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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]

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]

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]

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]

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 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]

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]

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]

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]

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.

This paper analyses the key findings of a study devoted to PET-modified bitumen. The research program was run according to the D-optimal experimental plan based on a factorial design. Five factors, i.e., the type of polymer (source), the type of bitumen (qualitative factors), PET amount, mixing rate, and mixing temperature (quantitative factors), controlled the bitumen–polymer mixing process. The experiment included a series of determinations of bitumen's rheological characteristics obtained by MSCR (Jnr, R) and G*/sin(δ) at 50 °C, 60 °C, and 70 °C. The low-temperature properties of the composite (critical temperature) were evaluated using a BBR test. The findings showed that bitumen modification with PET primarily reduced the creep susceptibility of the bituminous–polymer mixture. The low-temperature characteristics of the modified bitumen played a secondary but essential role. The amount of polymer and the mixing rate interacted with the temperature, significantly reducing the stiffness of the composite, while the type and amount of bitumen had a substantial effect on the results obtained in the BBR test. It is worth noting that when combining bitumen and plastomer, special attention should be paid to ensuring a high level of homogeneity of the mixture by controlling the parameters of the mixing process accordingly. The tests and analyses provided crucial models (GLM), which allowed for the prediction of the plastomer-modified bitumen's low- and high-temperature properties. The resulting relationships between factors and the identification of their impact on the bitumen properties enable a better understanding of the process of bitumen modification with PET. The conclusions presented here serve as a basis for future optimisation of the modified bitumen composition. The performed studies indicate that the use of >3% plastomer in bitumen 70/100 allows for a reduction in its susceptibility (MSCR) to below 0.5 kPa−1, making it suitable for bituminous mixtures for high-traffic roads. No significant increase in critical temperature (BBR) was observed. [ABSTRACT FROM AUTHOR]

The partial upgrading of "tar-like" Canadian bitumen is an essential process to reduce its viscosity to an acceptable range that meets the required pipeline specifications. An innovative and potentially greener solution has emerged in the form of microwave irradiation. This work proposes and demonstrates the use of an electrically powered commercial microwave along with carbon-based microwave susceptors (activated carbon, biochar, coke, and graphite) to promote localized thermal cracking within bitumen at a temperature as low as 150 °C, compared to the conventional method of 400 °C. The remarkable results show that just 0.1 wt% of carbon additives can reduce the viscosity of bitumen by 96% with just 10 min of microwaving at 200 °C. A Saturates, Aromatics, Resins, and Asphaltenes (SARA) analysis reveals that the mass fractions of light components (saturates) are almost doubled and that almost one-third of heavy polar hydrocarbon constituents are cracked and decomposed into much lighter molecules, resulting in higher-quality, less viscous bitumen. Furthermore, this study highlights the key role of the surface area and porosity of the carbon microwave susceptor in absorbing microwave radiation, offering exciting new avenues for optimization. Microwave-assisted partial upgrading of bitumen is a cost-effective and eco-friendly alternative to conventional upgrading, producing upgraded bitumen that requires significantly less diluent at a lower cost prior to pipeline transportation. [ABSTRACT FROM AUTHOR]

Styrene-butadiene-styrene (SBS) is widely used to improve the properties of the base bitumen and hence bituminous mixtures. As SBS modification induces cost increase, natural asphalts have become an important issue. In this study, the effects of gilsonite supplied from Iraq, a type of natural asphalt (NA) on conventional and rheological properties of bitumen, were investigated. NA was used 20%, 35%, and 50% by weight of bitumen. The properties of NA modified bitumen were compared to 2%, 3%, and 4% SBS modified bitumen. Conventional (penetration, softening point, rotational viscosity) and rheological (dynamic shear rheometer, bending beam rheometer) binder tests were conducted on base and modified bitumen. The index values representing together the workability, high and low temperature properties were defined by dividing the rutting parameter to viscosity and rutting parameter to low temperature stiffness. Overall, the test results show that 20% NA modified B160/220 bitumen exhibited similar performance with B160/220+3%SBS modification produced at 16% higher cost in terms of the high and low temperature properties. [ABSTRACT FROM AUTHOR]

