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The fuel leakage of fuel vehicles will exacerbate the occurrence of distresses on asphalt pavements, including peeling, chipping and potholes, especially under the synergistic effect of traffic load and environment. In this research, Sasobit, which is commonly used as a warm agent in asphalt, is selected as the anti-fuel erosion agent and incorporated into SBS-modified asphalt and its mixtures. Diesel and gasoline are selected as the fuel erosion media. Sasobit/SBS-modified asphalt binder and its mixtures are investigated for fuel erosion. The rheological properties of bitumen and the mechanical properties of asphalt mixtures are assessed. The experimental findings show that the dissolution velocity of SBS-modified asphalt with 3% Sasobit is 0.2%/min for diesel erosion, while it is 1.7%/min for gasoline erosion, lower than the control sample without Sasobit. Meanwhile, the rutting factor of Sasobit/SBS-modified asphalt decreases less than that of the control sample without Sasobit. Furthermore, the mass loss ratio after the Cantabro test of Sasobit/SBS-modified asphalt mixtures is 1.2% for diesel erosion, while it is 6.8% for gasoline erosion, lower than that of the control sample without Sasobit. The results of the mechanical properties for asphalt mixtures demonstrate that Sasobit can enhance the anti-fuel erosion performance. Moreover, the research results of the Sasobit modification mechanism show that Sasobit can form a microcrystalline structure in SBS-modified asphalt, which subsequently improves the anti-fuel of asphalt and its mixtures. This research provides a reference for anti-fuel erosion assessment methods and solutions to improve the anti-fuel erosion of asphalt pavement. [ABSTRACT FROM AUTHOR]

The use of waste polyethylene (WPE) in modified asphalt is frequently employed to reduce environmental pollution and improve asphalt properties. However, research has shown that using WPE alone as a modifier does not effectively enhance the low-temperature flexibility of asphalt. This study aims to investigate the potential of utilizing WPE and waste cooking oil (WCO) as composite modifiers to enhance the properties of virgin asphalt under both high and low-temperature conditions. The contents of WPE and WCO were used, and the preparation process for the modified asphalt was optimized through an orthogonal experiment. The experimental results indicate that the optimal formulation for the WPE/WCO composite modified asphalt (WPE/WCO-A) is obtained with an additive dosage of 8% and 1% by mass of virgin asphalt for WPE and WCO, respectively, as well as the maintenance process at a temperature of 140 °C and a duration of 2 h. Dynamic shear rheometer (DSR) results reveal that WPE/WCO composite modifier can greatly improve the high-temperature deformation resistance of asphalt. Bending beam rheometer (BBR) tests confirm that WPE adversely affects the low-temperature flexibility of asphalt, while the addition of WCO can improve it. WPE/WCO-A has even better low-temperature properties than virgin asphalt (VA). The Fourier transform infrared spectroscopy (FT-IR) results suggest that the composite modification of asphalt by WPE/WCO modifiers is dominated by physical action. Furthermore, the fluorescence microscopy test results demonstrate that WCO can promote WPE swelling in asphalt. This study offers a novel approach to improve the comprehensive properties of asphalt through composite modification using WPE and WCO. [ABSTRACT FROM AUTHOR]

The high-content waste rubber powder (WRP)-modified asphalt (WRMA) has poor storage stability and tends to produce many volatile organic compounds (VOCs). This study aimed to research the influence of incorporating high-content WRP on the performance enhancement and VOCs emission of asphalt and its mixtures. The storage stability, rheological properties and cracking resistance of WRMA were tested. Further, the high and low-temperature properties of WRMA mixtures were evaluated. Additionally, the VOCs emission characteristics of WRMA mixtures were analysed. The results indicate that activated WRP has good compatibility with asphalt. The high-content of WRP can significantly enhance the high-temperature rheological properties and low temperature cracking resistance of asphalt binder, and the addition of nanometre calcium carbonate (B3) adsorbent can further enhance the physicochemical properties of asphalt binder. Moreover, compared with 70# asphalt mixture, the dynamic stability of WRMA mixture increases by about 50%, and the immersion residual stability and freeze–thaw splitting strength values increase by 6.34% and 5.98%, respectively. In addition, the B3 adsorbent can significantly reduce the VOCs emission from WRMA mixtures. The corresponding conclusions could provide guidance for the large-scale application of high-content WRMA mixtures and promote cleaner and greener products. [ABSTRACT FROM AUTHOR]

Widespread interest has been drawn to the use of solid waste fillers as a partial replacement for natural fillers in high-performance asphalt mixtures in recent years. However, variations in the material properties of solid waste fillers remain a problem for the recycling method. To address this issue, the limestone powder in asphalt mixtures was replaced with three solid waste fillers, including steel slag powder, tailings powder and calcium carbide slag powder in this study. The chemical composition of the fillers was first characterized to assess the homogeneity of the material. Then, a dense-graded asphalt mixture (AC) and a stone matrix asphalt (SMA) mixture were designed, produced and characterized for wet stability. The results show that the asphalt mixtures with solid waste fillers were superior to limestone powder (LP) asphalt mixtures in terms of resistance to water damage, and the steel slag powder showed the best improvement in moisture stability of the asphalt mixtures. The optimum substitution of solid waste filler for limestone filler was 25%. With the addition of anti-stripping agents, the moisture stability of the asphalt mixture with limestone filler was also greatly enhanced. On the contrary, a marginal enhancement was observed in the moisture stability of asphalt mixtures using solid waste fillers. Solid waste fillers can be used in asphalt mixtures and have a similar function as that of anti-stripping agents. In summary, the use of solid waste fillers to replace mineral fillers in asphalt mixtures is a reliable, value-added recycling option. [ABSTRACT FROM AUTHOR]

