Effects of rejuvenator on performance-based properties of rejuvenated asphalt binder and mixtures

ArticleinConstruction and Building Materials 21(5):958-964 · May 2007with 301 Reads
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Abstract
Firstly, the performance-based properties of rejuvenated aged asphalt binders, i.e., the blends of aged binders containing a rejuvenator at various percentages, were investigated under high, intermediate and low temperatures. The tests were conducted on the blends at three stages as follows: no aging, rolling thin film oven (RTFO) residuals and as well RTFO + pressure aging vessel (PAV) residuals through dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. Optimum concentrations of the rejuvenator needed for the blends to reach a target PG grade were obtained from the blending charts of the rejuvenated aged binders in terms of performance properties. The rejuvenator is a soft binder containing a low asphaltene content of 2 wt%. Secondly, selected performance-based properties were conducted on hot mix asphalt (HMA) using the rejuvenated aged binder and a virgin HMA as a control mixture. Results showed that the rejuvenator affected significantly the performance-based properties of both the rejuvenated aged binders and the mixtures containing the rejuvenated aged binders. It was possible to get optimum concentrations of the rejuvenator using the blending charts so that the rejuvenated binders reach a target PG grade. The mean value of the concentrations was proved to be more reliable through the performance-based properties of the mixtures if it is used for a design value for recycling. The properties of the asphalt paving mixtures with the rejuvenated binders were even improved or in the same level as the properties of the virgin mixtures.

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  • Article
    Full-text available
    The use of recycled materials such as Reclaimed Asphalt Pavement (RAP) and Recycled Asphalt Shingle (RAS) in asphalt pavements is a valuable approach to construct sustainable pavements and to preserve natural resources and energy. However, the use of high amounts of RAP and RAS can potentially cause durability-related distresses such as cracking and raveling due to the presence of severely aged asphalt binders. Rejuvenators have been widely used to overcome this issue and to mitigate the problems associated with the use of aged binders. They can improve the viscoelastic and rheological properties of asphalt mixtures containing RAP and RAS. Much has been learned about various types of rejuvenating agents, techniques to apply these agents, and challenges associated with their applications. This article reviews the literature on the applications of various types of rejuvenators in paving industry and their effects on the properties of the aged binders. The techniques for rejuvenating the aged asphalt binders and the mechanism of rejuvenation are also reviewed. Moreover, methods to determine the optimum rejuvenator content to achieve optimized mechanical and durability properties of the asphalt binders and mixtures are discussed. The findings in this research show that rejuvenators can be successfully used to restore the properties of the aged binders. It is hoped that this review will serve as a guidelines for pavement engineers to better design the asphalt mixtures containing rejuvenators. This review will also help scientists to find future avenues of research on the applications of rejuvenators in asphalt industry
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    Full-text available
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  • Technical Report
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    Recycled materials replacing part of virgin materials in highway applications has shown great benefits to the society and environment. Beneficial use of recycled materials can save landfill places, sparse natural resources, and energy consumed in milling and hauling virgin materials. Low price of recycled materials is favorable to cost-saving in pavement projects. Considering the availability of recycled materials in the State of Maryland (MD), four abundant recycled materials, recycled concrete aggregate (RCA), recycled asphalt pavement (RAP), foundry sand (FS), and dredged materials (DM), were studied. A survey was conducted to collect the information of current usage of the four recycled materials in States’ Department of Transportation (DOTs). Based on literature review, mechanical and environmental properties, recommendations, and suggested test standards were investigated separately for the four recycled materials in different applications. Constrains in using these materials were further studied in order to provide recommendations for the development of related MD specifications. To measure social and environmental benefits from using recycled materials, life-cycle assessment was carried out with life-cycle analysis (LCA) program, PaLATE, and green highway rating system, BEST-in-Highway. The survey results indicated the wide use of RAP and RCA in hot mix asphalt (HMA) and graded aggregate base (GAB) respectively, while FS and DM are less used in field. Environmental concerns are less, but the possibly low quality and some adverse mechanical characteristics may hinder the widely use of these recycled materials. Technical documents and current specifications provided by State DOTs are good references to the usage of these materials in MD. Literature review showed consistent results with the survey. Studies from experimental research or site tests showed satisfactory performance of these materials in highway applications, when the substitution rate, gradation, temperature, moisture, or usage of additives, etc. meet some requirements. The results from LCA revealed significant cost savings in using recycled materials. Energy and water consumption, gas emission, and hazardous waste generation generally showed reductions to some degree. Use of new recycled technologies will contribute to more sustainable highways.
