Aged Asphalt Binders Research Articles

Aging effects of ultraviolet lights with same dominant wavelength and different wavelength ranges on a hydrocarbon-based polymer (asphalt)

To investigate the effects of different wavelength ranges of UV lights on chemical compositions and macro-properties of asphalt, three UV lights were used to conduct the aging test of asphalt for 1–288 h. The elemental analysis and Fourier transform infrared spectroscopy (FTIR) were performed to analyze the chemical changes of asphalt, the surface micro-topographies of asphalt before and after UV aging were studied by atomic force microscopy (AFM). In addition, the physical performance, viscosity and rheological performance of asphalt was studied with softening point test and dynamic shear rheometer (DSR), respectively. The chemical compositions and structures analyses show that the oxidation mechanism exists during the UV aging of asphalt binder. The numbers of bee-like structures in AFM height figures decrease obviously after UV aging, meanwhile the sizes of which increase. The relationships of RCC, RCS and SPI values with UV expose time follow a power function model in the first 24 h, while follows a liner model after 24 h. UV lights with different wavelength ranges have significantly different effects on the chemical compositions and macro-properties of asphalt. The UV 350–370 nm has the most obvious aging effect on asphalt binder, second is the UV 340–380 nm, the UV 200–400 nm has the lightest aging effect.

Sustainable lignin to enhance asphalt binder oxidative aging properties and mix properties

Using sustainable, renewable substances that can be locally-sourced instead of petroleum-based asphalt binders would be better for our environment. Replacing a small portion (maximum of 6%) of asphalt binder with three different types of lignin was investigated to determine its effects on aged and unaged asphalt binder and mix. Commercially available Kraft lignin, lignin precipitated from black liquor in the laboratory, lignin produced from rice hulls in the laboratory using a deep eutectic solvent, and a standard asphalt binder (control) were evaluated. Lignin improved the high temperature performance grade. All lignin-modified binders showed higher strain tolerance than unmodified binders in strain sweep tests. Lignin precipitated from black liquor and lignin produced from rice hulls improved the long-term aging index. Rutting, cracking, and moisture damage susceptibility tests were performed on an asphalt mix prepared with 6% lignin precipitated from black liquor asphalt binder. Improved rutting resistance was observed from the lignin-modified asphalt mix, without sacrificing moisture-induced damage resistance. Better cracking resistance with respect to increased flexibility index was observed according to the semi-circular bend test. Replacing petroleum-based binder with up to 6% of lignin precipitated from black liquor is practicable for hot mix asphalt, and may be feasible in the lower temperature warm mix asphalt process.

Aided regeneration system of aged asphalt binder based on microcapsule technology

The microencapsulated rejuvenator within asphalt is a promising alternative approach to prolong the service life of asphalt pavement. The aim of this paper is to investigate the aided regeneration system of aged asphalt binder based on microcapsule technology. The microcapsules containing rejuvenator were fabricated by in-situ polymerization method, and the capsule shell was made of melamine-urea-formaldehyde (MUF) resin. Firstly, the micro-morphology of microcapsules was characterized by scanning electron microscope (SEM). It could be found that the volume ratio of the core materials (rejuvenator) to microcapsule reached to 95%. Further, the time sweep fatigue test together with fluorescence microscope (FM) was employed to study the rupture behavior of microcapsules in aged asphalt binder before and after loading. The test results indicated that the microcapsules had sufficient thermal stability and strength to suffer from mechanical agitation at a high temperature. In addition, the rejuvenator released from microcapsules partially restored complex shear modulus and phase angle of aged asphalt binder thus extended its fatigue life. Finally, the fatigue-rest-fatigue test using dynamic shear rheometer (DSR) was conducted to study the effect of microcapsules on the fatigue resistance and healing capacity of aged asphalt binder. The test results showed that the fatigue resistance of aged asphalt binder was enhanced by microcapsules containing rejuvenator and the fatigue life of aged asphalt binder with 1 wt% microcapsules was 45.68% higher than that of non-aged neat asphalt binder. Moreover, the microcapsules could improve the healing capacity of aged asphalt binder, and its healing efficiency was proportional to the content of microcapsules.

