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High-content polyurethane modified asphalt (HPMA) has ignited the enthusiasm of researchers due to its low-carbon characteristics and excellent performance. The workability and service performance of HPMA are both affected by complex curing reaction. The viscosity of HPMA changes over time at simulated construction temperature, and the evolution of the chemical structure and rheological properties at different environmental temperatures at the early stage were systematically investigated in this work. After thorough exploration, the construction tolerance time for HPMA-50 % (with isocyanate pre-polymer content of 50 %) and HPMA-30 % (with isocyanate pre-polymer content of 30 %) at a construction temperature of 130 ℃ are 46 minutes and 72 minutes, respectively, which can basically meet the construction time requirements. The complex modulus of HPMA gradually increases with the increasing curing time, and the phase angle temperature dependence of HPMA-50 % is significantly weakened compared to HPMA-30 %, its viscoelasticity gradually transforms to thermoset. Meanwhile, the high-temperature rutting factor improvement rate of HPMA-50 % reaches 142.1 % after curing for 14 days, indicating a tremendously improved rutting resistance. The high-temperature creep recovery rates of HPMA-50 % and HPMA-30 % increased from 65.9 % and 3.6–96.1 % and 7.6 %, respectively, after 14 days of curing. This reveals that increasing the isocyanate pre-polymer content and extending the curing time all can significantly improve the entropy-elastic properties and creep recovery ability of HPMA. Fluorescence microscopy analysis showed that the polyurethane particles in HPMA changed from a granular structure to a network structure during the curing process, and gradually transitioned to a continuous phase as the pre-polymer content increased. Further research also revealed a good correlation between the conversion rate of isocyanates and the rheological performance index of HPMA. Additionally, a functional model between the rheological performance index of HPMA and curing times was successfully established, which accurately predicted the evolution law of the rheological performance of HPMA under different ambient temperatures. The evolution mechanism of the early performance of environmentally friendly HPMA was investigated in this work, which laid the methodological foundation and theoretical basis for determining the construction tolerance time of HPMA and accurately evaluating its performance at the early stage. • HPMA's early chemical structure and performance were quantitatively analyzed. • The early performance evolution mechanism of HPMA was revealed. • The early performance prediction models for HPMA were proposed. [ABSTRACT FROM AUTHOR]

Due to the relative scarcity of freshwater resources in coastal regions, the use of seawater in concrete construction has great potential due to its benefits in cost and resource. To further advance the application of seawater concrete, a deeper understanding of its rheological properties is essential. This study investigates the effects of fly ash on the time-dependent rheological behavior of seawater cementitious paste, such as yield stress, plastic viscosity, and structural build-up rate. The underlying mechanisms are analyzed using the theories of water film thickness (WFT), ion concentration, and hydration heat. The research findings confirm that the rheological parameters of seawater paste are generally higher than those of deionized water paste, regardless of the cementitious compositions. As fly ash content increases, the plastic viscosity of seawater paste increase, while the fluidity and dynamic yield stress decreases. Further analysis reveals that the decrease in the yield stress with fly ash content is well related to the increase in the WFT, but it cannot sufficiently explain the change of yield stress over time. Instead, the amount of hydration products in seawater paste shows a linear increasing relationship with the dynamic yield stress at 65 min. By contrast, the plastic viscosity can be related to the ion concentration in the interstitial solution, wherein an increase in the concentration of Ca2+ corresponds to an increase in the plastic viscosity. Moreover, the rheological parameters increase over time, with the growth rates between 5 and 35 minutes being higher than those between 35 and 65 minutes, possibly due to the rapid early hydration of the binder materials. This study offers a fundamental theoretical support for the use of seawater in various concrete applications. • This study examines the rheological properties of seawater cement paste. • FA reduces dynamic yield stress and fluidity while increases plastic viscosity. • WFT and hydration influence dynamic yield stress and its time-dependent changes. • Plastic viscosity is affected by Ca²⁺ concentration in interstitial solution. [ABSTRACT FROM AUTHOR]

Developing waste crumb rubber modified asphalt (CRMA) with enhanced self-healing properties can improve the crack-healing ability of asphalt, which is conducive to extending the service life of asphalt pavements. The objective of this study is to introduce dynamic disulfide bonds into desulfurized waste crumb rubber and to prepare two types of intrinsic self-healing waste crumb rubber modified asphalt by the breakage-rearrangement effect of dynamic disulfide bonds. Chemical structure analysis revealed that through the esterification reaction between -COOH in dithiodipropionic acid (DPA) and dithiosalicylic acid (DTSA) and -OH in desulfurized waste crumb rubber, DPA/CRMA with aliphatic disulfide bonds and DTSA/CRMA with aromatic disulfide bonds were successfully prepared. The results of the healing tests showed that DPA/CRMA and DTSA/CRMA exhibited better healing properties due to the breakage-rearrangement effect of dynamic disulfide bonds. The fatigue healing indices of DPA/CRMA and DTSA/CRMA were 31.3 % and 36.3 % higher than those of CRMA. The fracture healing rates of DPA/CRMA and DTSA/CRMA were enhanced by 67.6 % and 79.9 % compared to CRMA. The rheological test results revealed that DPA/CRMA exhibited better cracking resistance both before and after aging compared to DTSA/CRMA. Overall, the DTSA/CRMA exhibited better self-healing performance due to the lower bond energies and stronger breakage-rearrangement effect of the aromatic disulfide bonds, while the DPA/CRMA had better cracking resistance. [Display omitted] • Self-healing desulfurized waste crumb rubber modified asphalt based on disulfide bonds was first successfully synthesized. • DTSA/CRMA containing aromatic disulfide bonds had superior healing property due to intense breakage-rearrangement effect. • DPA/CRMA containing aliphatic dynamic disulfide bonds had better rheological properties and crack resistance capability. [ABSTRACT FROM AUTHOR]

Efficient gangue grouting in goafs requires accurate measurement of time-dependent rheological properties of the slurry and slurry fluidity to ensure proper transport. This paper measured the relevant parameters for cemented fine-grained coal gangue backfill containing HPMC, analyzed them by the response surface method, and explained the chemical environment and hydration products in the slurry through Zeta potential and electrical conductivity. Furthermore, the relationships between slump flow (S f), yield stress (τ 0), viscosity coefficient (η), and curing time were studied. It is found that (1) based on the constructed quadratic polynomial regression models of the S f , τ 0 and η , the fluidity of CFGHB decreases with increasing concentration and HPMC and OPC2 contents, (concentration > HPMC content > OPC content). S f is significantly affected by the interaction terms in the order of x 1 x 3 > x 1 x 2 > x 2 x 3 , while τ 0 and η are significantly influenced by x 1 x 2 and x 1 x 3 ; (2) as curing time increases, S f decreases, while τ 0 and η increase. The influence of curing time on η are approximate convex quadratic functions, and τ 0 are approximate concave quadratic functions; (3) the addition of HPMC and OPC enhances the cohesion of the CFGHB matrix through flocculation, increasing the flow resistance of coal gangue particles. The lower concentration facilitates the hydration reaction, adding HPMC negatively impacts it. Concentration has a more significant effect on hydration reactions than HPMC content; (4) the S f of the slurry exhibits a negative correlation with τ 0 and η. CFGHB slurry was fitted with quadratic curves and cubic curves. Additionally, the statistical model of τ 0 and η for CFGHB as a function of curing time describes the continuous flow state of the slurry within 120 minutes, indicating a strong time dependence in the rheological parameters of the slurry. This study provides the optimization of coal gangue grouting and goaf materials and their engineering application. • The fluidity and rheology parameters for cemented fine-grained coal gangue backfill containing HPMC are measured and analyzed. • The slurry's chemical environment and hydration products through Zeta potential and electrical conductivity are analyzed. • The evolution of the fluidity and rheological properties of the slurry with the increase in curing time was revealed. • The mathematical relationships among slump flow, yield stress, viscosity coefficient, and curing time are revealed. [ABSTRACT FROM AUTHOR]

Discarded rubber tires, categorized as industrial waste, are escalating in volume and pose significant environmental concerns. The present investigation is designed to engineer a novel strategy for the valorization of end-of-life tires by fabricating rubber powder-modified emulsified asphalt through a one-time cold mixing process. Microscopic tests and chemical analyses were conducted to investigate the microscopic morphology, distribution, and chemical alterations of emulsified asphalt evaporation residue at varying rubber powder dosages. The microscopic properties of emulsified asphalt residue were examined to elucidate the molding and stabilization mechanism of emulsified asphalt. Rheological properties of emulsified asphalt evaporation residues with different rubber powder contents were analyzed. The results revealed that the emulsified asphalt, when fortified with appropriately treated rubber powder, not only achieves stable emulsification but also exhibits commendable storage stability. An optimal dispersion of the rubber powder within the emulsified asphalt matrix was observed at concentrations up to 12 % by weight. Beyond this threshold, specifically at a 15 % rubber powder concentration, the distribution became uneven, leading to localized aggregation within the mixture. The study suggests that a rubber powder dosage of 12 % is the most efficacious, as it not only ensures a homogenous blend but also significantly bolsters the strength of the emulsified asphalt's evaporated residue. This enhancement in strength is particularly beneficial for improving the high-temperature rheological performance of the asphalt, a critical factor in pavement construction. This research provides insights into the application of rubber powder in pavement construction, offering an environmentally beneficial method for tire disposal and contributing to the long-term sustainability of road construction. • develop rubber powder-modified emulsified asphalt using a one-time cold mixing method. • investigate the microscopic morphology, distribution, and chemical alterations of emulsified asphalt evaporation residue. • optimal rubber powder dosage is suggested to be 12 % in emulsified asphalt. [ABSTRACT FROM AUTHOR]

Antioxidants can effectively mitigate or delay the oxidative aging degradation of asphalt binder, thereby improving pavement durability. While research has largely concentrated on the application of antioxidants to asphalt binders from a single source, limited studies have explored their effects on binders derived from different crude oil sources. Moreover, the relationship between the chemical and rheological properties of antioxidant-modified asphalt binders remains insufficiently understood. In this study, three antioxidants - zinc diethyldithiocarbamate (ZDC), Irganox 1010 and kraft lignin - were utilized and blended with base binders sourced from three distinct regions globally. Fourier transform infrared spectroscopy (FTIR) was utilized to analyze the impact of these antioxidants on the chemical composition of aged binders. Additionally, dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests were conducted to assess the high- and low-temperature performance of the antioxidant-modified binders, identifying the most effective antioxidant. The linear amplitude sweep (LAS) test further evaluated the performance of ZDC across binders from different crude oil sources. The results revealed three key findings: first, chemical functional group changes due to antioxidants are not always reflected in rheological performance; second, ZDC demonstrated superior performance across different base binders, as evidenced by improved aging indices, high-temperature rutting resistance, and enhanced fatigue and low-temperature cracking resistance; and third, asphalt binders from different crude oil sources exhibit varying sensitivities to antioxidant type and dosage. This study underscores the necessity of determining optimal antioxidant dosages for different asphalt binders, as the relationship between antioxidant dosage and effectiveness is not straightforward. [Display omitted] • Explored the antioxidant effects of zinc diethyldithiocarbamate, Irganox 1010, and kraft lignin. • Employed asphalt binders sourced from three different crude oil origins. • Performed chemical composition characterization and performance testing on both original and modified asphalt binders. • Examined the impact of antioxidant type and dosage on asphalt binders from various crude oil sources. • Investigated discrepancies between chemical composition characterizations and performance test results. [ABSTRACT FROM AUTHOR]

