging, and restores asphalt binder structure. The rejuvenator, enriched with polar groups as per FT-IR tests, increases the proportion of polar groups in the recycled asphalt binder. The recycled asphalt binder exhibits a higher proportion of polar molecules, and the rejuvenator reacts with the polar molecules in the asphalt binder at high temperatures.

Investigation of cracking resistance of cold asphalt mixture designed for ultra-thin asphalt layer

Ultra-thin asphalt layers are mostly constructed at high producing temperatures of 165–180 ℃, which results in high energy consumption and extra aging of asphalt binders. Those influences could be eliminated by employing the cold-mix process. However, the reduced cracking resistance of cold asphalt mixtures should be addressed. The objective of this study is to design a preferable cold mix asphalt mixture which can be used for ultra-thin asphalt layer. A cold mix ultra-thin asphalt layer (GT-10 C) with comparable anti-cracking performance was developed through the use of high-performance binder, basalt fibers, and specially designed aggregate gradation. Several cracking resistance tests were employed including the low-temperature bending test, impact toughness test, and semi-circular bending test. In addition, a specified test method was developed for determining cracking resistance and durability of the ultra-thin asphalt layers by using compounded slabs. The testing results were compared with the performance of a conventional hot mix ultra-thin asphalt layer (Hot-UA) and a common micro-surfacing layer with cold mix (Cold-UA). It was found that GT-10 C had larger ultimate tensile strain, impact and fracture toughness than Hot-UA and Cold-UA, and a better fracture life in the thin layer cracking resistance test as well. This research provides a potential technology for producing cold mix ultra-thin asphalt layers.

Ecuadorian asphalt aging in laboratory and field. Relationships and analysis

The aging of asphalt binders has a great impact on the behavior of pavement. The specifications for performance grade include tests on short-term (RTFOT) and long-term (PAV) aged residues. However, aging is greater at the top of wearing course than deeper zones, long-term tests do not correlate accurately with field aging and in the latter, the incidence of local temperature is not considered accurately. The objective is to relate the aging of Ecuadorian asphalt at the laboratory level, applying different conditioning times in the PAV, with the field aging from asphalts recovered from the top of pavements surface in selected roads of the Andean and Coastal regions, with different construction times and cumulated degree-days (CDD), using certain rheological parameters. As a result, in the Ecuadorian asphalt, the RTFOT residue is equivalent to field aging of 1.1 years in the Coastal region and 1.7 years in the Andean region. On the other hand, the usual PAV of 20 hours corresponds to field aging of 5.8 years for the Coastal region and 9.3 years for the Andean region. The progressive evolution of damage to our roads, without considering traffic, corresponds to conditioning times in the PAV between 13.0 and 26.6 hours.

Rejuvenating Aged Asphalt Binder from Reclaimed Asphalt Pavement through the Utilization of Waste Cooking Oil

Abstract: This study investigates the use of waste cooking oil to rejuvenate aged asphalt binder from reclaimed asphalt pavement (RAP) in Peshawar, aligning with National Highway Authority (NHA) standards. Aged binder from RAP near Zintara Residence on Peshawar's Ring Road was combined with filtered cooking oil from local restaurants in varying proportions (1% to 5%). The rejuvenated binders underwent extensive physical and rheological tests, showing that certain fractions of cooking oil effectively revitalized the old binder, aligning it with virgin bitumen qualities. Superpave experiments on RAP mixes (30%, 40%, 50%) demonstrated comparable performance to fresh asphalt, particularly at 30% to 40% replacement levels. The results suggest that revitalized RAP holds promise as a sustainable alternative, enhancing asphalt mixes for road construction.

Effect of aging on damping properties of rubberized asphalt binder and rubberized porous asphalt mixture

The purpose of the study is to explore the effect of aging on the damping properties of rubberized asphalt binder and rubberized porous asphalt mixture (RPAM), and to reveal the attenuation mechanism of damping properties. The effect of aging on the damping properties of asphalt binder was analyzed through temperature scanning test. Fourier transform infrared spectroscopy, gel permeation chromatography, and fluorescence microscopic test were conducted to analyze the aging mechanism of damping properties from the perspectives of chemical composition and morphology. The dynamic modulus test and free vibration damping test were used to investigate the effect of aging on the damping properties of asphalt mixtures. Results showed that aging led to a decrease in the damping properties of asphalt mixtures. Compared to porous asphalt mixture, RPAM had lower sensitivity to aging, so its damping properties was less prone to decay. The effect of aging on asphalt binders obtained from the temperature scanning test was consistent with the results of asphalt mixtures, indicating that the decrease in damping properties of asphalt mixtures was attributed to the deterioration of damping properties of asphalt binders. The results of chemical composition and phase morphology indicated that the proportion of large molecules in the asphalt binder increased significantly during the aging process. The decrease in intermolecular mobility led to a decrease in the damping properties of asphalt binder. Significantly, crumb rubber can prevent the aging of asphalt binder, thereby delaying the attenuation of damping properties of RPAM.