Multi-scaled properties of asphalt binders extracted from weathered asphalt mixtures

ABSTRACT The objective of this study was to examine the relationship between the multi-scaled mechanical properties of an unmodified asphalt binder and a styrene–butadiene-styrene (SBS) modified asphalt binder, both of which were recovered from weathered open-graded friction course mixtures using an Abson method. The aging of asphalt binders in asphalt pavements was simulated in the lab using an accelerated weathering machine, which produces more authentic results than conventional techniques. The samples were then subjected to Atomic Force Microscopy to investigate their nano-properties. Three indices commonly used for measuring nano-adhesion, were determined for each sample. The results revealed that the roughness of the nano-adhesion increased with the degree of weathering, a clear demonstration of how asphalt surfaces stiffen with age. The behaviours of the three phases (para, peri and catana) shown in the nano-adhesion images of the weathered binders changed as the degree of weathering increased. The para phase expanded size and became more widely dispersed across the domains, eventually becoming the dominant phase by annexing the peri phase as the weathering process proceeded. There was a linear relationship between the nano-adhesion indices and the macroscopic rheological properties. The presence of the SBS modifier consistently affected the areas and shapes of all three phases.

Examining the Implications of Wax-Based Additives on the Sustainability of Construction Practices: Multiscale Characterization of Wax-Doped Aged Asphalt Binder

Paraffin wax is a component of many additives and rejuvenators commonly used in the asphalt industry to promote sustainability by facilitating recycling and/or reducing mixing and compaction temper...

The impact of bio-oil as rejuvenator for aged asphalt binder

Recycling technology has been widely applied on road pavement due to the aging problem of asphalt binder and the extensive requirement for maintenance. The aim of this research is to use bio-oil generated from sawdust as a rejuvenator to recycle aged asphalt. In this research, the performance graded asphalts PG 58-28 and PG 64-22 were selected as the base binders. The bio-oil contents were 10%, 15% and 20% of the total binder by weight. The Rotational Viscometer (RV) test, Dynamic Shear Rheometer (DSR) test, and Asphalt Binder Cracking Device (ABCD) test were applied to characterize the properties of bio-rejuvenated asphalts and virgin control asphalts. Additionally, the Fourier Transform Infrared Spectroscopy (FTIR) test was conducted to characterize the degree of restoration of aged asphalt binders from the aspect of functional groups. It was found that the bio-rejuvenator decreases the viscosity and activation energy, while increasing the temperature susceptibility and the content of viscous components of the aged asphalts. The aged asphalt can be softened by the bio-rejuvenator significantly; with the use of bio-rejuvenator, the rutting index of aged asphalts PAV PG 58-28 and PAV PG 64-22 at high temperatures from 52 °C to 76 °C was decreased by 75.5% and 77.2% in average, respectively. The bio-oil can restore the low temperature crack resistance of aged asphalts PAV PG 58-28 and PAV PG 64-22 to, or even better than, the level of virgin asphalts. The sulfoxide (SO) index and aromatic (CC) index can be used to evaluate the degree of restoration using bio-rejuvenator to recycle aged asphalt, but carbonyl (CO) is not applicable. Therefore, the bio-oil generated from sawdust can be used as a rejuvenator to recycle the aged asphalts PAV PG 58-28 and PAV PG 64-22. Moreover, the bio-rejuvenator contents of 15% and 20% are recommended to recycle the aged asphalt PAV PG 58-28 and aged asphalt PAV PG 64-22, respectively.