To conserve non-renewable petroleum-based asphalt resources and address the limitations of incorporating high-content waste crumb rubber (CR) in conventional crumb rubber modified asphalt (CRMA), this study examines the feasibility of utilizing waste cooking oil desulfurized crumb rubber (ODR) in conjunction with CR to prepare high-content rubberized asphalt (HCRA). The basic, chemical, rheological, and asphalt-aggregate adhesion properties of HCRA, both with and without a small quantity of styrene-butadiene-styrene (SBS) copolymer modifier, were evaluated using infrared spectroscopy (FTIR), dynamic shear rheometer (DSR), bending beam rheometer (BBR), asphalt-aggregate pull-off test, contact angle test, and atomic force microscopy (AFM). The results showed that the modification involving ODR and CR primarily constitutes a physical process, rather than a chemical reaction, as evidenced by the lack of new functional groups. Similarly, the addition of an SBS modifier predominantly results in physical modifications accompanied by minor chemical interactions. The improved desulfurization degree of ODR diminishes the elastic stiffening effect of CR on the matrix asphalt at the high-temperature (low-frequency) domain and reduces adhesion properties between HCRA and aggregates, while enhancing the flexibility of HCRA at the low-temperature (high-frequency) domain. The inclusion of a small quantity of SBS modifier allows HCRA to demonstrate high-temperature performance and adhesion properties on par with CRMA, alongside superior low-temperature stress relaxation, phase stability, storage stability, and water damage resistance. These attributes indicate that the HCRA with a small quantity of SBS modifier has a broader service temperature range compared to CRMA. This study achieves approximately 33.3 % replacement of asphalt materials while preserving the performance of rubberized asphalt. • The feasibility of using ODR and CR to prepare HCRA was investigated. • Increased ODR desulfurization reduces the elastic stiffening effect of CR on HCRA. • Increased ODR desulfurization will facilitate HCRA adhesion to granite. • The adhesion properties of HCRA were investigated using various evaluation methods. • The composite modification of ODR and CR provides HCRA with good road performance. [ABSTRACT FROM AUTHOR]

Recycled glass fibers from wind turbine blades have significant potential for enhancing the performance of asphalt mixtures. However, the impact of residual polyurethane (PU) components on asphalt performance remains uncertain, presenting a challenge to the high-value utilization of wind turbine blades in pavement engineering. This study investigates the effects of waste polyurethane (WPU) on the rheological properties and compatibility of SBS modified asphalt, widely used in pavement engineering under various temperature conditions. Molecular dynamics (MD) simulations were employed to analyze the underlying mechanisms. The results reveal that incorporating WPU improves the rutting factor and creep recovery rate of SBS modified asphalt, demonstrating superior high-temperature performance compared to SBS modified asphalt alone. The synergistic effect of WPU and SBS significantly enhances low-temperature crack resistance and overall asphalt compatibility. Additionally, the interaction between SBS and the four components of asphalt is strengthened, and diffusion mobility is reduced due to WPU incorporation. This indicates that WPU promotes a more compact structure and a higher relative concentration of SBS and the four components within the spatial system, thereby enhancing the stability of the WPU/SBS modified asphalt system. Furthermore, using WPU in asphalt mixtures not only avoids environmental pollution compared to traditional disposal methods but also offers considerable long-term economic benefits. Overall, WPU positively impacts the rheological properties and compatibility of SBS-modified asphalt, suggesting that processed wind turbine blades can be a viable solution for enhancing asphalt mixture performance. • WPU from the surface of glass fibers stripped from wind turbine blades can enhance the performance of SBS modified asphalt. • The synergistic interaction between WPU and SBS significantly enhances the low-temperature crack resistance and compatibility of the asphalt. • WPU promotes a tightly structured and uniformly distributed system between SBS and asphalt components. [ABSTRACT FROM AUTHOR]

This study reports a novel interfacial enhancement strategy for fiber-reinforced asphalt binders. The graphene oxide (GO) nanosheets were used and grafted onto polyester (PET) and polyacrylonitrile (PAN) fibers in order to enhance the performance of modified asphalt binders. Prior to this, ultraviolet ozone (UVO) treatment was primarily adopted for activating the inert surface of fibers. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Scanning electron microscope (SEM) confirmed that GO-modified fibers were successfully prepared via surface modification. For the rheological properties determined by dynamic shear rheometer (DSR), the asphalt binders with GO-modified fibers exhibit improved high-temperature rutting resistance, better creep and recovery characteristics and increased anti-fatigue properties. Remarkably, it demonstrates that the recovery (R) value of GO-PAN modified asphalt binder is increased by 21.9 %, and the non-recoverable compliance (J nr) value of GO-PET modified asphalt binder has been reduced by 31.9 % compared to that reinforced with the unmodified fiber in multiple stress creep recovery (MSCR) tests. These enhancements are mainly attributed to the increased roughness and modulus of the GO-grafted fibers, which promote effective stress transfer at the fiber-asphalt interfaces. Results from the atomic force microscope (AFM) indicate that the Young's modulus of GO-PET and GO-PAN is 94.2 % and 260.0 % higher than that of PET and PAN, respectively. This research not only provides a simple and cost-effective method for improving the rheological performance, but also elucidates the enhancement mechanism of interfacial behavior in fiber-reinforced asphalt binders. [Display omitted] • GO surface grafting enhance fiber-reinforced asphalt via interfacial modulation. • UVO treatment enables successful GO grafting on PET and PAN fibers. • GO-modified binders show superior rutting and fatigue resistance. • Increased roughness and Young's modulus improve interfacial strength between fiber-asphalt. [ABSTRACT FROM AUTHOR]

This study investigated the effects of new organic composite warm mix additive on the performance and microstructure of SBS modified asphalt binder. Acmp, as an organic composite warm mix additive, was used to prepare warm mix SBS modified asphalt binders with different contents, and compared and analyzed with Sasobit and Evotherm warm mix additives. The rheological properties of asphalt binders were evaluated by rotational viscometer, dynamic shear rheometer and bending beam rheometer. The effects of the warm mix additives on chemical composition and microstructure of binders were analyzed by fourier transform infrared spectroscopy, thermogravimetric analysis and fluorescence microscope. The results showed that, Acmp had significant viscosity reducing effect, and 6 % Acmp reduced the rotational viscosity of binder by approximately 50 %. Acmp warm mix modified asphalt binder exhibited better low temperature performance compared to Sasobit and Evotherm, but Acmp had negative impact on the high temperature performance. Acmp was mainly composed of light components produced by the cracking of rubber powder and plastic powder, which were mainly short chain alkanes and did not affect the distribution of SBS in binder. These light components were well soluble in asphalt binder to improve its fluidity and were the main components that affected the performance of binders and achieved warm mix effects. Considering the performance of asphalt binder and mixture, Acmp is more suitable for pavements in cold regions, with a recommended dosage of 5 % of asphalt mass. The findings validate the effectiveness of organic composite warm mix additives and contribute to the exploration of more efficient new warm mix technologies. • The viscosity reduction effect of Acmp is better than that of Sasobit and Evotherm. • Acmp warm mix modified asphalt binder has superior low temperature performance. • The main component of Acmp is short chain alkanes cracked from rubber and plastic. • Light components in Acmp are the main reason for the changes in binder properties. [ABSTRACT FROM AUTHOR]

The thermo-oxidative aging of Styrene-Butadiene-Styrene (SBS) modified asphalt (SMA) includes the aging of base asphalt and the degradation of SBS modifiers. With the aim of restoring the performance of base asphalt and making up for the loss of performance advantage caused by the degradation of SBS modifier, tall oil and crumb rubber (CR) were applied to synergistically regenerate aged SBS modified asphalt (ASMA). The effect of the particle size and content of CR, as well as the degree of microwave-activated CR on the properties and storage stability of the reclaimed ASMA were discussed in details. The regeneration mechanism of ASMA by CR was studied from the surface properties, morphology and thermal behavior, respectively. The results show that tall oil can restore the low-temperature properties of ASMA significantly, but it seriously detrimental to the high-temperature properties. CR play the role of secondary modification on the reclaimed ASMA, which can improve the high-temperature properties of the reclaimed ASMA at the cost of low-temperature properties and storage stability, and the modification effect is related to the particle size and content of CR. Microwave activation of CR can improve the storage stability of the reclaimed ASMA with CR, which is because that microwave activation modification disrupts the cross-linking structure of the CR and improves the surface properties, which are conducive to the diffusion migration of molecular chains and multiphase material exchange between the CR and the reclaimed ASMA. Thus, the interaction between the multiphases can be enhanced in the reclaimed ASMA with CR. This work provides an effective regeneration method for aged SBS modified asphalt, and also achieves the reuse of non-renewable resources. • Synergistic regeneration of tall oil and CR restored ASMA properties effectively. • CR played the role of secondary modification on the reclaimed ASMA. • Storage stability of reclaimed ASMA was improved by microwave activation of CR. • Regenerating ASMA mainly involved material exchange between multiphases. [ABSTRACT FROM AUTHOR]

Under high-temperature construction conditions, the use of asphalt can release a large amount of volatile organic compounds (VOCs), which has adverse effect on the environment and human health. Part of fluorite oxides show potential application in VOCs conversion due to their excellent photoresponse and chemical stability in addition to ferroelectricity, piezoelectricity and pyroelectricity properties. In this paper, La 2 Ce 2 O 7 -based fluorite was modified with alkali metal doping and its photo-thermal coupling catalytic effects on the degradation performance of VOCs in asphalt were investigated. The results show that the fluorite catalysts La 1.85 A 0.15 Ce 2 O 7 (A=Li, Na, K, Rb, Cs) have efficient electron-hole pair separation ability. Among them, the Rb+ doped La 2 Ce 2 O 7 sample not only has stronger pyroelectric effect due to increased lattice distortion and oxygen vacancies, but also has the best photogenerated charge transport property and more favorable valence band position for oxidation reaction. Under the photo-thermal synergistic effect, the catalytic degradation performance of VOCs in asphalt by Rb+ doped La 2 Ce 2 O 7 catalyst can reach 82.61 % at 50 min. Additionally, dynamic shear rheological tests indicate that the addition of catalysts at this blending ratio can enhance the rutting resistance of the asphalt material. This study introduces an innovative approach to enhance the efficiency of multi-field coupled degradation processes of volatile organic compounds (VOCs) in asphalt. • A new catalyst without noble metal for asphalt VOCs degradation was successfully prepared. • The photo-thermal coupling was realized to catalyze the degradation of VOCs. • The catalyst can enhance the rutting resistance of the asphalt. • The catalytic performance is more than 2 times higher than traditional adsorbents. [ABSTRACT FROM AUTHOR]

