Rheological Properties Of Asphalt Binders Research Articles

Investigation of Surface Modification of Bagasse Fibers: Performance of Asphalt Binders/Mixtures with Bagasse Fibers

The influence of surface modification on the properties of bagasse fibers and asphalt binders/mixtures was investigated. Bagasse fibers were modified by single, binary, and ternary methods with hydrochloric acid, sodium hydroxide, and sodium chlorite, respectively. The physical and chemical properties of bagasse fibers were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, and an adsorption test, respectively. The rheological properties of asphalt binders with bagasse fibers or lignin fibers were analyzed by the dynamic shear rheometer test and bending beam rheometer test. In addition, the performance of asphalt mixtures with bagasse fibers or lignin fibers were evaluated by a wheel rutting test, bending test at a low temperature, and water stability test, respectively. In conclusion, the hydrophilic functional groups on the fiber surface were partially eliminated by modification, facilitating the degradation of different fiber components. Furthermore, the degree of fibrillation was improved, and more interfaces with asphalt components were formed, thus enhancing the high-temperature deformation resistance of asphalt binders, but slightly impairing its low-temperature performance. Among all modification methods, the ternary composite modification exerted important influences on fiber structure, oil absorption, and rheological properties of asphalt binders, significantly enhancing the performance of asphalt mixtures. Combined with surface modification methods, bagasse fibers would be promising reinforced pavement materials.

Evaluation of benzaldehyd and dioctyl phthalate modified direct coal liquefaction residue asphalt binder based on rheology and microscopic mechanisms

This study intends to investigate the influence of benzaldehyde and dioctyl phthalate (DOP) on the rheological properties and microstructure of direct coal liquefaction residue (DCLR) modified asphalt binder. The high and low temperature rheological properties and fatigue properties were obtained by dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR) tests were conducted to evaluate the mechanism of property improvement in the DCLR modified asphalt binder. The results showed that the addition of DCLR increased the complex shear modulus G*, rutting factor G*/sin δ and fatigue life Nf of base asphalt binder, significantly improving the high temperature deformation resistance and fatigue resistance of base asphalt binder. This was attributed to the hardening effect resulting from the addition of DCLR, which enhanced the elastic properties, weakened the viscous properties and fluidity of asphalt binder. Additionally, the use of benzaldehyde and DOP reduced the creep stiffness S and lower continuous grading temperature Tc of DCLR modified asphalt binder, which compensated for the shortcomings of low temperature rheological properties of asphalt binder. The SEM images indicated that benzaldehyde and DOP significantly increased the compatibility of DCLR with the base asphalt binder. The FTIR tests showed that the addition of benzaldehyde and DOP introduced the aldehyde and ester groups, which were interacted with more polar functional groups in the asphalt to reduce the resistance to movement between the heavy components in the DCLR modified asphalt binder, which promoted the flow of asphalt and the dispersion of DCLR, and as a result, the benzaldehyde and DOP modified DCLR asphalt binder exhibited satisfied rheological properties.

Evolution of Rheological and Microscopic Properties of Asphalt Binders under Fuel Corrosion

Vehicle fuel leaks can adversely affect the performance of asphalt pavements. To study the mechanisms of fuel corrosion damage in asphalt, four asphalt binders were selected in this study, and the evolution of their rheological and microscopic properties was investigated. Fuel corrosion caused continuous mass loss in asphalt binders. Base asphalt lost more than 50% of its mass after 24 h of fuel corrosion, while modified asphalts had better resistance. According to dynamic shear rheometer tests and multiple stress creep recovery tests, modifiers improved the high-temperature rheological properties of these asphalt binders. As the degree of fuel corrosion deepened, the indexes characterizing the high-temperature performance deteriorated. Rubber-modified asphalt showed the best resistance to high-temperature deformation, while the performance of LDPE-modified asphalt was more stable. In contrast, fuel corrosion improved the resistance of asphalt binders to low-temperature cracking to some extent: the creep strength (S) decreased as the creep rate (m) increased, and the resistance of SBS-modified asphalt to low-temperature cracking was optimal, with a 36% decrease in S-value after 24 h of fuel corrosion. Fourier transform infrared spectroscopy tests showed that diesel corrosion was a process of this physical dissolution, with no change in the chemical functional groups. Meanwhile, by using fluorescence images and analyzing the four-component test results, we found that fuel corrosion disrupted the stabilized structure formed by the modifiers, and the heavy components in the asphalt binders were converted into light components. This study reveals the evolution of the rheological and microscopic properties of asphalt under fuel corrosion, which can provide a reference for the optimization of fuel corrosion resistance in asphalt pavement.