Biomass waste to produce bio oil as rejuvenator for asphalt based on pyrolysis technology

ABSTRACT The objective of the current study is to research the suitability of using two bio-oils produced from corncob and birch bark as two bio-rejuvenators to regenerate aged asphalt binders. To this end, the pyrolysis characteristics of corncob and birch bark were analysed using a thermogravimetric analyzer. The chemical characteristics of the bio-rejuvenators were then evaluated via an elemental analyzer and the Gas Chromatograph Mass Spectrometer (GC-MS) test. The results revealed the presence of a great quantity of lightly weighted compounds in bio-oils. Pen70 asphalt was used as control asphalt binders. The Rotational Viscometer (RV) test result showed that bio-rejuvenators could help reduce the viscosity of aged asphalt binders. In addition, the Dynamic Shear Rheometer (DSR) experiments revealed that bio-rejuvenators could reduce the complex shear modulus, decrease percent strain recovery, increase non-recoverable creep compliance and restore the fatigue performance of the aged asphalt. The Bending Beam Rheometer (BBR) tests indicated that the cracking performance of the bio-rejuvenated asphalt was also improved compared with the aged asphalt. The Fourier transform infrared spectra demonstrated that the bio-rejuvenators helped reduce the aged asphalt's carbonyl and sulfoxide indexes. In addition, the Gel Permeation Chromatography (GPC) test indicated that bio-rejuvenators reduced the polydispersity and molecular weight of the aged asphalt.

Investigation of the Performance of Bio-Oils from Three Different Agricultural Wastes as Rejuvenators for Recycled Asphalt

The aim of this study was to investigate the possibility of using bio-oil obtained from pine cones, olive mill pomace, and wheat straw as rejuvenators for the reuse of aged asphalt binders. Additionally, the biomass used for bio-oil production was selected from waste materials. Therefore, it makes great contributions to both the environment and the economy. B50/70 bitumen was selected as the neat binder. The bio-oils used in the study were obtained as a result of pyrolysis. Bio-oil rejuvenators at 5%, 10% and 20% by the weight of the binder were added to the aged binder obtained from recycled asphalt mixtures to obtaine bioregenerated asphalts. The physical and rheological properties of bioregenerated asphalts were investigated and not compared on neat and aged binders through penetration, softening point, rotational viscometer and dynamic shear rheometer tests. In addition, the effects of temperature and biooil content on complex modulus properties were examined using response surface methods. It was foud that while the bio-oils increased the penetration values of the aged binders, they also decreased the softening point and viscosity values. The bio-oils significantly modified rutting resistance of the aged binder. The addition of bio-oil improved the viscous components and can rejuvenate the viscoelastic properties of aged asphalt binders to that of almost the original level. In addition, response surface methods results showed that the interactions between both independent variables were effective. Finally, high coefficient of determination (R2) values indicated good agreement between the actual and predicted values. It was recommended as a result of the study that 20% concentration of bio-oil should be used to rejuvenate the aged asphalt binder for reuse in pavement construction.

Effect of polyisobutylene on low-temperature thermoreversible aging properties in asphalt binders

In order to study the influence of polyisobutylene (PIB) on pavement performance of asphalt binders, two asphalt binders with large differences in wax content and the similar performance grades were selected as the base asphalt binders, and three kinds of waxes and PIB were selected as additives. Extended bending beam rheometer (Ex-BBR) test, double-edge-notched tension (DENT) test, multiple stress creep recovery (MSCR) test and rotational viscosity test were used to study the effect of PIB on the low, medium and high temperature properties of asphalt binders, respectively. The phase transition pattern of PIB when interacting with waxes was analyzed by variable temperature polarizing microscope (VT-PLM). The results show that PIB can be miscible with waxes and reduce the melting point of waxes by about 20∼60%. PIB can improve the low-temperature performance (reducing creep stiffness), medium-temperature performance (increasing toughness and fracture resistance), high-temperature performance (improving high-temperature deformation resistance and deformation recovery ability) and workability (reducing mixing and compaction temperature) of asphalt binders (including high-wax and wax-based warm-mixed asphalt binders). It is worth noting that PIB will aggravate the thermoreversible aging (the results of P-value analysis showed that PIB had a significant effect on the grade loss (GL) of asphalt binders), which will affect the low-temperature performance of asphalt binders during the isothermal low-temperature storage, resulting in premature damage to the pavement.