  • Article
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  • Article
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  • Article
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  • Article
    Full-text available
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  • Article
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  • Article
    Full-text available
    Both chemical and rheological aspects of aged bitumen in reclaimed asphalt pavement (RAP) material play an important role in the final performance of bituminous mixtures containing recycled asphalt material. This must be especially considered in the case of pavements containing high RAP content. The use of rejuvenators and/or virgin bitumen in recycled mixtures helps improving the properties of aged bitumen. This research study investigates RAP oxidised bitumen and its possible rejuvenation with virgin bitumen and addition of various additives as rejuvenator agents. Tests were conducted to analyse the chemical, rheological and physical behaviours of several binder mixes before and after laboratory ageing processes. Longterm ageing of rejuvenated binder mixes was also investigated to assess the effectiveness of rejuvenation over time. The results showed that the addition of virgin bitumen and rejuvenators could improve the performance of oxidised bitumen and increase its resistance to further ageing.
  • Chapter
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  • Article
    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.
  • Article
    Despite the well-recognized benefits of recycling milled asphalt pavement material, some remaining challenges limit the reclaimed asphalt pavement (RAP) content in asphalt mixtures. Rejuvenators are frequently used to enhance the properties of the aged binder in asphalt mixtures containing RAP. The blending process between the rejuvenator and the aged binder continues to be a source of performance uncertainty, especially for high-RAP mixtures. This study investigates the diffusion of a rejuvenator into RAP binder and the effect of aging and blending procedures on the homogeneity of the rejuvenated binder. A staged extraction method was used to separate the different layers within the asphalt film that covers the aggregates. Each layer was characterized by its rheological properties measured by a dynamic shear rheometer. Results showed that the rejuvenator was initially mostly absorbed by outer binder layers but continued to diffuse into inner layers as time elapsed. Aging also affects outer layers more intensely. A homogeneity index is introduced to quantify the consistency of the binder.
  • Article
    The effects of using waste engine oil (WEO) and waste cooking oil (WCO) as rejuvenators on some engineering properties of asphalt concrete containing reclaimed asphalt pavement (RAP) have been studied. 10% (by the weight of total binder) of the rejuvenators has been added to asphalt concrete containing 25%, 50% and 75% (by the weight of aggregate) of RAP, and the Marshall properties, indirect tensile strength (ITS), permanent deformation and fatigue properties of the mixtures have been evaluated. The effect of rejuvenators on Marshall properties depends on RAP content and type of rejuvenator, with higher values for the mixtures containing WEO. The ITS of the mixtures increase with increasing RAP content, and decreases with increasing rejuvenators content. Addition of WEO results in lower accumulated strain in the mixtures than adding WCO. In addition, the accumulated strain in the mixtures containing 50% of RAP is higher than that in the mixtures containing 25% and 75% of RAP. The fatigue life of the mixtures was found to increase with increasing RAP content and decrease by addition of rejuvenator with a higher reduction for the WCO. In general, it is concluded that using the rejuvenators enables using higher RAP content in recycled asphaltic mixtures. Keywords: reclaimed asphalt pavement, waste engine oil, waste cooking oil, fatigue test, creep properties, tensile strength
  • Article
    Full-text available
    Multicycle repeated utilization of reclaimed asphalt pavement (RAP) is a quite recent development of sustainable pavement materials technology. To investigate ageing rules and recycling possibility of asphalt binders in repeatedly used asphalt mixture, virgin asphalt AH-70 samples were heated by the rolling thin film oven test (RTFOT) at 163°C, respectively, for 40, 85, 180, 240, and 300 minutes to simulate different ageing degrees, and then the aged ones were rejuvenated by adding a self-made rejuvenator. This ageing and recycling process was repeated altogether for 5 cycles to simulate repeated use of RAP binders. In repeated recycling, rejuvenator contents for different cycle numbers or ageing durations were not the same, and the optimum ones were initially estimated by an empirical formula and finally obtained by comparative tests. Empirical rheological tests and the infrared spectral (IR) analysis were done before and after each cycle of recycling. Results indicate that for impact on deterioration of asphalt binders, ageing time is more important than cycle number. Meanwhile, the asphalt after multicycle repeated ageing and recycling can be restored to the empirical rheological indices level of the virgin asphalt and meet specifications requirements.