Pretreatment of crumb rubber (CR) can significantly enhance its interfacial compatibility with asphalt and improve the workability of crumb rubber modified asphalt (CRMA). However, the structure and internal composition of pretreated CR are inevitably altered, the difference in aging resistance of CRMA with different pretreated CR need to be systematically studied. In this research, CR was pretreated by microwave activation, waste cooking oil (WCO) swelling and alkali solution soaking respectively, and corresponding modified asphalt namely CRMA-activated, CRMA-swelled and CRMA-soaked were prepared. Then, laboratory thin-film oven test (TFOT) and pressurized aging vessel (PAV) were carried out on different types of binders, the rheological properties of different CRMAs before and after aging were systematically investigated. Afterwards, the thermal stability, functional group and microstructures of all samples were also analyzed, and possible anti-aging mechanism of CRMA was proposed. The experimental results indicate that CRMA-activated and CRMA-soaked have more significant viscous behavior after aging compared with untreated CRMA. Also, the increments of their sulfoxide index and carboxyl index before and after aging are lower than that of untreated CRMA. Moreover, both activated CR and soaked CR enhance the adsorption capacity to the light components of asphalt, and therefore their anti-aging ability are improved. Unfortunately, the temperature sensitivity of CRMA-swelled shows the largest reduction before and after aging. During aging, both the asphalt light components and free WCO molecules are volatilized and oxidized more easily, which causes the deterioration of its aging resistance and low temperature performance. Overall, The findings are instructive for the optimization of CR pretreatment method and high-performance clean application of CRMA. • Pretreated CR had a significant effect on the aging behavior of prepared CRMA. • Both activated CR and soaked CR can enhance the anti-aging ability of asphalt. • The aging resistance of modified asphalt with WCO-swollen CR was reduced. • The aging behavior of CRMA was attributed to the different adsorption capacity of pretreatment CR to the light components of asphalt. [ABSTRACT FROM AUTHOR]

Applying basic oxygen furnace (BOF) slag as aggregate in asphalt mixture is continuously investigated due to the increasing shortage of natural aggregate in recent years. However, the negative effect of BOF's expansion in water greatly limits its further application in pavement construction. To address this problem, this paper studied the volume stability of BOF, and its asphalt mixture relied on actual engineering. The asphalt mixtures contained BOF aggregate was designed by the Marshall method with three different gradation types (AC-16, AC-20, and ATB-25). Besides, both laboratory samples and the core samples from field drilling were investigated in volume expansion rate after curing in a water bath. The economic and resource benefits of BOF replacement of natural aggregates were also analyzed. The results showed that the free calcium oxide content of BOF slag is positively related to the particle sizes. Nevertheless, the expansion rates of both the BOF aggregate and its asphalt mixture were less than 1%, which meant the BOF aggregate applied to the asphalt mixture meets the practical engineering requirements. The maximum allowable free calcium oxide content for large-grain size of steel slag is the smallest; it is also recommended that the expansibility of large-grain steel slag should be the first concern in the application. The resource assessment indicated that the use of steel slag for the construction of a trial section of one kilometer of single lane can save 967 tons of natural aggregates. The economic evaluation showed that the use of steel slag instead of natural aggregates for surface course construction could reduce the investment by 16.87%. The experimental methods and conclusions mentioned in this article provide stable references to enhance the development of sustainable pavement by recycling metallurgical slag in highway construction. [ABSTRACT FROM AUTHOR]

Crumb rubber modified asphalt (CRMA) in the application process often produces lots of toxic fumes, and the composition is dominated by total volatile organic compounds (TVOCs) and H 2 S, which restricts its large-scale use in practical engineering. Therefore, three preferred agricultural wastes namely wood chip powder (WCP), peanut shell flour (PSF) and moxa stick ash (MSA) were added to CRMA to investigate their inhibition effect on CRMA fume in this work, and their inhibition mechanism on CRMA fume emission was discussed. Meanwhile, the influence effect of added agricultural waste on the physicochemical properties of CRMA was further analyzed and the modification mechanism was also explored. The experimental results indicate that the incorporated WCP, PSF and MSA can all inhibit the emission of TVOCs and H 2 S in CRMA to varying degrees. Compared with CRMA, the TVOCs concentrations of CRMA-WCP, CRMA-PSF and CRMA-MSA are reduced by 36.87 %, 11.72 % and 46.22 % under 190°C, respectively, while the H 2 S concentrations can be reduced by 53.45 %, 5.03 % and 62.67 %, respectively. The three agricultural wastes contain different mesoporous structures and their inhibition of CRMA fume is dominated by physical adsorption. Moreover, the added WCP, PSF and MSA can also synergize with crumb rubber to strengthen the rutting resistance of asphalt and upgrade the elastic recovery capacity of asphalt under different loads, and the enhancement effect is in the order of WCP > PSF > MSA. In summary, the three agricultural wastes preferred in this research are effective in suppressing the emission of toxic fumes from CRMA while improving its working performance, which can provide a new avenue for fume suppression in CRMA and multi-channel utilization of agricultural waste. • The agricultural wastes added in this study can reduce the fume emission of crumb rubber modified asphalt (CRMA). • The inhibition of CRMA fume by three agricultural wastes is mainly physical adsorption. • The added agricultural wastes can synergize with crumb rubber (CR) to improve the working performance of asphalt. [ABSTRACT FROM AUTHOR]

Waste cooking oil (WCO) can be recycled cleanly as the rejuvenating agent for aged asphalt, boosting the utilization of reclaimed asphalt pavement materials in road engineering. However, the sensitivity of asphalt rejuvenated by WCO to secondary aging is unknown, which has an impact on its durability in practical engineering. The objective of this work is to explore the aging behaviors of asphalt binders rejuvenated by different chemical fractions of WCO. The performance of different fractions of WCO before and after aging treatment was evaluated. The sensitivity to aging was discussed for rejuvenated binders with WCO's fractions as rejuvenating agents including the differences in aging resistance between them and the virgin binder. The experimental results indicate that the aging resistance of WCO's fractions depends mainly on their carbon chain length. The sensitivity of rejuvenated asphalt to aging depends strongly on the aging resistance of WCO's fractions. Additionally, it is found that the resistance of rejuvenated binders to aging is better than that of the virgin binder because the WCO's fractions are less volatile than the original light components of the virgin binder. Therefore, substances with strong fluidity and weak volatility in WCO are the optimal candidates for rejuvenating agents of aged asphalt considering both the rejuvenation effect and the resistance to aging. The findings of the research contribute to the sustainability of road engineering. • The aging behaviors of asphalt rejuvenated by waste cooking oil (WCO) were explored. • The performance of different fractions of WCO before and after aging was evaluated. • The aging resistance of rejuvenated asphalt is better than that of the virgin binder. • The sensitivity of WCO rejuvenated asphalt to secondary aging depends strongly on the anti-aging ability of WCO's fractions. [ABSTRACT FROM AUTHOR]