Predict the rheological properties of aged asphalt binders using a universal kinetic model

In this study, universal models were proposed to predict the aging behaviors of five different asphalt binders, where the rheological properties were emphasized on. The carbonyl content and crossover modulus of binders during oxidative aging process were predicted using the proposed universal kinetic models. The carbonyl content test using the Fourier Transform infrared spectroscopy (FTIR) technique and the frequency sweep test using a Dynamic Shear Rheometer (DSR) were performed to obtain the optimum model parameters. From the testing results, the crossover modulus of binders under oxidative aging effect showed similar growth trend to the carbonyl content that follows the two-reaction kinetics of aging. An approximately linear relation was established between the log crossover frequency and the inverse of log crossover modulus. A sufficient good agreement was achieved between the measured and predicted results of carbonyl content and crossover modulus of asphalt binders at given aging temperature and duration. However, it lost a little prediction accuracy when using the universal model parameters, compared to the specific model parameters. Moreover, based on the calculated crossover modulus and crossover frequency, the complex shear modulus and phase angle were successfully predicted based on the Christensen-Anderson model. The proposed universal model provides an effective approach of predicting the rheological properties of aged asphalt binders.

Quantification of asphalt binder ageing from apparent molecular weight distributions using a new approximated analytical approach of the phase angle

This paper aims to explore the effect of ageing on macromolecular organisation of pure petroleum asphalts by interpreting their rheological behaviours. Phase angle measurements are used to determine apparent molecular weight distributions (AMWD) assuming a special relationship between relaxation times and molecular sizes. This procedure is called the ‘delta method’. Four asphalt binders have been characterised in their original state and after lab ageing using conventional tests simulating ageing during the mixing process (RTFOT) and after several years of road service (PAV). Rheological properties have been measured with a visco-analyser METRAVIB under annular shearing and tension-compression mode of loadings. Measurements have been performed from –20°C to 60°C with a frequency sweep from 1 to 80 Hz. An analytical approximation of the phase angle, derived from the Huet-Such model, is used to calculate the AMWDs for each sample. A deconvolution procedure is then applied in order to identify four populations of molecular objects. This procedure allows to identify an increase of large molecular objects with ageing. The deconvolution procedure allows proving that it is the effect of smaller molecules that agglomerate themselves with the increase of the polar species content due to oxidation. This work shows that it is possible to get useful information on the asphalt macromolecular structure from linear viscoelastic measurements.

Influence of Cereclor on the performance of aged asphalt binder

ABSTRACT Recycling of an asphalt pavement reduces construction cost as well as the environmental degradation. Adding the bitumen emulsion as a rejuvenator in aged and oxidised asphalt binder improves its viscosity and stiffness without significantly decreasing the carbonyl index. This results in a high aging rate of such asphalt materials. This study proposes Cereclor as an alternate rejuvenator in the replacement of conventional bitumen-based emulsion. The main objectives of this study were to investigate the effect of Cereclor on aged asphalt binder’s characteristics, aging resistance and on the durability of Reclaimed Asphalt Pavement (RAP) modified asphalt mixtures. Carbonyl index was calculated from IR spectra of samples before and after laboratory aging to evaluate the aging resistance. It was observed that a 9% by weight of Cereclor rejuvenates 40/50 pen grade aged asphalt binder to the level of 60/70 pen grade bitumen. For durability assessment of RAP and rejuvenated mixes, fatigue, rutting and moisture susceptibility tests were performed. Four-point beam fatigue test showed that a 9% dose of Cereclor has increased the fatigue life of RAP by almost two times as compared to emulsion. Rut depth for all samples was in the range of 3–4 mm satisfying the rutting failure criteria. Overall, this study revealed that Cereclor has higher rejuvenation potential as compared to bitumen-based emulsion and thus it can potentially be used in pavement recycling.

Nanosized Morphology and Mechanical Properties of Recovered Binders from Weathered Asphalt Mixtures

Abstract Aging of asphalt binders can be more accurately simulated in the laboratory by an accelerated weathering machine (AWM) considering most of the weathering factors, and the nanosized properties of the aged binders can be examined at the nanoscale level by Atomic Force Microscopy (AFM). In this study, two gradations of asphalt mixtures, i.e., stone matrix mixture (SMA) and asphalt concrete (AC), were at first weathered by the AWM, and then asphalt binders were recovered. AFM technologies were applied for measuring the nanomorphology and nanomechanical properties of the recovered binders. The results are the following: (1) the roughness of morphology of recovered binders was gradually reduced, indicating a flattening asphalt surface phenomenon as the weathering time increased; (2) the average roughnesses of both adhesion and nanomodulus of the recovered binders increased as the weathering time increased because of the increased polymerization and the macromolecule; (3) there were fairly good linear correlations between the nanomorphology and the nanomechanical properties of the aged binders.