Bituminous mixes are prepared with aggregates, filler and bitumen as binder. Ageing of bitumen due to oxidation reduces the durability of such mixes. Various research efforts are therefore put in to decrease the ageing potential of binders and use of anti-oxidants has shown substantial success. In this research, Irganox 1010 has been identified as an anti-oxidant which has been found to be economical and yet of limited use in the field of pavement engineering. Various physical and rheological tests were conducted to determine the influence of Irganox 1010 on short-termed as well as long termed aged binders and results were analyzed. Softening Point Index (SPI) and Viscosity Ageing Index (VAI) were determined to understand the influence of Irganox 1010 on bituminous mixes. It was observed that Irganox 1010 significantly reduce ageing potential with usage of 0.6% by weight of bitumen. It has been found to be cost-effective due requirement of small quantities and being of comparatively lesser cost. This material has the potential of large scale usage to increase durability of bituminous mixes. [ABSTRACT FROM AUTHOR]

Stone matrix asphalt (SMA) mixtures are the most resistant type of asphalt mixtures today in which the aggregate skeleton bears the bulk load. In this study, the effect of nano hydrated lime (NHL) on the moisture sensitivity of SMA mixtures was investigated. To examine the effect of NHL, the surface free energy (SFE) method and the dynamic modulus (DM) test were applied under wet and dry conditions on mixtures constructed with limestone and granite aggregates. The SFE results indicated that the granite aggregates had a greater polar component and limestone aggregates had a higher non-polar component which shows their higher moisture resistance. The adhesion free energy (AFE) results showed that the adhesion of base bitumen and limestone aggregate was higher, and using NHL improved the AFE values. The results of DM tests indicated that as the load cycles raised, the wet to dry DM ratio reduced and using NHL increased this ratio. The reduction slope of the DM ratio in samples constructed with granite aggregates showed a faster trend compared to limestone aggregates, and using NHL improved the resistance of SMA mixtures constructed with granite aggregates to moisture more than limestone aggregates. [ABSTRACT FROM AUTHOR]

In order to raise the utilization rate of industrial waste and mitigate issues involving land resource occupation and environmental damage, in this study, industrial-waste-based artificial aggregates (IWAAs) were fabricated using steel slag powders, fly ash, and cement. They were processed under accelerated carbonation and were utilized in a bitumen mixture. During the experiment, the micromorphology, internal structure, and phase composition of IWAAs before and after accelerated carbonation were characterized using X-ray phase analysis, thermal analysis, and scanning electron microscopy (SEM); concurrently, the possibility of IWAAs being used as a partial substitute for natural aggregate to prepare bituminous mixture was qualitatively and quantitatively analyzed based on Marshall's design procedure in combination with road performance tests and microcosmic analyses. The results indicated that the presence of carbonate crystals brought about by accelerated carbonation was the main phase composition inside the IWAAs, enhancing the microstructure densification and diminishing the immersion expansion and crushing values; this is due to the depletion of the interior Ca-based (e.g., f-CaO and Portlandite) and Mg-based (e.g., periclase and brucite) compounds together with the formation of cement hydration products. Additionally, the 12 h carbonation time obtained the optimum CO2-sequestration efficiency on the premise of satisfying the performance standard. The expansion rate and crushing value of the IWAAs decreased by 82.21% and 41.58%, respectively, whilst the anti-rutting properties, the moisture damage resistance, and the skid resistance rose by 31.92%, 5.59%, and 10.00%, respectively, in the IWAAs–bituminous mixture. This study lays a foundation for research on the CO2 sequestration and resource utilization of industrial wastes in bitumen mixtures. [ABSTRACT FROM AUTHOR]

Hot- and cold-applied joint sealants are materials commonly used for the surface repairs of the upper layers of asphalt or concrete road surfaces. Our investigations covered six hot-applied joint sealants, classified as the high-extension type N1 (elastic) or low-extension type N2 (normal), in accordance with the standard EN 14188-1; the sealants were obtained commercially from four European manufacturers. The present paper focuses on the characterization of the consistency of the joint sealants, the bituminous binders that contain them, and the characterization of their insoluble components. Additional testing methods included an FTIR analysis of the sealants and the extracted binders, as well as SEM, EDS, and sieving analyses of the insoluble material. Joint sealants are complex formulations and include a broad range of base asphalt binders and other components. Their compositions may vary widely, while still fulfilling the performance specifications. Through the extraction of the solvents and the separation of the crack sealants, it was found that radically different compositions of crack sealants resulted in the comparatively similar performance of the tested material. The EDS and FTIR analysis methods provided insights into the composition of the crack sealants and the types of mineral materials used. [ABSTRACT FROM AUTHOR]

