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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 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 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]

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]

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]

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]

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]

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]

Cold recycling using foam bitumen is one of the most popular rehabilitation techniques for bituminous pavements. Effect on mixing temperature reclaimed asphalt pavement (RAP) material content and foam binder content on the performance of foam bitumen mix (FBM) has been evaluated in the present study. This paper discusses the statistical approach adopted for FBM design and the development of the model consisting of three factors which are mixing temperature, foam bitumen content, and RAP material content. The experiment was designed according to the 23 factorial design using the central composite design (CCD) method and the desirability approach was adopted for determining the optimum parameter. Dry and wet indirect tensile strength parameters were considered as responses to optimise the input parameters. Results show that with increasing the mixing temperature of FBM, the performance of FBM improves at lesser binder content. The developed quadratic models using the response surface methodology (RSM) optimisation tool have higher determination coefficients for dry IDT and wet IDT indicating a good model fit between the actual and predicted values. A scanning electron microscope analysis was conducted to evaluate the impact of RAP content and mixing temperature on the dispersion of bitumen in the FBM matrix. [ABSTRACT FROM AUTHOR]

The available skid resistance, or friction, in a pavement surface is a vital parameter for functional evaluations of roads due to its relation with crashes. Therefore, highway administrations must collect friction data on their road network to provide safe roads to users. Additionally, a prediction model that can forecast the available skid resistance in each road segment is necessary for an efficient pavement management system (PMS). The aim of this paper is to develop a skid resistance prediction model for the bituminous pavements of the motorway network of federal state of Bavaria, in Germany, with information that is typically available in a PMS: the Annual Average Daily Traffic , the Annual Average Daily Heavy Traffic , and the number of lanes in each segment. Despite its simplicity, with 6410 road segments of 2 and 3 lanes of the Bavarian motorway network, the model achieves a determination coefficient (R2) of 0.405. If information about the surface layer material is added, R2 increases to 0.480. Consequently, apart from predicting the minimum available friction in each lane in a motorway, the study underlines the necessity that a PMS should contain the recommended elements and additional surface layer material, because the quality of the prediction improves. [ABSTRACT FROM AUTHOR]

Bituminized waste products (BWPs) were produced by conditioning in bitumen the co‐precipitation sludge resulting from industrial reprocessing of spent nuclear fuel. Underground geological disposal is a solution for the long‐term disposal of some intermediate level long‐lived (ILW‐LL) categorized BWPs in France. After one or several hundred thousand years, the water from the host rock will fully saturate the disposal cells. By an osmotic phenomenon enabled by the semi‐permeable capacity of the bituminous matrix, water in direct contact with BWPs could cause them to swell, which would lead to pressure on the host rock and may damage the disposal facility. Therefore, the BWPs' swelling behavior has to be taken into account in safety studies for disposal facilities. This paper presents an experimental and numerical investigation of BWPs' swelling behavior due to water uptake. Experimentally, water uptake, swelling and released salts were monitored for about 4 years during free leaching tests of simplified BWPs. The numerical model presented is extended from an existing one that incorporates transport mechanisms (diffusion, permeation, osmosis) with mechanics via Maxwell's viscoelastic model. An original coupled homogenization of transport terms is proposed to better capture the role of the semi‐permeable membrane played by the bitumen and the porosity dependency of coupled transport coefficients during water uptake. The presented numerical model is able to reproduce the experimental results of free leaching tests and shows its validity for the entire leaching process. [ABSTRACT FROM AUTHOR]

Bituminous pavement layers are composite in nature, consisting of binder, filler, and aggregates. Understanding the mechanical behaviour of bituminous layers demands investigation of their different material scales, such as the binder, mastic, and mixture scales. While substantial investigation has been carried out on binder and mixture related to fatigue damage, not much research is carried out on mastic. Of the methods used to characterise fatigue damage, energy dissipation is widely used; however, it is complicated due to the presence of other modes of dissipation, such as viscous dissipation. In this study, an attempt is made to separate viscous dissipation and dissipation due to damage for both binder and mastic using a nonlinear viscoelastic fluid model. For this purpose, six types of materials were tested at temperatures of 20 $^\circ$ ∘ C and 25 $^\circ$ ∘ C, 10 Hz frequency, and five different strain levels spanning the linear and non-linear regimes, for 20,000 cycles. Material parameters for the non-linear White-Metzner model incorporated with the Williamson model were determined for an initial cycle and using these parameters, the viscous component of energy dissipation was determined. Dissipation due to damage was estimated by separating viscous dissipation from total dissipation at every 2000th cycle and based on the evolution of viscous and damage dissipation across cycles, three trends were observed. Based on the trends observed, the influence of strain amplitude, temperature and modifiers on the fatigue resistance of the materials was ascertained. [ABSTRACT FROM AUTHOR]