Low-temperature aliphatic eutectic phase change materials for asphalt: Design and characterization

Cost and thermal stability are critical for the application of low-temperature phase change materials (PCMs) in asphalt pavements. Aliphatic eutectic phase change materials (AEPCMs) are expected to be potential candidates for new low-temperature PCMs. The objective of this study was to develop a set of low-temperature AEPCMs with a phase transition temperature of − 3.58 to 16.21 °C and a latent heat of 144.01 to 195.96 J/g in an attempt to replace tetradecane (TD). To fully evaluate the properties of low-temperature AEPCMs and TD, and the impacts of their direct incorporation into asphalt, the chemical structures, enthalpies, mass retention, economic costs, and changes in the physical and rheological properties of the modified asphalt were investigated. The results showed that AEPCMs with a phase transition temperature similar to that of TD could be obtained by eutectic crystallization and retained the chemical properties of their components. However, the latent heat decreased progressively with the increase in the number of components. The AEPCMs exhibited higher thermal stability than TD, with a maximal increase in mass retention from 37.24% to 86.66% at 180 °C. In addition, AEPCMs exhibited significant cost advantages. The most inexpensive AEPCMs synthesized in the laboratory is only 112.01 ¥/kg and an enthalpy cost of 0.57 ¥/kJ, accounting for 30.1% and 35.8% of TD cost, respectively. Incorporation of AEPCMs and TD increased the lightweight component of asphalt binders and caused damage to the conventional physical and rheological properties of asphalt binders, but polar AEPCMs had fewer deleterious effects on asphalt compared to nonpolar TD.

A Bayesian deep learning approach for rheological properties prediction of asphalt binders considering uncertainty of output

Traditional methods for assessing rheological properties are often time-consuming, labor-intensive, and subject to operator bias. Moreover, conventional deep learning models may suffer from overconfidence in their predictions, limiting their applicability in real-world scenarios. A Bayesian deep learning framework that provides accurate predictions of asphalt binder rheological properties and quantifies the associated uncertainties is proposed to address these challenges. Atomic Force Microscopy images were employed as input values for the model, and the Dynamic Shear Rheometer test for the rheological property measurements was used. The proposed Bayesian deep learning model used Markov Chain Monte Carlo techniques to estimate model parameters and associated uncertainties. The effectiveness of the approach through an application involving multiple additives to validate the generality of the proposed framework was demonstrated. The results indicate that the Bayesian deep learning model offers improved prediction accuracy, reduced testing time, and operator-independent results compared to conventional methods. Additionally, quantifying uncertainties in predictions enable more informed decision-making and risk assessments in asphalt binder selection and pavement design. Overall, this study provides a novel and robust approach for predicting the rheological properties of asphalt binders, paving the way for more efficient and reliable pavement engineering practices.

Evaluation of asphaltenes a potential alternative for cement in stabilized base courses using asphalt emulsion

Stabilization of pavement base material using asphalt emulsion has been widely used to improve pavement performance. This technology produces a high-quality base course material with decreased energy consumption, carbon footprint, and raw material usage. Cement has been used as a common additive to improve these mixes strength and moisture resistance. However, some drawbacks are also associated with cement, such as negative environmental impacts, high costs, and low-temperature deficiencies. Asphaltenes is a by-product of oil-sand bitumen with little commercial value in current practice. To investigate the impact of asphaltenes on improving the rheological properties of asphalt binder, a series of binder characteristics tests using a dynamic shear rheometer, breaking time and microscopic evaluation is conducted on modified asphalt emulsion with asphaltenes. Asphaltenes is then added to asphalt emulsion-stabilized granular material, to be compared with mixtures prepared with cement. Two asphaltenes and cement-modified mixes are prepared and compared to unmodified mixtures. All mixes are tested for permanent deformation and moisture sensitivity using a Hamburg wheel tracker and flow number test, while the low-temperature properties are evaluated using indirect tensile strength tests. Dynamic modulus is also evaluated to analyze the viscoelastic behavior of the mixes. The results of this study reveal a considerable increase in the rutting resistance of asphalt mixes by adding 1% of both additives (by total weight of mix), and asphaltenes-modification shows less adverse impacts at intermediate and low temperatures than cement-modification.

