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To investigate the effects of aging on the microstructure, mechanical behavior, and thermal performance of bitumen surfaces, this study utilizes atomic force microscopy (AFM) for a qualitative and quantitative assessment of the surface morphology, roughness, and surface energy evolution at the microscopic scale during the fusion process of both virgin and aged bitumen. The formation mechanism of beelike structures is also analyzed. Additionally, the thermal stability of bitumen is evaluated through thermogravimetric (TG) and derivative thermogravimetry (DTG) curves. Results revealed substantial differences in polarity and structure between asphaltene and surrounding bitumen molecules, leading to ineffective dissolution and dispersion of asphaltene in surrounding bitumen molecules, ultimately forming distinct striped beelike structures. With an increase in the content of virgin bitumen, the quantity and total area of beelike structures significantly increase, whereas their size and average area decrease. Aging induces the migration and alteration of bitumen internal components, resulting in the aggregation, dispersion, and fusion of biomass on the microsurface, thereby increasing surface roughness and decreasing surface energy. With the introduction of virgin bitumen and rejuvenators, bitumen surface roughness markedly decreases, whereas surface energy exhibits an increasing trend. This suggests that the microstructural properties of rejuvenated bitumen are effectively restored, with high fusion homogeneity between virgin and aged bitumen. Thermal analysis results indicate that the characteristic temperature and residual weight of rejuvenated bitumen are lower than aged bitumen, approaching the virgin bitumen. Specifically, the residual weight for virgin bitumen, aged bitumen, and rejuvenated bitumen are 17.23%, 22.03%, and 17.65%, respectively. This suggests that the introduction of rejuvenators increases the content of light components in bitumen, leading to a lower thermal decomposition temperature due to the volatilization of light components during heat treatment. [ABSTRACT FROM AUTHOR]

This study evaluated the individual and cumulative impact of different design factors on moisture damage of hot-mix asphalt (HMA) using the modified Lottman test. This study considered five different types of design aggregate gradations (DAG), three binder types, and three levels of compactive effort. To evaluate the significance of the influential factors that affected the moisture sensitivity of the mix, statistical analysis was performed. This study also investigated the influence of volumetric parameters of the bituminous mixes on moisture damage. The correlation of different design factors and various volumetric parameters with the tensile strength ratio (TSR) was further investigated through analysis using the Pearson correlation coefficient. The need for this investigation arises from the scarcity of comprehensive studies examining the individual and combined effects of various factors and the impact of volumetric parameters on moisture susceptibility. Additionally, linear regression models were developed to predict TSR based on the design factors and volumetric parameters considered in the study. The final model showed a close fit, with low mean absolute percentage error (MAPE=0.931) and a good coefficient of determination (R2=0.752). Moreover, based on the tested mixtures, the study establishes a threshold value of dry indirect tensile strength (ITSdry=750 kPa) and wet indirect tensile strength (ITSwet=650 kPa), along with TSR (= 0.85). [ABSTRACT FROM AUTHOR]

The process of reclaimed asphalt pavement (RAP) recycling may occur multiple times during the life of the pavement. This study investigates the effect of multiple recycling on binder properties by employing a virgin 3045 PEN grade binder that was aged in the laboratory intended to simulate aging of binders in RAP. The aged binder was rejuvenated using two bio-oils and one softer binder. The doses of the bio-oils and softer binder were determined by matching the continuous high-temperature performance grade (PGH) of the rejuvenated RAP binder to that of the virgin binder. This aging and rejuvenation cycle was repeated three times. Finally, fatigue and rutting performance of the binder was evaluated for the three reuse levels. Results indicate that the material can be reused up to three cycles keeping good performance on fatigue or rutting. However, care should be taken regarding the cumulative effect of bio-oils causing an over-softening effect on the of the RAP. [ABSTRACT FROM AUTHOR]

Waste rubber modified bitumen has gained significant attention as a sustainable and innovative material in the field of pavement engineering. This study aims to evaluate the performance of rubber modified bitumen mastic by considering its rheological properties, specifically focusing on preparation parameters, i.e., rubber content, mesh number, and filler to bitumen ratio. From the experimental results, the rheological properties of rubber modified bitumen mastic were significantly influenced by preparation parameters. Increasing the rubber powder content in bitumen mastic results in higher viscosity. Increasing the rubber content improves high-temperature rutting resistance to a certain extent, however, excessive rubber powder content would result in weakened high-temperature performance improvement. The rutting factor decreases gradually with an increase in the rubber mesh number. A ratio of filler to bitumen of 0.95 exhibits the best resistance to rutting at high temperatures. Higher rubber content and larger mesh number correspond to stronger low-temperature crack resistance in bitumen mastic. As the ratio of filler to bitumen increases, the low-temperature deformation capacity gradually decreases, resulting in weaker low-temperature crack resistance. Based on the grey relation analysis, the ratio of filler to bitumen has the greatest impact on the high and low-temperature rheological properties of bitumen mastic, followed by the rubber content. The rubber mesh number has a relatively lower impact. It is crucial to control the ratio of filler to bitumen to avoid excessive values. When possible, a higher rubber powder content should be used while meeting process requirements. These findings provide valuable insights into the design and optimization of rubber modified bitumen mastic, which can contribute to the development of sustainable and high-performance bitumen mixtures, promoting the use of recycled rubber in pavement engineering. [ABSTRACT FROM AUTHOR]

