Search Results (182)

In order to promote the sustainable development of road engineering, this study used waste tire rubber powder (RP) and surface organic layered double hydroxide (SOM-LDHs) to modify 70# matrix asphalt. The Box–Behnken design response surface method with three factors (rubber powder content, surface organic layered double hydroxide content, shear temperature) and three responses (penetration, ductility, softening point) was used to optimize the preparation parameters. The optimum formula was determined to be 21.7% rubber powder content, 4.8% surface organic layered double hydroxide content, and 160 °C shear temperature. The effect of the modifier on the surface morphology was analyzed using a rotating film oven test and ultraviolet aging test. The high and low temperature rheological properties of asphalt were evaluated by dynamic shear rheometer (DSR), bending beam rheometer (BBR), and the multi-stress creep recovery test (MSCR). The microstructure was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The aging mechanism was investigated by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The results show that after aging, the complex shear modulus of rubber powder/surface organic layered double hydroxide composite modified asphalt is the highest, which is 27.35% higher than that of matrix asphalt. The rutting factor reaches 79.86 kPa at 46 °C, the phase angle decreases by 11.83% after UV aging, and the high temperature plastic deformation resistance is the best. In the low temperature range of −18 °C to −24 °C, the creep stiffness of the composite modified asphalt is about 30% lower than that of the matrix asphalt, while the m value is increased by about 15%, and the low temperature stress relaxation performance is significantly improved. The strain recovery rate of composite modified asphalt under 3.2 kPa stress reaches 78.5%, and the unrecoverable creep compliance is as low as 0.18 kPa⁻¹, which is better than that of matrix asphalt and single rubber powder modified asphalt. Full article

Conventional rubber-modified asphalt faces critical limitations, including phase separation and compromised low-temperature flexibility, which typically restrict rubber content to 15–25%. This study investigates the viscoelastic rheology and fatigue life prediction of asphalt binders modified with 20% waste tire rubber, utilizing a chemical–thermal desulfurization process and a synergistic styrene–butadiene–styrene (SBS) composite. Five binders were evaluated: base asphalt (BA), SBS-P, WTR, WTD, and WTC. The WTC exhibited the highest softening point at 89 °C and a ductility of 35 cm, successfully overcoming the traditional stiffness–flexibility trade-off. Dynamic shear rheometer (DSR) tests revealed a 440% increase in complex shear modulus (G*) at 58 °C 10.8 kPa vs. 2.0 kPa for BA and a 13.2% reduction in phase angle (61.2°). Multiple stress creep recovery (MSCR) results showed WTC achieved a 60% recovery rate at 0.1 kPa and maintained 25% at 3.2 kPa, with non-recoverable creep compliance (J_nr3.2) well below the 1.0 kPa⁻¹ threshold for heavy traffic. Bending beam rheometer (BBR) tests confirmed WTC low-temperature suitability, achieving a creep stiffness of 280 MPa and an m-value of 0.58 at −24 °C. Furthermore, viscoelastic continuum damage (VECD) modeling demonstrated that WTC increased yield stress by 80.8% (470 kPa) and extended fatigue life by over two orders of magnitude at low strain (2%) compared to BA. Finally, WTC exhibited excellent storage stability, with a softening point difference (SPD) below 2.2 °C. These findings confirm that the rubber/SBS composite provides a highly durable, storage-stable, and fatigue-resistant binder suitable for long-life asphalt pavements under extreme climatic and heavy-traffic conditions. Full article

To investigate the macroscopic and microscopic aging mechanisms of asphalt under combined light, heat, and oxygen exposure in southwestern China, four aging schemes were designed and tested on three base asphalts. Chemical changes—components, elements, and functional groups—were characterized by SARA and elemental analyses, and FTIR. High- and low-temperature rheological properties were measured via MSCR and BBR tests, and the gray correlation method linked microscopic mechanisms to macroscopic performance. The results show that coupled aging causes bond breakage and dehydrogenation, with recombined small molecules increasing the asphaltene content. Dehydrogenated bonds combine with oxygen to form polar functional groups, increasing chain stiffness and restricting internal rotation. Macroscopically, high-temperature performance improves while low-temperature performance degrades. Carbonyl and sulfoxide indices serve as effective aging indicators. Correlation analysis identifies functional group changes as the most significant factor affecting rheological decay. Engineering implications are as follows: oxygen-containing polar groups enhance chemical stability but accelerate low-temperature performance loss; thus, their evolution should be monitored in high-radiation, high-temperature regions to mitigate premature cracking. Full article