A Comprehensive Literature Review on Polymer-Modified Asphalt Binder

Due to periodic variations in temperature and heavy traffic loading, hot-mix asphalt (HMA) pavements undergo considerable distress during their service life. The rheological properties of asphalt binder, when subjected to complex physical and chemical processes, make it stiff and sometimes brittle, which ultimately plays a huge part in pavement deterioration. This phenomenon is commonly known as asphalt aging. Incorporating polymer modifiers with virgin asphalt can work as an effective means to change the binder properties and alleviate the issues related to asphalt aging. Different types of polymers, including elastomers, plastomers, and reactive polymers, can mixed in different combinations with the virgin asphalt to create polymer-modified binders (PMBs). In general, polymers are typically added to the virgin asphalt binder in PMB manufacturing at weight percentages ranging from 3% to 7%. Previous research suggests that many polymer-modified binders (PMBs) show great resiliency and perform extremely well during field and laboratory testing, although the complex nature of asphalt itself makes it significantly difficult to understand the relationship and compatibility of the asphalt–polymer system. This paper aims to develop a comprehensive literature review on the chemical aspects, microscopic structure, and compatibility of polymers with virgin asphalt. It was found that swelling, storage stability, blend morphology, and the polymer mixing technique play a great role in the compatibility of asphalt–polymer systems. Thermoplastic elastomers (e.g., styrene–butadiene–styrene) and plastomers (e.g., ethylene–vinyl acetate) are the most used polymer modifiers for asphalt binders. The compatibility of the polymer–asphalt system can be improved by sulfur vulcanization, antioxidants, hydrophobic clay minerals, functionalization, and reactive polymers, among other techniques.

Influence of hybrid fibers on rheological properties of asphalt binders and its prediction with computing techniques

The research investigated the influence of hybrid fibers on rheological properties of asphalt binders and its prediction with computing techniques. First, the morphology and high temperature resistance of steel wool fibers and basalt fibers were evaluated. Then, the asphalt binders with different fibers-asphalt volume ratios and basalt fibers-steel wool fibers volume ratios were prepared, and the rheological properties of asphalt binders were characterized. The statistical analysis including multi-factors analysis of variance and simple-effects analysis were conducted. Finally, non-linear regression, back propagation (BP) neural network with illustration by SHapley Additive exPlanations (SHAP) were employed for the prediction. The results indicated that there was a great difference in morphology between basalt fibers and steel wool fibers, meanwhile steel wool fibers are more stable under high temperature environment. The hybrid fibers were proved contributed for increment of complex modulus and rutting resistance, but it showed a severe segregation between fibers and bitumen as the temperature was raised. The volume content of 6% might be a critical value for the formation of fiber network in statistics. Furthermore, the results of computational evaluation clearly showed that the BP neural network was more capable of accurately calculating the rheological properties of asphalt binders than non-linear regression. The sensitivity analysis by SHAP demonstrated temperature and steel wool fibers content are the more influential inputs for rheological properties. Therefore, the use of hybrid fibers improves in general the rheological properties of asphalt binders, but the proportion needs to be limited.

Study on effect of thermal, oxidative and ultraviolet coupled aging on rheological properties of asphalt binder and their contribution rates

ABSTRACT This paper aims to investigate the effect of different environmental conditions on the aging properties of virgin asphalt binder and evaluate the magnitude of aging on asphalt binder under different environmental conditions. The effect of thermal, oxidative and ultraviolet aging on the rutting resistance, fatigue resistance and cracking resistance of virgin asphalt binder was characterised based on rheological parameters. The contribution rate of different environmental factors to the aging of asphalt binder was quantitatively analysed. Results showed that high temperature repaired cracks in the asphalt binder caused by ultraviolet aging. The single aging factor of heat, oxygen and light had little effect on the rheological properties of asphalt binder. High temperature and oxygen would accelerate the aging effect of the asphalt binder aging process. Thermal–oxidative–UV-coupled aging had a more pronounced effect on the aging of asphalt binder than thermal–oxidative aging. The fatigue resistance of asphalt binder is more sensitive to the response of aging. The contribution rates of thermal–UV aging, UV–oxidative aging and thermal–oxidative aging were all greater than the sum of the contribution rates of the two corresponding single factors. The aging of asphalt binder was mainly due to thermal–oxidative aging when the aging temperature exceeded 80°C.