The use of waste rubber powder (WRP) to produce WRP modified asphalt (WRMA) has been proved to have wide application prospects, however, WRMA has poor storage stability and is prone to release H 2 S and other toxic fumes. Therefore, the one-step method to ameliorate these two problems through pretreating WRP was proposed, and the microwave activation, waste cooking oil (WCO) swelling and acid or alkali solution soaking were applied to pretreat WRP in this study, respectively. The scanning electron microscope and infrared spectroscopy were selected to analyze the microstructures and functional groups of different pretreated WRP. The fluorescence microscopy and hot tube test were employed to evaluate the compatibility of pretreated WRP with asphalt. The H 2 S gas detector and gas chromatography-mass spectrometry were introduced to research the flue gas emissions of pretreated WRP and prepared WRMA. The experimental results show that the microstructure and functional groups of the pretreated WRP are greatly changed and its surface activity is increased. The storage stability of WRMA prepared with pretreated WRP is obviously improved, and the optimized result is obtained with the microwave/WCO composite treatment, with a segregation index reduction of 40.91%. Also, the pretreatment of WRP does reduce H 2 S and flue gas emissions. The cumulative H 2 S concentration reduction of WRP after NaOH solution soaked reaches 32.14% at 30 min, and the total flue gas concentration reduction of the prepared WRMA reaches 21.54%. The results could offer guidance for the clean utilization of WRP, the efficient storage of WRMA and the effective suppression of its flue gas. • The microstructure and chemical composition of pretreated WRP were changed. • The segregation index of WRMA was reduced by 40.91% by microwave/WCO composite treatment. • Pretreated WRP can reduce the H 2 S emissions of WRP and its WRMA. • Soaking with HCl or NaOH solution significantly improved the high temperature rutting resistance of WRMA. [ABSTRACT FROM AUTHOR]

[Display omitted] • The NaCl crystallization process was simulated. • NaCl/SBS asphalt blends physical properties were predicted. • The molecular structure of asphalt was eroded by Na+, Cl- respectively. • SBS could decelerate the erosion on asphalt through reinforcement. The pavement damage caused by salt-induced volume expansion is becoming increasingly noticeable. Molecular dynamics (MD) method was applied to evaluate the effects of varied volumes of NaCl crystals on physical properties and structure of asphalt. The effects of NaCl crystals on the compatibility between styrene–butadiene–styrene triblock copolymer (SBS) and asphalt, as well as the influence of SBS on the diffusion coefficient of NaCl crystals in the asphalt system, were investigated alongside their effects on the physical modulus and molecular structure of asphalt. The results show that the solubility parameter of the asphalt blends decreases as the volume of NaCl crystals increases. Specifically, the solubility parameter decreases by 52.5 % for the biaxial crystalline growth of NaCl and asphalt blends compared to the matrix asphalt. The analysis of the ion diffusion coefficient reveals that the primary disruption of NaCl crystals in asphalt blends is due to early Cl- and late Na+ diffusion. Furthermore, the rise in shear modulus of the asphalt blends suggests that the salt erosion process of SBS-modified asphalt is advantageous for its high temperature and shear resistance. The changes in peak radial distribution function and radius of gyration indicate that the inclusion of NaCl and SBS into asphalt is a physical aging process. In this case, SBS incorporation acts as a reinforcement to the asphalt to retard the erosion of NaCl. [ABSTRACT FROM AUTHOR]