Laboratory evaluation on residue in castor oil production as rejuvenator for aged paving asphalt binder

In this study, residue in castor oil production is evaluated as a rejuvenator for aged paving asphalt binder. Different contents of the bio-based rejuvenator, ranging from 0% to 50%, were added to PAV aged binder to prepare samples. DSR tests and BBR tests were carried out to characterize rheological properties of rejuvenated binder. Furthermore, continuous PG grading temperatures were determined from DSR and BBR test data. Test results and data analyses show a notable decrease in complex modulus and an increase in phase angle with increasing rejuvenator content, indicating restoration in viscoelastic properties of the binder. The binder with 30% rejuvenator reaches a level similar to original binder in rutting parameter. The binder with 20% rejuvenator reaches a level similar to original binder in control thermal cracking parameter. The grading temperatures show that all the upper, lower, and intermediate grading temperatures decrease with increasing rejuvenator content, indicating a negative effect on rutting resistance, and positive effects on thermal and fatigue cracking resistances of the binder. The serviceability temperature shows that the gaining in low temperature behavior is more significant than the loss in high temperature behavior, indicating an improving effect of the rejuvenator on temperature susceptibility of the rejuvenated binder.

Using bio-based rejuvenator derived from waste wood to recycle old asphalt

The objective of this study is to investigate the possibility of using bio-oil derived from waste wood as a rejuvenator to recycle aged asphalt binders. In this study, petroleum asphalt of PG58-28 was selected as the base binder. The bio-oil rejuvenators with concentrations of 10%, 15% and 20% by weight were added into the Pressure Aging Vessel (PAV) aged base binder to prepare the bio-rejuvenated asphalts. Through the chemical compounds analysis of the bio-oil using the Gas Chromatograph Mass Spectrometer (GC–MS) test, it can be found that the bio-oil derived from waste wood contains a high content of light compounds, including phenol, naphthalene, diethyl phthalate and so on. The rheological properties of bio-rejuvenated asphalts were evaluated and compared with the virgin and aged asphalts by Rotational Viscometer (RV), Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) tests. The bio-rejuvenator can increase the viscous components and alleviate the stiffness of the aged asphalt binder. The high content of light compounds in the bio-oil balanced the chemical compounds of the aged asphalt. As a result, the rutting resistance and fatigue resistance of the aged asphalt binder were restored by the bio-oil significantly. The low temperature crack resistance of aged asphalt binder can be restored to approximately to that of the PG 58-28 by the bio-rejuvenator with the concentration of 15% and 20%. The bio-oil concentration had less impact on the rheological properties of bio-rejuvenated asphalts when the bio-oil concentration was higher than 15%. Therefore, the bio-oil with a concentration of 15% was recommended to rejuvenate the aged asphalt binder to be reused in the construction of pavement.

Micromechanism of the Dispersion Behavior of Polymer-Modified Rejuvenators in Aged Asphalt Material

Polymer-modified rejuvenator has a different composition and dispersion behavior to traditional rejuvenators. The objective of this study was to investigate the micromechanism of polymer-modified rejuvenators on the behavior of aged asphalt binder. Firstly, gel permeation chromatography (GPC) analysis was conducted to determine the dispersion effectiveness. Secondly, the dispersal behavior of polymer-modified rejuvenators was studied by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM). Rheological, toughness-tenacity, and force–ductility analyses of the rejuvenated asphalt binder were additionally performed. The results indicate that the contacted asphaltenic micelles in aged asphalt binder were dispersed by dispersion agent in the polymer-modified rejuvenator, and that the dispersion ability of the polymer-modified rejuvenator was promoted to the commercial rejuvenator level. Additionally, the polymer-modified rejuvenator was found to improve the rejuvenated asphalt binder’s resistance to deformation, through the formation of polymeric network structures in the asphalt binder. The results may be used to improve the performance of rejuvenated asphalt binder in recycled-pavement engineering.