Abstract: This study employs the One-Dimensional Vertical Electrical Resistivity technique to elucidate the subsurface stratigraphy and structures beneath the axis and abutments of the suggested Smaquli dam, situated to the east of Erbil City in Kurdistan Region of Iraq (KRI). Three traverses were conducted using a Schlumberger array. Data interpretation was performed using the Russian commercial software, IPI2WIN. Each measurement point featured a maximum total electrode spread ranging from 400-600m, reaching an investigation depth of 130m to 150m. The inter-distance between successive measurement points varied from 16m to 17.5m. Geo-electrical sections were generated by interpreting the data, revealing three distinct lithological groups: alluvial deposits (upper first group) with a thickness ranging from 3 to 10 meters, marl and marly limestone of the Shiranish Formation (second group) with thickness ranging from 18 up to 110 meters, and dolomitic limestone of the Bekhme Formation (third group) which its thickness is not defined. These lithological groups exhibited significant resistivity contrasts, rendering the resistivity method effective for delineating their interfaces. The resistivity of the upper horizon ranged from 18 to 136 Ω·m, the second horizon exhibited values between 19 and 304 Ω·m, while the lower third horizon showed high resistivity values ranging from 97 to over 50000 Ω.m.. The relatively low resistivity values of the lower horizon (Bekhme Formation) are interpreted as fractured and water-saturated limestones, whereas the high values are indicative of bituminous material. A correlation was established between the geo-electrical sections and borehole geologic columns, demonstrating consistency in indicating the presence of two rock units within the uppermost 20m, which corresponds to the borehole depth. [ABSTRACT FROM AUTHOR]

Plastic addition to bitumen increases the stiffness of the binder, reduces its workability due to the increase in viscosity, and causes storage stability issues. Thus, plastic pre-treatment methods are needed. This research aims to address these shortcomings by developing a wax derived from the pyrolysis of polyethylene (PE) waste and investigating its efficacy as an additive in virgin bitumen and bitumen modified with recycled polypropylene (PP). Penetration, softening point, segregation, stress ratio, consistency, stiffness, and viscosity of the modified bitumen were measured. The interior structure and chemical changes of the proposed binders were also studied using a fluorescence microscope and Fourier-transform infrared spectroscopy (FTIR). When virgin bitumen is modified with 7% PE wax, its softening point increases (+ 15%), its viscosity is reduced (− 27%), and no segregation issue is observed. It also presented a stiffness increase (+ 32%) and better resistance to hot climates. Adding 7% of PE wax to bitumen modified with 5% PP reduces its viscosity by 70% and segregation by 26% while increasing its stiffness and rutting resistance in comparison to the bitumen solely modified with PP. These results reveal that, in addition to enhancing bitumen properties, the proposed substance reduces compaction and mixing energy requirements. [ABSTRACT FROM AUTHOR]

Waterborne polyurethane asphalt emulsion (WPUA) is an environmentally friendly bituminous material, whose performance is highly dependent on the phase structure of the continuous phase. In this paper, WPUAs in the vicinity of phase inversion were prepared using waterborne polyurethane (WPU) and asphalt emulsion. The chemical structures, thermal stability, dynamic mechanical properties, phase-separated morphology and mechanical performance of WPUAs were studied. Fourier-transform infrared (FTIR) spectra revealed that there are no –NCO bonds in either the pure WPU or WPUAs. Moreover, the preparation of WPUA is a physical process. The addition of WPU weakens the thermal stability of asphalt emulsion. WPU improves the storage modulus of asphalt emulsion at lower and higher temperatures. The glass transition temperatures of the WPUA films are higher than that of the pure WPU film. When the WPU concentration increases from 30 wt% to 40 wt%, phase inversion occurs; that is, the continuous phase shifts from asphalt to WPU. The WPUA films have lower tensile strength and toughness than the pure WPU film. However, the elongations at break of the WPUA films are higher than that of the pure WPU film. Both the tensile strength and toughness of the WPUA films increase with the WPU concentration. Due to the occurrence of phase inversion, the elongation at break, tensile strength and toughness of the WPUA film containing 30 wt% WPU are increased by 29%, 250% and 369%, respectively, compared to the film with 40 wt% WPU. [ABSTRACT FROM AUTHOR]

Interface bonding between different asphalt pavement layers is crucial in maintaining the integrity of the pavement structure. To improve the interface bonding, bitumen emulsion is commonly used as the tack coat material. However, the bonding performance of conventional bitumen emulsion is limited. This study investigated the possibility of using waterborne epoxy resin modified bitumen emulsion as a novel tack coat material. The resistance to moisture damage of waterborne epoxy resin modified bitumen emulsion was evaluated using the boiling water test, followed by the characterization of the interface adhesion between waterborne epoxy resin modified bitumen emulsion and aggregate using the binder bond strength test. To further determine the interface bonding between different asphalt layers bonded by waterborne epoxy resin modified bitumen emulsion, a two-layer asphalt mixture structure was fabricated, and the shear strength was measured. The results indicated that the incorporation of waterborne epoxy resin can increase the interface bonding between the two asphalt mixture layers. [ABSTRACT FROM AUTHOR]

Traditional tests for low-temperature cracking mainly focus on bitumen or overall mixture properties, overlooking the contribution of asphalt mixture elements. This study investigated the fundamental material properties influencing low-temperature cracking by considering mix design and surface free energy (SFE) parameters. The SFE elements of four aggregate types and eight bitumen types were measured using the universal sorption device and Wilhelmy plate methods, respectively. Based on these measurements, important SFE parameters such as cohesion free energy (CFE), adhesion free energy (AFE), and the ratio between base and acid elements (RBA) in the aggregate SFE were calculated utilizing bitumen and aggregate SFE data. Additionally, material parameters, including the bitumen's creep stiffness (CS) and CS diagram slope (m-value), were determined through bending beam rheometer tests. Further, factors related to the mix design, such as the aggregates' specific surface area (SSA), bitumen film thickness (BFT) on aggregate surfaces, and aggregate index (Ia), were examined. A semicircular bending (SCB) test was conducted on 32 fabricated asphalt mixtures to assess the correlation between these parameters and their impact on low-temperature cracking potential in the asphalt mixtures. Multiple linear regressions were employed to predict the objective functions. The statistical analysis demonstrated that SFE concepts can effectively determine the potential for low-temperature cracking in asphalt mixtures. According to SCB test results concerning fracture toughness and fracture energy, our proposed models indicated the significantly positive influence of factors such as BFT, Ia , AFE, CFE, SSA, and RBA. [ABSTRACT FROM AUTHOR]