Considering the global burden of cigarette consumption, the disposal of cigarette butts has become an inevitable issue. Compared to traditional disposal methods, such as landfilling or incinerating, the recycling of these wastes is clearly an eco-friendlier solution. In this research, waste electronic cigarette butts (E-CBs) were collected and recycled in bituminous mixtures, aiming to increase the use of sustainable road construction materials. The objective of this research is to explore the possibility of using waste E-CBs as an alternative stabilising fibre in asphalt mixtures. To this end, shredded waste E-CBs were incorporated in Stone Mastic Asphalt (SMA) and compared with the conventional cellulose fibres. Furthermore, to investigate the effects of powders (below 0.063 mm) from the waste E-CBs on the rheological properties of bitumen, tests were conducted on base SBS-modified bitumen and its mastics. Results show that the waste powder was unfavourable to the thermal susceptibility of the resulting binder. SMA samples with shredded E-CBs were also characterised through physical and mechanical tests and compared to the reference mixture using cellulose fibres. It was concluded that using waste E-CBs in SMA can be considered a promising alternative for replacing cellulose fibres and avoiding the disposal of cigarette butts. [ABSTRACT FROM AUTHOR]

The primary objective of the present study is to evaluate the effectiveness of the widely used moisture conditioning methods for moisture susceptibility evaluation while designing the Foamed Bitumen Stabilised Mixes (FBMs). The effectiveness of three different moisture conditioning methods, such as the conventional 24 h of water soaking, vacuum saturation (AASHTO T283), and ASTM D7870 conditioning (hydrostatic pore pressure) were compared based on their ability to distinguish between moisture susceptible and moisture damage resistant FBMs. It was observed that the ASTM D7870 moisture conditioning method could distinguish between moisture-resistant and moisture-susceptible mixes more effectively compared to the existing 24 h of water-soaking method, and can potentially be a more suitable conditioning method for moisture susceptibility evaluation of FBMs. The study also recommended threshold moisture susceptibility criteria in terms of retained tensile strength (TSR) for the ASTM D7870 conditioning method based on the existing moisture susceptibility criteria for 24 h of water soaking by performing Receiver Operation Characteristics (ROC) analysis on the TSR results. For different TSR criteria of 80%, 70%, and 60% for 24 h of water soaking, the equivalent TSR threshold for ASTM D7870 conditioning is recommended as 60%, 55%, and 50% respectively. [ABSTRACT FROM AUTHOR]

Different types of additives are used in asphalt modification to enhance several properties within the asphalt pavement. In various cases, modification is needed by using multiple additives, which is called composite modification. In this study, glass fibre and nano clay were used to modify the asphalt pavement. The amount of these two additives, together with the optimum bitumen content, was determined by the response surface methodology (RSM). Central composite method (CCD) was used for determining the optimum amount of independent variables (nano clay, glass fibre, bitumen content), by evaluating the dependent variables. Marshall mixture design criteria and minimum bitumen content, were the optimal conditions. As a result, the mixture containing 0.2% glass fibre, 3.693% nano clay and 4.096% bitumen content, was predicted to give the most desirable characteristics. Additionally, verification tests were conducted to evaluate the adequacy of the predicted model. The results were within the 95% confidence intervals for all response variables, which demonstrates the validity of the model obtained in the study. Consequently, CCD can be used to obtain design optimisation of asphalt modification with less mixture production for experimental stages. This is a substantial advantage, which supports human safety and environment- friendly practices. [ABSTRACT FROM AUTHOR]