Annually, a great deal of money is spent repairing and maintaining pavements. As a result, several pavement experts have investigated the effects of various modifiers on pavement performance and service life. The present research evaluated the performance of a binder and asphalt mixture containing combined styrene–butadiene–styrene (SBS) (5% by binder weight) and ceramic fiber (CF) additives (0%, 2%, 4%, and 6% by binder weight). One virgin binder (AC 85/100) was used to fabricate mixtures. Several rheological binder tests and performance mixture experiments were carried out, including penetration degree, dynamic shear rheometer, rotational viscosity, ductility, softening point, four-point bending beam fatigue, wheel track, dynamic creep, resilient modulus (Mr), indirect tensile strength (ITS), linear amplitude sweep, and multiple stress creep recovery experiments. To analyze the data set, ANOVA was conducted. Rheological behavior test outcomes showed that adding compound additives led to an enhancement of high- and intermediate-temperature behaviors in bitumen. Low-temperature properties of bitumens became worse after applying ceramic fiber, whereas they were enhanced by the use of SBS. Storage stability experiments showed that utilizing ceramic fiber up to 4% improved the storage stability of binders, but as the percentages of ceramic fiber increased, phase separation of bitumens became worse. Rutting performance of binders improved with the addition of SBS and ceramic fiber. The fatigue performance of binders modified by SBS improved, whereas that of binders modified by ceramic fiber decreased. The resilient modulus and tensile strength of samples increased as CF was added up to 4%, and with the addition of more CF, the ITS and Mr decreased. Therefore, results revealed that ceramic fiber can be used as an appropriate modifier to modify the binder and mixture, and its optimum content is 4%. [ABSTRACT FROM AUTHOR]

Plastics waste gets new life and positive reviews as an asphalt additive for roads and other hard surfaces The use of waste plastics as a paving material offers environmental benefits. [...]

The use of waste plastics as a paving material offers environmental benefits. The most obvious is that it can take tons of single-use plastics out of the waste stream and [...]

The ramped temperature oxidation (RTO) test is a screening method used to assess the stability of a reservoir for air-injection Enhanced Oil Recovery (EOR) and to evaluate the oxidation behavior of oil samples. It provides valuable kinetic data for specific cases. The RTO test allows for the analysis of various characteristics, such as temperature evolution, peak temperatures, oxygen uptake, carbon dioxide generation, oxidation and combustion front velocity, recovered and burned hydrocarbons, and residual coke. The adaptation of RTO experiments to in situ combustion (ISC) modeling involves validation and history matching based on numerical simulation of RTO tests, using 3D digital models of experimental setup. The objective is to estimate the kinetic parameters for a customized reaction model that accurately represents ISC. Within this research, the RTO test was provided for bitumen samples related to the Samara oil region. A 3D digital model of the RTO test is constructed using CMG STARS, a thermal hydrodynamic simulator. The model is designed with multiple layers and appropriate heating regimes to account for uncertainties in the experimental setup and to validate the numerical model. The insulation of the setup affects radial heat transfers and helps to control the observed temperature levels. The modified traditional reaction model incorporates thermal cracking of Asphaltenes, low-temperature oxidation (LTO) of Asphaltenes and Maltenes, and high-temperature combustion of coke. Additionally, the model incorporates high-temperature combustion of light oil in the vapor phase, which is generated through Asphaltenes cracking and LTO reactions. [ABSTRACT FROM AUTHOR]

Asphalt mixtures are multi-phase composites composed of aggregates, bitumen, mineral powders, and voids, and various structures are intertwined during the compaction process. Most of the traditional research focuses on the macro-scale domain, and it is difficult to obtain the internal structure of asphalt mixture in different compaction processes. With the continuous development of digital image technology, the influence of the meso-structure of the asphalt mixture on the compaction quality of the asphalt mixture has become a new means to evaluate the performance of the asphalt mixture. In this paper, different numbers of compactions are selected to represent different stages in the compaction process, the digital images of specimens in different compaction stages are obtained by industrial CT scanning technology. Then, the images are processed and reconstructed in three dimensions using improved image segmentation methods, and the position characteristics and geometric information of coarse aggregate are obtained by combining the Oriented Bounding Box (OBB). The meso-response characteristics of the skeleton structure of the asphalt mixture during compaction were studied. The influence of the internal structure of the mixture on the compaction quality of the mixture was obtained, which is of great significance for the study of improving the durability of the pavement. The results show that the "effective coordination number" (the number of aggregate particles that can transmit force in the skeleton structure) is greatly related to the aggregate size. With the compaction process, the centroid of coarse aggregate in the upper layer of the specimen reflects the overall downward movement trend. The inclination angle of the aggregate spindle tends to be in the range of 80°~100°; the anisotropic amplitude of the xy plane increases, and the direction of the aggregate spindle becomes more and more consistent. With the increase in the number of rotational compactions, these four parameters showed obvious rules, indicating that this meso-characteristic index could well characterize the compaction quality of the asphalt mixture in the compaction process. [ABSTRACT FROM AUTHOR]