Highlights • Thermal and rheological performance of EP-CPCM modified asphalt binders are studied. • EP-CPCM has favorable compatibility with base and SBS modified asphalt binders. • EP-CPCM improves the heat transfer and thermal storage properties of asphalt binders. • EP-CPCM enhances the rutting resistance of asphalt binders at the high-temperature. • EP-CPCM slightly increases the fatigue and cracking risks of asphalt binders. Abstract Phase change materials (PCMs) can be used as thermal regulation units to prevent thermal diseases of asphalt pavements. However, the effects of PCMs on the thermal and rheological properties of asphalt binders still need to be further studied. Therefore, the influence of an expanded graphite/polyethylene glycol composite phase change material (EP-CPCM) on the thermal and rheological performance of a Pen 60/80 base binder and a SBS modified binder were investigated in this research. Various experiments were conducted, and the thermal constants analyses show that the thermal conductivity gaps of the EP-CPCM modified base and SBS asphalt binders are lower than 8%, indicating a favorable compatibility between EP-CPCM and the asphalt binders. The thermal conductivity and thermal diffusivity of base and SBS binders are doubled after the incorporation of EP-CPCM, which ensures a rapid heat exchange with the ambient environment. Differential scanning calorimeter (DSC) results indicate that the melting and crystallization enthalpies of the EP-CPCM modified base binders are 13.77 J/g and 10.22 J/g respectively, meanwhile, the melting and crystallization enthalpies of the SBS binders are 14.63 J/g and 13.59 J/g respectively. The heating and cooling rate of the modified binders are separately reduced at the temperature range of 40–50 °C and 35–25 °C because of the phase transition of EP-CPCM. Dynamic shear rheometer (DSR) results reveal that both the rutting parameter G* / sinδ and the fatigue parameter G*sinδ of the modified binders are increased when the EP-CPCM is added, indicating the rutting resistance is improved while the fatigue resistance is damaged. Bending beam rheometer (BBR) tests show that the addition of EP-CPCM results in the decrease in the creep rate and the increase in the creep stiffness of the modified binders, and both effects are detrimental to the prevention of low-temperature cracking. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) have been widely applied as heat storage and thermal regulation units in many areas. However, the utilization of PCMs in asphalt pavements for thermal regulation is still limited because of the low thermal conductivity and melted phase leakage of the common used solid-liquid PCMs. The aim of this paper was to prepare a shape-stabilized expanded graphite (EG)/polyethylene glycol (PEG) composite phase change material (EG/PEG) with high thermal conductivity, and to verify its feasibility of regulating temperatures of asphalt binder. EG and PEG were selected as supporting material and working substance respectively. The EG/PEG composites and their modified asphalt binders were fabricated respectively by vacuum adsorption and physical blending process. X-ray diffraction (XRD) and differential scanning calorimeter (DSC) analyses indicated that the crystallization ability and phase change behavior of PEG was hindered by the increase of EG in the composites. The nitrogen adsorption analyses revealed that the EG matrix had an adsorptive limitation to PEG. The aforementioned results indicated that the maximum mass ratio of EG and PEG in the composites without any leakage during the melting period was 1:7. This conclusion was also proved by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectrum. The thermogravimetric analyses (TGA) verified the viability of EG/PEG composites during the hot mixing process of asphalt mixture. The thermal analysis experiments indicated that the thermal conductivity and compatible stability of asphalt binder were improved by adding EG/PEG composites, and the thermal regulation effects of EG/PEG composites on the asphalt binder was verified by a thermocouples proved. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cascade utilization of waste cooking oil (WCO) in asphalt materials is realized. • Different components of WCO can be employed to asphalt with different aging degree. • WCO-derived palmitic acid can be applied for thermoregulation of asphalt pavement. • WCO-derived palmitamide shows great potential as warm mix asphalt additives. Resources utilization of waste has become a global challenge with both environmental and economic issues. To realize the refinement recycling of waste cooking oil (WCO), a novel strategy was proposed in this work for the cascade utilization of different components of WCO in asphalt materials. Given the characteristics of each component in WCO, the analysis and verification were carried out for WCO as aged asphalt rejuvenators, warm mix asphalt additives, and thermal storage materials for asphalt thermoregulation. The results show that WCO components can be classified into three categories based on the nature of the fatty acid esters, namely waxy components, light oil components, and heavy oil components. Both light oils and heavy oils demonstrate great potential as rejuvenators of aged asphalt in terms of rheological properties and microscopic characteristics. Furthermore, it is worthy of expectation to select appropriate WCO components for performance recovery according to the actual aging degree of asphalt pavement. The waxy components of WCO can be applied for asphalt thermoregulation and warm mix asphalt additives after hydrolysis and ammonolysis respectively, which is conducive to improving the durability of roads, reducing the energy consumption and volatile organic compounds emissions during the construction process. The findings of the study contribute to the sustainable development of highway engineering and the recycling of waste resources. [ABSTRACT FROM AUTHOR]

The rationalized recycling of waste dry batteries is of great significance to the circular development of resources. In this research, the feasibility of using waste dry batteries in asphalt modification was discussed. Waste dry battery powder (WDBP) was extracted from discarded zinc-manganese dry batteries, and its composition, micromorphology and heavy metal emissions were characterized. Further, the modified asphalts with different WDBP contents were also prepared, and the enhancement effect of WDBP on the physicochemical properties of the binder was evaluated. The results indicate that WDBP mainly contains inorganic carbon and metal oxides. Under acid rain and neutral environment, the heavy metals from WDBP are mainly Zn, Mn and Cd, and their concentrations exceed the concentration limits of Class I surface water in China. The heavy metals in WDBP can be physically solidified for the use of WDBP in asphalt modification. Meanwhile, WDBP can enhance the flow deformation resistance of the binder at the medium-high temperatures, further improve its rutting resistance. However, the WDBP may be have adverse impact on the low-temperature cracking resistance of asphalt, and the WDBP modified asphalt (WDBP-MA) is more suitable for the application in the areas with heavy traffic and hot climate. In addition, the WDBP can enhance the aging resistance of asphalt. Overall, the conclusions confirm the feasibility of applying WDBP to asphalt modification, which can provide a new approach for rational recycling of waste batteries and development of modified asphalt. • The characteristics of waste dry battery powder (WDBP) were analyzed. • The WDBP modified asphalt (WDBP-MA) were successfully prepared. • The physicochemical properties and aging resistance of WDBP-MA were comprehensively investigated. [ABSTRACT FROM AUTHOR]

• Palmitamide derived from waste edible oil (WEO) as a warm mix asphalt additive. • WEO-derived palmitamide reduces the construction temperature and of asphalt. • WEO-derived palmitamide enhances the environmental benefits of asphalt construction. • Waste resources are used wisely in construction materials. The disposal of waste edible oil (WEO) has become a global challenge with both environmental and economic issues. To provide a novel strategy for the refinement recycling of WEO, this work investigated the feasibility of palmitamide derived from WEO as a warm mix asphalt (WMA) additive. The molecular structure and thermodynamic characteristics of palmitamide were first determined. Following, WMA binders with different palmitamide contents were prepared and their temperature sensitivity and rheological properties were evaluated. Additionally, the engineering performance of WMA mixtures was explored and the environmental benefits of WEO-derived palmitamide were assessed using the gas chromatography-mass spectrometry. The results demonstrate that the phase transition temperature of WEO-derived palmitamide is 98.87 °C, which shows great potential as a WMA additive. Palmitamide provides asphalt workability suitable for construction at relatively low temperatures through reducing the flow activation energy of asphalt. In addition, the moisture damage resistance and deformation resistance of WMA is also improved due to the hydrophobicity and filling effect of palmitamide, respectively. While it is inevitable that palmitamide slightly weakens the fatigue and low-temperature performance of WMA. Moreover, the application of WEO-derived palmitamide can reduce the volatile organic compounds of asphalt in the mixing stage and compaction stage by 40.3% and 30.8%, respectively. The findings contribute to the sustainable development of road engineering and the circular of waste resources. [ABSTRACT FROM AUTHOR]