Cement Grouted Bituminous Macadam (CGBM) is a composite pavement that can offer sustainability in the pavement construction sector. The main objective of this study emphasises designing and evaluating the CGBM mixes prepared with different cementitious grouts and aggregate gradations. Compressive strength (7 and 28 days), Flexural strength (28 days), Marsh cone flow, and Initial and final setting time were considered for optimising the cementitious grouts. The details of several investigations on CGBM that include Marshall stability, Compressive strength, Indirect Tensile Strength (ITS), Resilient Modulus (Mr), Fracture energy, and Cantabro abrasion test were reported. The experimental results showed that sand and micro silica influence the mobility of grout to a greater extent. Percolation of grouts into Open Graded Friction Course (OGFC) mixes was a critical concern for grouts with flow time longer than 35 s. A reduction in the pore volume and reduced interconnected links in finer gradation resulted in improper full-depth penetration (FDP) characteristics. Mixture level tests for CGBM revealed that Mr of CGBM improved by about 6 times compared to the bituminous mix. In addition, CGBM showed high tensile strength with rapid crack propagation behaviour. Further, pavement design demonstrated a 35% of thickness reduction and cost reduction due to CGBM implementation. [ABSTRACT FROM AUTHOR]

The warm mix asphalt (WMA) technology has brought environmental sustainability into the pavement industry with its preparation at lower production temperatures than hot mix asphalt (HMA). Nevertheless, it has also raised concerns regarding the mixture's resistance to permanent deformation as a result of its reduced aging during production. This study examines the effects of warm mix modification on the rutting potential of bituminous mixes. Two modifiers were used for WMA preparation – polyethylene wax (PEW) and waste cooking oil (WCO). Binder rutting properties were evaluated using the multiple stress creep recovery (MSCR) test. Subsequently, WMA mixtures were prepared at adequate production temperatures, and then their rutting characteristics were evaluated using the Cooper wheel tracker device. The study concluded that introducing warm mix modifiers in small amounts, approximately 1–2% by weight of bitumen, results in rutting characteristics comparable to virgin bituminous mix, whereas the characteristics deteriorate at higher modifier contents. Furthermore, a rutting prediction model based on the Weibull failure rate function (WFRF) was developed. A strong correlation was found between the measured wheel tracking data and the prediction model in all mixtures. PEW was discovered to be a superior warm mix modifier to WCO in terms of rutting resistance. [ABSTRACT FROM AUTHOR]

Acid sludge is an environmental pollutant that is produced daily in large amounts in used engine oil refineries. Recycling this waste is the primary goal of this paper. This study used 'washing with water' and 'neutralization with quicklime' methods to prepare acid sludge for use in bituminous materials as huge potential disposal. The neutralised sludge by the 'washing with water' method was added to bitumen in the wet blending process at 10, 20, and 30 wt%. This product is brittle without proper adhesion and cohesion and cannot meet the standard limits as an acceptable binder. It performs like long-term aged bitumen, reducing penetration and ductility and increasing the aging potential and viscosity. In another method, the neutralised sludge by adding quicklime was added to the asphalt mixture to replace fine aggregates in 50, 75, and 100 wt%. Using this product decreases the aging potential and moisture susceptibility up to 36.4, and increases rutting resistance up to 34.7%, indirect tensile strength up to 17.3%, and resilient modulus up to 17.3%. Despite the presence of large amounts of heavy metals in acid sludge, using this product in asphalt mixtures is an economical and completely hygienic solution for disposing of acid sludge. [ABSTRACT FROM AUTHOR]

This paper aims to develop a general form of the time-temperature-ageing shift model for bituminous materials based on free volume theory and validate its application in the Finite Element (FE) modelling for predicting aged asphalt mixtures' mechanical responses. The frequency sweep, dynamic modulus, and Fourier Transform Infrared Spectroscopy (FTIR) tests were used to validate the proposed time-temperature-ageing shift model. A generalised Maxwell model incorporating the proposed shift model of asphalt mixtures was used to predict the mechanical responses of aged asphalt mixtures using FE modelling, verified via laboratory cyclic load tests. Results indicate that the time-temperature-ageing shift function can model the complex shear modulus and dynamic modulus master curves of bituminous materials, addressing the modulus dependency of temperature and ageing. Temperature dominates the modulus change of bituminous materials in the ageing process. The coefficients of the time-temperature-ageing shift model have clear physical meanings and can potentially quantify the effects of asphalt mixtures' air voids on their temperature and ageing susceptibilities. The time-temperature-ageing shift model can be incorporated into the constitutive relations of the FE model to effectively couple and efficiently predict the effects of temperature and ageing on the mechanical responses of aged asphalt mixtures. [ABSTRACT FROM AUTHOR]