Graphene can significantly improve the mechanical performance and durability of a bitumen composite. However, the underlying reinforcement mechanism of this enhancement is not yet clear. Here, we use molecular dynamics (MD) simulation to study the mechanisms of tensile fracture and shear fracture in a graphene-reinforced bitumen composite. Two representative volume elements were developed from a single-crystal graphene-reinforced bitumen composite: graphene in the parallel plane and orthogonal plane. The MD results show that graphene in the orthogonal plane is better able to support and transmit shear loads, as evidenced by a 33% higher shear strength than graphene in the parallel plane. Under tensile loading, the failure type of the base bitumen and the graphene in the parallel plane is cohesive; for the graphene in the orthogonal plane, the failure type is adhesive. The shear failure for graphene in the parallel plane is an adhesive failure, which typically occurs at the graphene–bitumen interface. The shear failure for graphene in the orthogonal plane and for base bitumen is likely to be a cohesive failure. The results of the pull-off test validated the results of the simulation, which indicated that the interlayer sliding of graphene and the fracture of the bitumen matrix are the failure modes of a graphene-reinforced bitumen composite under tensile loading. This study provides atomic-level insight into the mechanical reinforcement mechanism of graphene-reinforced bitumen, and can contribute to the future application of advanced carbon nanomaterials in transportation infrastructure. [ABSTRACT FROM AUTHOR]

Industrial waste usage in the technology of construction materials is currently in a relevant and promising direction. Materials made of industrial waste have a lower cost and are highly environmentally friendly. The objective of this study is to develop effective compositions of sulfur concrete based on the maximum possible number of various wastes of the local industry for this and to investigate the characteristics of this composite. Test samples of sulfur concrete were made from sulfur, fly ash, mineral aggregates and bitumen additive. The dosages of fly ash, sand and bitumen varied, while the content of sulfur and crushed stone remained constant. The following main characteristics of sulfur concrete were determined: density; compressive strength; and water absorption. Tests of sulfur concrete were carried out after 1 day and 28 days of hardening. The best values of compressive strength (24.8 MPa) and water absorption (0.9%) were recorded for the composition of sulfur concrete at the age of 28 days with the following content of components: sulfur—25%, modified with 4% bitumen of its mass; fly ash—10%; crushed stone—40%; and sand—25%. The optimal composition of modified sulfur concrete showed compressive strength up to 78% more and water absorption up to 53% less than the control composition. The characteristics of the sulfur concrete samples after 28 days of hardening differ slightly from the values after 1 day of hardening (up to 1.8%). An analysis of the structure confirmed the effectiveness of the developed composition of sulfur concrete in comparison with the control. [ABSTRACT FROM AUTHOR]