This study explores the influence of intrinsic bitumen properties on foam characteristics, considering physical properties (penetration, softening point, viscosity), chemical compositions (SARA components, FTIR indices), and physico-chemical characteristics [surface free energy (SFE)]. Ten distinct bitumen samples from two different sources were analyzed. The results reveal that physical properties alone do not sufficiently account for variations in foaming potential among bitumen types. However, chemical compositions and SFE proved to be more informative, explaining the differences in maximum expansion ratio and foam index, specifically for bitumen from the same source. In contrast, when bitumen originates from different sources, none of these intrinsic properties can clarify foaming potential. Notably, intrinsic bitumen properties fail to elucidate the variability in the half-life of foamed bitumen, even when the bitumen types share the same source. These findings underscore the significance of considering multiple factors when assessing bitumen's foam characteristics, particularly when evaluating materials from diverse sources. [ABSTRACT FROM AUTHOR]

Bituminous binders, often referred to as asphalt, play a pivotal role in the construction and maintenance of flexible pavements. As the demand for durable and sustainable infrastructure continues to rise, a thorough understanding of the physical and rheological properties of bituminous binders becomes imperative. This manuscript presents a comprehensive review of various mechanical tests used to assess bituminous binder properties, including penetration (Pen), softening point (SP), penetration ratio (PR), penetration index (PI), ductility tests and absolute and kinematic viscosities. These mechanical tests serve as fundamental tools for evaluating binder consistency, hardness, ductility and flow behaviour. SP and Pen measurements are employed to grade bituminous binders based on their response to temperature. Additionally, PR and PI provide valuable insights into binder performance under varying environmental conditions. Ductility tests offer critical information about a binder's ability to elongate without breaking, a crucial factor in withstanding the stresses imposed by traffic. In parallel, the manuscript underscores the significance of understanding the rheological properties of bituminous binders. Dynamic shear rheometry (DSR) is introduced as a method for characterising complex modulus (G*), fail temperature and phase angle (d) behaviour under different temperature and loading conditions. These tests are well established in the USA based on Strategic Highway Research Program (SHRP) specifications. Their relevance in the Indian context is discussed, with recent inclusion of rheological parameters in the Bureau of Indian Standards (BIS) specification. The manuscript highlights the role of instrumental analysis techniques, including Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM), in uncovering the molecular and microstructural aspects of bituminous binders. FTIR aids in identifying functional groups within the binder, elucidating chemical composition and aging effects, while NMR provides insights into molecular mobility and heterogeneity. SEM is instrumental in revealing the binder's microstructure and its interaction with aggregates. In conclusion, this manuscript offers a comprehensive analysis of both mechanical and rheological testing, emphasising their significance in evaluating bituminous binder properties. It also stresses the growing importance of instrumental analysis techniques, particularly for chemically modified bitumen. The primary aim is to provide a valuable resource for researchers, engineers and practitioners in the field of civil engineering and infrastructure development. [ABSTRACT FROM AUTHOR]

The adaptation of traditional roads (tRoads) into electrified roads (eRoads) generally requires the inclusion of a charging unit (CU) in the pavement. In this study, the structural behaviour of a conductive eRoad is assessed using 2-D FEM simulations, and compared to the behaviour of a tRoad. Thermal and mechanical loadings representative of field configurations were applied and the relaxation response of the bituminous mixtures was calculated. Resulted strain and stress fields indicated a differential thermomechanical behaviour of the eRoad components. Strain and stress concentrations due to daily temperature fluctuations were pronounced near the interface with the CU. Traditional parameters obtained at the bottom of the bituminous layer were found similar for tRoad and eRoad. It is concluded that the development of new failure criteria is necessary to predict the service life of eRoads, in order to consider the thermally-induced strain and the impact of the volumetric rearrangement of the CU. [ABSTRACT FROM AUTHOR]

The mechanical properties of Bituminous Stabilized Materials (BSMs) have been widely studied in the past, however the influence of temperature on their non-linear constitutive properties has never been addressed. In this research, the role of temperature on the mechanical properties of a BSM prepared with asphalt emulsion and hydrated lime was investigated. Triaxial shear strength tests were performed at different temperatures and confining pressures. The experimental results allowed the development of finite element models defining the local stress and temperature-dependent mechanical properties. An approach for incorporating plasticity and temperature effects through a 2D axisymmetric finite element model of multilayer pavement was developed. Three pavement structures were subjected to the same load applications at different temperatures. Their responses were compared to determine the most critical scenario. In conclusion, plasticity and temperature are key factors for BSMs analysis and design while linear-elastic assumptions lead to overestimating the service life of rehabilitated pavements. [ABSTRACT FROM AUTHOR]

Research has shown that reversible phenomena such as non-linearity, self-heating and thixotropy occur during laboratory fatigue testing on bituminous mixes. This work aims to develop a test protocol to separate and quantify the recovery of reversible phenomena and the restoration of damage. Besides proposing some adjustments to the protocol, in the present paper, its repeatability is evaluated by comparing the results obtained for several samples of the same bituminous mixture. The test procedure is composed of two parts: short complex modulus tests (200 cycles at 10 Hz) at temperatures ranging from 8°C to 14°C with strain amplitudes ranging from 50 to 110 µm/m are used and five partial fatigue tests (at 10°C) are carried out at 100,000 cycles, 100 µm/m and 10 Hz. Each fatigue lag is followed by a 48-h rest period which consists of short complex modulus tests. The test protocol appears to show reliability and provide repeatable results. [ABSTRACT FROM AUTHOR]

Asphalt mixture is a complex heterogeneous material. Its mechanical behaviour strongly depends on its mastic characteristics. Thus, an analysis of mastic can predict the behaviour of its corresponding asphalt mix. This study focuses on numerical simulation of fatigue behaviour of bituminous mastic by using a heterogeneous multiscale approach. The fatigue equation, obtained from experimental tests was applied to the numerical models. Then, the fatigue damage was computed and presented through visual illustrations as well as the local damage distribution. A new numerical method was developed to determine the local damage failure in samples. Thereafter the local damage at the mesoscale scale can be related to global damage at the macroscopic scale. The results showed that the numerical values are close to the experimental data. Finally, the developed multiscale heterogeneous approach can be applied to the larger scale of given bituminous composites such as mortar and HMA models. [ABSTRACT FROM AUTHOR]