This paper studies the potential effects of Reclaimed Asphalt Pavement (RAP) fine particles on bituminous mixtures by means of a laboratory investigation performed at the mastic scale. Bituminous mastics, characterised by a constant filler to bitumen volume ratio, were prepared by combining virgin filler and virgin bitumen with several dosages of RAP fine particles. The influence of RAP type was evaluated by employing two RAP products supplied by different sources. The rheological behaviour of the mastics was investigated by means of oscillatory tests carried out with a dynamic shear rheometer. The time-temperature superposition principle and the generalised self-consistent scheme (GSCS) micromechanical model were used to explore the role played by RAP at the mastic scale. Results indicate that the adopted experimental and modelling approach allows a proper assessment of the effects of RAP on the linear viscoelastic properties of mastics and of the degree of blending occurring between virgin and RAP binder. [ABSTRACT FROM AUTHOR]

Significance of premature failures, such as thermal cracking, on the in-service performance of asphalt pavements, resulted in exploring how cracking resistance of Warm Mix Asphalt (WMA) is affected by its inherent characteristics. Three WMA technologies consisting of the application of organic materials, chemical agents, and foam bitumen technique, coupled with conventional Hot Mix Asphalt (HMA) were used to prepare WMA mixes. Semi-circular bending test was used to investigate cracking potential of the selected WMA mixes. Statistical analysis, comprising of ANOVA, Tukey pairwise, and Spearman's ranking-order, showed that indices such as WeibullCRI, RDCI, and FI can be adequately used for ranking WMA mixes. Weibull probability distribution function (Weibull PDF) analysis was also applied to determine effects of the testing factors on their failure probability. Results showed that temperature reduction towards −20°C increases probability of fracture failure. Fracture happened more in Sasobit and Foam WMA mixes. However, effects of moisture level and FT cycles on crack evolution was negligible. Finally, failure probability curves of the various WMA mixes were predicted based on the actual probability curves of the control HMA. [ABSTRACT FROM AUTHOR]

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 pavement layers are composite in nature, consisting of binder, filler, and aggregates. Understanding the mechanical behaviour of bituminous layers demands investigation of their different material scales, such as the binder, mastic, and mixture scales. While substantial investigation has been carried out on binder and mixture related to fatigue damage, not much research is carried out on mastic. Of the methods used to characterise fatigue damage, energy dissipation is widely used; however, it is complicated due to the presence of other modes of dissipation, such as viscous dissipation. In this study, an attempt is made to separate viscous dissipation and dissipation due to damage for both binder and mastic using a nonlinear viscoelastic fluid model. For this purpose, six types of materials were tested at temperatures of 20 $^\circ$ ∘ C and 25 $^\circ$ ∘ C, 10 Hz frequency, and five different strain levels spanning the linear and non-linear regimes, for 20,000 cycles. Material parameters for the non-linear White-Metzner model incorporated with the Williamson model were determined for an initial cycle and using these parameters, the viscous component of energy dissipation was determined. Dissipation due to damage was estimated by separating viscous dissipation from total dissipation at every 2000th cycle and based on the evolution of viscous and damage dissipation across cycles, three trends were observed. Based on the trends observed, the influence of strain amplitude, temperature and modifiers on the fatigue resistance of the materials was ascertained. [ABSTRACT FROM AUTHOR]

Considering the global burden of cigarette consumption, the disposal of cigarette butts has become an inevitable issue. Compared to traditional disposal methods, such as landfilling or incinerating, the recycling of these wastes is clearly an eco-friendlier solution. In this research, waste electronic cigarette butts (E-CBs) were collected and recycled in bituminous mixtures, aiming to increase the use of sustainable road construction materials. The objective of this research is to explore the possibility of using waste E-CBs as an alternative stabilising fibre in asphalt mixtures. To this end, shredded waste E-CBs were incorporated in Stone Mastic Asphalt (SMA) and compared with the conventional cellulose fibres. Furthermore, to investigate the effects of powders (below 0.063 mm) from the waste E-CBs on the rheological properties of bitumen, tests were conducted on base SBS-modified bitumen and its mastics. Results show that the waste powder was unfavourable to the thermal susceptibility of the resulting binder. SMA samples with shredded E-CBs were also characterised through physical and mechanical tests and compared to the reference mixture using cellulose fibres. It was concluded that using waste E-CBs in SMA can be considered a promising alternative for replacing cellulose fibres and avoiding the disposal of cigarette butts. [ABSTRACT FROM AUTHOR]