  • Article
    Full-text available
    Copper slag (CS) is a derivative of copper production that is mainly composed of heavy metals. The large amount of this material accumulated around the world entails a serious environmental danger. Its use as a replacement of mineral aggregate in asphalt mixtures would allow to increase the durability and resistance, taking advantage of its physical-chemical properties. In this research, physicochemical analyses of different combinations of CS, reclaimed asphalt pavements (RAP), asphalt cement and aggregates by X-Ray Diffraction (XRD) and Fourier-Transform InfraRed spectroscopy (FT-IR) were developed. Subsequently, Marshall stiffness ratio, indirect tensile strength (IDT) and resilient modulus tests were performed to determine their implication in mechanical behaviour. Asphalt mixes with ranges from 45 to 55% of recycled material have improved stability, Marshall Flow and Stiffness ratio, obtaining values comparable with those from a conventional mixture. At the same time, its resilient modulus and IDT values increased by 35% compared to conventional mixes. To maintain values similar to conventional mixes, when the amount of RAP decreases the amount of CS should be increased, with a maximum value of 35%. This behaviour is explained by the presence of fayalite and magnetite in CS, which are hard, dense and hydrophobic components that produce increased elastic deformation of the binder before breaking.
  • Article
    Rejuvenators are widely used to improve the properties of asphalt binders particularly low temperature and fatigue cracking behavior. Rejuvenators vary significantly in terms of their physical properties and chemical composition. The nature of the interaction between the rejuvenators and the base asphalt binders is very complex and an extensive study into the chemical and thermal properties of the rejuvenators and how they impact the rheological properties of rejuvenated binders is of paramount importance. In this research, a neat PG58-28 binder is rejuvenated with three different materials produced from soybean oil at a dosage of 6% by total weight of binder. The rheological properties of the control and rejuvenated binders are assessed using performance grades showing a drop in both the critical low and high temperature grades with rejuvenation. The oxidative stability of the rejuvenators as well as the rejuvenated binders is studied using thermogravimetric analysis (TGA). The crystallization and melting points of the rejuvenators are observed using differential scanning calorimetry (DSC). DSC is also used to examine the glass transition temperatures of the control and rejuvenated binders. The TGA results showed one of the rejuvenators to be susceptible to oxidation which agreed with the rolling thin film oven (RTFO) mass loss results. The glass transition temperature of the rejuvenated binders decreased denoting improved low temperature cracking properties in line with the performance grade results.
  • Article
    Full-text available
    Featured Application: This study of the dispersion behavior for polymer-modified rejuvenator would lay a foundation for the performance research and further recycling engineering practice of polymer-modified rejuvenated asphalt binders. Abstract: 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.
  • Article
    Full-text available
    Rejuvenators can restore the reclaimed asphalt pavement (RAP) binder for another service period. To achieve this, homogeneous distribution of rejuvenator and good diffusion into reclaimed asphalt binder film has to be ensured. Ten potential rejuvenator addition locations are summarised, and two most promising are compared in full-scale study: spraying of rejuvenator on cold reclaimed asphalt on the feeding belt before heating versus addition of rejuvenator to hot reclaimed asphalt in mixer. RAP samples were collected at various places in the production line to evaluate the effect of rejuvenator addition location on softening point, penetration, rheology and chemical composition of extracted binder. The results revealed that passing through the extreme temperatures in the RAP heating drum does not sacrifice mechanical performance or increase chemical ageing of the rejuvenated binder. A benefit of early rejuvenator addition is that it provides a longer residing time of rejuvenator on the binder and thus potentially may allow higher binder activation and better blending of RAP binder with rejuvenator and virgin binder. This has to be evaluated through mixture tests.