Asphalt mastic, an important raw material in asphalt pavement, is a mixture of asphalt binder and mineral filler. This study utilized coal gangue (CG) as alternative of natural filler in asphalt mastic, which has benefits to recycling solid waste and saving non-renewable resource. In order to achieve performance improvement of CG asphalt mastic (CGAM), thermal activation approach was applied to treat CG particles from 450 ℃ to 900 ℃. Before and after treatment, the surface morphology, mineral components and size distribution were characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and laser particle size analyzer. Meanwhile, the dynamic shear rheometer (DSR) and bending beam rheometer (BBR) experiments were conducted to compare the rheological responses of CGAM at high and low temperatures. Further, the interfacial behavior between asphalt binder and CG filler is simulated by molecular dynamic (MD) method, aiming to explore the interaction mechanism at atomistic scale. Results show that the activated CG possesses a smaller particle size and a rougher surface by comparison in virgin one (i.e., unactivated CG). And the calcination process results in the crystal phase transition of CG and the proportion increase of alkali minerals, contributing to the stronger interaction ability and higher adhesion energy with asphalt binder. Owing to the positive changes of CG during calcination process, the corresponding CGAM exhibits superior deformation resistance property under recycling loads at high temperature and flexural creep ability at low temperature, especially when the calcination temperature rises to 750 ℃. • Particle size distribution and morphology of activated CG are closely related to calcination temperature. • Thermal activation process on CG triggered to changes of mineral compositions. • 750℃ is suggested calcination temperature considering both of high and low-temperature properties of CGAM. • The adhesion energy of asphalt binder with activated CG increased with the ever-rising calcination temperature. [ABSTRACT FROM AUTHOR]

Under climatic conditions such as high temperature plus ultraviolet radiation and water, the mechanical properties of asphalt pavement will be significantly attenuated. Present research mainly focused on thermal oxidation and ultraviolet radiation aging, and there were many controversies about the effect of water on the aging performance of asphalt. In addition, the relationship between the aging behavior of asphalt under complex environments and the standard PAV test needs to be further clarified. This research comprehensively evaluated the rheological properties, microscopy, and functional group of matrix asphalt, SBS, and high viscosity modified asphalt under different climatic conditions. Compared with thermal oxidation aging, daily exposure to UV radiation can increase the aging degree of matrix and modified asphalt by about 5 % and 1.5 %, respectively. Compared with thermal oxidation aging, the presence of water and the coupling effect of UV and water can reduce the aging degree of asphalt by 3.5 % and 2.6 %, respectively. After 5 days of thermal oxidation and UV coupling, the aging degree was close to or even greater than that of the PAV experiment. Asphalt aging caused an upward shift in the complex modulus master curve, and a downward shift in the phase angle master curve of matrix asphalt and high viscosity modified asphalt. Due to the synergistic effects of hardening and polymer degradation, the phase angle master curve of SBS modified asphalt showed an upward trend in the low frequency range. Under the influence of climatic conditions, the polymer of asphalt would degrade, the particle size of the polymer phase decreased, and the brightness of fluorescent image became darker. The rich polymer phase structure of high viscosity modified asphalt enabled it to maintain excellent mechanical properties even after long-term aging. • UV radiation can accelerate the aging degree of asphalt, while water alleviate the aging degree. • After 5 days of aging under T+UV, the aging degree was close to or even greater than that of PAV experiment. • Aged modified asphalt has smaller polymer phase particle size and darker fluorescent image. [ABSTRACT FROM AUTHOR]

Biological additives are considered environmentally sustainable and play a significant role in enhancing the performance of cementitious materials. This study focused on utilizing welan gum (WG) as a biological thickening agent to evaluate its impact on the rheological characteristics, resistance to shrinkage cracking, and mechanical properties of cementitious materials. The findings indicate that the incorporation of WG can improve the cohesion and stability of cementitious materials while reducing shear-thinning behavior. WG has less effect on cement hydration. However, WG may form agglomeration, leading to the increase in the water loss rate and dry shrinkage of cementitious materials. A high dosage of WG could decrease water loss rate due to film formation, but excessive WG might introduce pores and increase dry shrinkage. WG demonstrated the ability to delay cracking caused by dry shrinkage in cementitious materials. The crack resistance is enhanced by the elevation of the deformation capacity of cementitious materials. A comprehensive analysis revealed that a mass fraction of 0.10 % WG is the most effective in cement paste with a water-cement ratio of 0.4. The cohesion, water retention, and resistance to shrinkage cracking are improved, while mechanical properties are maintained in this situation. • An inverse proportional viscosity model is proposed to describe the shear-thinning property of welan gum-modified cementitious materials. • Welan gum may aggregate into clusters or form film structures, which enhances resistance against shrinkage cracking of cementitious materials. • Excessive welan gum has a negative influence on the dry shrinkage and flexural strength of the cementitious materials. • Optimal performance improvements are achieved for the paste with a w/c ratio of 0.4 when the mass fraction of welan gum is 0.1 %. [ABSTRACT FROM AUTHOR]

Today, the construction sector experiences significant pressure to use green and sustainable materials. In this framework, using biological components derived from agricultural products is the most interesting topic for the stability of asphalt pavement construction materials. Furthermore, the escalation in demand for transportation infrastructure has resulted in a rapid surge in the volume of traffic and premature degradation of asphalt pavements. The primary objective of this study is to assess the efficacy of olive kernel ash (OKA) obtained from olive canning factories in modifying the characteristics of asphalt. The investigation of this function has not been explored in prior research. To this end, a comprehensive analysis of morphological, Thermogravimetric, chemical, and phase separation was conducted, in addition to physical and rheological testing, over three distinct temperature ranges: high, intermediate, and low. The results showed that OKA is thermally stable and has a slow decomposition. Also, using OKA, compared to most biomass employed in bitumen, exhibits a satisfactory amount of phase separation. Despite the enhanced shear strength, the modified samples incorporating OKA do not encounter any operational challenges regarding transportation and pumping. The findings from the rheological experiments indicate that incorporating 20 % OKA in bitumen can increase the shear modulus up to 71 % and recovery percentage up to 20 %. Therefore, it significantly enhances the resistance to permanent deformation under high temperatures. The increase in molecular weight and asphaltene phase creates a resistant binder against high temperatures. Meanwhile, the fatigue life of modified samples containing 20 % OKA decreased to 59 %. However, applying the highest shear stress to the sample containing OKA experiences demonstrates its ability to resist this stress for longer. Also, it was found that regulating the OKA dosage in bitumen can maintain its acceptable resistance level to cracking at low temperatures. This phenomenon is due to the positive effect of OKA on the viscoelastic characteristics of bitumen. Based on our assessments, it has been observed that incorporating OKA up to 20 % in bitumen consistently enhances its performance capabilities at high temperatures. Nevertheless, while using this modified bitumen in cold regions, limiting its utilization to a maximum of 5 % is advisable. [Display omitted] • Olive kernel ash (OKA) was utilized as a sustainable additive to modified bitumen. • The porous and rough structure of OKA was determined from the microscopic image. • OKA improved the temperature sensitivity and resistance against rutting. • High-temperature storage values were in the optimal range for OKA-modified bitumen. [ABSTRACT FROM AUTHOR]

During the production process of hot-mix asphalt mixtures, high-temperature heating of asphalt is required, which leads to the emission of a large amount of volatile organic compounds (VOCs). Additionally, during their service life, asphalt pavements are slowly and continuously releasing VOCs under ultraviolet radiation. This emission poses significant risks to the health of construction workers and the ecological environment. In this study, two types of layered double hydroxides (LDHs), Mg-Al-LDH (M-LDH) and Ca-Al-LDH (C-LDH), were used to modify SBS asphalt. The VOCs suppression ability under different conditions of the modified asphalt was tested on a laboratory scale. The VOCs suppression mechanism was analyzed through nitrogen adsorption-desorption experiments, synchronous thermal analysis, and UV–visible spectrophotometry. Additionally, the influence of LDHs on the performance of SBS asphalt was studied through Fourier transform infrared spectroscopy, aging simulation tests and dynamic shear rheological tests. The results showed that the VOCs suppression effect of C-LDH was superior to that of M-LDH. With the increase of C-LDH content, its inhibitory effect on VOCs first increases and then decreases. The optimal effect is achieved with 5 % C-LDH, with a VOCs inhibition rate of 52.48 % in a heating condition and 90.31 % under ultraviolet radiation conditions. The resistance of SBS-modified asphalt against ultraviolet aging and heat-oxidation is greatly increased by the inclusion of C-LDH. Moreover, greater complex modulus and rutting factor measurements indicate a discernible increase in the hardness of the asphalt due to the addition of Ca-Al-LDH. These enhancements suggest that LDH can strengthen SBS asphalt's resilience to rutting. Meanwhile, controlling the dosage of C-LDH at 5 % or less does not significantly reduce the low-temperature cracking resistance of the asphalt. Based on the advantages of both VOC reduction and performance improvement, the research concludes that the best compromise for changing SBS asphalt is a 5 % Ca-Al-LDH concentration. • LDHs significantly reduce VOC emissions in SBS asphalt. • Mechanisms of VOC reduction by LDHs are revealed. • 5 % Ca-Al-LDH addition optimally reduces VOC emissions by 52.48 %. • LDH addition boosts asphalt's resistance to heat and UV aging. • Ca-Al-LDH improves asphalt's high-temperature rutting resistance. [ABSTRACT FROM AUTHOR]

In order to solve the problems that the fluidity of semi-flexible pavement grouting materials (SFPGM) is not up to standard, the early strength is not enough, or the fluidity meets the requirements but the early strength is not up to standard, the power plant by-Product -ultra-fine fly ash (UFA) was used to optimized the performance of grouting materials (GM) in this study. The microstructure of hardened slurry was analyzed by XRD, FTIR, MIP and SEM. The findings indicate that when the UFA content increases, the fluidity of the GM initially increases and then declines, whereas the compressive strength initially reduces and then increases. The sample exhibits optimal fluidity performance when the content of UFA is 9 %. The flow cone fluidity of the initial and 20 min is 12.33 % and 17.63 % lower than that of the reference sample. When the amount of UFA is 12 %, the compressive strength of sample is the highest at each age. Additionally, that the fluidity of sample S12 is sub-optimal in all samples, only worse than that of sample S9. In the early stage of GM hydration, UFA with slow hydration rate produces a significant 'ball-bearings effect' between irregular cement particles. This is beneficial to the relative sliding between the slurry particles, reduces the yield stress and plastic viscosity of the fresh slurry, and improves the flow performance of the GM. The pozzolanic effects of UFA in GM primarily manifests during the later stages of hydration. The primary hydration products of UFA modified GM include ettringite, C-S-H gel, C-A-S-H gel, calcium carbonate, and aluminium glue (AH 3). During the progression of the hydration reaction, the quantity of ettringite (AFt) in the slurry steadily augments, causing the initial fine needle-like structure to evolve into a more fully formed needle-like structure. A complex three-dimensional network of interlocking spatial structures is formed by many hydration products that continually interlace and develop, improving strength. The higher the perfusion rate of the GM, the higher the compactness of the SFPGM, and the better the high temperature stability and low temperature crack resistance. • The Ultra-fine fly ash(UFA) is finer and the spherical particles are more enriched. • The UFA produces a 'ball' effect and improves the flow performance of the GM. • The modification mechanism of UFA on grouting material is analyzed. • UFA first plays a spherical effect, and then plays a pozzolanic activity effect. [ABSTRACT FROM AUTHOR]