Different types of additives are used in asphalt modification to enhance several properties within the asphalt pavement. In various cases, modification is needed by using multiple additives, which is called composite modification. In this study, glass fibre and nano clay were used to modify the asphalt pavement. The amount of these two additives, together with the optimum bitumen content, was determined by the response surface methodology (RSM). Central composite method (CCD) was used for determining the optimum amount of independent variables (nano clay, glass fibre, bitumen content), by evaluating the dependent variables. Marshall mixture design criteria and minimum bitumen content, were the optimal conditions. As a result, the mixture containing 0.2% glass fibre, 3.693% nano clay and 4.096% bitumen content, was predicted to give the most desirable characteristics. Additionally, verification tests were conducted to evaluate the adequacy of the predicted model. The results were within the 95% confidence intervals for all response variables, which demonstrates the validity of the model obtained in the study. Consequently, CCD can be used to obtain design optimisation of asphalt modification with less mixture production for experimental stages. This is a substantial advantage, which supports human safety and environment- friendly practices. [ABSTRACT FROM AUTHOR]

The primary objective of the present study is to evaluate the effectiveness of the widely used moisture conditioning methods for moisture susceptibility evaluation while designing the Foamed Bitumen Stabilised Mixes (FBMs). The effectiveness of three different moisture conditioning methods, such as the conventional 24 h of water soaking, vacuum saturation (AASHTO T283), and ASTM D7870 conditioning (hydrostatic pore pressure) were compared based on their ability to distinguish between moisture susceptible and moisture damage resistant FBMs. It was observed that the ASTM D7870 moisture conditioning method could distinguish between moisture-resistant and moisture-susceptible mixes more effectively compared to the existing 24 h of water-soaking method, and can potentially be a more suitable conditioning method for moisture susceptibility evaluation of FBMs. The study also recommended threshold moisture susceptibility criteria in terms of retained tensile strength (TSR) for the ASTM D7870 conditioning method based on the existing moisture susceptibility criteria for 24 h of water soaking by performing Receiver Operation Characteristics (ROC) analysis on the TSR results. For different TSR criteria of 80%, 70%, and 60% for 24 h of water soaking, the equivalent TSR threshold for ASTM D7870 conditioning is recommended as 60%, 55%, and 50% respectively. [ABSTRACT FROM AUTHOR]

Cement Grouted Bituminous Macadam (CGBM) is a composite pavement that can offer sustainability in the pavement construction sector. The main objective of this study emphasises designing and evaluating the CGBM mixes prepared with different cementitious grouts and aggregate gradations. Compressive strength (7 and 28 days), Flexural strength (28 days), Marsh cone flow, and Initial and final setting time were considered for optimising the cementitious grouts. The details of several investigations on CGBM that include Marshall stability, Compressive strength, Indirect Tensile Strength (ITS), Resilient Modulus (Mr), Fracture energy, and Cantabro abrasion test were reported. The experimental results showed that sand and micro silica influence the mobility of grout to a greater extent. Percolation of grouts into Open Graded Friction Course (OGFC) mixes was a critical concern for grouts with flow time longer than 35 s. A reduction in the pore volume and reduced interconnected links in finer gradation resulted in improper full-depth penetration (FDP) characteristics. Mixture level tests for CGBM revealed that Mr of CGBM improved by about 6 times compared to the bituminous mix. In addition, CGBM showed high tensile strength with rapid crack propagation behaviour. Further, pavement design demonstrated a 35% of thickness reduction and cost reduction due to CGBM implementation. [ABSTRACT FROM AUTHOR]

The warm mix asphalt (WMA) technology has brought environmental sustainability into the pavement industry with its preparation at lower production temperatures than hot mix asphalt (HMA). Nevertheless, it has also raised concerns regarding the mixture's resistance to permanent deformation as a result of its reduced aging during production. This study examines the effects of warm mix modification on the rutting potential of bituminous mixes. Two modifiers were used for WMA preparation – polyethylene wax (PEW) and waste cooking oil (WCO). Binder rutting properties were evaluated using the multiple stress creep recovery (MSCR) test. Subsequently, WMA mixtures were prepared at adequate production temperatures, and then their rutting characteristics were evaluated using the Cooper wheel tracker device. The study concluded that introducing warm mix modifiers in small amounts, approximately 1–2% by weight of bitumen, results in rutting characteristics comparable to virgin bituminous mix, whereas the characteristics deteriorate at higher modifier contents. Furthermore, a rutting prediction model based on the Weibull failure rate function (WFRF) was developed. A strong correlation was found between the measured wheel tracking data and the prediction model in all mixtures. PEW was discovered to be a superior warm mix modifier to WCO in terms of rutting resistance. [ABSTRACT FROM AUTHOR]