Characterization of the fatigue behavior of asphalt binders, FAMs, and AC mixtures based on multiscale approaches and the S-VECD model

Although investigations on upscaling methodologies across binder, Fine Aggregate Matrix (FAM), and Asphalt Concrete (AC) have been reported in the literature, additional evaluations should be performed considering the characteristics of the materials. This study investigates the relationship between the fatigue damage behavior of asphaltic material constituents based on a correlational assessment, as well as on experimental and analytical approaches. For that, rheological properties of asphalt binders were determined and AC and FAM were characterized by uniaxial tests. The fatigue parameters presented strong correlations across the scales and upscaling experimental equations were obtained from experimental data with good and promising results.

Evaluation of Aging Evolution of Olive Pomace–Modified Asphalt Binders under Natural Weather Aging Conditions

Abstract The natural weather aging test (NWAT) for asphalt binders is an essential benchmark aging test used to investigate the aging evolution of asphalt binders under actual weather conditions. This study assessed the aging rates of olive pomace–modified asphalt binders and the control neat binder under NWAT. Instead of aging days, weather factors were proposed as metrics to correlate with the aging evolution of the rheological properties of asphalt binders. The test results showed that the olive pulp–rich fraction-modified asphalt binders after the rolling thin-film oven (RTFO) test had lower aging susceptibility than the RTFO-aged control binder. The RTFO-aged binders exhibited lower aging rates than the corresponding unaged asphalt binders under NWAT. The sums of weather indexes such as the sum of the daily maximum ultraviolet index are rational field metrics to correlate with the rheological aging properties of natural weather–aged asphalt binders. Caution shall be taken when using aging days to interpret the aging rates of asphalt binders under NWAT.

Effect of two organic phase change materials on the thermal performance of asphalt pavements

ABSTRACT Higher temperature is one of the key reasons for thermal distresses in asphalt pavement. It also adds to the Urban Heat Island (UHI) effect as it influences the near-surface air temperature. To design cooler pavements, phase change materials (PCMs) can be incorporated into asphalt pavements. However, considering the negative effects of PCM leakage on the physical and rheological properties of asphalt binder, a cent-percent effective core-shell encapsulated PCM suitable for asphalt pavement applications was developed under this study. With the incorporation of two organic mixture (OM) based PCMs, i.e., OM-35 and OM-42, a peak decrease in the pavement surface temperature of 3.05 °C and 4.36 °C, respectively were observed under the field condition. Furthermore, from the long-term thermal performance assessment, it was found that the magnitude of temperature reduction depends on the phase change temperature and latent heat of PCM. The season of occurrence of the peak temperature reduction depends on the phase change temperature of the PCM. Due to PCM solidification, the increase in night-time pavement surface temperature was observed to be about half of that during day time. Further, the statistical analysis reveals that the decrease in pavement surface temperature due to PCM incorporation is significant and consistent.