Hot-gas drum heating (HDH) of bituminous mixtures is a new approach to heating bituminous mixtures that is influenced by the parameters of the hot gas and drum. A fluid thermal numerical model was developed to evaluate the effects of heating bituminous mixtures with HDH using a finite-volume method (FVM). The FVM was verified through the heating test of a bituminous mixture. The effects of the drum rotating speed and hot-gas speed on the efficiency of heating the bituminous mixture during HDH were analyzed using Fluent. The results indicated that the drum rotating speed directly influenced the formation of a bituminous-mixture curtain, which had a significant effect on the efficiency of heating the bituminous mixture. The efficiency of the heat exchange between the hot gas and the bituminous mixture was high, with full contact between the hot gas and the bituminous mixture. With an increase in the hot-gas speed, the heating time became shorter; however, the rate of hot-gas utilization was reduced. A symmetrical temperature distribution and a superior heating efficiency of the bituminous mixture were achieved when the drum rotating speed was 7 rpm and the hot-gas speed was 1.4 m/s. [ABSTRACT FROM AUTHOR]

The fatigue behaviour of bituminous layers must be taken into account when dimensioning road structures and projecting streets. To satisfy this fatigue criterion, laboratory tests must be used to determine the material characteristics and fatigue life of bituminous mixtures. The aim of this article is to study the crack initiation stage using a specific laboratory test: the two-point constant strain bending fatigue test on trapezoidal specimens. The laboratory tests were carried out on three types of bituminous mixes used in the wearing course, each containing successively two different types of bitumen (one imported and one Romanian). The conclusions drawn from this article refer to the influence of mix type and bitumen on the characteristics obtained. [ABSTRACT FROM AUTHOR]

The use of sustainable materials in road construction has been gaining popularity to provide a better future for the next generations. This study investigates the possible use of two common sustainable road construction materials, recycled asphalt pavement (RAP) and recycled tire rubber (RTR), for pavement maintenance applications. Mixtures were produced either with combined RAP and RTRs or 100% RAP with petroleum-based (RAP-A) and bio-based (RAP-B) rejuvenating oils. Because pavement maintenance applications such as pothole patching have traditionally been performed with cold mixtures (CM), a typical cold patching mixture was also investigated along with six hot asphalt mixtures. RTR mixtures were produced using different rubber modification technologies. They were manufactured using crumb rubber wet (WET), crumb rubber dry (DRY), devulcanized rubber (DEV), and crumb rubber terminal blend (TB) technologies. Each RTR-modified mixture included 40% RAP and approximately 12% rubber content by weight of the binder. The performance of the mixtures was compared using dynamic modus (DM) testing for linear viscoelastic characterization, flow number (FN) testing for rutting potential, and tensile strength ratio (TSR) testing for moisture susceptibility. The cost-effectiveness of different mixtures was performed using the life cycle cost analyses (LCCA) approach for bituminous materials. The results showed that any recycled hot-mix asphalt outperformed the CM. The 100% hot RAP mixture with petroleum-based rejuvenator performed as well as any combined RTR-RAP mixtures, and it became the most cost-effective alternative for pavement maintenance applications. [ABSTRACT FROM AUTHOR]

The rheological properties of bitumen largely influence the performance of the pavement. Determination of rheological properties of bitumen depends on thermal equilibrium time. The main objective of this study is to evaluate the effect of Evotherm, a chemical warm mix additive on the thermal equilibrium time of bituminous binders. The bituminous binders used for this study included two unmodified binders, a polymer-modified bitumen (PMB) and a crumb rubber-modified bitumen (CRMB). The thermal equilibrium times for bituminous binders with and without Evotherm were measured using a dynamic shear rheometer. The results indicate that the thermal equilibrium time primarily depends on the type of binder, wherein the asphaltene content, presence of polymer and rubber influence thermal equilibrium time. The higher thermal equilibrium times observed for the Evotherm-modified PMB40 binder and Evotherm-modified CRMB60 binder in unaged condition can be attributed to a change in morphology and chemical interaction respectively upon the addition of Evotherm. Lesser thermal equilibrium time exhibited by short-term aged Evotherm binders can be because of the reduced formation of ageing compounds due to reduced short-term ageing temperature and presence of Evotherm. The linear regression model well predicted the thermal equilibrium time based on test temperature and softening point of binders. [ABSTRACT FROM AUTHOR]

In order to investigate the dynamic mechanical properties of polyphosphoric acid (PPA) and SBS co-modified asphalt mixtures, uniaxial compression dynamic modulus tests were conducted. The influences of temperature and frequency on the dynamic modulus and phase angle were analyzed. Additionally, dynamic modulus and phase angle master curves were constructed based on the modified Havriliak-Negami (HN) model. A comparative analysis was also performed with SBS-modified asphalt mixtures. The results indicate that both types of asphalt mixtures exhibit similar trends in dynamic modulus and phase angle variations with changes in temperature and frequency. The HN model accurately fits the master curves of dynamic modulus and phase angle for both asphalt mixtures. In comparison to SBS-modified asphalt mixtures, the phase angle of PPA+SBS co-modified asphalt mixtures decreases at -10, 20, and 50 °C, while the dynamic modulus decreases at -10 °C, changes minorly at 20 °C, and increases at 50 °C. Over a wide frequency range, PPA+SBS co-modified asphalt mixtures exhibit increased dynamic modulus and decreased phase angle at high temperatures and low frequencies, while they show decreased dynamic modulus and relatively stable phase angle at low temperatures and high frequencies. These findings suggest that PPA+SBS comodification endows asphalt mixtures superior dynamic mechanical properties. [ABSTRACT FROM AUTHOR]