Acid sludge is an environmental pollutant that is produced daily in large amounts in used engine oil refineries. Recycling this waste is the primary goal of this paper. This study used 'washing with water' and 'neutralization with quicklime' methods to prepare acid sludge for use in bituminous materials as huge potential disposal. The neutralised sludge by the 'washing with water' method was added to bitumen in the wet blending process at 10, 20, and 30 wt%. This product is brittle without proper adhesion and cohesion and cannot meet the standard limits as an acceptable binder. It performs like long-term aged bitumen, reducing penetration and ductility and increasing the aging potential and viscosity. In another method, the neutralised sludge by adding quicklime was added to the asphalt mixture to replace fine aggregates in 50, 75, and 100 wt%. Using this product decreases the aging potential and moisture susceptibility up to 36.4, and increases rutting resistance up to 34.7%, indirect tensile strength up to 17.3%, and resilient modulus up to 17.3%. Despite the presence of large amounts of heavy metals in acid sludge, using this product in asphalt mixtures is an economical and completely hygienic solution for disposing of acid sludge. [ABSTRACT FROM AUTHOR]

This paper aims to develop a general form of the time-temperature-ageing shift model for bituminous materials based on free volume theory and validate its application in the Finite Element (FE) modelling for predicting aged asphalt mixtures' mechanical responses. The frequency sweep, dynamic modulus, and Fourier Transform Infrared Spectroscopy (FTIR) tests were used to validate the proposed time-temperature-ageing shift model. A generalised Maxwell model incorporating the proposed shift model of asphalt mixtures was used to predict the mechanical responses of aged asphalt mixtures using FE modelling, verified via laboratory cyclic load tests. Results indicate that the time-temperature-ageing shift function can model the complex shear modulus and dynamic modulus master curves of bituminous materials, addressing the modulus dependency of temperature and ageing. Temperature dominates the modulus change of bituminous materials in the ageing process. The coefficients of the time-temperature-ageing shift model have clear physical meanings and can potentially quantify the effects of asphalt mixtures' air voids on their temperature and ageing susceptibilities. The time-temperature-ageing shift model can be incorporated into the constitutive relations of the FE model to effectively couple and efficiently predict the effects of temperature and ageing on the mechanical responses of aged asphalt mixtures. [ABSTRACT FROM AUTHOR]

This paper studies the potential effects of Reclaimed Asphalt Pavement (RAP) fine particles on bituminous mixtures by means of a laboratory investigation performed at the mastic scale. Bituminous mastics, characterised by a constant filler to bitumen volume ratio, were prepared by combining virgin filler and virgin bitumen with several dosages of RAP fine particles. The influence of RAP type was evaluated by employing two RAP products supplied by different sources. The rheological behaviour of the mastics was investigated by means of oscillatory tests carried out with a dynamic shear rheometer. The time-temperature superposition principle and the generalised self-consistent scheme (GSCS) micromechanical model were used to explore the role played by RAP at the mastic scale. Results indicate that the adopted experimental and modelling approach allows a proper assessment of the effects of RAP on the linear viscoelastic properties of mastics and of the degree of blending occurring between virgin and RAP binder. [ABSTRACT FROM AUTHOR]

Significance of premature failures, such as thermal cracking, on the in-service performance of asphalt pavements, resulted in exploring how cracking resistance of Warm Mix Asphalt (WMA) is affected by its inherent characteristics. Three WMA technologies consisting of the application of organic materials, chemical agents, and foam bitumen technique, coupled with conventional Hot Mix Asphalt (HMA) were used to prepare WMA mixes. Semi-circular bending test was used to investigate cracking potential of the selected WMA mixes. Statistical analysis, comprising of ANOVA, Tukey pairwise, and Spearman's ranking-order, showed that indices such as WeibullCRI, RDCI, and FI can be adequately used for ranking WMA mixes. Weibull probability distribution function (Weibull PDF) analysis was also applied to determine effects of the testing factors on their failure probability. Results showed that temperature reduction towards −20°C increases probability of fracture failure. Fracture happened more in Sasobit and Foam WMA mixes. However, effects of moisture level and FT cycles on crack evolution was negligible. Finally, failure probability curves of the various WMA mixes were predicted based on the actual probability curves of the control HMA. [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]