Rheological properties of asphaltene-modified asphalt binder and mastic

Asphaltene is one of the component of asphalt binder. Asphaltene certainly contributes to the elasticity and stiffness of a binder's traditional viscoelastic behaviour. Introducing asphaltene as a separate modifier may improve the qualities of asphalt mastic. The influence of asphaltene on the rheological properties of asphalt binder and mastic is discussed in this paper. Asphalt binder grade 60/70 PEN was modified by adding with 1% asphaltene content. Asphalt mastic was then prepared using asphaltene-modified asphalt binder and aggregates passing 75 μm. A viscosity and a dynamic shear rheometer (DSR) test were performed to evaluate the rheological properties indexes such as rutting factor (G*/sin δ), phase angle δ, complex modulus G* and elasticity modulus of asphaltene-modified asphalt binder and mastic. It is anticipated that adding 1% asphaltene would enhance viscosity, stiffness, and rutting resistance. Based on the data analysis, modified mastic viscosity and stiffness reduced. Increased asphaltene did not improve mastic to be more rut-resistance. Among the three types of asphalt binder, PG76 binder has the best rut-resistance performance, modified asphalt binder takes the second place, and 60/70 PEN has the worst rut-resistance performance. While for the mastics, PG76 mastics have the best rut resistance performance, 60/70 PEN mastics take the second place, and modified mastics have the worst rut-resistance performance. Overall, PG76 mastic had the highest complex shear modulus value (G*), rutting parameter (G*/sin), and phase angle (δ), indicating that it had the best viscosity properties, stiffness, and resistance to rutting. Therefore, it is advised to increase the asphaltene content in order to support future research.

An investigation into the nonlinear rheological behavior of modified asphalt binders using large amplitude oscillatory shear rheology

ABSTRACT Asphalt binders have been studied extensively with respect to their linear viscoelastic properties. From these properties, performance metrics have been derived and used for specification purposes. However, these materials are used in asphalt concrete pavements where they may experience time-dependent loads in the nonlinear regime. In the past, the vast majority of asphalt binders exhibited strong correlations between their linear and nonlinear properties and so despite this mismatch in characterization and the actual use phase domains, a system based on linear properties could be reliably deployed. More recently though, novel binders and additives have been introduced with differing relationships between linear and nonlinear behaviors. As such there is a need to characterize the asphalt binder response under large strains and use specifications that more explicitly account for the binder nonlinearity. Here, an attempt has been made to characterize the nonlinear rheological properties of asphalt binder using large amplitude oscillatory shear. The response of a single terminal blend, crumb rubber modified binder under large strains is analyzed using Lissajous-Bowditch plots while the contribution of higher harmonics is evaluated using Fourier-transform rheology. Finally, the elastic and viscous contributions are obtained using stress decomposition to an orthogonal set of Chebyshev polynomials. It is found that the relative nonlinearity increases with increasing strain and frequency under the tested conditions. The asphalt binder evaluated in this study predominantly exhibits shear thinning and either strain stiffening or softening behavior depending upon the test conditions. The applicability of time-temperature superposition in the nonlinear regime for asphalt binders is also evaluated.

Assessment of the effect of straw lignin-based synthetic resin as a modifier on the rheological properties of asphalt binder towards better utilization of straw biomass

PurposeTo extend the reuse method and rate of straw biomass, this paper investigated the effect of lignin synthetic phenolic resin (LPF) on the rheological properties of asphalt binder.Design/methodology/approachFour LPFs with 25%, 50%, 75% and 100% substitution rates were prepared by replacing phenol with lignin in synthetic resins and using it as a modifier to prepare a bio-asphalt binder. Temperature sweep tests were conducted to evaluate aging resistance and temperature sensitivity of the bio-asphalt binder. The rutting resistance of the bio-asphalt binder was evaluated by frequency sweeps and multiple stress creep recovery (MSCR) test. Linear amplitude sweep (LAS) tests were conducted to evaluate the fatigue resistance of the bio-asphalt binder. A master curve was constructed to further analyze the rheological properties of the bio-asphalt binder at different frequencies. The low-temperature cracking resistance of the binder was evaluated by G-R parameters, critical temperatures and ΔTc. Fourier transform infrared spectroscopy (FTIR) was performed to investigate the changes in the functional groups of the binder before and after aging.FindingsThe results indicated that adding LPF could improve the high-temperature rutting resistance, fatigue resistance, aging resistance of asphalt and the binders are less affected by temperature. Additionally, LPF slightly prohibited the low-temperature performance of the asphalt binder, which, however, was significantly lower than the base asphalt degradation during aging. Compared with base asphalt binders, the bio-asphalt binder showed no new absorption peaks generated after adding LPF, identifying that the improved asphalt binder performance by LPF was a mainly physical modification.Originality/valueThe main objective of this paper is to further improve the substitution rate (i.e. the mass substitution ratio of lignin to phenol) of lignin and broaden the application of biomass resins, thus realizing resource sustainability.