As the core binder material of asphalt pavement, the rheological properties of asphalt directly determine the service performance and service life of the pavement. Under actual service conditions, asphalt is constantly exposed to a multi-coupling environment involving temperature variation, vehicle load, and ultraviolet aging, which easily leads to irreversible rheological deterioration and induces diseases such as rutting and cracking. Aiming at the insufficient research on the rheological evolution law and microscopic damage mechanism under the coupling of the above three factors, this study took 70# base asphalt as the research object and adopted a combination of macro-performance testing and microstructure characterization. The high- and low-temperature rheological properties, permanent deformation resistance, and fatigue resistance of asphalt under multi-coupling effects were systematically evaluated through three conventional index tests: dynamic shear rheology (DSR), multiple stress creep recovery (MSCR), linear amplitude sweep (LAS) and bending beam rheology (BBR). Combined with gel permeation chromatography (GPC) and thin-layer chromatography with flame ionization detection (TLC–FID), the evolution laws of molecular distribution and chemical components were revealed, and the deterioration mechanism of multi-coupling effects was clarified. The results show that compared with the control group, after 72 h of coupling treatment, the penetration decreases by 32.6%, the softening point increases by 18.3%, and the ductility decreases by 45.8%. The high-temperature complex modulus decreases by 51.2%, the low-temperature creep stiffness increases by 76.4%, and the fatigue life decreases by 58.6% on average. At the microscopic level, obvious molecular polymerization and component weight gain occur in asphalt: the content of macromolecular components rises from 18.7% to 32.1%, asphaltene content increases from 12.3% to 25.8%, and aromatic content decreases from 42.6% to 28.3%. Temperature variation, load, and ultraviolet aging present significant deterioration effects, rather than a simple superposition of single factors. Prolonged aging and increased load aggravate the hardening of asphalt, while extreme temperature variation further weakens the rheological properties through microscopic damage. This study clarifies the internal relationship between the microscopic structure and macroscopic properties of asphalt under multi-coupling effects, improves the theory of anti-coupling damage to asphalt, and provides an important theoretical basis and experimental support for damage-resistant design, material selection, and service life prediction of asphalt pavement. Full article

The growing use of reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) is an important practice to achieve more sustainable pavements, as it reduces the consumption and environmental impact of virgin materials. However, aging induces binder stiffening that requires effective rejuvenation to restore overall performance. This study provides a comprehensive comparative analysis of ten chemically different waste oils—waste engine oil (WEO), waste cooking oil (WCO), yellow grease (YG), waste hydraulic oil (WHO) waste electric transformer oil (WETO), slop oil (SO), sludge-derived bio-oil (SDBO), tire pyrolysis oil (TPO), plastic pyrolysis oil (PPO), and algal residue oil (ARO)—as recycled HMA mixture rejuvenators, linking oil composition to binder regeneration and mixture performance. Binder properties were determined by rotational viscosity (RV), dynamic shear rheometer (DSR) and bending beam rheometer (BBR), whereas mixture performance was assessed in terms of Superpave mechanical properties, Hamburg wheel-tracking test (HWTT) for rutting resistance and mixture BBR for low-temperature cracking resistance. Performance grade (PG) evaluations showed that WETO and WEO restored the 50% and 75% RAP binders, respectively, to a grade close to PG 64-16 at the lowest dosages. The Superpave volumetric properties of all restored mixtures were similar to those of the control mixture, denoting corrected mixture balance and compaction level. HWTT results indicated that WETO-recycled mixtures revealed the lowest rut depth at 50% RAP, while WEO-recycled mixtures exhibited the lowest rut depth at 75% RAP after 20000 passes. Additional evidence supporting these results can be found in BBR mixture data, which demonstrated that WETO at 50% RAP and WEO/WETO at 75% RAP showed the most reduction in creep stiffness and improvement in creep rate. The correlation, regression, and PI analyses were in good agreement with the experimental results, where WETO and WEO exhibited the best overall performance at 50% and 75% RAP, respectively. In summary, these results indicate that the performance of waste oil rejuvenator in recycled HMA mixtures is highly dependent on RAP content and point to WETO and WEO as feasible, environmentally friendly options for high-RAP recycled HMA. Full article