Plastic asphalt mixtures (PAM) have attracted extensive attention lately; however, their application in the field has not been so common because of the lack of clear understanding of the behavior of the asphalt mix after modification. In the interest of closing this gap, a modeling tool able to estimate the plastic effect on asphalt mixtures properties is needed. Nevertheless, the suggestion of a generalized model is complex due to the numerous variables involved. To facilitate this process, the present article aims to expand the current knowledge about PAM modeling by providing a clearer understanding of what variables have the highest impact on PAM properties. To do so, data from previous articles have been gathered and machine learning and shapley additive explanation values have been applied. PAM properties assessed were air voids, Marshall stability, Marshall flow, indirect tensile strength, and tensile strength ratio. Overall, the features with the highest impact are plastic type and content (35%), aggregates gradation (35%), aggregates absorption (9%), bitumen content (8%), mixing technique (4%), and bitumen penetration (3%). The final proposed models extend the application of previous machine learning models and feature importance understanding, and, in the field, they can serve as an initial estimate of the plastic effect on different asphalt mixture types. It is suggested that future articles intending to model PAM should consider these critical features during model formulation, and articles evaluating new types of PAM should clearly report these properties, for they might be the basis of these generalized future models. [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]

The air voids in the bituminous mix are filled with a cementitious grout to create cement grouted bituminous (CGB) mix, which is a semi-flexible material. The material has a high resistance to permanent deformation at high temperatures and under heavy loads because of the cementitious grout used in the mixture. Despite their increased brittleness, CGB layers are more prone to cracking when used as thin (40–60 mm) surface or base layers. Increase in binder content in mix decreases air void content and grout content, which leads to reduction in rutting resistance and expected to improve the fatigue cracking resistance. The results of an investigation into the impact of aggregate gradation and binder content on the fatigue performance of CGB mixes are presented in this paper. In a four-point bending test mode at 25 °C, beam specimens of CGB Mixes made with four different aggregate gradations and four different binder contents were tested at four strain levels. The fatigue life measured at higher strain levels of 225 and 250 µε and various mechanical properties like indirect tensile strength and modulus of rupture showed good correlation. By analysing pavements with CGB layers used as the base or surface layer, the fatigue cracking susceptibility of the CGB layer in a typical highway pavement has been determined. It has been found that using the CGB mix as the surface layer is a good choice because the mix also provides a very strong rut as well as an oil and chemical-resistant layer. [ABSTRACT FROM AUTHOR]

Mix design of asphalt concrete is carried out in order to produce a mixture of asphalt bitumen and aggregate that satisfies both minimum design requirements and cost-effectiveness. Marshall mix design, similar to other mix design methods, aims to determine an optimum mix for a given design criteria, having an optimum bitumen content, and has still been one of the most used asphalt mix design method in the world. Marshall mix design procedure requires significant amount of time and skilled workmanship for lengthy laboratory experiments. Time required for the mix design may negatively affect construction schedule especially during the peak construction season. In Marshall mix design procedure, optimum bitumen content is determined based on Marshall stability and flow test results, and other volumetric properties of the mixes. Prediction models that quickly predict all required Marshall mix design parameters based on very few numbers of input parameters requiring significantly less amount of time to obtain compared to the time needed to obtain all Marshall mix design parameters through lengthy laboratory experiments could be quite useful. In this study, artificial neural network-based prediction models based on the data of 200 asphalt mixes designed for asphalt wearing course, obtained from 5th district of the General Directorate of Highways of Turkey, were developed to predict all required Marshall mix design parameters. As part of the paper, a Microsoft Excel Macro-based tool, to be potentially used by 5th district of the General Directorate of Highways of Turkey, was also developed that makes prediction of all required mix design parameters for any given mix in seconds using the developed models and very few numbers of user-defined input parameters requiring significantly less amount time to obtain so that optimum bitumen content could be quickly determined. This will significantly reduce the amount of time and other resources required to determine optimum bitumen content. [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]

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]