  • Thesis
    The effects of using recycling agents (RAs) on hot mixture asphalt (HMA) have recently acquired special attention in the academic community due to the fact that recycled mixtures typically have high stiffness as a result of long periods of oxidative aging, mainly driven by environmental conditions (e.g., sunlight, temperature, and oxygen). In addition, the use of RAs in HMA aims at restoring the rheological and physicochemical properties of the aged binder contained in the reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) to provide the HMA mixtures with adequate performance, similar or superior to that of virgin HMA (i.e., without RAP, RAS, or RA). Subsequently, the objective of this thesis is to study the rheological and ageing characteristics of asphalt binder blends fabricated with RAP, RAS, and recycling agents using high recycled binder ratios (RBRs). The materials were retrieved from a recent field project constructed in Texas that incorporated high percentages of RAP/RAS materials with recycling agents and warm mixture asphalt additives in five highway sections. The laboratory characterization included: (1) blending charts, dosage estimations, and master curves from dynamic shear rheometer, (2) the Glover-Rowe (GR) parameter in Black Space diagrams, and (3) Fourier transform infrared spectroscopy (FTIR). The results indicated that the use of the T1 recycling agent allowed for restoring the rheology (i.e., G* and phase angle) in all the combinations studied. Furthermore, validation of the regional linear blending concept allowed for calculating dosages of RA. The G-R parameter in Black Space diagrams showed that more than 40 pressure aging vessel (PAV) hours of artificial aging produce high stiff blends with high cracking susceptibility (i.e., damage zone between 180 kPa and 450 kPa). Furthermore, FTIR data showed a tendency of increase in the carbonyl area when using the T1 RA. Results include a suggested set of laboratory tools for characterizing binder blends, and a proposed methodology for determination of optimum dosages of RA in recycled mixtures with high RBR to be used in future research.
  • Article
    This study used multiple chemical-rheological tests to investigate the long-term characteristics of rejuvenating agents in reclaimed asphalt binders. To this end, a base binder and its blending with an extracted binder obtained from recycled asphalt pavements were selected, and two different types of rejuvenating agents: agriculture-based and petroleum-based agents were used to modify the blended binder. The base binder and the blended binders that were modified by the two rejuvenators were then aged using a typical laboratory long-term aging procedure. The chemical studies included: a saturates-aromatics-resins-asphaltenes analysis, Fourier transform infrared spectroscopy, and elemental (carbon, hydrogen, nitrogen, sulfur and oxygen) analysis. The rheological tests primarily investigated the linear viscoelastic properties through aging and rejuvenation. The effects of rejuvenators on restoration were quite material-dependent, which was related to the different chemical compositions of the rejuvenators and their chemical-molecular interactions with the parent binder. The tests and analysis results showed that the immediate effects of rejuvenators are mostly the result of the addition of lighter molecules in rejuvenators, while the long-term effects were material-specific and further chemistry-driven. From the two rejuvenating agents studied herein, the petroleum-based material improves performance of the binder in the next round of service by preserving the chemical composition and maintaining the stability, whereas the agriculture-based agent used in this study might increase the aging issues because of its pre-existing high oxygen content, which could negatively affect long-term durability over service period.