The article presents the chemical composition of vermiculite ores from the Kulantau deposits and the atomic structure of vermiculite during dehydration, in 1-, 2- and 3-layer hydrated states. It has been shown that vermiculites from deposits in the Turkestan region have significant differences in mineralogical composition. Rational ways of using Kulantau vermiculite as an innovative modifying additive in bitumen compositions are considered, which are intended to improve the asphalt concrete mixture during its preparation. A slight increase in structuring resins is a result of the elevated content of high-molecular-weight asphaltenes in the modified bitumen, as indicated by the analysis of the provided spectra. In turn, the systematization or structuring of bitumen leads to an increase in the mixture density, accompanied by a simultaneous rise in internal friction coefficients, and resistance to loads (shear and impact), as well as an enhancement in compressive strength. The influence of the chemical composition of Kulantau vermiculite on the structure of bitumen compositions is characterized by high adsorption capacity and effectively absorbs products resulting from the oxidation of hydrocarbons. Vermiculite is characterized by high efficiency in the activation phase, large pore volume, and selectivity. The alteration of the bitumen's group composition due to the selective diffusion of oils, as well as resins in the material, occurs as a result of the interaction between bitumen and a material characterized by a fine-porous structure and high specific surface area. This process modifies the properties of bituminous layers on the surface of particles and leads to the formation of robust bitumen films appearing on the grain surfaces. Thus, enhancing the longevity of coatings, improving the quality of binding bitumen, and reducing asphalt concrete coverings necessitate the use of vermiculite in creating modified bituminous compositions. [ABSTRACT FROM AUTHOR]

Bituminous mixtures containing various defects, such as cracks and voids, exhibit ductile behavior in hot environments and brittle behavior in cold environments. Such materials can only be simulated realistically with the criteria of nonlinear fracture mechanics. In this investigation, the semi-circular bending (SCB) specimens, which have commonly been used to measure linear elastic fracture toughness parameters and fracture energy of asphalt and rock materials up to now, are studied to estimate several nonlinear fracture parameters of bituminous composites such as nonlinear fracture toughness, effective crack extension, critical crack tip opening displacement and brittleness. For this, the compliance functions of SCB specimens based on crack mouth opening displacement and load line displacement are derived by the finite element method at first. Subsequently, eight series of SCB tests in the literature, which were experimented with at low and room temperature environments, are examined by using two different compliance methods in fracture mechanics of quasi-brittle materials. This study's findings reveal that the crack extension in the pre-peak regime for mixes with bituminous at both low and normal temperatures is not statistically negligible and the use of nonlinear fracture toughness is, therefore, a necessity.

The presence of water badly affects the moisture susceptibility of the reclaimed asphalt Foamed Bituminous Mix (FBM). The present study is mainly emphasized to assess the moisture susceptibility of reclaimed asphalt FBM, Where RAP is being incorporated as a replacement of fresh aggregates. Moisture susceptibility of the mix is evaluated in terms of tensile strength ratio (TSR) and resilient modulus ratio, subjected to different conditioning procedures namely AASHTO T283, modified IDOT, TG-2 guidelines, and MIST. Further data analytics and regression modeling are also carried out to determine the moisture susceptibility of the mix and to check the statistics among the variables. The findings show that the incorporation of RAP in the FBM improves moisture resistance. Further, FBM containing 100% RAP shows the least moisture susceptibility in terms of TSR and Mr ratio irrespective of any conditioning type. Moreover, MIST conditioning may be preferred to assess the moisture sensitivity as it simulates the field pore pressure effects. Further, mathematical analysis is carried out to predict the moisture susceptibility of mix. Adjusted R square coefficient indicates a better fit of the prediction model developed. Overall, the study may be helpful to highway professionals in analyzing the conditioning procedures and determining the moisture sensitivity of the reclaimed asphalt Foamed Bituminous Mix. [ABSTRACT FROM AUTHOR]

The conventional design approaches for reclaimed asphalt pavement (RAP) mix follow blending rules to select the grade of the virgin binder for hot recycled bituminous mixtures. The interactions of RAP binder with the virgin binder are highly complex in the presence of the rejuvenator. Identifying the optimal proportion of RAP binder, virgin binder, and rejuvenator is often a trial-and-error procedure, involving considerable experimental data collection. The current research study proposes the statistical-based design of experiments (DoE) framework to design ternary RAP binder blend, develop response surface prediction models, and optimize the proportions to meet targeted binder properties of viscosity grade (VG30) binder. A desirability-based multiple response optimization is carried out, and the optimal blend proportions with target binder properties are arrived at with different desirability levels. A total of 13 RAP binder blends are formulated using the I-Optimal algorithm in the current study. Experimental data such as softening point, high-temperature performance grade (PG), and linear viscoelastic parameters in the temperature range of 46°C to 70°C and frequency range of 0.1 to 50 Hz are collected. The binder blends are evaluated using master curve parameters and relaxation spectrum. The response surface models are developed for two measured parameters (high-temperature PG and softening point), three computed master curve parameters, and four relaxation spectrum parameters. These models capture the possible individual component effects and combined component effects on the final RAP binder blend through linear and nonlinear terms. A desirability-based simplex optimization is adopted to identify combinations of constituents at various levels of desirability that comprises only direct measurements, direct measurements and master curve parameters, and direct measurements, master curve parameters, and relaxation spectrum. Using this proposed approach, a wide range of solution zones are identified with various levels of desirability. Reclaimed asphalt pavement (RAP) consisting of aged bitumen coated on mineral aggregates is used for recycling in pavement construction. Many challenges exist related to the optimal use of such material. The aged binder may need to have the required properties suitable for recycling. Generally, rejuvenators are added to the RAP to enhance the properties of aged binder. However, how much rejuvenator should be added is unclear. Aged bitumen from different sources of RAP can have different degrees of aging. In addition, it may not be easy to estimate the extent of blending of the RAP with the virgin materials (aggregates and bitumen), as it is linked to the characteristics of aged binder and the choice of fresh bitumen and rejuvenator. Also, the aged bitumen, when mixed with a rejuvenator and virgin bitumen, may not necessarily result in a final mix with bitumen that meets the requirements. As can be seen, the choices are entirely diverse and varied. This research attempts to solve such issues using a statistics-based tool called design of experiments (DoE). Using such a tool, this study demonstrates how to optimally choose the proportions of virgin bitumen, RAP bitumen, and rejuvenator. This work presents a methodology that can be implemented efficiently using commercial software by any asphalt mix designer. [ABSTRACT FROM AUTHOR]