[Display omitted] • Waxy components of waste cooking oil were extracted as phase change materials. • Capsules with phase change heat storage function were prepared. • Phase change capsules can be used for thermoregulation of asphalt. • Waste resources are used wisely in construction materials. The green utilization of waste is of great significance to the sustainable development of human society. In this work, a new kind of capsule with the phase change heat storage function was prepared using waxy components extracted from waste cooking oil (WCO) as core material for the thermoregulation of asphalt binder. The differences in waxy components before and after hydrolysis treatment were studied including functional groups, phase transition temperature, and phase transition enthalpy. Meanwhile, the surface morphology, thermodynamic properties, and mechanical properties of the phase change capsules (PCCs) were also characterized comprehensively. Additionally, the effect of PCCs on asphalt thermoregulation was also examined in the laboratory. The results indicate that the waxy components after hydrolysis treatment are more suitable for asphalt binder thermoregulation in terms of the phase transition temperature, phase transition enthalpy, and thermal stability. According to the results of differential scanning calorimeter and thermogravimetric experiments, it can be calculated that the ratio of wall material and core material in PCCs is about 1:1, which endows the capsule with excellent heat storage properties (125 J/g), mechanical properties (>13 N), and thermal stability (>190 ℃). With the help of the temperature sensor, it is found that PCCs can delay the change rate of asphalt temperature with the environment by undergoing a phase transition to mitigate the damage of asphalt pavement in extremely hot climates. However, the performance of PCCs in asphalt mixtures still needs to be further explored. Overall, the findings of this research can further promote the green utilization of WCO and the functionalization of construction and building materials. [ABSTRACT FROM AUTHOR]

Highlights: [•] Rejuvenator, waste cooking and cotton seed oils were employed for rejuvenation of RAP. [•] High temperature characteristics of rejuvenated asphalt binder were tested. [•] The used rejuvenated additives can reduce the viscosity value and fail temperature. [•] Rejuvenator, cotton seed oil or waste cooking oil result in an increase of phase angle. [ABSTRACT FROM AUTHOR]

• The method for classification of waste cooking oil (WCO) components was proposed. • The physicochemical properties of different components of WCO were investigated. • The effect of different components of WCO on the physical and chemical properties of aging asphalt were studied. • The rejuvenation effect of different components of WCO on aging asphalt is mainly determined by their own characteristics. The combined utilization of waste cooking oil (WCO) and reclaimed asphalt pavement (RAP) is attractive for economic, environmental, and energy benefits. However, the quality stability of WCO is poor due to its wide sources, which limits the further development of WCO recycled RAP. In this study, the classification method of WCO was proposed according to the molecular weight difference of its chemical components, and WCO was classified into three categories including light components (LC), intermediate components (IC), and heavy components (HC). Meanwhile, the characteristics of these three WCO components and their effects on the physicochemical properties of aging asphalt were investigated comprehensively. The experimental results show that the softening ability of different components of WCO on aging asphalt is mainly determined by their molecular weight and thermal stability. Furthermore, LC rich in methyl palmitate is easy solidification and volume expansion at the low temperature, which is not conducive to the repair of low-temperature ductility of aged asphalt. The chemical property analyses of recycled asphalt indicate that there is no chemical reaction between the components of WCO and the aging asphalt. The physical dilution ability of WCO components on carbonyl index, sulfoxide index, and high molecular weight substances of aging asphalt is positively correlated with their molecular weight. In addition, HC contains chemical substances similar in composition to asphalt, which has the most obvious effect on the colloidal structure of aging asphalt. Overall, the classification method for WCO and related findings found in this study provides a reference for ensuring the quality stability of WCO and its industrial application in the recycling of aged asphalt. [ABSTRACT FROM AUTHOR]

The maintenance of asphalt pavement has become recognized as a critical issue in China. The objective of this study is to investigate the influence of using rejuvenator sealer materials on aged asphalt by means of laboratory analysis. First, asphalt binder first aged by rolling thin-film oven test and ultraviolet light. This aged asphalt was treated by two kinds of rejuvenator sealer materials. The performances of both aged binder and rejuvenator treated binder were evaluated by means of viscosity, temperature sweep, creep recovery, fatigue, and component analysis tests. The results indicated that both rejuvenator sealer materials can significantly decrease the viscosity and complex modulus of aged asphalt. Moreover, applying rejuvenator sealer materials can balance the asphaltene-maltene ratio of aged asphalt to some degree. Aged asphalt can be efficiently softened with the rejuvenator materials, which proves that rejuvenator sealer materials can be used for maintenance to improve the performance of existing pavements. [ABSTRACT FROM AUTHOR]

Abstract: The main objective of this study is to investigate the potential of using recycled fine aggregates powder (RFAP) as filler in asphalt mixtures. RFAP is a by-product of the production of Recycled Concrete Aggregate (RCA). The disposal of RFAP may cause many serious environmental problems. It is necessary to find potential usage to avoid these problems. In this study, RFAP is used as filler in asphalt mixture by totally replacing conventional limestone powder (LP). Firstly, the properties of RFAP is studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray fluorescence spectroscopy (XRF). Then the indirect tensile strength and modulus tests, three-point bending tests, dynamic creep tests and fatigue tests are conducted to compare the properties between asphalt mixtures with RFAP and traditional asphalt mixture with LP. Results indicate that RFAP can improve the properties of asphalt mixture, such as including water sensitivity and fatigue resistance. However, it may cause a little decrease of the low-temperature performance. All the results indicate that the RFAP can be used in asphalt pavement, especially in hot regions. [Copyright &y& Elsevier]