  • Article
    The use of reclaimed asphalt pavements (RAP) and recycled asphalt shingles (RAS) in pavements has already become a norm in the United States because of the substantial reduction in construction cost, energy consumption, and greenhouse gas emissions. However, highway agencies are still reluctant to increase the overall percentage of RAP and RAS in asphalt pavement mixtures because of a higher potential of premature cracking in these pavements. To avoid early pavement failures and untoward maintenance cost, rejuvenators are being increasingly used in asphalt mixtures to reconstruct the chemical structures of oxidized RAP and RAS binders. However, the overall effects of rejuvenators on the properties of asphalt binders have not been well studied in recent years and used in determining the optimum dosages for different rejuvenators. This study characterizes the effects of rejuvenators on the rheological, chemical, aging, rutting, and cracking properties of asphalt binders containing recycled binders and then uses the findings to recommend optimum dosages. To that end, PG 64-22 virgin binders were blended with different types of rejuvenators and recycled binders at various concentrations. Laboratory test results showed that rejuvenators could reduce the stiffness, oxidation, and cracking potential of these blends. Results also suggested that selecting the rejuvenator dosage and type on the basis of only one criterion could not meet the specifications of traditional virgin binders. In addition, the results showed that different rejuvenators worked differently with different mixtures.
  • Article
    Full-text available
    This paper presents an experimental investigation on the combined use of high content of reclaimed asphalt pavement (RAP) and rejuvenators, for producing asphalt mixtures for wearing courses. First, the new Binder-Fast-Characterization-Test (Bitumen Typisierungs Schnell Verfahren in German) BTSV method, recently proposed in Germany, is used to determine the amount of rejuvenator required to design recycled mixtures for a specific RAP source. Then, a set of seven asphalt mixtures for wearing course is prepared with different amounts of RAP and with three types of rejuvenators. The BTSV procedure is further applied to evaluate the rheological properties of the binder extracted from the mixtures. Resistance to permanent deformation, stiffness, fatigue, and low temperature behavior tests are then performed to determine the material response. It is observed that the use of recycled material and rejuvenators results in similar or better deformation resistance, higher stiffness and enhanced low temperature properties, with an improved fatigue behavior, also for high RAP content, when compared to mixtures prepared with virgin material. These findings suggest the possibility of using rejuvenators for field tests on wearing courses.
  • Article
    Full-text available
    In this paper, the combined use of reclaimed asphalt pavement (RAP) and rejuvenators for producing hot recycled asphalt mixture is investigated based on the new Bitumen Typisierungs Schnell Verfahren - BTSV method (Binder-Fast-Characterization-Test), recently proposed in Germany, and through laboratory experimentation. For this purpose, a set of three different asphalt mixtures is prepared with different amounts of RAP and with three types of rejuvenators. Then, the BTSV method is used to obtain the rheological properties of the binder extracted from the mixtures. Resistance to permanent deformation, stiffness, fatigue and low temperature behavior are evaluated to determine the material response. It is observed that the combined use of RAP and rejuvenators results in mechanical properties are comparable to mixtures prepared with virgin material, confirming the validity of BTSV in determined the rejuvenator’s proportions. These findings suggest the possibility of using rejuvenators for field applications.
  • Article
    The long-term effects of SBS-modified binders and rejuvenators on the properties of high-RAP mixtures, especially the cracking resistance, have not been resolved. Therefore, this paper evaluates the cracking resistance of polymer-modified asphalt binders, mastics, fine aggregate matrices (FAMs) and mixtures containing RAP material and a rejuvenator. A series of laboratory tests is performed on different asphalt material scales, including a frequency sweep test; a BBR test for asphalt binders, mastics and FAM mixes; and a dynamic modulus test and the Illinois flexibility index test for asphalt mixtures. Short-term ageing and long-term ageing are also considered for different asphalt material scales. The results show that the asphalt binders and mixes containing RAP materials have similar Glover-Rowe (G-R) values and flexibility index (FI) values to those of the virgin binders and mixtures that are only subjected to short-term ageing. These results indicate that a rejuvenator can partially decrease the stiffness of the RAP material before long-term ageing; however, the cracking resistance of asphalt materials obviously decreases after long-term ageing. Asphalt materials containing RAP are more susceptible than virgin asphalt material to thermal cracking, and the rejuvenator does not improve the long-term cracking resistance of high-RAP material. The correlations between different laboratory ageing conditions for the asphalt binder, mastic, FAM and mixture are analysed. Binders subjected to PAV 20 h ageing present rheological properties equivalent to those of mixes subjected to the long-term oven ageing (LTOA) protocol for 5 d at 85°C. Binders subjected to PAV 40 h ageing present rheological properties equivalent to those of loose mixtures subjected to the LTOA protocol for 12 h at 135°C. The cracking resistance parameters of the binders, mastics and FAMs are also compared with the cracking resistance parameters of the mixture, and the results illustrate that the G-R parameters of asphalt binder, mastic and FAM are well correlated with the G-R parameter and FI parameter of the mixture. Moreover, the G-R parameter can predict the cracking performance of the asphalt mixture.