Diffusion and interaction mechanism of rejuvenating agent with virgin and recycled asphalt binder: a molecular dynamics study

ABSTRACTThe quality of asphalt binder recycling is largely dependent on molecular diffusion between virgin asphalt binder, aged asphalt binder, and rejuvenator. In this study, molecular dynamics (MD) simulations were used to study diffusion and interaction mechanism of rejuvenating agent in recycled asphalt binder. The diffusion process of rejuvenator into virgin and aged asphalt binder was studied using a three-layered model. A mixture model of virgin and aged asphalt binder was built to evaluate the effect of rejuvenator on the molecular structure of asphalt binder, such as nanoaggregate behaviour and translational mobility. The simulation results of the layered model suggest that rejuvenator may improve blending efficiency of virgin and aged asphalt binder depending on temperature. The calculated inter-diffusion coefficients indicate that the rejuvenator diffuses faster into virgin asphalt binder than aged asphalt binder. The radial distribution functions of asphaltene, resin, and aromatic pairs show that rejuvenator causes the molecular structures of virgin and aged asphalt binder more similar to that of virgin asphalt binder. The rejuvenator reduces the self-association trends of asphaltene molecules, but saturates from local aggregation inside the rejuvenated asphalt binder. On the other hand, rejuvenator increases translational mobility of saturate, aromatic, resin and asphaltene fractions.

The State-of-the-Art Review on Molecular Dynamics Simulation of Asphalt Binder

Asphalt pavement has been widely used in the world. As the main components of asphalt pavement, the asphalt binder is crucial to the service performance and life of the road. In the past decades, numerous studies were conducted on technical performance, aging, and modification of the asphalt binder. With the development of modern technology, it was discovered that the microscopic properties, aging mechanism, and modification mechanism of the asphalt binder affect the macroscopic performance of asphalt pavement significantly. As a new emerging powerful numerical tool, the molecular dynamics (MD) simulation has been developed to study the asphalt binder material from a micro perspective. Based on the previous studies, some average asphalt binder models, fractional asphalt binder models, aged asphalt binder models, and modifier models were proposed by many researchers, which have made remarkable progress in asphalt studies; the microproperties, aging mechanism, and modification mechanism of the asphalt binder can also be analyzed using the MD simulation. Overall, the state-of-the-art review provides a comprehensive view for the readers to better understand the development, establishment, and application of the asphalt molecular model.

A Comprehensive Evaluation of Rejuvenator on Mechanical Properties, Durability, and Dynamic Characteristics of Artificially Aged Asphalt Mixture.

In this study, the aged asphalt binder and mixture were laboratory prepared through short-term ageing testing and long-term ageing testing. Firstly, the effect of rejuvenator on physical properties of aged asphalt binders was investigated. In addition, a series of laboratory tests were performed to evaluate the influence of ageing and rejuvenator content on the mechanical properties, durability and dynamic characteristics of asphalt mixtures. Physical test results of asphalt binder testified that rejuvenator used can efficiently recover the aged asphalt binder. However, the effect of ageing and rejuvenator content exhibits different trends depending on the physical property tests conducted. Moreover, artificially aged asphalt mixture with rejuvenator has better ability to resist moisture damage and ravelling. In addition, the ITSR value is more suitable to evaluate the moisture susceptibility for asphalt recycling. Although rejuvenator improves the thermal cracking resistance and fatigue property of aged asphalt mixture, rejuvenated mixture shows greater modulus and inferior ability to resist reflective cracking than the unaged mixture. Moreover, rejuvenated mixture shows less dependence on frequency at high temperature regions and stronger dependence at low temperature regions compared to unaged and long-term aged mixtures.