Bitumen is a temperature-susceptible material. The performance of the bitumen largely depends on the sensitivity of its characteristic properties to the variation in temperature. This paper uses the Arrhenius equation to predict the temperature-sensitive properties of various bitumens. Three modified and unmodified binders of various grades were tested under study shear, frequency mode (oscillatory shearing), and time mode (multiple stress creep and recovery) at different temperatures from 10 to 70°C. This paper focuses on the activation energy to understand the temperaturesusceptible behavior of the bitumen and the influence of aging on the bitumen. To analyze the temperature susceptibility of the bitumen, Steady shear, MSCR, and LAOS tests were performed. From these tests, parameters such as viscosity, dynamic modulus, energy dissipation, and creep compliance at different temperatures were observed to follow the Arrhenius equation. The activation energy constant of the Arrhenius equation is found to vary with the characteristic function used. It is also statistically proven that the activation energy depends on the shear rate or shear stress, indicating that the temperature-susceptible properties of the bitumen are shear rate-dependent. Also, as the bitumen ages, its temperature-susceptible properties improve. [ABSTRACT FROM AUTHOR]

For the successful reuse of old asphalt as reclaimed asphalt pavement (RAP) added to new bituminous mixtures, it is necessary to improve some of its properties. This can be attained, for example, by adding an appropriate rejuvenator. The aim of this study was to evaluate the properties of lab-aged 35/50 pen grade bitumen rejuvenated with the addition of two varieties of rapeseed imidazoline. Dynamic shear rheometer (DSR) and ductilometer tests were further conducted to evaluate the properties of bituminous binders at the intermediate operating temperature of road pavements. The obtained results demonstrated a beneficial effect of rapeseed imidazoline on the properties of the tested pen grade bitumen after ageing when added at a rate of 6% or more. This effect was the most pronounced in the case of the fatigue cracking critical temperature (FCCT), where a lower value was obtained for the aged and rejuvenated 35/50 bitumen than for the same bitumen before ageing. The tensile curves developed from the results of the tensile force tests using the ductilometer confirmed the previous conclusions from the measurements using the DSR. However, the original plastic behaviour of the aged pen grade bitumen was restored only through the addition of rapeseed imidazoline at a rate of 8%. [ABSTRACT FROM AUTHOR]

The mixing and compaction temperatures of the bituminous mixture are determined by the viscosity of the binder. It was always a concern to understand the influence of the type of filler on the workability of the bituminous mixture. The interaction of the filler with the bitumen plays a key role in this. The inert filler has a physical interaction with the binder, and the active filler will have both a physical and chemical interaction. Based on the type of interaction, the viscosity and shear thinning characteristics of the mastic (binder + filler) change, which will hence influence the workability of the bituminous mixture. An experimental investigation is conducted to measure the viscosity of the mastic with two types of filler, one chosen from the active filler category (hydrated lime) and another from the inert filler category (quarry dust). A shear rate sweep experiment was carried out within the temperature range of 100 to 160 °C to analyze the Newtonian and shear thinning responses of the mastic. Results indicate that, for an equivalent weight proportion of the filler, mastic containing quarry dust exhibited elevated Newtonian viscosity and zero-shear viscosity (as predicted using the Carreau Yasuda Model). Additionally, quarry dust mastic demonstrated a higher rate of shear thinning. Consequently, the beneficial effect of shear thinning during the compaction of bituminous mixtures has the potential to enhance workability and streamline the compaction process. [ABSTRACT FROM AUTHOR]

A full understanding of bitumen fatigue cracking behavior is extremely important as this phenomenon has a considerable influence on bituminous pavement performance. The current framework for assessing this asphalt binder property is inconsistent in ranking bitumen fatigue performance in terms of the failure definition and damage characteristic curve (DCC) analysis. This study used four different types of asphalt binders: neat asphalt (NA), self-healing thermoplastic polyurethane (STP)-modified bitumen, self-healing poly (dimethyl siloxane) crosslinked with urea bond (IPA1w)-modified bitumen, and styrene–butadiene–styrene (SBS)-modified bitumen (SBSB). All the bitumens were subjected to short-term and long-term aging, and they were also tested by utilizing the linear amplitude sweep (LAS) test and the simplified viscoelastic continuum damage (S-VECD) model. LAS and S-VECD procedures were used to apply the newly proposed and current frameworks in order to analyze bitumen performance. The current framework showed that the bitumens that used a higher number of loading cycles (N) to reach their failure points ( N f ) failed to exhibit greater fatigue performances in terms of DCC analysis. The developed framework (mainly based on the damage intensity [S] instead of N) was used to solve the inconsistency between the failure definition and DCC assessment in ranking bitumen performance. Additionally, the current framework (failure criterion) presented two R2 values below 0.1, but the developed framework (failure criterion) showed that all R2 values were greater than 0.9. The developed framework represents a turning point because, for the first time, this type of procedure is mainly being based on S instead of N. Although further tests are needed to confirm its efficiency, it eliminates the inconsistency between the failure definition and DCC assessment. [ABSTRACT FROM AUTHOR]

Corrosive chloride (Cl-) and sulfate (SO42-) in sabkha are major environmental factors accelerating the deterioration of concrete structures with steel rebars or steel structures through long-term exposure. The dissolution of these corrosive anions from the surrounding soil must be reduced to increase the lifespan and durability and to ensure the protection of such structures. This study investigated the impact of bitumen addition on the amount of leached corrosive Cl- and SO42- in terms of quantity and rate as the percentage of total dissolved solids. Representative sabkha soil samples obtained from southern Kuwait were blended with various bitumen contents and leached with distilled water for more than 25 days, and the leached pore volumes were examined for the detected anions. Bitumen percentages of 0%, 4%, and 12% (by dry weight of sabkha) were selected as the mixing percentages based on geotechnical testing (density results obtained via modified Proctor tests) below and above the optimum bitumen contents. Results show that corrosive anion dissolution is reduced more in the bitumen-mixed sabkha than in the natural soil samples. The SO42-and Cl- concentrations almost diminish at the early leaching stages in the 12% bitumen-mixed sabkha sample, showing a strong reduction trend in the corrosive anion concentration. These findings highlight the importance of the waterproofing effect of bitumen in reducing corrosive anion dissolution from sabkha soil, which will reduce the impact of these soils on various structures, particularly buried gas, or oil steel pipes, and improve the effectiveness of other protective methods used for these structures. [ABSTRACT FROM AUTHOR]