  • Article
    The aged pavement material from a defunct pavement – commonly known as reclaimed asphalt pavement (RAP) – contains stiffened binder caused by loss of volatile materials and oxidation. Therefore, addition of a high amount of the RAP to asphalt mix, in case of pavement recycling, may make it prone to fatigue failure. Due to this reason, the addition of RAP to asphalt mixture in substantial amount has been a challenge so far. “Rejuvenators” are generally used to restore the properties of the aged binders in the recycled mixes. The present study deals with the assessment of two non-edible oils, that is, pongamia oil and composite castor oil (a composite rejuvenator having castor oil and coke-oven gas condensate) as asphalt rejuvenators to achieve 100% RAP recycling. The study mainly comprises rheological characterisation studies such as rutting behaviour, fatigue behaviour, dynamic mechanical analysis and creep-recovery studies of the rejuvenated binder specimens. Chemical investigations using infrared spectroscopy also affirmed use of these oils in effectively restoring the properties of aged binders. In addition, for assessment of the long-term performance in terms of thermostability of the rejuvenated binders, a thermal analysis was carried out using a simultaneous thermal analyser, which confirmed the adequate thermal stability of the rejuvenated binders. From the investigations taken up under this study, it was concluded that 5% oil (for both pongamia and composite castor oil) rejuvenated aged binder could show desirable rutting and fatigue behaviours and sometimes even better than the virgin binder. However, its confirmation can be laid only after suitable mix performance studies.
  • Article
    Using some kinds of rejuvenators to restore the characteristics of aged binder in reclaimed asphalt pavement might lead to reduction in rutting resistance. In this research, nanocaly was used as virgin bitumen modifier to compensate for the negative effect of rejuvenator in asphalt mixtures containing high percentages of reclaimed asphalt pavement. For this purpose, dynamic creep test was conducted on the mixtures containing 2%, 4% and 6% modified NC and 25%, 50%, 75% RAP. Laboratory test results indicated that the reduction of flow number due to adding rejuvenator in the mixture can be compensated by using nanoclay modified virgin bitumen.
  • Chapter
    In this paper, the organic compounds with aromatic odor in waste peel were extracted by steam distillation in the laboratory, and then were analyzed by techniques of gas chromatography-mass spectrometry. The waste peel extract with different dosages were added to the aged asphalt to produce the recycled asphalt binders. The rheological properties of base asphalt, aged asphalt and recycled asphalt were tested. The results showed that the main chemical compositions of the waste peel extract are light oil which similar to the aromatic component of asphalt. Penetration, softening point, viscosity, complex modulus, phase angle and low temperature stiffness of recycled asphalt can be fully restored to the level of base asphalt with the addition of the waste peel extract. The research of this paper provides a new idea for the treatment of waste peel, and the waste peel extract can be used as a kind of bio-rejuvenator for the recycling of asphalt pavement.