The relationships between the chemical components of hard asphalt, the most commonly used in Enrobé a Module Élevé (EME) asphalt, and its macroscopic rheological properties remain unclear. Four chemical components: saturates, aromatics, resins, and asphaltenes (SARA), were extracted from the hard asphalt of the same source to prepare seven asphalt binder samples. The viscoelasticity, permanent deformation and fatigue performance of the binders were characterized by a dynamic shear rheometer (DSR), differential scanning calorimetry (DSC), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy to describe their microscopic behavior. The results showed that with increasing asphaltene and resin contents, the complex modulus increased rapidly, while the phase angle decreased, which improved the elastic recovery ability and resistance to permanent deformation of the asphalt. The stress sensitivity of the asphalt varied, declining initially and then increasing with decreasing content of aromatics and saturates. The fatigue life of the asphalt also exhibited a peak-and-trough pattern with increasing strain in the viscoelastic continuum damage (VECD) model. The correlational analysis revealed a good correlation between the fatigue life and stress sensitivity; when the strain was greater than 5 %, the correlation coefficient R2 was greater than 0.95. The roughness was correlated to the SARA content according to the AFM topographic images; the higher the asphaltene and resin contents were, the rougher the binder became. FTIR showed that I Ar , I B and I B , a can represent the deformation vibrations of benzene ring C C bonds and aliphatic chains, which may be related to the fatigue life. The gray relational analysis showed that saturates had the greatest effect on the rheological properties of the asphalt binders. This study reveals the effect and mechanisms of SARA on the rheological properties of hard asphalt binder, providing significant insights for improving the engineering performance of both hard asphalt and EME mixtures. • Aromatics and saturates can improve the deformation coordination. • Excessive clusters may cause a higher strain sensitivity. • R and Jnr can be effectively improved with increasing number of clusters. • The fatigue life N f is highly correlated with J nr-diff. • Saturates have the greatest effect on the rheological properties of hard asphalt. [ABSTRACT FROM AUTHOR]

The rheological responses of Styrene-Butadiene-Styrene (SBS) modified asphalt are stress-dependent, yet the underlying mechanisms and their relationship to the phase structures formed by SBS in the asphalt matrix remain unclear. To address this issue, this study utilized varying dosages of SBS to prepare binders (SBSMA), which were then characterized through fluorescence microscopy, FTIR, and rheological tests including temperature sweeps and Multi-Stress Creep Recovery (MSCR) at four stress levels. Additionally, rutting resistance of the mixtures was evaluated using wheel tracking tests, correlating the results with rheological data. The test results indicate that the formation of a three-dimensional SBS network structure within the asphalt significantly increases the Stress Sensitivity Index (SSI) by 69.5 %, thereby enhancing the binder's stress sensitivity. Based on the theory of entropic elasticity, the stress sensitivity of SBSMA is explained. The cross-linked network structure exhibits superelastic behavior under low stress but may be overstretched and reorganized under high stress, leading to weakened entropic elasticity. Furthermore, the J nr values obtained at higher stress levels show stronger correlation (r > 0.9) with the Dynamic Stability (DS) from the wheel tracking test results. This finding suggests that entropic elasticity does not significantly improve the rutting resistance performance at the mixture level. Consequently, increasing the stress level in MSCR tests is recommended to more accurately predict the binder's rutting performance by inhibiting the network's entropic elasticity. • SBSMA binders' stress-dependent behavior is linked to SBS phase structures in asphalt. • The strong entropic elasticity of the network structure imparts robust recovery capabilities to SBSMA. • High test stress effectively weakens the network structure's entropic elasticity and stress sensitivity. [ABSTRACT FROM AUTHOR]

Incorporating bio-oil as a partial alternative to bitumen in road construction shows potential for advancing carbon neutrality and addressing challenges arising from the depletion of petroleum resources. However, insufficient research exists concerning the rheological properties of aged bio-bitumen derived from slow pyrolysis when compared to petroleum bitumen. Furthermore, uncertainties prevail regarding the adhesive bonding properties at the interface between bio-bitumen and aggregates. To address this issue, this study systematically investigates the rheological and bonding characteristics of short and long-term aged bio-bitumen derived from the slow pyrolysis of bamboo wastes. The test materials encompass virgin bitumen, bio-bitumen with 6 %, 9 %, 12 %, and 15 % bio-oil contents, alongside five types of aggregates. Additionally, crumb rubber is employed to enhance the performance of bio-bitumen with the optimal 12 % bio-oil content. Results demonstrate that bio-oil derived from the slow pyrolysis of bamboo wastes can impede the formation of S O during aging. Rheological properties among bio-bitumen have no obvious difference following a short-term aging. However, when the content of bio-oil reaches 15 %, the rheological property deteriorates significantly after long-term aging. Blending bio-oil significantly diminishes the fatigue crack length of bitumen, with the best fatigue performance observed in bio-bitumen with 12 % bio-oil content. The elevated bio-oil content significantly diminishes the deformation recovery ability of bitumen. Following long-term aging, bio-oil diminishes the adhesive bonding performance between bitumen and aggregates. Water markedly diminishes adhesive bonding performance between bio-bitumen and aggregates, irrespective of the aging duration, with bio-bitumen containing 9 % bio-oil content exhibiting heightened susceptibility to water-induced replacement. The recommended optimal bio-oil content is 12 %, and blending crumb rubber proves effective in improving the rheological and bonding properties of bio-bitumen. • Bio-oil derived from the slow pyrolysis of bamboo wastes can impede the formation of S O during aging. • The elevated bio-oil content significantly diminishes the deformation recovery ability of bitumen. • Following long-term aging, bio-oil diminishes the adhesive bonding performance between bitumen and aggregates. • Water markedly diminishes adhesive bonding performance between bio-bitumen and aggregates. • The recommended optimal bio-oil content is 12 %, and blending crumb rubber is valid in improving properties of bio-bitumen. [ABSTRACT FROM AUTHOR]

Recycled aggregate (RA) is generated through the crushing process of Construction and Demolition Waste (CDW). Although there has been extensive research on the mechanical properties of recycled aggregate asphalt mixture (RAAM), the impact of recycled aggregate (RA) on its rheological characteristics remains underexplored. This paper aims to assess the rheological properties of recycled aggregate asphalt mixture (RAAM) during the processes of mixing and compaction. Firstly, different percentages of recycled aggregate (RA) were utilized in the design of the recycled aggregate asphalt mixture (RAAM), and rheological behaviors of RAAM during the mixing and compaction stage were characterized by mixing torque and compaction energy, respectively. Then, high-precision three-dimensional models of RA were reconstructed utilizing CT images, and four indices were established to quantitatively assess the macro shape and micro-morphology of RA particles, utilizing the spatial model data for precise measurements. Finally, a correlation was found between rheological properties of RAAM and RA morphology through a comprehensive analysis of laboratory test results and spatial model indicators. Results show that aggregate particles' microstructural morphology significantly influences asphalt mixture's rheological behavior during mixing and compaction. Additionally, the 3D spherical degree and Needle-flake index performed more significant correlations with mixing and compaction than the 3D angular index and 3D texture index. As opposed to natural aggregate, RA exhibits more intricate morphological characteristics stemming from its porous cement mortar composition. Increasing the RA content causes more energy consumption and increases the thickness of asphalt mortar film during the compaction process. In general, methods established in this study offer an efficient mean of quantifying the morphological characteristics of aggregate particles, thereby enabling the assessment of the impact of RA on the rheological properties of asphalt mixtures. • A quantitative method for microstructural morphology of aggregate particle is proposed. • Rheological properties of asphalt mixture containing recycled aggregates are measured. • The relationship between rheological properties and morphological indicators is obtained. [ABSTRACT FROM AUTHOR]

This study proposes carbonatable 3D printing magnesium slag mixtures to reduce preparation cost and CO 2 emission compared to conventional 3D printing concrete. Results show magnesium slag slurries with plastic viscosity of 2.05–2.81 Pa·s and yield stress of 297.4–401.75 Pa exhibit suitable extrudability and buildability. Among printable mixtures containing various rheology modifying agents, the printed samples with welan gum (WG) exhibit optimal carbonation reactivity. This is attributed to the three-dimensional threaded network formed by dissolved WG molecules providing channels for calcium ion dissolution, which maintains a sustained carbonation reaction. After 12 h carbonation, the formation of calcite product bonds particles together and fills pores, creating a dense matrix that improves the compressive strength and interlayer bond strength of the MS-WG printed samples to 78.29 MPa and 3.99 MPa, respectively. The foil-like structure of dissolved hydroxypropyl methylcellulose (HPMC) molecules appears to coat magnesium slag particle, restricting calcium ion dissolution and impeding the carbonation reaction. The limited formation of calcite products also contributes to inferior mechanical properties in MS-HPMC printed samples. Additionally, HPMC introduction creates bubble defects within the printed samples, further compromising the mechanical properties of the MS-HPMC printed sample. • Carbonatable 3D printing materials represent an innovative solution for sustainably magnesium slag valorization. • Critical rheological parameters for the successful extrusion-based additive manufacturing of magnesium slag mixtures are validated. • Multi-scale characterizations elucidate the mechanistic interplay between rheology modified agents and strength development in the printed samples. • Welan gum is identified favorable compatibility with carbonation reactivity of the printed samples, enabling notable mechanical properties. [ABSTRACT FROM AUTHOR]

To improve the interfacial adhesion between Basalt Fiber (BF) and asphalt, surface treatment of BF was performed based on the principle of mussel bionics. Firstly, mussel-inspired biomimetic modifier (Dopamine hydrochloride (DA)) combined with three kinds of amine modifiers (AM) were used for multistage treatment of the surface of BF. Then, the surface properties of BF were characterized. Next, the effect of surface treatment BF on the rheological properties of asphalt was investigated. Finally, the mechanism of surface treated BF to enhance asphalt properties was revealed based on multi-scale characterization. The results of the study are as follows: For the surface properties of BF: combining DA with AM can effectively improve the surface properties of BF by surface multistage treatment. Among them, the contact angles of the three kinds of mussel-inspired biomimetic treated BF were increased by 11.66 %, 27.81 % and 35.67 %, respectively, compared with that of BF. The significant increase in the wetting characteristics and surface roughness of the BF was mainly attributed to the effective co-deposition of DA and AM on the surface of BF. For the rheological properties of BF modified asphalt: mussel-inspired surface treated BF significantly enhanced the rheological properties of asphalt, which was mainly attributed to the reinforcement effect of BF. The difference in the rheological properties of different surface treated BF with asphalt originates from the interfacial properties. For the enhancement mechanism of the interface between BF and asphalt the interactive behavior under the meso-scale, the morphological characteristics under the micro-scale, and the interfacial adhesion under the molecular-scale indicated that the treatment of BF with DA composite AM could effectively enhance the adhesion properties of the interface between BF and asphalt, thus enhancing the performance of the BF modified asphalt. In conclusion, mussel-inspired biomimetic surface treatment is a convenient and efficient BF surface modification technology with broad application prospects. [Display omitted] • Dopamine and amine modifiers were used for multistage surface treatment of BF based on the principle of mussel bionics. • Wetting behavior, chemical composition, and microstructure of surfaces of surface treated BF were characterized. • Rheological properties of surface treated BF modified asphalt were systematically investigated. • Interfacial interactions, micromorphology, and adhesion behavior were used to explore the enhancement mechanisms. [ABSTRACT FROM AUTHOR]