The escalating quantities of waste are coming from old bituminous road pavements in Thailand has led to significant environmental and economic challenges. This research explores an innovative solution by investigating the feasibility of using Reclaimed Asphalt Pavement (RAP) as a substitute for natural coarse aggregate in roller compacted concrete (RCC). This study explores optimal proportions between cement to RAP-specifically at ratios of 1:6, 1:8, and 1:10-to achieve maximum dry density. The research includes essential tests, such as dry density and maximum compressive strength assessments, to determine the suitability of the material for compacted concrete production. Intriguingly, the research reveals that the 1:6 ratio not only has the highest dry density and maximum compressive strength but also may minimize environmental impact. These findings align with the ACI 325.10R-95 standard (1995), presenting a promising alternative for engineering applications and contributing to the responsible use of reclaimed materials. [ABSTRACT FROM AUTHOR]

Conventional rejuvenation techniques, such as adding oil-based substances, are proved very effective to improve some properties of aged styrene-butadiene-styrene modified asphalt (SBSMA), including low-temperature cracking resistance and fatigue characteristic. However, its significant reduction of high-temperature properties needs to be closely focused on because it is related to the deformation resistance to rut. The major reason is that these rejuvenators play as viscosity-reducing agents to physically soften the aged SBSMA binder, whereas it does not work to repair the molecular structure and properties of aged SBS. Therefore, this study adopted polyurethane (PU) prepolymer as reactive chemical together with tall oil (TO) as common asphalt rejuvenator for the physicochemical rejuvenation of aged SBSMA. A series of tests including Fourier transform infrared (FTIR) spectra, softening point, viscosity, dynamic shear rheology (DSR), and multiple stress creep recovery (MSCR) were carried out to identify the above-mentioned issues. The results obtained showed that the chemical rejuvenation of PU contributes to fix the molecular structure of SBS degradation products in the aged binder, which is able to improve the high-temperature deformation resistance and elastic recovery of aged SBSMA binder. TO can help supplement partial loss of light components for a better workability of PU rejuvenated binder. Surprisingly, limited use of TO will not significantly decrease the elastic recovery of PU rejuvenated SBSMA at high temperature based on the physicochemical rejuvenation effects. The research achievements can address the worrying issues, especially the early-stage rutting deformation resistance, in terms of fresh rejuvenated SBSMA mixtures. [ABSTRACT FROM AUTHOR]

To effectively utilize waste mask materials in road engineering and minimize resource waste, the melt-blown fabric (MBF) of waste masks was utilized to modify the virgin bitumen. The preparation process of MBF-modified bitumen was investigated, and the physical and rheological properties of bitumen were measured. Subsequently, the blending mechanism during preparation and the dispersion morphology of the modifier were explored. Finally, the pavement performance of the mixture was investigated, and a radar chart analysis was performed to quantitatively assess the effects of MBF modification. Results suggested that the recommended preparation process of shear time, shear rate, and shear temperature was 170 °C, 4000 r/min, and 15 min, respectively. MBF enhanced the high-temperature stability of the binder and weakened the temperature susceptibility. The modification was primarily a physical process. No network structure and agglomeration formed in the bitumen after modification. The addition of MBF significantly improved the resistance of the asphalt mixture to a high-temperature deformation and water damage but harmed its low-temperature crack resistance. The comprehensive assessment results of 0% ( f 1 ), 1% ( f 2 ), 3% ( f 3 ), and 5% ( f 4 ) MBF to improve the properties of the mixture were in the following order: f 3 > f 4 > f 2 > f 1 , where the impact of 3% MBF was the most significant, followed by 5% and 1% MBF. [ABSTRACT FROM AUTHOR]

Examples of nanostructured fluids (NSFs) used as highly specialized "brush‐on, wipe‐off" detergents for the removal of graffiti coatings resistant to removal are water‐in‐oil nanoemulsions that have been stabilized with nonionic saccharide surfactants. Nanodetergents with safe, ecofriendly ingredients were produced using high‐pressure homogenization (HPH). These ingredients included D‐limonene or 3‐methoxy‐3‐methyl‐1‐butanol, esterified vegetable oils, and alkyl polyglucosides (APG). Responsive surface methodology (RSM) optimization was used to identify the most efficient detergents for removing stubborn graffiti coatings. Two different types of black paint containing nitrocellulose or bitumen as components to strengthen the paint properties were used to create a stubborn graffiti coating on a marble surface. The effectiveness of the nanodetergents in removing the stubborn graffiti coatings was evaluated, and the results revealed a considerable variation in the pace at which the coatings could be removed by the nanodetergents, despite the fact that both paints strengthened with different additives showed similar surface properties. It was found that alkyl polyglucosides are highly efficient in stabilizing water‐in‐oil nanoemulsion systems, including diverse solvent types. These nanoemulsions can be used as specialized "brush‐on, wipe‐off" detergents for the precise removal of different graffiti coatings, which require a specified action period to prevent destroying the underlying original substrate. [ABSTRACT FROM AUTHOR]

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Asphalt mixtures age during service in the field, primarily as the result of chemical changes in the bituminous binder phase. The ageing phenomenon changes the properties of the asphalt mixture, including the stiffness modulus, the resistance to deformation and the resistance to cracking, and it leads to surface weathering or erosion that often leads to pavement resurfacing. Consequently, many researchers have attempted to understand and to simulate the ageing of bituminous binders and asphalt mixtures in the laboratory. This review of bituminous binder and asphalt mixture ageing considers ageing simulation techniques, the effect of ageing on both bituminous binders and asphalt mixtures, the potential benefits of ageing inhibitors, and efforts to relate simulated laboratory ageing to observed field ageing. It is concluded that ageing has a significant effect on the properties of bituminous binders and asphalt mixtures, and that improved simulated ageing is important for comparing the effect of ageing on different materials and mixtures, as well as for quantifying the potential benefits of ageing inhibitors, which have generally been promising. It is also concluded that current ageing protocols are based on heat only, omitting the important contribution of solar radiation to the weathering and ageing of asphalt surfaces in the field. In the future, different simulated ageing protocols should be developed for binder and mixture samples. Similarly, a different ageing protocol is appropriate for understanding base-layer fatigue, compared to research on surface-layer weathering. Finally, it is concluded that a universal ageing protocol is unlikely to be found and that mixture- and climate-specific protocols need to be developed. However, given the importance of simulated ageing to asphalt researchers, the development of reliable, robust and calibrated laboratory ageing protocols is essential for the future. [ABSTRACT FROM AUTHOR]