Crumb rubber modified asphalt (CRMA) has been put forward and become a research hotspot due to the environmental pressure and the actual demand for road engineering. However, worrying issues such as poorer storage stability and more serious VOCs emissions have emerged one after another. In this work, waterborne polyurethane (WPU) was employed as the shell material to package the crumb rubber (CR) to prepare a porous composite modifier (CM) by solvent volatilization. The effects of WPU on storage stability, rheological properties, and VOCs release of CRMA were investigated. The experimental results indicate that the asphalt with CM as a modifier (CMMA) has better high temperatures storage stability than traditional CRMA. The temperature sweep experiment designates that CM can improve the high temperatures performance of the asphalt binder by increasing the rutting factor (G*/sin δ) and complex modulus (G*), but the fatigue performance is slightly weakened. The direct tensile tests (DTT) demonstrate that the fracture energy of CMMA is slightly lower than that of CRMA but still 2.3 times that of virgin asphalt. Moreover, GC-MS test results prove that the VOCs emission of CMMA is extremely lower than that of CRMA and virgin asphalt. The nitrogen adsorption test of CM and CM's SEM images suggest that the inhibition mechanism of VOCs by CM might be the synergistic effect of adsorption and shielding. The conclusions of this study can provide a new method of cleaner production with a lower carbon footprint for building materials such as asphalt. [ABSTRACT FROM AUTHOR]

• The use of waste glass as an alternative of recycled aggregate in micro-surfacing. • The morphological feature of waste glass was evaluated by aggregate image measurement system. • The addition of waste glass can improve the skid resistance ability of micro-surfacing to some extent. Huge amounts of waste glass are produced every year in China, which brings great pressure on the environment. Meanwhile, a large number of natural aggregates are required for highway construction every year. In this study, it is intended to prepare asphalt micro-surfacing materials using waste glass as aggregate and evaluate their performance. The morphology of basalt and waste glass was quantitatively analyzed through aggregate image measurement system to characterize the morphological differences. In addition, the wet stripping test, wet track abrasion test, wheel load test, sand patch test and British pendulum test were used to investigate the resistance to the action of water, the wear performance, rutting resistance and skid resistance of asphalt micro-surfacing mixtures. The results indicate that the two-dimensional (2D) form of waste glass is more abundant than that of basalt, and as the content of waste glass increases, the British pendulum number (BPN) value and the texture depth (TD) value of micro-surfacing mixtures increase, which means that the addition of waste glass can improve the skid resistance ability of micro-surfacing mixtures to some extent. The abrasion loss, lateral and vertical displacement are all increased after replacing basalt with waste glass due to its brittleness and weak bonding. Considering the feasibility of mechanical properties, it is recommended that the maximum volume amount of fine waste glass and coarse waste glass should be less than 15% and 10%, respectively. The potential use of waste glass can alleviate the overconsumption of natural resources and is a good choice for applying in micro-surfacing pavement materials. [ABSTRACT FROM AUTHOR]

• The effect of HC-WRMA with low VOCs emission was systematically studied. • The compatibility of WRP with virgin asphalt was observed. • VOCs inhibitors significantly reduced the VOCs emissions of HC-WRMA. • HC-WRMA has good resistance to flow deformation at high temperature. • Excessive WRP has adverse effect on the low temperature performance of asphalt. Waste rubber powder (WRP) has become a widely used and sustainable replacement for asphalt modifier. At present, the mixing content of WRP in waste rubber modified asphalt (WRMA) is basically between 18 and 22%, while the high-content (25–45%) WRP modified asphalt (HC-WRMA) can realize the high added value utilization of solid waste and show excellent high temperature properties at the same time. However, more volatile organic compounds (VOCs) will be generated with the increase of the content of WRP, which would lead to environment pollution. This research aimed to explore the optimal mixing content of WRP in asphalt and how to effectively suppress the VOCs produced of HC-WRMA. First, the compatibility between WRP and asphalt was analyzed for HC-WRMA. Then, different VOCs inhibitors including activated carbon, 4A zeolite and nano calcium carbonate were added into HC-WRMA to inhibit VOCs emission. In addition, the high temperature rheological properties of HC-WRMA were studied using dynamic shear rheometer (DSR) and the low temperature properties of HC-WRMA were studied using differential scanning calorimetry (DSC). The optimum contents of WRP are 35% according to the storage stability experiments results. The GC–MS results show that different inhibitors have a significant inhibited effect on asphalt VOCs, and the addition of 6% nano calcium carbonate has the best inhibited effect. The DSR results show that complex modulus of HC-WRMA increased gradually with the increase of WRP content, and the phase angle decreased with the increase of WRP content, which indicates that the addition of WRP can improve the resistance deformation ability of asphalt and enhance the flexibility of asphalt. The DSC results show that the addition of excessive WRP has adverse effect on the low temperature performance of asphalt. Also, the Fourier transform infrared spectroscopy (FT-IR) results show that there are no chemical reaction and only physical blending between the WRP and asphalt. In short, HC-WRMA has broad development prospects in the future. [ABSTRACT FROM AUTHOR]

In order to improve the utilization efficiency of road runoff and the remove effects of heavy metals, porous asphalt pavements have been used as an effective measure to deal with heavy metals in road runoff. However, the removal effect on dissolved heavy metal is weak. In this paper, basic oxygen furnace (BOF) slag was used as aggregate in porous asphalt concrete to improve the removal capacity of heavy metal. Road runoff solution with a copper concentration of 0.533 mg/L and a zinc concentration of 0.865 mg/L was artificially synthesized. The removal effect of BOF slag porous asphalt concrete on cooper and zinc in runoff was evaluated by removal tests. The influence of rainfall intensity and time on the removal effect was discussed. The results obtained indicated that BOF slag porous asphalt concrete has a better removal effect on copper. The removal rate of copper is 57–79% at the rainfall intensity of 5–40 mm/h. The removal rate of zinc is more susceptible to the changes of rainfall intensity than copper. The removal rate of zinc in heavy rain conditions (40 mm/h) is only 25%. But in light rain conditions (5 mm/h), BOF slag porous asphalt concrete maintains favorable removal rates of both copper and zinc, which are more than 60%. The heavy metal content of runoff infiltrating through the BOF slag porous asphalt concrete meets the requirements for irrigation water and wastewater discharge. The results of this study provide evidence for the environmentally friendly reuse of BOF slag as a road material and the improvement of the removal of heavy metal by porous asphalt concrete. [ABSTRACT FROM AUTHOR]