Fly ash (FA) and silica fume (SF) are two commonly used materials for modifying magnesium phosphate cement (MPC). MPC- emulsified asphalt (MPC-EA), a new type of pavement rehabilitation material, poses a challenge in combining MPC hydration and EA emulsion breaking to enhance its performance. In this study, FA and SF were used to modify MPC-EA, and their effects on the rheological properties of MPC-EA at different substitution amounts were analyzed. Rheological curves were obtained using an RST-SST rheometer. Three commonly used rheological models—the Bingham model, the Herschel-Bulkley (H-B) model, and the modified Bingham model—were used to fit the rheological curves. The matching relationship between yield stress and plastic viscosity in these three models was analyzed to reveal the different rheological loss mechanisms of the two dopants on the MPC-EA slurry. Results indicated that the H-B model was the most suitable for fitting the modified MPC-EA. Substituting magnesium oxide (MgO) with FA and SF did not alter the flow pattern of MPC-EA but did change its rheological parameters. In the FA and SF substitution groups, both yield stress and plastic viscosity were proportional to the substitution amount and negatively affected the fluidity of the MPC-EA slurry. By analyzing the rheological parameters, the different modification mechanisms of the two dopants at high dosages were clarified: FA provided more nucleation sites, increasing the number of flocculated structures, while SF absorbed more water, leading to increased EA emulsion breaking behavior and, consequently, an increase in the volume of flocculated structures. This study established the rheological constitutive equations of MPC-EA for the first time, considering FA and SF substitution amounts ranging from 5% to 25%. The research findings can provide theoretical support for the field application design of FA- and SF-modified MPC-EA for pavement remediation. • The H-B model exhibited the highest accuracy in fitting the MPC-EA modified by FA or SF. • The addition of FA and SF did not alter the rheological behavior of MPC-EA. • This study elucidated distinct rheological loss mechanisms of FA and SF with MPC-EA. • The rheological constitutive equations of FA and SF with MPC-EA were developed. [ABSTRACT FROM AUTHOR]

In order to evaluate the effects of three preparation processes, namely dry process (DP), wet process (WP) and wet/dry mixing process (MP), and resin high viscosity modifier (RHVM) on the road performance of porous asphalt mixtures, the frequency scanning, multi-stress creep recovery, and bending beam rheometer tests were used to analyze the rheological performance of resin-modified high viscosity asphalt under different processes. Uniaxial compression, Wheel tracking, Semi-circular bending and Freeze-thaw indirect tensile tests were used to test the properties of resin-modified porous asphalt mixtures under different processes. The commonly used TAFPACK-Super (TPS) modifier was a control group. Finally, the changes in the microscopic morphology characteristics and chemical composition were used to illustrate the enhancement mechanism of resin modifiers. The results showed that the high-temperature deformation resistance and low-temperature cracking resistance of RHVM modified asphalt prepared by DP and MP are weaker than that of the WP. Compared to the RHVM(WP), the J nr (3.2) of RHVM(DP) and RHVM(WP) decreased by 14.3 % and 63.8 %, the strength modulus of RHVM(DP) and RHVM(MP) increased by 21.5 %, 28.0 % and the creep rate decreased by 2.37 %, 4.45 %, respectively. As for the performance of asphalt mixture, compared to the RHVM(WP) asphalt mixture, the dynamic stability of RHVM asphalt mixture prepared by the DP and MP decreased by 17.3–18.2 %, σ s and ε s of RHVM(DP) and RHVM(MP) increased by 15–35 % and 21–29 %, respectively. The water stability of RHVM(DP) asphalt mixtures was better than that of RHVM(WP) when the mixing time reached 180 s. RHVM(WP) asphalt mixtures have superior low-temperature cracking resistance, comparable water stability, and slightly poorer high-temperature stability than that of TPS(WP) asphalt mixture. Microscopic morphology observation found that some modifier particles and asphalt binder did not realize effective mixing under the DP and MP, and infrared spectroscopy results confirmed that TPS modifiers are mainly physically co-mingled with asphalt, while the tackifier resin in the RHVM reacts with the asphalt to form new functional groups to increase the viscosity of the asphalt. • The road performance of resin porous asphalt mixtures under dry, wet and dry-wet mixed processes was evaluated. • The rheological performance of resin modified high viscosity asphalt extracted from dry, wet and dry-wet mixed process asphalt mixture was evaluated. • The modification mechanism of resin high viscosity modifiers on asphalt was discovered. [ABSTRACT FROM AUTHOR]

This paper aims to examine the effect of coal gangue aggregate (CGA), fly ash (FA), and ground-granulated blast slag (GGBS) on the rheological, mechanical and microstructure properties of concrete. The rheological properties, compressive strength, splitting tensile strength, flexural strength, and uniaxial tensile behaviour of coal gangue concrete (CGC) were determined, and the microstructure of the concrete mixtures were investigated by use of XRD and SEM analyses. The results revealed the action mechanism of CGA and mineral admixtures on the microstructure and macroscopic properties of CGC. FA first increased and then decreased the yield stress and plastic viscosity, while GGBS considerably increased the yield stress and plastic viscosity. Furthermore, a constitutive model was established for CGC containing FA and GGBS under compression. The proposed stress–strain model for CGC is accurate and can be used for nonlinear analysis of structures made of this type of concrete. Moreover, the addition of FA and GGBS consumes calcium hydroxide, but increases products such as hydrated calcium silicate aluminate. These findings elucidate the understanding and optimisation of CGA use in concrete production, while contributing to lowering carbon emissions. • Concrete strength degrades with increasing coal gangue aggregate substitution rate. • Fly ash degrades coal gangue concrete mechanical properties, and slag enhances them. • Fly ash and slag combination provides a complementary superposition effect. • A precise coal gangue concrete uniaxial compression analysis model is proposed. [ABSTRACT FROM AUTHOR]

The influence of air entrainment on rheological behavior of fresh cementitious materials has attracted a lot of attention in the past years, but the results are still in controversy. In this research, cement mortars were prepared with equivalent air contents using different air-entraining admixtures (AEAs) to measure their fresh-state performance and hardened air-void system at variable temperature conditions, which aimed to clarify and unveil the coupled effects of different surfactants and temperature for the first time. The adsorption amount of AEA, zeta potential of cement, along with hydration kinetics of mixtures were evaluated to characterize the interaction of air bubbles with cement grains. It was found that for mixture without superplasticizer (SP), the impact of air entrainment on rheological parameters was dependent on the interaction intensity of AEA molecules with cement. For SP-plasticized mixture, air entrainment tended to cause a shear-thinning behavior with decreased plastic viscosity, while its influence on yield stress was in accordance with the situation without SP. The hardened samples with anionic surfactant contained more small voids and lacked big voids, whereas the samples with cationic surfactant showed opposite outcomes. With temperature decreasing, both the average chord length and the spacing factor of air voids increased owing to the reduced yield stress of mixture. The results will provide in-depth illustrations for understanding how air bubbles change the rheological behavior of mixture, and more importantly it will explain the seemingly inconsistent findings reported by previous literatures. • How air bubbles affected rheological behavior of mixtures with various states was clarified. • The coupled influence of surfactant type and temperature on air-void system were explored. • The crucial role of surfactant interaction with cement for fresh-state performance was revealed. • The reasons why temperature decreasing at fresh-state degraded air-void structure were analyzed. [ABSTRACT FROM AUTHOR]

To improve the compatibility of crumb rubber in asphalt, two de-crosslinking crumb rubber (DCR) were obtained via mechano-chemical modification with two modifiers. Physicochemical properties of DCR were investigated to analyze its de-crosslinking mechanism. The de-crosslinking efficiency of DCR was characterized through the sol content and crosslinking density test. Next, the physical properties and storage stability of de-crosslinking crumb rubber modified asphalt (DCRMA) and unmodified crumb rubber modified asphalt (UCRMA) were analyzed to investigate the influence of DCR on modified asphalt binder. The rheological behaviors of DCRMA and UCRMA were determined from high- and low-temperature condition using the dynamic shear rheometer and bending beam rheometer. The results manifested that the de-crosslinking reaction in CR caused a rough and dispersed microstructure. Moreover, during this process, rubber macro-molecular chains were increased and thermal stability of CR was decreased. Elemental analysis confirmed the decreasing in polysulfide crosslinking bonds and carbon-sulfur bonds, while increasing in sulfur-oxygen bonds. All the above results reveal degradation of the crosslinked network in the rubber. Moreover, the de-crosslinking rates of two types of DCR were 46% and 50%, which further certified a successful de-crosslinking modification. Subsequently, the rotation viscosity and softening point difference of asphalt was reduced after adding DCR, indicating that the compatibility between CR and asphalt was enhanced. Rheological results showed that the high-temperature properties of DCRMA were lower than that of UCRMA. Moreover, the gap of rutting factor and recovery between DCRMA and UCRMA reduced with increased rubber content in the high-temperature condition. In the low-temperature condition, the crack resistance properties of DCRMA were higher than that of the UCRMA, particularly when the rubber content exceeded 20%. [Display omitted] • The de-crosslinking process had a great influence on the chemical combining state of sulfur atoms of CR. • Crosslinking density of crumb rubber decreased after mechano-chemical modification. • The de-crosslinking process enhanced the compatibility of modified rubber asphalt. • The influence of the de-crosslinking process on the rheological properties of CRMA was related to rubber content. [ABSTRACT FROM AUTHOR]

Rheological properties play a crucial role in determining the grouting effectiveness of magnesium phosphate cement (MPC) slurry. This study aims to investigate the effects of the magnesia-to-phosphate (M/P) ratio, water-to-cement (w/c) ratio, fly ash (FA), and metakaolin (MK) on the rheological properties of seawater-mixed MPC slurries using rheological tests and low-field 1H nuclear magnetic resonance (NMR). Two methods for incorporating FA were explored to modulate the rheological properties of the MPC. The results demonstrated time-dependent viscosity changes with two distinct phases, including a plateau and a subsequent period of sudden change, with the minimum apparent viscosity occurring as hydration progressed. The apparent MPC viscosity was influenced by the MgO-particle content and the theoretical water consumption, with M/P = 3 exhibiting the lowest apparent viscosity within a w/c range of 0.14–0.2. Moreover, the addition of FA increased the minimum apparent viscosity of the MPC slurry. During the pre-hydration stage, using FA as an MPC substitute yielded better rheological properties than using FA as an MgO substitute. The MK increased the apparent MPC viscosity considerably and adversely affected its rheology. • Viscosity of MPC showed a period of plateau followed by a sudden change over time. • Minimum apparent viscosity of MPC occurred as hydration progresses. • MgO particle content and theoretical water consumption determined viscosity of MPC. • Replacing MPC with FA yielded better rheology than replacing MgO with FA. [ABSTRACT FROM AUTHOR]