Polyester (PET) fibers are widely used to reinforce asphalt materials; however, their smooth and hydrophobic surfaces limit interfacial bonding and restrict their reinforcing efficiency. This study develops an eco-friendly surface modification method based on the chemical modification of gallic acid (GA) and aminosilane (KH792) to enhance the compatibility between PET fibers and asphalt. Modified fibers with various molar ratios of GA/KH792 were prepared and incorporated into asphalt mastic. Their performance was evaluated using softening point, cone penetration, dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), and bending beam rheometer (BBR) tests, combined with interfacial interaction analysis and scanning electron microscopy (SEM). The results show that surface modification significantly improves the reinforcing effect of PET fibers. In particular, the co-modified fiber with a GA/KH792 ratio of 1:1 exhibits the best performance, with increases of 27% in softening point and 105% in shear strength, as well as notable improvements in rutting resistance, fatigue performance, and temperature stability. Interfacial indices and SEM observations confirm enhanced adhesion, dispersion, and load transfer capacity. However, the improvement in low-temperature performance is limited. Overall, GA/KH792 chemical modification effectively enhances fiber asphalt interfacial interaction and provides a simple and sustainable approach for developing high-performance asphalt materials. Full article

To achieve warm-mix production of crumb rubber-modified asphalt (CRA), an organic warm-mix agent, a surfactant-based warm-mix agent, and a composite warm-mix agent were employed to prepare warm-mix CRA. The effects of warm-mix agents on the physical properties of CRA were evaluated using the penetration test, softening point test, viscosity test, ductility test, and elastic recovery test. The effects of warm-mix agents on the high- and low-temperature rheological properties were investigated through dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), and bending beam rheometer (BBR) tests. Moreover, the viscosity–temperature characteristics and the VOC emissions of different warm-mix CRAs were explored. The results show that Sasobit, an organic warm-mix agent, increases the elastic fraction and stiffness of CRA, which enhances its high-temperature resistance to permanent deformation but compromises its low-temperature cracking resistance. UWM, a surfactant-based warm-mix agent, elevates the viscous fraction and flexibility of CRA, which improves its low-temperature cracking resistance but weakens its high-temperature rutting resistance. The composite warm-mix agent, consisting of 2 wt.% Sasobit and 5 wt.% UWM, can balance the stiffness and flexibility of CRA, endowing CRA with satisfactory pavement performance. All three warm-mix agents effectively reduce the viscosity, mixing temperature, and VOC emissions of CRA. The composite warm-mix agent reduces the VOC emissions of CRA by 53.0%, exhibiting the most pronounced reduction. Full article