Rheological, Spectroscopic, and Chemical Characterization of Asphalt Binders Modified with Phase Change Materials, Polymers, and Glass Powder

Recently, asphalt modifiers have increasingly gained attention for improving the mechanical and thermal characteristics of asphalt mixtures. As a result, innovative additives are being constantly developed to achieve this purpose. However, some modifiers can significantly impact the chemical and rheological properties of the asphalt binder. This paper investigates the rheological, spectroscopic, and chemical properties of asphalt binders modified with a bio-based phase change material (PCM) and phase change material mixed with glass powder (GPCM). Two binders were investigated, PG 58-28 and PG 70-28 polymer modified asphalt binder with 3% SBS. Two different percentages of GPCM (5% and 7%) were added to PG 58-28 and PG 70-28, and 5% PCM was added to PG 58-28. The results indicated that the PCMs effectively reduced the viscosity values of the asphalt binder. Moreover, testing the modified binders using differential scanning calorimetry (DSC) showed that the PCMs released the stored heat when the melting/freezing temperature was reached. However, adding glass powder with the PCMs negatively affected the thermal properties of PCMs in the asphalt mix. In addition, considerable changes in the stiffness of the binders modified with GPCM at an intermediate temperature were obtained when tested using DSR. Finally, the TGA results revealed that this specific type of PCM would not be suitable as a hot mix asphalt (HMA) modifier as its evaporation temperature is lower than the mixing temperature HMA. However, the use of PCM in warm mix asphalt (WMA) would be a more viable option. The results showed that the evaporation temperature for the PCMs was low; therefore, the PCMs cannot be used in HMA. In addition, modified binders with PCMs and GPCM showed lower viscosity compared to the control binder. The DSR rheological analysis showed that the control binder and 5%PCM, 5%GPCM, 7%GPCM, 5%GPCM, and 7%GPCM binders had similar overall properties. However, the addition of GPCM significantly decreases the stiffness at intermediate temperatures.

Effects of zeolite on rheological properties of asphalt materials and asphalt-filler interaction ability

The rheological properties of asphalt materials (asphalt binder and mastic) and asphalt-filler interactions play critical roles in the performance of asphalt mixtures. However, the rheological properties of zeolite-foamed asphalt materials and zeolite-foamed asphalt-filler interactions are significantly influenced by zeolite, which is used as a foaming additive. To study the effects of zeolite on the rheological properties of asphalt materials and asphalt-filler interaction, the base asphalt, limestone filler, and two kinds of zeolites in two dehydrated states were selected to prepare zeolite asphalt/mastic and zeolite-foamed asphalt/mastic. First, the effects of zeolite on the chemical composition and micromorphology of asphalt binders were evaluated using a Fourier transform infrared spectrometer (FTIR) and fluorescence microscopy (FM), respectively. Then, the rheological properties of asphalt binders and mastics were measured by rotational viscosity (RV) and dynamic shear rheometer (DSR) tests. The results indicated that zeolite did not chemically react with the components of asphalt, and zeolite minerals played a role in volume filling and physical adsorption in asphalt, which dispersed in the asphalt in the form of floccules. Adding zeolite minerals to asphalt binders and mastics enhanced the elasticity, which was beneficial to high-temperature performance and adverse to fatigue performance. Conversely, the effect of zeolite water released by zeolite was the opposite. The effect of zeolite on the rheological properties of asphalt materials was consistent with that of zeolite minerals because the enhancing effect of zeolite minerals was dominant, offsetting the weakening effect of zeolite water in asphalt binders and mastics. The three indices, namely, intrinsic viscosity [η], Palierne-C-G* parameter, and Ziegel-B-δ parameter, were selected to evaluate the zeolite asphalt-filler interaction ability and zeolite-foamed asphalt-filler interaction ability. The results showed that the asphalt-filler interaction ability was enhanced after adding zeolite minerals to asphalt, and the influence of zeolite on asphalt-filler interaction was consistent with zeolite minerals. However, the opposite effect was observed for zeolite water.