Self-healing asphalt is considered as one of the desirable methods to extend the service life of asphalt pavement. This research prepared a polyurea elastomer containing dynamic disulfide bonds (PUA)/styrene butadiene styrene block copolymer (SBS) composite modified asphalt. Moreover, a new asphalt self-healing performance evaluation method based on the damage process and results has been proposed. Subsequently, the self-healing ability of PUA, the distribution of modifier, the functional group and molecular weight of composite modified asphalt were characterized by fluorescence microscope, Fourier transform infrared spectroscopy (FTIR) and Gel permeation chromatography (GPC). The self-healing potential and limits of PUA/SBS composite modified asphalt was investigated through the proposed healing linear amplitude scanning (HLAS) test. Results show that the SBS content and fatigue load level are the main factors affecting the self-healing promotion effect of PUA. The critical point of healing fatigue strain (HFS) can indirectly characterize the threshold at which healing promoters exert their effects. Next, the addition of fillers will reduce the self-healing performance of PUA/SBS composite modified asphalt, but it still improves by at least 61.318% compared with SBS modified asphalt. Finally, the addition of self-healing elastomers (PUA) improves the permanent deformation resistance at high temperature and low-temperature crack resistance of SBS modified asphalt. The dynamic recombination of disulfide bonds can increase the fatigue cycle number of 4%SBS modified asphalt by 93.52% at a 5% load strain level. • PUA can promote the self-healing performance of SBS modified asphalt. • The addition of fillers does not weaken the self-healing performance advantage of PUA/SBS composite modified asphalt. • PUA/SBS modified asphalt has good high and low temperature performance. • The addition of PUA improves the fatigue cycle life of SBS modified asphalt [ABSTRACT FROM AUTHOR]

SBS modified asphalt (SBSMA) pavements have gained popularity worldwide due to their prominent performance. However, its maintenance and reconstruction projects will produce a large amount of reclaimed asphalt pavement (RAP) during the long-term service of asphalt pavement. Adding rejuvenators products is a common method to recycling RAP. However, conventional rejuvenators are typical component regulators applicable to recycling unmodified asphalt, while there is a poor regeneration effect for the aged SBS modified asphalt (A-SBSMA), because it cannot repair the degraded SBS polymer. Fortunately, reactive rejuvenator (RR) has achieved this breakthrough based on the research findings in recent years. It contains special compounds that have the ability to repair the degraded SBS. The vital questions to be investigated in the present review are how the four current systems of RR (epoxy system, isocyanate system, compound system and polymer system) affect A-SBSMA's properties and how well does its regeneration effect. Existing research indicated that RRs are favorable for the regeneration of A-SBSMA and have their respective characteristics. This review summaries various RR different regeneration mechanism, and analyzed its effects on physical properties, rheological properties, high and low temperature properties, and microscopic characteristics of A-SBSMA. Although research on RR is still in its infancy with a limited number of relevant studies, they show an excellent regeneration effect for A-SBSMA and hold a promising prospect. Overall, this review provides information on the feasibility of using RR as a sustainable SBSMA rejuvenator to promote conserving resources and reusing RAP. [Display omitted] • Traditional regenerant is not completely suitable for A-SBSMA regeneration. • RR can realize the re-crosslinking of SBS polymer fragments. • RR can comprehensively regenerate A-SBSMA performance. • RR has a unique regeneration mechanism for A-SBSMA. [ABSTRACT FROM AUTHOR]

The use of polymers to modify asphalt binders has become a widely accepted practice in modern pavement construction, offering a promising solution to address key factors contributing to asphalt pavement deficiencies. These factors include issues such as rutting, moisture-induced deterioration, and fatigue-related wear. The copolymer referred to as PGXpand was utilized as the modifying additive for the virgin binder in this study. It demonstrates exceptional performance in terms of high-temperature resilience and resistance to rutting. The impact of incorporating the PGXpand on asphalt properties was investigated. A comprehensive series of tests were conducted, covering storage stability, penetration, softening point, ductility, viscosity, and elastic recovery. Further analyses involved calculations of stiffness modulus, complex modulus, and phase angle. Mechanical and performance evaluations were also carried out, including Marshall properties, moisture susceptibility, creep compliance, and Kim tests. The results demonstrate the effectiveness of the PGXpand in enhancing asphalt performance, with modified mixtures exhibiting significant improvements compared to their unmodified counterparts. Consequently, integrating the PGXpand into asphalt technology emerges as a highly promising approach for optimizing road infrastructure, especially in regions with high-temperature conditions. Ultimately, such integration contributes substantially to the development of sustainable and resilient transportation networks. • A copolymer ranging from 0% to 3% has been introduced into pure asphalt as a modifier. • Physical, rheological, and performance assessments of the modified asphalt have been carried out. • The PGXpand copolymer shows promise as a potential modifier for asphalt binder. [ABSTRACT FROM AUTHOR]

Recycling of UV-aged asphalt has been a hot research issue. In this paper, waste cooking oil, plasticizer, toughener, and petroleum resin were used as raw materials for asphalt rejuvenator. This paper explores the effect of regeneration conditions on the regeneration effect of UV-aged asphalt binders through high-temperature rheology and chemical compositions. The paper also attempts to reveal the regeneration mechanism of asphalt binder regeneration using waste cooking oil. Dynamic shear rheology (DSR) and fourier transform infrared (FTIR) spectroscopy assess high-temperature rheological properties and chemical compositions. The Pearson correlation coefficient relates the rheological parameters to the chemical microstructure. And the functional relationship between carbonyl-corrected peak area and aging factor Ai of recycled asphalt and high temperature rheological parameters were established. Molecular simulation investigates WCO-recycled asphalt binder micro-morphology and adsorption mechanisms. The results showed that significant changes in the carbonyl and sulfoxide peak areas affected the high-temperature rheological properties. Regeneration conditions significantly affect asphalt regeneration effectiveness. WCO reduces C O and S O groups, crucial in asphalt viscoelastic behavior. Molecular interaction analysis reveals WCO's regenerative mechanism. This work emphasizes integrating molecular structure, chemical composition, and macroscopic properties in asphalt binder research, providing insights for sustainable pavement practices. • The content of C=O and S=O are the main factors determining the recycling effect of WCO recycled asphalt. • WCO rejuvenator changes the molecular structure of aged asphalt. • The -OH group of WCO increases the interaction between WCO molecules and aged asphalt molecules. [ABSTRACT FROM AUTHOR]

To accurately evaluate the modification effect of direct-to-plant styrene–butadiene–styrene block copolymer (SBS) modifier on asphalt, a collection method for direct-to-plant SBS-modified asphalt was proposed in this paper, the qualitative and quantitative evaluation index system was established, and the feasibility of quantitative evaluation based on fluorescence microscopy images and visual inspection of the mixing effect was evaluated, the feasibility of quantitative evaluation indicators was also verified based on the asphalt indicators, rheological properties, and asphalt mixtures's pavement performances. The research results indicate that based on fluorescence microscopy images, by observing the distribution and swelling state of direct-to-plant SBS modifiers can qualitatively evaluate the modification effect of direct-to-plant SBS modifiers on asphalt. Based on the visual inspection of the mixing effect, observe the size and quantity of unmelted particles, determine the melting state of the direct-to-plant SBS modifier, and its modification effect on asphalt can be qualitatively evaluated. For the same direct-to-plant SBS-modified asphalt, the percentage of rotation viscosity between direct-to-plant SBS-modified asphalt and traditional SBS-modified asphalt at 135 ℃ (DA η (135 ℃)) and discrete coefficient of 135 ℃ rotational viscosity of direct-to-plant SBS-modified asphalt (CV η (135 ℃)) exhibit a linear relationship with direct-to-plant SBS-modified asphalt's penetration, softening point, and ductility, the smaller the CV η (135 ℃) , the greater the DA η (135 ℃). The smaller the CV η (135 ℃) (the larger the DA η (135 ℃)), the larger the dynamic shear modulus (G *), the smaller the phase angle (δ), and the larger the rutting factor ( G * / sin δ) at the same scanning temperature. The relationship between CV η (135 ℃) (DA η (135 ℃)) and direct-to-plant SBS modifier on the main technical indicators and rheological performance indicators of asphalt is relatively stable. There is a clear relationship between CV η (135 ℃) (DA η (135 ℃)) and the high-temperature stability, low-temperature crack resistance, and water stability of direct-to-plant SBS-modified asphalt mixture, all of which show that as CV η (135 ℃) decreases (DA η (135 ℃) increases), the pavement performances improve. • The collection method for direct-to-plant SBS-modified asphalt is proposed. • A qualitative evaluation method for the modification effect of direct-to-plant SBS modifier on asphalt is proposed. • The quantitative evaluation index for the modification effect of direct-to-plant SBS modifier on asphalt is proposed. [ABSTRACT FROM AUTHOR]

High-asphalt-content emulsified asphalts (HIACEs) have a broad application potential in the field of asphalt mixtures due to their ultrahigh asphalt content (≥74%) and adjustable rheological properties. The latter is an important property of HIACEs that has a substantial effect on their preparation, storage, transportation, and mixing. Therefore, in this study, the rheological properties were investigated by steady-state shear tests and oscillation tests. The results show that the rheological properties of HIACEs are clearly temperature sensitive, showing a "gel-like" structure with increasing temperature, and when the temperature is higher than the temperature corresponding to the gel-like point, HIACEs behave as a pseudoplastic fluid with a yield stress. The results of amplitude scanning showed that the high HIACEs had a broad linear viscoelastic interval. Under a small amplitude (linear region) oscillation, the HIACEs had a gel-like structure within a specific angular frequency range, and the elastic behavior was more prominent than the viscous behavior. With a continuous increase in the angular frequency, the gel-like structure was destroyed. The storage modulus calculated with the use of the modified Mougel model was in good agreement with the experimental values. Also, the rheological properties of HIACEs depended on the asphalt content and droplet size, which provides theoretical guidance for the practical application of HIACEs in engineering. [Display omitted] • HIACEs has a very high bitumen content compared to conventional emulsified bitumen. • Rheological properties can affect the production, transportation and use of HIACEs. • Rheological properties of HIACEs were obviously temperature sensitive. • Rheological properties of HIACEs depend on asphalt content and droplet size. [ABSTRACT FROM AUTHOR]