Quantifying recycled asphalt binder availability in recycled asphalt pavement (RAP) mix design is very essential, as the widely adopted 100% RAP binder availability assumption in RAP mix design never holds correct. Depending on the mix production condition, recycled binder stiffness, and virgin binder properties, the degree of binder availability in the mix is always partial. The present study proposes a simple procedure to estimate the degree of recycled binder availability in RAP mix design. In the proposed methodology, the designer needs to compare optimum binder content of bituminous mixes prepared using white rock aggregate gradation and virgin aggregates, along with mixes designed by blending black rock gradation and virgin aggregates blended in proportion to achieve the target white rock gradation. The binder content in the RAP fraction used in the blending exercise was determined using ignition oven method. RAP mix designs were performed for RAP material collected from two different sources, and design was performed for three mixing durations in a laboratory pug mill—60, 120, and 180s. The mixes were prepared with 50% RAP incorporation level. RAP material was conditioned at 110°C for 2 h, whereas virgin aggregates were superheated to 175°C. Using the methodology proposed, RAP binder availability was found to vary between 92.5% and 96.6% for softer RAP material, 75.9% to 91.5% for mixes incorporating stiffer RAP. With increasing mixing time, even though the total active binder content did not change significantly, a mixture performance test quantified the implication of increased RAP binder availability in mixes. A higher degree of binder activation resulted in mixes being rut resistant, while the same mixes exhibited relatively higher cracking susceptibility. Recycling of bituminous mixes has been considered as one of the sustainable practices in the highway construction industry. In a recycled bituminous mix, the milled material contributes good quality aggregates, and aged bituminous binder. The amount of aged bituminous binder that can be mobilized in the recycling process largely depends on mix production condition, milled, and virgin material property. The paper presents a simple methodology to quantify the degree of bituminous binder which becomes available in recycled mix design. The methodology can be used by mix designers to account for appropriate adjustment in virgin binder grade selection. The knowledge of degree of binder availability would also enable, if one targets to synthesize recycled mixes of a definite binder content. The paper also investigated the implication of different degree of binder availability on mix performance, arising due to different mixing time (production condition) and milled material property. [ABSTRACT FROM AUTHOR]

In this research, the properties of two tailings solvent recovery unit (TSRU) samples, one bitumen froth sample and two aggregates, are evaluated using various laboratory tests. The TSRU-modified mixtures are prepared at different concentrations of bitumen froth (0%–6% of weight of mixture increasing in 1% intervals) where TSRU materials were added based on optimum moisture content of the mixture. The properties of the mixtures are investigated using indirect tensile strength and Marshall stability tests. The results show that TSRU modification results in a higher tensile strength. The granular layer thickness can be reduced by 42% and 60% for modified samples made with both aggregates. It should be noted that the modified samples fail to meet the soaked indirect tensile strength requirement. A potential solution to improve the indirect tensile strength of the soaked mixture is using cementitious additives such as Portland cement. [ABSTRACT FROM AUTHOR]

This study aims to enhance the performance of the microsurfacing mixture and evaluate the parameters affecting this mixture. For these purposes, the effects of pure bitumen types for producing bitumen emulsion, types of aggregates, and the percentages of bitumen emulsion and emulsifier on the microsurfacing mixture are investigated. Three different types of pure bitumen with penetration grades of 40–50, 60–70, and 85–100 were used to make bitumen emulsion. In addition, limestone and siliceous aggregates, 0.9%, 1.2%, 1.5% emulsifier, and 9%, 10%, and 11% bitumen emulsion were used for test samples. The microsurfacing mixture was then evaluated by cohesion, wet track abrasion, loaded wheel, and mixing time tests. The results revealed that increasing the percentages of bitumen emulsion, emulsifier, limestone aggregates, and bitumen emulsion made from softer pure bitumen increased the microsurfacing mixture's breaking time. Moreover, the test sample containing bitumen emulsion made from harder pure bitumen, limestone aggregates, and lower emulsifier percentages showed a better setting time, which is suitable for a quick traffic reopening system. In addition, using limestone aggregates, pure bitumen with a lower penetration grade and a higher emulsifier percentage declined the optimum bitumen emulsion percentage. It also enhanced the microsurfacing mixture's resistance to abrasion, rutting, and moisture sensitivity. Overall, using limestone aggregates and bitumen emulsion made from harder pure bitumen improved the microsurfacing mixture performance, preventing some distresses, including rutting, stripping, bleeding, and aggregates' polishing, which can lead to the longer service life of this mixture. [ABSTRACT FROM AUTHOR]

To investigate the effect of recycled engine oil bottoms (REOB) as a compatibilizer on the properties of styrene–butadiene–styrene-modified bitumen (SBS-PMB), this paper studied the preparation method, properties, and micro-mechanism of composite modification of matrix bitumen with SBS and REOB. Firstly, a multi-factor orthogonal experiment determined the optimal preparation scheme of REOB/SBS composite-modified bitumen (REOB/SBS-PMB). Then, the high-temperature stability rheological properties, and anti-aging performance of REOB-PMB were studied by testing Brookfield viscosity, elasticity recovery, and dynamic shear rheology (DSR) and by short-term aging simulation (TFOT). Finally, the microstructure, fraction content, and SBS particle dispersion of 70# matrix bitumen (70-MB), SBS-PMB, and REOB/SBS-PMB were compared and analyzed by tests of Fourier transform infrared spectroscopy (FTIR), rod-shaped thin-layer chromatography, and fluorescence microscopy to reveal the micro-mechanism of REOB improving SBS and bitumen compatibility. The research results showed that the mixing form of SBS and REOB in bitumen was mainly physical swelling and blending, with chemical changes also present that have a minor impact. The light fraction in REOB increased the flowability of bitumen, promoted the swelling of SBS, improved the compatibility between SBS and bitumen, and improved the high-temperature stability and rheological properties while reducing the impact of aging. [ABSTRACT FROM AUTHOR]