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

Abstract In this study, the low temperature creep properties of multiphase bituminous materials (binder, mastic, Fine Aggregate Matrix—FAM, and mixture) were experimentally evaluated, and the impact of size effect on FAM and mixture specimen was also assessed. First, the mix design of mastic and FAM was performed based on the reference mixture Asphalt Concrete (AC) 22 TS. The mathematical adaptation to the boundary sieve method was applied to calculate FAM gradation and binder content. Next, a preparation method was proposed to produce Fine Aggregate Matrix (FAM) in a laboratory environment, and scale-up slab samples were also fabricated for FAM and mixture specimens to evaluate the size effect phenomenon. Finally, three-point bending (3 PB) creep tests were conducted on the multiphase bituminous specimens with different dimensions at -6 °C, -12 °C, and -18 °C with a modified Bending Beam Rheometer (BBR) device and a dynamic loading machine, depending on the sample size. Results indicate that the creep stiffness of the FAM was close to mixtures and much higher than the one observed in binder and mastic. The proposed fabrication approach provides a satisfactory method for preparing a representative FAM phase in the mixture, while the air voids can be easily adjusted during the slab compaction procedure. This study supports the idea of using FAM to discriminate asphalt mixtures for cold regions. The correlation between up-scaled FAM and mixture specimens should be further investigated, including different mixture types and corresponding FAM.

The objective of the present study is to investigate the effect of foam characteristics of bitumen such as maximum expansion ratio (ERm) and half-life (HL) on the moisture susceptibility of foamed bitumen stabilised mixes (FBMs). The study investigated the individual as well as the interaction effect of ERm and HL on moisture susceptibility of FBMs. Considering the individual effect of ERm, it was observed that for a given HL, the beneficial effect of ERm on the moisture susceptibility of FBMs exists up to a certain level of ERm, beyond which the performance of the FBMs was found to be compromised. On the other hand, at controlled ERm, the higher HL was found to have beneficial effect on the moisture susceptibility of FBMs, provided the controlled ERm was sufficiently high. When the interaction effect of ERm and HL was considered, the FBMs were found to have higher moisture damage resistance with the increase in ERm as long as the HL was above a certain threshold level. The study also proposed performance-based minimum threshold limits for ERm and HL based on the Receiver Operation Characteristics (ROC) analysis on the retained tensile strength (TSR) results obtained for the FBMs prepared at varying foam characteristics. [ABSTRACT FROM AUTHOR]

The delineation of the linear/nonlinear response of bituminous material in the frequency domain is conducted using the small-amplitude oscillatory shear test, wherein only the peak stress and strain are available. In contrast, the large-amplitude oscillatory shear tests provide complete waveform data. Analysis of such data can help to unravel the linear/nonlinear response with greater accuracy. This investigation reports such an exercise. An experimental investigation is conducted on five different materials at different strain amplitudes, frequencies, and temperatures. The geometry-based parameters obtained from the Lissajous plot gave contradictory linear/nonlinear delineation. Analysis of the higher order harmonics did not show any appreciable presence of nonlinearity. However, the orientation of the Lissajous plots differed from the strain amplitude. The elastic and viscous stress could be predicted using the first-order Chebyshev coefficients indicating the linear response, but the coefficients differed with the strain amplitude. The scaling-superposition of the waveform revealed a clear demarcation of the linear/nonlinear response. This indicated that the response of the bituminous material needs to be analysed for a range of frequency and amplitude. The mere analysis of the waveform data at any test condition can help only to establish the necessary condition for linearity but not a sufficient condition. [ABSTRACT FROM AUTHOR]

Equivalent temperature ($T_e$ T e ) is one of the most important parameters in the design of asphalt pavement structures. The calculation of this temperature considers the variations in the following parameters: pavement temperature, modulus, and the law of fatigue. In Morocco, the $T_e$ T e used for pavement design varies between 19 and 25 $^\circ$ ∘ C, depending on the choice of the road manager. The objective of this study is to determine the values of $T_e$ T e depending on the region. The hourly distribution of roadway temperature was calculated according to the Barber model, which was validated using a reduced model. The temperature values obtained, coupled with data relating to heavy vehicle traffic, make it possible to calculate $T_e$ T e for different sites representing different regions of the country. The results indicate variations in $T_e$ T e according to the climatic temperature, law of fatigue, and types and thicknesses of pavement layers. For the various parameters studied, the calculated value of $T_e$ T e was between 20 and 30 $^\circ$ ∘ C. [ABSTRACT FROM AUTHOR]

The specific objective of this study was to investigate the effect of reactive ethylene terpolymer (RET) modification on bitumen properties at the nano and macro scales, as well as on porous asphalt (PA) mix properties. Measurements using the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR) showed that RET modification of bitumen significantly improved the high-temperature properties, while intermediate- and low-temperature properties were similar to the base bitumen. The linear amplitude sweep (LAS) test conducted using the DSR showed that RET modification improved fatigue resistance. Consequently, chemical analysis and PeakForce™ Quantitative Nano-Mechanical™ (PF-QNM) atomic force microscopy (AFM) imaging were used to evaluate the microstructure and nanomechanical properties of the polymer modified bitumen (PMB) and the base bitumen before and after long-term ageing. The chemical analysis provided useful insights that complemented and helped to explain the AFM and rheology tests. The AFM results supported the LAS test findings in showing that RET modification improved the resistance of aged bitumens to cracking. The results of testing the PA mix showed significant improvements in moisture damage and ravelling resistance due to RET modification. [ABSTRACT FROM AUTHOR]