The rise in environmental and economic concerns suggests that there will be a growing reliance on crumb rubber (CR) derived from discarded vehicle tires for bitumen modification in the future. The modification process involving CR is conducted on a large scale, either as a single pass or multi-pass, within specialized plants equipped with mixing equipment and crucially, grinding mills. In the laboratory, CR modification is carried out at different stirring speeds, times and temperatures using different mixing equipment in very small quantities compared to the plant. The extent to which this mixing process in the laboratory is similar to the mixing in the modified plant in the field is an issue that needs to be determined in order to make an efficient pavement design. This study aimed to make the most efficient use of CR modification by comparing laboratory and field conditions in the production of CR modified bitumen. For this purpose, a binder sample with CR additive was taken from the plant. In the laboratory, binders with the same CR content as in the plant were prepared in a high shear mixer at different stirring speed and time. It was found that increasing the stirring speed and time in the laboratory resulted in a binder with superior performance, in particular 4000 rpm and 60–90 minutes mixing conditions produced a binder with improved elastic properties by forming a good CR-bitumen interaction; there were significant differences in the rheological properties between the CR-modified binder produced in the laboratory and in the plant; the performance obtained in the plant can be obtained in the laboratory at low speeds such as 1000–2000 rpm and stirring time of about 30 minutes; the stirring time in the plant should be kept longer than in a single pass to obtain better performance from the binder in the plant. [Display omitted] • Laboratory and field conditions compared to make efficient use of CR modification. • Increasing stirring speed, time in the laboratory resulted in superior performance. • Notable differences between laboratory and plant-produced CR-modified binder. • Binder with superior performance was produced at 4000 rpm and 60–90 min. mixing. • Longer stirring time and pass in the plant is required to obtain better performance. [ABSTRACT FROM AUTHOR]

Partially replacing cement with recycled brick powder (RBP) in 3D printing concrete (3DPC) is an effective way to reduce carbon footprint and resolve the construction and demolition waste disposal problems. Understanding the impact of RBP on the rheological parameters of 3DPC is of utmost importance, given its critical role in ensuring the requisite printability. Here, three types of RBPs with various particle features were prepared by mechanical grinding, and their effects on several rheological parameters of cement-RBP pastes were characterized by hydration kinetic and water state distribution. Results show that incorporating RBP increases the growth rate of static yield stress due to the nucleation effect in the first 2 h. The initial static yield stress and thixotropy of cement-RBP pastes are governed by morphology effect and Debye length, while the mean interparticle distance and water lubrication effect under shear process play the dominant role in dynamic yield stress. RBP can promote the evolution of structural build-up and thixotropy of cement paste, all of which have a significant positive impact on filament shape retention and structural stability of 3DPC. • The particle features of RBP change significantly after grinding. • RBP considerably accelerates the structural build-up rate of blended cement paste. • RBP increases the thixotropy of blended cement paste. • RBP reduces water freedom degree and weakens the water lubrication effect. • RBP enhances the interaction between particles. [ABSTRACT FROM AUTHOR]

To enhance the dispersion of graphene oxide (GO) in Styrene-butadiene-styrene (SBS) modified asphalt (SA) and the comprehensive physical properties of GO/SBS-modified asphalt (GSA), PEA-GO composites were prepared by grafting polyetheramine (PEA) onto GO for the preparation of PEA-GO/SBS-modified asphalt (PGSA). In this study, the chemical structure of PEA-GO was examined using fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The conventional properties of GSA and PGSA were analyzed. The effects of GO and PEA-GO on the high and low-temperature prevalent properties of SA were investigated by dynamic shear rheology (DSR) test and bending beam rheology (BBR) test. The adhesion properties of GSA and PGSA were investigated by surface free energy theory (SFE). The surface micro-morphology of GSA and PGSA and the dispersion state of GO in SA were analyzed using atomic force microscopy (AFM) and fluorescence microscopy (FM). The results showed that the characteristic absorption peaks of N-H, CH 2 -CH 2, and C-N appeared in the FTIR diagram of PEA-GO. A new peak appeared in the XPS diagram: C-N. The high-temperature performance, low-temperature crack resistance, and adhesion of PGSA were superior to those of GSA. The size of the "bee structure" in PGSA is larger than in GSA, and PEA-GO demonstrates uniform dispersion in SA. This study serves as a reference for fine-tuning graphene oxide (GO) at the microscopic level to enhance the physical properties of GSA. • A functional composite of polyetheramine grafted graphene oxide was successfully prepared. • The spatial site resistance effect of polyetheramine improves the dispersion of GO in asphalt. • PEA significantly improved the physical properties of GO/SBS modified asphalt. [ABSTRACT FROM AUTHOR]

Epoxy asphalt (EA) is considered a highly promising solution for long-term asphalt pavement due to its excellent comprehensive properties. This study proposed a novel curing agent, which is a modified amine with an unsaturated fatty carbon chain. For the first time, this agent is suggested to be employed to generate roadway-oriented epoxy-modified asphalt (REA). The rheological characteristics, ductile failure resistance, and microscopic morphology of the REA binder were assessed. Additionally, the pavement performance of both semi-cured and fully-cured REA mixtures was analyzed. The substitution reaction occurring between the unsaturated C C bond in the curing agent and the C-H bond in asphalt considerably enhances the compatibility between epoxy and asphalt. Furthermore, the reactivity of the unsaturated C C bond in SBS with the curing agent facilitates the fusion of SBS phase and the epoxy phase. The presence of SBS reduces the critical epoxy content required for phase inversion in REA. The rheological properties of REA modified by SBS-epoxy exhibit substantial improvements in both high and low temperatures, outperforming the effects achieved by single epoxy or SBS modifications. The construction duration of REA mixtures is further extended to 5–6 h, fully satisfying the requirements for workability during construction. The co-modification of epoxy and SBS significantly enhances the high-temperature deformation resistance, low-temperature crack resistance, and fatigue resistance of REA mixtures. Specifically, the semi-cured REA mixtures possess a dynamic stability of 12115 times/mm, enabling immediate traffic opening after construction. The results of this study had a positive impact on the practical application of REA in engineering. • A novel curing agent was used to prepare roadway-oriented epoxy-modified asphalt (REA). • The substitution reaction between curing agent and asphalt enhances the compatibility between epoxy and asphalt. • The interaction between SBS phase and epoxy phase reduces the critical epoxy content associated with phase inversion. • The REA mixture perfectly solves the contradiction between construction duration and curing time. [ABSTRACT FROM AUTHOR]

With the application of recycled asphalt pavements, many recycled roads will face secondary regeneration in the near future. The variation in properties of asphalt pavement after primary regeneration will directly affect the quality of secondary recycled asphalt pavement. To investigate the mechanisms and performance of secondary asphalt regeneration, this study conducted laboratory simulations to prepare primary aged asphalt and regenerated asphalt. Building upon the foundation of primary regenerated asphalt, secondary aged asphalt and regenerated asphalt were produced and subjected to testing. Subsequently, changes in the chemical composition, functional group contents, and rheological properties of asphalt, before and after two rounds of regeneration, were analyzed through Thin-Layer Chromatography with Flame Ionization Detection (TLC-FID), Fourier Transform Infrared (FTIR) spectroscopy, and Dynamic Shear Rheometer (DSR) testing. The results indicate that generic fractions can largely be restored to primary regeneration levels during secondary asphalt regeneration by incorporating regenerant and new asphalt. However, the carbonyl and sulfoxide indices are not effectively recovered in the secondary regeneration process, resulting in viscoelastic properties that do not match those of primary asphalt regeneration. • The mechanisms of secondary regeneration of asphalt was revealed. • The microstructure changes of asphalt before and after two times of regenerations were studied. • The performance evaluation of secondary asphalt regeneration was evaluated. [ABSTRACT FROM AUTHOR]

Embracing the principles of circular economy and zero-waste, this study aligns with the United Nations' twelfth sustainable development goal by investigating warm mix recycled asphalt technology as a sustainable solution for utilizing aged asphalt materials. This approach not only enhances pavement quality but also minimizes resource consumption and environmental impact. We critically examine the limitations of conventional warm mix technologies in improving the high and low-temperature performance of aged asphalt and propose innovative solutions. Our research focuses on the rheological characteristics of warm mix reclaimed asphalt, emphasizing the roles of Sasobit, Evotherm M-1, and YDWB-1 warm-mix additive in rejuvenating aged asphalt. We reveal that Sasobit and Evotherm M-1 enhance the asphalt's elasticity, thus improving its resistance to permanent deformation, while YDWB-1 displays unique properties that can influence the asphalt's mechanical behavior in different ways. Our findings suggest optimal mixing ratios for these agents and demonstrate their varied impacts on rutting properties at high temperatures and other mechanical characteristics. The study concludes with insights into the optimal combinations of these warm-mix additives to enhance the high and low-temperature qualities of aged asphalt, marking a step forward in sustainable road construction and material science. • Investigated high and low temperature properties of aged asphalt with Sasobit, Evotherm M-1, YDWB-1. • Conducted comparative analysis of asphalt rheological properties in composite and single warm mixes. • Proposed optimal dosages for various warm mix agents and their combinations. • Demonstrated improved rutting resistance at high temperatures with selected warm mixes. • Revealed significant enhancement in both high and low temperature asphalt performance. [ABSTRACT FROM AUTHOR]

Rubber aggregate recycled from waste tires are added to self-compacting concrete to improve some of its properties, such as durability, toughness, and concrete resistance to impact and vibrations. In this study, modified hybrid rubberized self-compacting concrete (SCC) was produced by utilization of recycled tire rubber aggregate, plastic waste (PET), and steel fibers. Rubber was used as a partial substitute for sand, with only 10%, while the fibers were utilized in two different proportions of 0.25% and 0.35% (volume). Several tests were achieved to evaluate the rheological properties of the modified hybrid fiber rubberized SCC such as slump flow, T500, V-funnel, L-box, and segregation resistance. In addition, the hardened properties such as density, compressive, tensile strengths, and modulus of elasticity were evaluated. Microstructural evaluation of rubberized mixes was conducted. The results showed that the addition of rubber aggregate at 10% content reduces the rheological properties of SCC. The T500 mm was influenced significantly up to 15% increase. Moreover, compressive strength decreased by about 14% at same amount of rubber aggregate, while the addition of hybrid fibers improves the mechanical properties despite the negative effect on the rheological properties of rubberized SCC. The tensile strengths increased significantly by the inclusion of 0.35% hybrid fibers. The positive action of the two types of fibers led to this increase. The combination of rubber aggregate and the hybrid fibers in SCC could affect its mechanical properties positively by balancing the weakness in strength due to the lack in of bonding between rubber aggregate and cement paste and to avoid the severe deterioration in tensile strength, improve the ductility, and enhance the energy absorption capacity, especially for members subjected to earthquake effects. • Crumb tire rubber aggregate, plastic waste (PET), and hooked ended steel fibers was utilized in this study. • Several tests were achieved to evaluate the rheological properties.. • The hybrid fibers improve the internal cohesion and interaction of rubberized SCC. • The low content of rubber aggregate (10%) maintained an acceptable reduction in strengths. • There was a balance between the reduction in fresh properties and the desired strength. [ABSTRACT FROM AUTHOR]