Over the years, there have been many studies on the performance improvement of asphalt mixtures using different materials and additives, especially those of the recycled variety, because of the environmental benefits they bring to the design. This study investigated the properties of asphalt mixtures made with different amounts of calcium lignosulfonate (CLS), which is a waste product, and used the Balanced Mix Design (BMD) approach to determine the appropriate mix design for CLS-containing mixtures. In this process, the results of the dynamic creep test were used as a measure of rutting resistance, the results of the indirect tensile test were used as a measure of moisture susceptibility, and the results of the Illinois Flexibility Index Test (IFIT) and Indirect Tensile Cracking Test (IDEAL-CT) were used independently as a measure of cracking resistance. On the other hand, since previous studies have suggested that CLS has antiaging properties, the specimens were made and tested in two groups: those with long-term aging and without long-term aging. So the objective was to determine the amount of CLS that should ideally be used as a bitumen additive in aged and unaged asphalt mixtures. The results showed that using 15% or 20% CLS will always yield acceptable outcomes in terms of BMD criteria for both aged and unaged conditions. However, a CLS content of 10% may also be acceptable for both aged and unaged conditions if IDEAL-CT results are used as the measure of cracking resistance. [ABSTRACT FROM AUTHOR]

This study focused on the preparation, structural characterization and evaluation of some dynamic and rheological properties of a new type of mastic material, clay-mastic, which consists of bituminous binders mixed with mineral fillers. For this purpose, mastic samples were prepared by mixing conventional bitumen (50/70) with organo-montmorillonite (OMMT) in various proportions. X-ray powder diffraction (XRD) spectra and scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM) images of raw clay (MMT), organo-clay (OMMT) and raw bitumen with the prepared mastics were taken, and the changes in the crystallographic properties of the clay and its dispersion characteristics in the bitumen matrix as well as the changes in the morphological properties of the mastic samples were investigated comparatively. In addition, penetration, softening point, flash point, dynamic viscosity, dynamic shear rheometer (DSR) and Fraass breaking point tests were carried out together with those of base bitumen in order to evaluate the properties of the prepared mastic samples in terms of dynamics and rheology. A comparison of the images of raw clay and organo-clay indicated delamination based on surface modification in clay layers in those belonging to organo-clay, and diffractograms of prepared mastic samples showed that the characteristic smectite peak of Montmorillonite shifted to the left gradually with an increasing clay ratio. This shows that due to the successful lyophilic modification on the clay surface, the effective intercalated and even exfoliated dispersion of the clay layers in the bitumen matrix can occur. The penetration viscosity number (PVN) values, defined as a function of penetration and dynamic viscosity, and the penetration index (PI) values, defined as a function of penetration and softening point, were found to be within a well-accepted thermal stability range for all of the prepared mastic samples. For this reason, it was concluded that the sensitivity of the samples to temperature decreased with the addition of organo-clay, thus providing applicability in a wider temperature range. The Fraass breaking point and dynamic viscosity values of the prepared mastic samples decreased and increased, respectively, with an increasing clay ratio, meaning that the addition of organo-clay lead to an increase in the crack resistance of the samples at low temperatures and a decrease in their permeability. [ABSTRACT FROM AUTHOR]

In the production of asphalt mixtures, the possibility of recycling rubber grits has appeared for decades. A rubber bituminous mixture appearing as a special Hungarian patent greatly reduced the viscosity problems of rubber bitumen mixtures, resulting in a bitumen type that is easily transportable and does not require special equipment, The asphalt mechanical properties of the MOL rubber bituminous mixture are excellent both in the field of plastic deformation, cold behavior, and fatigue properties, so they are real competitors to polymer-modified bituminous mixtures. New research possibilities have emerged for use at reduced production temperatures, as a so-called WMA asphalt mix, in which case the first experimental – wheel tracking and cold behavior test - results are also encouraging. [ABSTRACT FROM AUTHOR]