Investigation of the Rheological Properties of Asphalt Binders Modified with Nanomaterial

This study examined the effects of the Aerosil 150 addition on the rheological characteristics of bituminous binders at various temperatures. In the study, a frequency sweep test was applied to determine the rheological properties of pure binders and binders with 2%, 4% and 6% Aerosil 150 additives. Unaged binders were subjected to the frequency sweep test using a Bohlin DSR rheometer at test temperatures ranging from 40°C to 80°C (increasing by 10°C). The results showed that adding Aerosil 150 additive to the pure binder raised the binder's complex modulus (G*) values while decreasing the phase angle (δ) values. At 40 °C 0.1 Hz frequency, 2%, 4% and 6% Aerosil 150 doped binders gave G* values 1.52, 2.02 and 3 times higher than pure binder, respectively. The same ratio is 1.31, 1.54 and 1.99 times at 5 Hz frequency and 1.28, 1.47 and 1.82 times at 10 Hz frequency. At the same temperature, as the frequency value increases, the binders' complex modulus values approach each other. When the phase angle values at 40°C were examined, the 2%, 4%, and 6% Aerosil 150 modified binders, when compared to pure binder at 0.1 Hz frequency, yielded 2.75°C, 5.56°C, and 9.17°C lower phase angle values, respectively. This decrease is 3.19, 5.04 and 7.33 °C at 5 Hz frequency and 3.09, 4.84 and 6.76 °C at 10 Hz frequency. This shows that at various frequencies, the modified binder behaves more adaptably than the pure binder. The fact that the binder has a low δ value against a high G* value indicates that it will exhibit more flexible behavior. It was discovered as a result that Aeresil 150 modified binders performed better in terms of rheological qualities than pure binders.

Characterizing the Aging and Performance of Asphalt Binder Blends Containing Recycled Materials

Abstract The aging of asphalt concrete is mainly governed by the aging of the asphalt binder, which is a naturally occurring organic hydrocarbon. Both chemical and rheological properties of asphalt binder are expected to change as aging continues. The pavement industry is increasing the use of different recycled materials in the construction and rehabilitation of flexible pavements to preserve natural resources, save costs, and reduce environmental emissions. The aged binder from recycled materials is expected to alter the binder properties and its aging characteristics in the new mix. In this study, 3 different virgin base binder types (PG 64-16, PG 58-22, and PG 70-10) and 7 different binder blends containing recycled binders (up to 100 % binder replacement) were subjected to different aging conditions. The rheological and chemical properties of these binders were characterized using a dynamic shear rheometer and Fourier transform infrared spectroscopy, respectively. It was found that the Glover-Rowe parameter distinctively captured the change in binder rheological properties with aging for the different binder blends. A good correlation (R2 value of 0.83–1.00) was observed between binder chemical and rheological properties. The source and performance grade of the base binder were found to govern the correlation between the rheological and chemical properties of the blended binder. Hamburg wheel tracking (for rutting and moisture sensitivity) and indirect tensile asphalt cracking test (for fracture) tests were conducted on asphalt mixes maintaining the same blended binder ratios. The laboratory mix performance parameters were found to correlate well with the properties of the blended binders. Therefore, properties of the blended binders can be an important source of information for predicting the performance of asphalt mixes containing recycled materials.

Ageing Evaluation of Foamed Polymer Modified Bitumen with Bio-Flux Additive

This paper presents the results of an analysis of the changes in the stiffness of asphalt binders modified with a bio-flux additive and subjected to the processes of foaming and short-term ageing. The purpose of the analyses was to determine changes in the rheological properties of asphalt binder as a result of technological processes characteristic of hot and warm mix asphalt technology. Three asphalt binders with similar penetration but varying degrees of polymer modification were tested: 50/70, 45/80-55 polymer-modified bitumen, and 45/80-80 highly modified bitumen. Tests were carried out on four groups of binders: original binders, foamed binders after 14 days of storage, non-foamed binders after Rolling Thin Film Oven Test (RTFOT) ageing, and foamed binders after 14 days of storage subjected to RTFOT ageing. The master curves of the complex shear modulus G* were analysed, and three indexes of binder stiffening were determined, characterising the investigated effects. The tests showed that some of the stiffening indices significantly depended on the degree of polymer modification and the content of the bio-flux additive. Moreover, it was found that the foaming process in the case of paving-grade bitumen and polymer-modified bitumen did not contribute to the additional stiffening of the binders.