The high global need for non-renewable resources such as bitumen for the construction of flexible pavements is a foremost concern in the pavement industry. Thus, researchers are looking for novel approaches such as bio-modifiers to reduce dependency on bitumen. This study investigated the effect of the modified waste cooking oil beads (MWCOBs) as a bio-modifier on the rheological properties, morphological properties, and chemical characteristics. The waste cooking oil (WCO) was pre-processed and modified at two ratios (45:55 and 50:50) with the SBS to form the rubbery material (MWCOBs). The base bitumen (BB) with 60/70 grade was blended with five percentages of MWCOBs for each ratio (5%, 10%, 15%, 20%, and 25%). The results indicated that viscosity has systematically increased with increasing content of MWCOBs and provided a better response at higher temperatures. Adding 5 wt% of MWCOB-A and MWCOB-B improves the viscosities to 513 cp and 562 cp at 135 ℃ respectively compared to 429 cp of BB. The incorporation of the MWCOBSs substantially enhances the elasticity and stiffness of modified bitumens. Additionally, based on the rutting and fatigue parameters, the incorporation of the MWCOBs provides enhanced performance. The 15 A and 15B demonstrated a performance grade (PG) 76 with failing temperatures of 76.2 °C and 78.7 °C respectively. However, 5B exhibited fatigue failure at 13 °C, whereas all other modified bitumens demonstrated fatigue parameter values below 5000 kPa. The separation indices (SIs) based on complex modulus at a temperature of 64 °C of modified bitumen are within the specified range regardless of the 25 A and 25B with SIs of 1.27 and 1.36 respectively. The master curve of 15 A demonstrated higher stiffness at a lower frequency than other bitumen curves and is less stiff at a higher frequency. The field emission scanning electron microscope (FESEM) investigation showed that the MWCOBs are dispersed in the base bitumen and produced a homogeneous matrix. In conclusion, the modified bitumen 15 A and 10B have shown optimal rheological performance and could be utilised as a sustainable bio-modifier. • Modification of waste cooking oil in the form of beads significantly enhanced the bitumen performance. • WCO promotes the swelling and homogenous distribution of SBS, thus improving the storage stability of modified bitumen. • MWCOBs-modified bitumen improved the viscoelastic properties of modified bitumen. • MWCOBs-modified bitumen decreased the rutting and improved the fatigue performance. [ABSTRACT FROM AUTHOR]

Recovering aged bitumen from reclaimed asphalt pavement (RAP) is crucial for the evolution of pavement recycling. This study delves deeply into the effects of rejuvenator components on the rheological properties of rejuvenated bitumen across a wide temperature range. The investigation utilized the rolling thin film oven test (RTFOT) and the pressure aging vessel (PAV) test to simulate the short-term and long-term aging of the bitumen binder, respectively. Four distinct rejuvenators were then applied to recover the bitumen at varied aging levels. Detailed chemical analyses, encompassing the four-fraction (SARA) method and Fourier transform infrared spectroscopy (FTIR), were employed to identify the chemical compositions and key functional groups of both the rejuvenators and the rejuvenated bitumen. The rheological behavior of rejuvenated bitumen was assessed through a comprehensive series of tests, including conventional, temperature sweep, frequency sweep, multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), and bending beam rheometer (BBR) tests. A Pearson correlation analysis highlighted a significant positive association between specific rejuvenator components, notably asphaltene (As), saturate (S), and aromatic (Ar), and the high-temperature performance of the rejuvenated bitumen. The findings of this research offer insights into the formulation of rejuvenators, potentially enhancing the performance of rejuvenated asphalt pavements and facilitating sustainable infrastructure advancements. • A significant correlation between high-temperature property and component was found. • The deterioration no only relied on the chemical components at low temperature. • MSCR, G-R parameter, and m-valve are more representative to evaluate properties. • The findings of this research offer insights into the formulation of rejuvenators. [ABSTRACT FROM AUTHOR]

To promote the anti-ageing performance of asphalt, layered double hydroxides (LDHs) modified by propyl trimethoxylsilane (MPMS) was prepared and applied to modify asphalt. Fourier transform infrared spectroscopy (FTIR) showed that MPMS was chemically-grafted on the surface of LDHs. The interaction between LDHs and asphalt was significantly enhanced after MPMS organic modification, and MPMS organic LDHs (OMLDHs) exhibited better compatibility in asphalt. OMLDHs and LDHs could enhance the high-temperature properties of asphalt, particularly OMLDHs. After ageing, the properties and structure of asphalt were dramatically degenerated. The incorporation of LDHs could inhibit the oxygenic groups increase in asphalt molecules during ageing, and retard the gelatinization of colloidal structures. LDHs could alleviate the negative effect of ageing on asphalt, and improve the anti-ageing performance of asphalt. The improvement effectiveness of LDHs on the anti-ageing performance of asphalt was remarkably improved after MPMS modification. • Propyl trimethoxylsilane (MPMS) was chemically-grafted on layered double hydroxides (LDHs). • The interaction between LDHs and asphalt was enhanced after MPMS modification. • MPMS organic LDHs (OMLDHs) showed better dispersity and stability in asphalt compared with LDHs. • OMLDHs modified asphalt exhibited more excellent anti-ageing performance than LDHs. [ABSTRACT FROM AUTHOR]

This study investigates the effect of ethylene-bis-stearamide (EBS) on viscosity reducing of crumb rubber modified asphalt (CRMA) and explores the interaction mechanism via molecular dynamics simulation (MD), microscope method and rheological experiment. It is confirmed that the EBS play an important role in reducing the viscosity of ethylene-bis-stearamide and crumb rubber modified asphalt (EBS-CRMA), especially when the content is within 3%. The micro morphology and MD results showed that the EBS is coating on rubber and asphaltenes and then forming lubrication film, which is the main reason leading to the viscosity decrease of EBS-CRMA. Additionally, other factors also have significant effect in reducing the viscosity of EBS-CRMA, including the more uniform distribution of asphaltenes, the enhanced diffusion ability of saturates and resins, the reduction of hydrogen bonds and soluble substances within asphalt phase. When EBS content exceeds 3%, the influence on viscosity of EBS-CRMA is not obvious with the EBS content continuously increasing. It can be concluded from Fourier Transform Infrared (FTIR) Spectrometer and MD results that the molecular aggregation, the concentration increase of intermolecular hydrogen bonds and the diffusion ability decrease of EBS-CRMA molecular system are main reasons. Meanwhile, the coating effect of EBS and soluble substances concentration within asphalt phase are limited as the EBS content over 3%. • Various aspects were used to study the viscosity reduction mechanism of EBS-CRMA. • The EBS can effectively reduce the viscosity of CRMA. • The viscosity reduction mechanism of EBS-CRMA was revealed. • The viscosity reduction conclusions were verified by rheological properties. • EBS is coating on rubber and asphaltenes and then formed lubrication film. [ABSTRACT FROM AUTHOR]

Fly ash (FA) and direct coal liquefaction residue (DCLR) are coal-based industrial solid waste. Their unreasonable disposal has brought enormous economic, resource and environmental pressures. An effective treatment method is urgently needed. This study used FA and DCLR as fillers to replace limestone mineral powder (LP). The rheological properties of their corresponding asphalt mastics were evaluated by conventional performance tests and DSR tests. The effect of different properties of fillers on the rheological properties of mastic was revealed through finite element simulation. The test results show that FA and DCLR improve the viscosity, rutting resistance, elasticity and permanent deformation resistance of asphalt mastic, and reduce the temperature sensitivity. The improvement effect of FA is the most significant. The simulation results show that particle size and shape of filler affect the rheological properties and temperature sensitivity of asphalt mastic to different degrees respectively, and the filler particle size is the dominant factor. • Fly ash and direct coal liquefaction residue improve the high-temperature performance of asphalt mastic. • The effect of the fillers on the asphalt mastic properties were revealed through finite element simulation. • The filler particle size has greater effect on asphalt mastic properties than filler shape. [ABSTRACT FROM AUTHOR]

This study aims to explore the feasibility of using dry flue gas desulphurization ash (DFGDA) as a filler in asphalt pavements. Two DFGDA materials were added into the base asphalt with different mineral powder proportions to prepare asphalt mastic and mixture, and the pure mineral powder asphalt mastic and mixture were used as the blank control group to evaluate the properties of DFGDA-doped asphalt mastic and mixture. The results show that the addition of DFGDA can improve the high-temperature rheological property and reduce the low-temperature rheological property of asphalt mastic; similarly, the high-temperature stability of asphalt mixture can be greatly improved, while its low-temperature performance and water stability are reduced; despite these decreases, all outcomes still meet the requirements of relevant specifications. No chemical reactions are observed between DFGDA and asphalt, indicating that the physicochemical properties of fillers are responsible for the change in the properties of DFGDA-doped slurry and mixture. Notably, the DFGDA-added asphalt mixture does not bring additional negative effects to the environment. Based on cost analysis, the high-quality use of DFGDA in asphalt mixture can save direct material costs of about $920,000 per 100 kilometers of asphalt road construction. In summary, the application of DFGDA in the asphalt mixture can not only meet the basic performance requirements of asphalt pavements but also greatly save material costs and protect the environment. • The feasibility of using DFGDA as an alternative filler in asphalt was examined. • DFGDA decreased the asphalt mastic strain and enhanced rutting resistance. • DFGDA reduced the low temperature performance and water stability of mixture. • Asphalt mastic performance depends on the physicochemical properties of fillers. • The application of DFGDA can save material costs and protect the environment. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) is one of the common polymer modifiers used for asphalt, and the PU modified asphalt currently plays a fundamental role in road constructions. However, most of the PU as the modification could bring about an increasement in viscosity and rigidity to asphalt binders, thus leading to insufficient ductility and deformation compatibility for the materials to some extent. In the present study, a composite polymer material synthesized with polyurethane and polyurea (PU-PUa) was introduced as a modifier to the asphalt binder in an attempt to integrate their individual advantages into the asphaltic material. The curing time, tensile strength, and Fourier Transform infrared spectroscopy (FTIR) tests were conducted to determine the optimal proportion of the PU and PUa in the compound polymer, and its formation mechanism was also discussed. The fundamental properties of the asphalt binders modified with various contents of PU-PUa (5%, 10%, and 15% by weight), such as the storage stability, rheological properties, creep recovery capacity, and fatigue resistance, were investigated through the thermal storage, dynamic rheological, stress creep recovery (MSCR), and linear amplitude sweep (LAS) tests. Furthermore, in order to understand the adhesion property of the PU-PUa modified asphalt on aggregates, the pull-off tests considering both dry and water immersion conditions were performed. The test results showed that the PU-PUa could be effectively used to modify asphalt binders, and 7:3 was found to be the best proportion of the PU and PUa. The addition of PU-PUa could promote the high temperature performance, enhance the recovery ability for creep, and extend the fatigue life of the asphalt binders (for both 70# and SBS asphalt). The optimal content of PU-PUa for the modification was found to be 10% based on the storage stability and mechanical performance of the modified asphalt binders. • The method of using polyurethane(PU) and polyurea(PUa) to modify asphalt was introduced. • The fundamental properties of PU-PUa modifier were systematically introduced. • Some basic properties of PU-PUa modified asphalt were discussed in detail. [ABSTRACT FROM AUTHOR]