Rheological and anti-aging performance of SBS modified asphalt binders with different multi-dimensional nanomaterials

Multi-dimensional nanomaterials composed of layered silicates and inorganic nanoparticles are promising anti-aging agents for styrene–butadiene–styrene triblock copolymer modified asphalt binder (SBSMA) aging. However, different combinations of nanomaterials may exhibit different effect on SBSMA. Thus, the objective of this paper was to determine an optimal combination among multi-dimensional nanomaterials composed of 1%organic expanded vermiculite (OEVMT) + 2%nano-silica (SiO2), 2%nano-titanium (TiO2), 2%nano-zinc oxide (ZnO). Further, more appropriate and pavement performance-related methods, such as multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), DSR function (DSRFn) value and shear stress relaxation (SSR) test, were adopted to evaluate effect of multi-dimensional nanomaterials on rheological performance of SBSMA. The results showed that multi-dimensional nanomaterials can improve rutting resistance of SBSMA by increasing its elastic recovery while decreasing viscous flow. The results of DSRFn value and residual stress were nearly consistent, all showing that improvement of cracking resistance of SBSMA was dependent on different combinations of nanomaterials. Except 1%OEVMT + 2%SiO2, other two multi-dimensional nanomaterials obviously improved cracking resistance of SBSMA. In addition, fatigue life of SBSMA was decreased by addition of multi-dimensional nanomaterials, especially for 1%OEVMT + 2%ZnO. Aging resistance of SBSMA was improved by multi-dimensional nanomaterials, especially for 1%OEVMT + 2%TiO2. Among multi-dimensional nanomaterials investigated, 1%OEVMT + 2%TiO2 is recommended for SBSMA after considering both rheological and anti-aging assessments.

Diluting or dissolving? The use of relaxation spectrum to assess rejuvenation effects in asphalt recycling

In asphalt pavement recycling, rejuvenators are often used to improve the engineering properties of asphalt binders in old pavements. A key question interested by practitioners is if the rejuvenators simply dilute the microstructures formed in aged asphalt binders or dissolve them. The latter is clearly preferred in effective asphalt pavement recycling. In this paper, a new approach is developed to assess rejuvenation effectiveness, using relaxation spectra calculated from the oscillation shear test data of asphalt binders. An indicator developed from the relaxation spectra enables the assessment of reduction in the proportion of large microstructures in aged asphalt binder. Experiments using three rejuvenators and three asphalt binders aged in different conditions prove the validity of this approach. Scan tunneling electron microscope (STEM) was also used to examine the possible changes of microstructures in asphalt binders before and after rejuvenation. STEM images indicate that rejuvenators can break down some microstructures formed during asphalt aging, but they cannot totally dissolve them. Observations from the STEM images are consistent with the results shown in the relaxation spectra. It is anticipated that the proposed indicator provides pavement practitioners a convenient way to evaluate the rejuvenation effectiveness.

Comparison of ESEM and physical properties of virgin and laboratory aged asphalt binders

The physical and microstructural properties of four straight run asphalt binders were examined and compared in combination with short term aging (RTFOT) and long-term (PAV) laboratory aging. RTFOT aging was conducted at temperatures of 123, 143 and 163 °C. The physical testing parameters included penetration, softening point and Dynamic Shear Rheology (DSR) complex shear modulus and phase angle at 10 °C. The binders selected came from four different sources and had the same penetration grading (70/100). They all showed an increase in stiffness with aging, including with the increase in RTFOT temperatures and especially with PAV aging. The microstructural evolution of the binder was examined by Environmental Scanning Electron Microscopy (ESEM) on aged binders at 123 and 163 °C. The physical changes with aging corresponded to an evolution in the binders’ ‘fibril’ microstructure under ESEM, as a result of electron beam exposure, with the microstructure getting denser with PAV aging. This densification (fibril area) of the microstructure was quantified with image analysis for the virgin and RTFOT aged samples, and the fibril formation time was also measured. The asphalt binders showed varied ESEM ‘fingerprints’ and aged in different ways. The ESEM ‘formation time’ and ‘fibril area’ of the binders generally showed good correlation with the physical properties, although this was not the case for all of the binders due to their unique aging characteristics.

Effect of Asphalt Binder Aging on Thermodynamic Parameters and Its Relationship with Moisture Sensitivity of Asphalt Mixes

AbstractIn the existent methods for investigating the potential of moisture damage based on thermodynamic concepts in asphalt mixes, the role of asphalt binder aging on thermodynamic parameters has...