Evaluating the Influence of Waste Cooking Oil Molecular Structure on Aged Asphalt Modification

Recycling aged asphalt pavement has become increasingly important due to its environmental and economic advantages. Asphalt, serving as the binding agent for aggregates, plays a crucial role in pavement integrity. The deterioration of asphalt binder properties upon aging poses a significant challenge to asphalt pavement recycling. Consequently, various rejuvenators have been developed to restore aged asphalt binder properties and facilitate pavement reclamation. Waste cooking oil (WCO) is a widely used rejuvenator that mitigates the high viscosity and brittleness of aged asphalt, preventing cracking. WCO consists of triglycerides (TG) and free fatty acids (FFA), each with distinct molecular structures. In this study, molecular dynamics simulations were employed to investigate the individual effects of 10 wt.% TG and FFA on the viscosity, self-diffusion, and microstructure of aged asphalt at 1 atm and 404 K. The results demonstrate that both TG and FFA can reduce the viscosity of aged asphalt, albeit through different mechanisms. TG and FFA, characterized by high molecular mobility when dispersed in aged asphalt, enhance its mobility and reduce its viscosity. Additionally, TG effectively disrupts preferential interactions among asphaltenes, preventing their self-aggregation. In contrast, FFA has a limited impact on reducing these interactions. Furthermore, the study delves into the entanglement behaviors of FFA and TG with varying chain lengths within aged asphalt. Shorter chain lengths, as opposed to longer ones, exhibit a lower likelihood of entanglement with other asphalt molecules, resulting in increased molecular mobility and reduced asphalt viscosity. The fundamental insights gained from this research serve as a valuable reference for the application of waste cooking oil in the recycling of aged asphalt pavement. By shedding light on underlying molecular dynamics, this study contributes to the development of more effective and sustainable approaches to asphalt recycling.

Leaching potential of metals and PAHs of asphalt rubber paving materials

Asphalt rubber (AR), a waste-based paving binder prepared with waste tyre rubber and asphalt binder, may contain hazardous components that pose environmental risks when applied to the road surface. This study aims to quantify this concern by characterizing the leaching process of AR using a multi-scale experimental method. The effects of various experimental variables on the leaching process were determined, and the leaching of metals and polycyclic aromatic hydrocarbons (PAHs) were characterized at three scales, i.e., binder, mortar, and mixture. The results suggested that AR presents no significant leaching concerns under most conditions, but the leaching of metals from AR might pose risks to the aquatic environments in the areas with acid rain. Furthermore, the leachability of metals increases with service time due to the aging of asphalt binder. The findings of this study can contribute to a better understanding of the environmental performance of AR and help conduct AR construction and maintenance in a more sustainable manner.

Evaluation of the Aging of Asphalt Binders Using Artificial Neural Networks

Evaluation of the Aging of Asphalt Binders Using Artificial Neural Networks

Impact of aging protocols on asphalt binder behavior: A laboratory and field study

In this study, the focus was on the analysis of asphalt binder aging, a complex process that induces physical, chemical, and rheological changes in these materials, affecting the performance of asphalt mixtures over time. While thermal-oxidative aging is well-documented, the aspects of photo-oxidative aging and the influence of moisture are frequently overlooked. The investigation assessed 50/70 asphalt binder that underwent short-term and long-term aging in both laboratory and field climatic conditions in Brazil. Initially, these binders underwent short-term aging using the Rolling Thin-Film Oven (RTFO) method. Subsequently, the binders were subjected to prolonged aging, exposing them to heat, oxygen, UV radiation, and moisture. The chemical results unveiled distinct reaction mechanisms during thermal and photochemical aging processes. Greater oxidation was observed when binders were exposed to UV radiation, while the oven protocol resulted in increased binder stiffness. Following prolonged aging, a noticeable increase in binder stiffness was observed, particularly when exposed to a temperature of 85 °C. Concurrently, a decrease in fatigue resistance at high strains and a reduction in permanent deformations were identified after aging. The effects of UV radiation were less pronounced than anticipated, mainly due to the lower chamber temperature (60 °C). Nevertheless, the applied stimuli expedited the aging process, underscoring the significance of including UV radiation and moisture in laboratory aging studies. Additionally, it was observed that the aging protocol at 85 °C yielded results analogous to those observed under field conditions over a six-month period in the northeastern region of Brazil.