The fillers of ordinary and pyrolytic basic oxygen furnace (BOF) slag were selected to investigate the properties of their asphalt mastic. XRF (X-Ray Fluorescence) was used to analyze chemical composition of fillers. Meanwhile, SEM (Scanning Electron Microscope) and AIMS (Aggregate Image Measurement System) were utilized to explore meso-morphology, angularity and sphericity. Penetration, softening point and viscosity of asphalt mastic were discussed, while the rheological properties of asphalt mastic were studied by means of DSR (dynamic shear rheometer) and BBR (bending beam rheometer) tests. The experimental results show that chemical composition of different types of BOF slag is similar. The grinding energy consumption of pyrolytic BOF slag is higher than that of limestone and ordinary BOF slag. It is not recommended that pyrolytic BOF slag filler is produced by grinding process. The micro-texture structure of ordinary BOF slag filler is more abundant and their angularity index is about 15% higher than that of limestone filler. The stiffness modulus and rutting factor of asphalt mastic with ordinary BOF slag filler is higher than that of limestone filler. Meanwhile the incorporation of BOF slag filler will further reduce the low-temperature flow performance of asphalt mastic. The effect of pyrolytic BOF slag filler on the performance of asphalt mastic is less than that of ordinary BOF slag. Ordinary BOF slag filler can effectively improve high temperature anti-rutting stability of asphalt mixture. Ordinary BOF slag has a useful application prospect as filler in asphalt mixture. [ABSTRACT FROM AUTHOR]

The primary objective of this paper was to investigate the effect of replacing steel slag powder (SSP) with limestone filler (LF) with different contents as an inorganic anti-stripping agent on the moisture susceptibility of asphalt mixtures. Two traditional inorganic anti-stripping agents were selected for comparison, namely cement (CE) and slaked lime (SL). Apparent morphology, chemical compositions, and the particle size distribution of the four fillers were firstly studied. LF was replaced by SSP, CE, and SL with different contents, and then mixed with asphalt to prepare asphalt mortars. An 80 °C water immersion test was conducted to investigate the adhesion of asphalt mortar and aggregates, and an image analysis technique was utilized to evaluate the stripping of asphalt from the aggregates. A Marshall stability test and freeze-thaw split test were then conducted to analyze the effect of different fillers on the moisture susceptibility of asphalt mixtures. The results show that SSP contains a large amount of CaO, which indicates that SSP has a certain alkalinity. Compared with LF, SSP has a rougher surface texture and a finer particle size. Image analysis results show that the partially replacement of LF by SSP increases the asphalt coverage rate of aggregates, which means that SSP can improve the adhesion between asphalt mortar and aggregates. However, the excessive addition of SSP will result in a decrease in adhesion. The results of both the Marshall stability test and freeze-thaw split test demonstrate that CE, SL, and SSP can improve the moisture susceptibility of asphalt mixtures compared with the LF group, and that asphalt mixtures containing SSP have better moisture damage resistance than those with CE, but less such resistance than those with SL. With the increase of the amount of SSP replacing LF, the moisture susceptibility of the asphalt mixture decreases gradually. The optimum substitution amount of SSP was 25% of the total volume of fillers in this test. [ABSTRACT FROM AUTHOR]

Different proportions of bio-oil (5, 10, 15, and 20 wt%) were added into aged asphalt for its regeneration. Molecular dynamic simulations were used to measure the thermal and mechanical performances of bio-oil regenerated aged asphalt (BRAA). A new, simplified BRAA model was built to calculate the specific heat capacity, thermal expansion coefficient, elastic constant, shear modulus, bulk modulus, and Young's modulus. Simulation results showed that the thermal expansion coefficient (CTE α) of asphalt at 298 K decreased by 10% after aging. Bio-oil of 5 wt% could make the CTE α restore to the original level of base asphalt, while the addition of bio-oil would further decrease the specific heat capacity of aged asphalt. The shear modulus (G), Young's modulus (K) and bulk modulus (E) of asphalt increased after aging and decreased with the increasing amount of bio-oil. According to the calculated E/G value, the ductility of aged asphalt increased by 6.0% with the addition of 10 wt% bio-oil, while over 15 wt% bio-oil would make the ductility of BRAA decrease. In summary, the regeneration effects of bio-oil to the thermal expansion coefficient, flexibility, and ductility of aged asphalt had been proven, while excessive bio-oil would decrease the thermal stability of asphalt. [ABSTRACT FROM AUTHOR]