  • Chapter
    Waste cooking oil (WCO) can be used to rejuvenate aged asphalt and restore its properties. However, the influence of WCO properties on rejuvenating behavior of aged asphalt is still unknown. The objective of this study is to investigate the effect of WCO viscosity on basic and rheological properties of aged asphalt. The materials used for this study included eight kinds of WCO (fabricated by fresh soybean oil in the laboratory) and one aged asphalt (AH-90). The basic properties of rejuvenated asphalt were characterized by penetration value, softening point and ductility, then the influence of WCO viscosity on rheological properties of rejuvenated asphalts were evaluated by rotational viscosity, rutting parameter, complex modulus and phase angle master curves, and creep recovery ratio. The experimental results indicate that WCO viscosity has a great influence on the properties of rejuvenated asphalt, and different aged asphalts require WCOs with different viscosity to achieve the desirable rejuvenation effects. Basic and rheological properties of aged asphalt can be restored to some extent but there are still gaps between the basic performances of WCO rejuvenated asphalts and virgin asphalt. WCOs with too high or too low viscosity values would have an adverse impact on the performance recovery of rejuvenated asphalt. WCO with viscosity ranging from 420–700 mm²/s are preferable to restore the properties of rejuvenated asphalt in this research.
  • Article
    Softer binders have been used to compensate for the stiffness of reclaimed asphalt pavement (RAP) binders in mixtures; however, several studies have shown that asphalt rejuvenators can allow more RAP to be incorporated in mixtures than can softer binders alone. Nevertheless, rejuvenators are not specifiied by some state agencies because of potential rutting-related concerns. Therefore, the use of polymer modified asphalt (PMA) binder was evaluated to ascertain if it can remedy any rutting performance degradation while maintaining or improving the cracking characteristics of the mixtures. The objective was to produce mixtures with high RAP content that perform similar to or better than an allvirgin-material control mixture. The effect of five asphalt rejuvenators on the performance of a 50% RAP surface-layer mixture was evaluated relative to rutting and cracking. The results illustrated that the rejuvenators degraded the rutting resistance of the 50% RAP mixture, although the use of PMA binders remedied these degradations. The rejuvenators improved the fatigue cracking resistance of the 50% RAP mixture to a level higher than did the all-virgin control mixture and also the 50% RAP mixture with softer binder alone. Overall, the data indicated that a combination of an asphalt rejuvenator and a PMA binder was required to yield a high RAP mixture with similar or better performance than a similar conventional mixture.
  • An integrated approach for determining additive requirements in hot mix recycling. The sixth international conference structural design of asphalt pavements
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    • Ac Edler
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    • Assen
    Servas VP, Edler AC, Ferreira MA, Assen EJ van. An integrated approach for determining additive requirements in hot mix recycling. The sixth international conference structural design of asphalt pavements, vol. 1. The University of Michigan; 1987, p. 23–33.
  • Evaluation of low temperature properties of asphalt mixture
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    Zeng H, Isacsson U. Evaluation of low temperature properties of asphalt mixture. In: Proceedings of the third international conference on road and Airfield Pavement Technology, Beijing, China, vol. 1. 1998, p. 10–18. 964 J. Shen et al. / Construction and Building Materials 21 (2007) 958–964
  • Low temperature cracking: Test selection, SHRP-A-400
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  • Low temperature cracking: binder validation, SHRP-A-399
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    Jung DH, Vinson TS. Low temperature cracking: binder validation, SHRP-A-399, 1994b.
  • Article
    This paper describes the results of 3 kinds of thermal fracture tests of asphaltic mixture and stress relaxation test of asphaltic mixture in tension at low temperature. Test results indicate that the difference between the fracture temperature and the temperature at intercept is about 20 degree C under various thermal loading conditions, thermal stress under thermal repeated loading conditions corresponds to thermal stress under stress relaxation at constant temperature and the characteristics of stress relaxation under various thermal loading conditions are similar with that of stress relaxation in tension.
  • Article
    Full-text available
    Recycled asphalts were evaluated based on SHRP binder specification. DSR (Dynamic Shear Rheometer) and BBR (Bending Beam Rheometer) tests were carried out on samples of the recycled asphalts under three conditions: original binder, RTFOT (Rolling Thin Film Oven Test) residue and RTFOT+PAV (Pressurized Aging Vessel) residue. PG (Performance-Graded) classification was conducted. New straight asphalts at which the recycled asphalts are aimed with a same penetration were also tested as control samples. It is indicated that there is no significant difference between the recycled and the controlled samples for the obtained results. It is suggested the agent for asphalt recycling is effective with respect to the SHRP specification.