When a fire occurs in a tunnel, the instantaneous high temperature and smoke cause great danger to people. Therefore, the asphalt pavement material in the tunnel must have sufficient fire resistance. In this study, the effects of aluminum hydroxide and layered double hydroxide on the fire resistance of styrene-butadiene-styrene (SBS) polymer-modified asphalt was investigated. The fire resistance of the asphalt was evaluated by using a limiting oxygen index (LOI). The impact of aluminum hydroxide (ATH), layered double hydroxide (LDHs), and mixed flame retardant (MFR) on LOI was studied. The synergistic fire resistance mechanism of ATH and LDHs in asphalt binder was analyzed by using an integrated thermal analyzer‒mass spectrometry combined system (TG-DSC-MS) and Fourier transform infrared spectrometer (FTIR). The experimental results indicated that the main active temperature range of these flame retardants was 221–483 °C. The main components of smoke were methane, hydroxyl, water, carbon monoxide, aldehyde, carbon dioxide, etc. The addition of flame retardants could inhibit the production of methane, carbon monoxide, and aldehyde. Moreover, due to the good synergistic effects of ATH and LDHs, 20 wt % MFR had the best fire resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nano-scale moisture migration model in the asphalt-aggregate interface is built for the first time. • The nano-scale moisture distribution in asphalt-aggregate interface was investigated. • Effects of aggregate type, humidity and hydraulic pressure on moisture diffusion in asphalt-aggregate interface are studied. Presence of moisture can weaken the asphalt-aggregate bond and result in aggregate stripping and moisture damage in asphalt mixture. This study investigates how the moisture affects the asphalt-aggregate bond and simulates moisture distribution of nano-scale in asphalt-aggregate interface. Effects of aggregate type (basalt, dolomite and limestone minerals), humidity and hydraulic pressure on moisture diffusion in asphalt-aggregate interface are studied. Diffusion coefficient (D), radial distribution function (RDF), contact angle (CA), free volume (FV) are calculated through molecular dynamic simulations. Polarizability of moisture in the asphalt-aggregate interface was measured using density function theory (DFT). Nano-scale moisture migration model in the asphalt-aggregate interface is built for the first time. The results show that D depends more on the hydraulic pressure than humidity and aggregate type which represents the significance of hydraulic pressure on the moisture diffusion. In addition, the aggregate type has significant effects on RDF, CA and FV. DFT results indicate that polarizability of moisture changes for different types of aggregate and hydraulic pressure values. In the asphalt-water-aggregate interface, the asphalt competitively interacts with moisture and ions from minerals through intermolecular forces. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) emission not only cause the environmental pollution, but also severely threaten human health as they are known to be toxic and carcinogenic. This study investigates the effects of biochar on removing the VOCs emission from asphalt. The biochar was obtained from the pyrolyzed productions of pig manure, waste wood and straw biomasses. Molecular model for the adsorption of the VOCs was developed and used to measure the adsorption energy and heat. The VOCs removal model was built and used to determine the VOCs removal mechanism in the asphalt. The results showed that biochar could remove alkanes, polycyclic aromatic hydrocarbons (PAHs) and sulphide compounds because of its intrinsic carbon negativity and porosity. Furthermore, source of the biochar was an influential factor on the adsorption of the VOCs compounds. Based on the results, waste wood-based biochar had the best adsorption performance which could be related to the amorphous carbon, graphite and its porous structure. Also, it shows that biochar has the great potential to be used as VOCs inhibitors. Unlabelled Image • Straw, waste wood, and pig manure-based biochar were used as VOCs inhibitor. • The chemical component change of VOCs was investigated after biochar addition. • The adsorption parameters of VOCs were calculated using molecular dynamic simulation. • The vortex VOCs removal model of biochar from asphalt was proposed. [ABSTRACT FROM AUTHOR]

Bio-asphalt replaced petroleum-asphalt for paving asphalt pavements, which is a technology with a wide range of application prospect. This work is aimed at improving the performance of aged bio-oil modified asphalt (bio-asphalt) for use in road pavement construction. Biochar and bio-oil are renewable resources and use in this research that are pyrolyzed from waste wood. The effects of different aging conditions on biochar-modified bio-asphalt and ordinary bio-asphalt were investigated in terms of their chemical functional groups, molecular formulas, radius distribution functions, rheological parameters, and phase separation. The aging conditions considered in this research are short-term aging, ultraviolet (UV) aging, pressure aging vessel (PAV), and low-temperature hardening. Biochar plays a significant role in the UV aging process. This study found that, with an increase in biochar modification, the alkyl group numbers increased and the sulfoxide and carbonyl numbers decreased during the aging process of bio-asphalt. It also shows that the inclusion of biochar improved the aging resistance of the bio-asphalt, but that biochar modification did not affect the bio-asphalt's low-temperature hardening performance. Four asphalt components were studied: saturates, asphaltenes, resins, and aromatics (SARA). The effects of biochar on saturates and aromatics were significant, and the biochar was able to adsorb these components. This study also found that, with an increase in UV aging and PAV, the phase separation grows. • Biochar and bio-oil are renewable resources, which were derived from sawdust. • The chemical change and phase separation of biochar-modified bio-asphalt were investigated. • The molecular model and numerical model of biochar-modified bio-asphalt were built. [ABSTRACT FROM AUTHOR]

The interface between asphalt and aggregate. • The adhesive properties of FAM composed of basalt, steel slag, and andesite were investigated. • The roughness of aggregate and the distribution of asphalt in the aggregate surface were estimated with qualitative and quantitative methods. • Movement rules and failure mechanisms of FAM were evaluated quantitatively. Quantitative analysis was conducted in this study using a three-dimensional field microscope, scanning electron microscope, energy dispersive spectroscopy, and molecular simulation to investigate the surface and interface adhesive properties of three fine aggregate asphalt mixtures (FAM): basalt, steel slag, and andesite. The roughness of the aggregate and the contact angle of the asphalt on the aggregate surfaces also were analyzed quantitatively. Molecular dynamics simulations were carried out to evaluate the adhesive properties, molecular diffusion, and interfacial failure mechanisms of the basalt-, steel slag-, and andesite-based FAM. The average roughness values of the basalt, steel slag, and andesite were found to be 138.2 µm, 244.0 µm, and 185.2 µm, respectively. The stripping percentages of the basalt, steel slag, and andesite were 11.3%, 3.3%, and 10.8%, respectively. The diffusion coefficients of the resins (3.32 × 10−9 m2/s) and asphaltenes (3.05 × 10−9 m2/s) were higher than the diffusion coefficient of the oils (2.98 × 10−9 m2/s). The results indicate that the surface roughness and adhesive capacity of the aggregate used in this study can be ranked in decreasing order as steel slag, andesite, and basalt. The asphaltenes and resins contributed to the asphalt's increased adhesion to the aggregate particles. Both adhesive and cohesive failure were found for the basalt-, steel slag-, and andesite-based FAM, but the steel slag FAM exhibited more cohesive failure, whereas the basalt and andesite FAM exhibited more adhesive failure. [ABSTRACT FROM AUTHOR]