Intensive aquaculture of rice field eel (Monopterus albus) is constrained by oxidative stress induced by high-density culture resulting in growth inhibition, while prophylactic antibiotics pose escalating risks of drug resistance and food safety hazards. This study addresses the critical need for developing efficient, environmentally friendly functional feed additives as sustainable growth promoters in intensive aquaculture. To investigate the dietary berberine (BBR) effect on promoting growth performance, hepatic antioxidant capacity and metabolism in M. albus, four experimental groups were established: control (CON, 0 mg/kg) and berberine-supplemented groups (BBR25, 25 mg/kg; BBR50, 50 mg/kg; BBR100, 100 mg/kg). Growth performance, serum biochemical parameters, hepatic antioxidant capacity, and liver metabolomics (LC-MS) were evaluated after the 8-week feeding trial. BBR50 and BBR100 had significantly increased final weight, weight gain rate (WG), and survival rate (SR), while reducing feed conversion ratio (FCR) (p < 0.05). Serum glucose (Glc), total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) were decreased (p < 0.05), while high-density lipoprotein cholesterol (HDL-C) and phosphofructokinase (PFK) activity were increased (p < 0.05). Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were significantly reduced (p < 0.05). Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were upregulated (p < 0.05), whereas malondialdehyde (MDA) was downregulated (p < 0.05). Metabolomics identified 98 differential metabolites, with significant enrichment of metabolites associated with arachidonic acid metabolism, histidine metabolism, arginine/proline metabolism, tryptophan metabolism, and pathways related to mTOR signaling. Overall, dietary supplementation with 50 mg/kg BBR emerged as a practically favorable dose among the tested concentrations for promoting growth performance and feed utilization efficiency, whereas 100 mg/kg BBR was associated with lipid and amino acid metabolic alterations suggestive of metabolic reprogramming and antioxidant-related shifts, without conferring additional growth benefits. Full article

Owing to the pronounced compositional heterogeneity of waste cooking oil (WCO), WCO-rejuvenated asphalt often exhibits unstable performance. To improve the compositional controllability of WCO-based rejuvenators, WCO was fractionated according to molecular weight differences into three characteristic fractions: light, medium, and heavy components. Nine rejuvenator formulations with different component ratios were prepared to investigate the synergistic mechanism among WCO fractions with different molecular weights and to propose an optimal blending range. Thermal stability tests, dynamic shear rheometer (DSR) tests, multiple stress creep recovery (MSCR) tests, and bending beam rheometer (BBR) tests were conducted to evaluate the performance of the rejuvenators and rejuvenated asphalts. Gas chromatography (GC) and gel permeation chromatography (GPC) were further used to analyze the chemical composition and molecular-weight distribution. The results show that increasing the proportions of light and medium WCO components improves the low-temperature performance of rejuvenated asphalt; however, when the combined content of light and medium components exceeds 40%, the high-temperature performance is adversely affected. The heavy component improves the rutting factor, creep recovery capacity, and thermal oxidative aging resistance of rejuvenated asphalt, and the coefficient of determination between the long-term aging CAI and heavy-component content reaches 0.959. Thermal stability tests show that the mass loss rate of the nine rejuvenators after 1.5 h of heating ranges from 2.8% to 4.3%, with greater mass loss for formulations containing higher light-component contents. GPC results show that the Mn and Mw of R-4 (492 g/mol and 641 g/mol) are higher than those of R-8 (463 g/mol and 600 g/mol), indicating that a higher macromolecular fraction contributes to improved thermal stability. Considering high-temperature, low-temperature, and aging performance together, rejuvenated asphalt achieves the closest overall performance to the base binder when the heavy component is controlled at 50–60% and the medium component is approximately 30%. Full article

To improve the low-temperature crack resistance of asphalt pavement, this paper investigates the effects of fiber length, content, and type on the flexural and tensile properties of asphalt mastic. Firstly, a numerical program was developed in MATLAB to establish a three-dimensional finite element model of asphalt mastic with an uneven fiber distribution in ABAQUS. Then, the Burgers model selected for simulation was obtained through the asphalt low-temperature bending beam rheological test (BBR). Constructing a three-point bending virtual test of asphalt mastic using a three-dimensional fiber model and systematically analyzing the influence of fiber parameters on bending and tensile properties. The accuracy of the three-dimensional fiber model was verified through BBR experiments. The finite element simulation results show that the addition of fibers can significantly improve the tensile performance of asphalt mastic; increasing the fiber content or length can reduce the peak stress at the bottom of the mid-span and delay cracking. The higher the fiber elastic modulus, the smaller the vertical displacement of the specimen. The model established in this article can effectively elucidate the mechanism of fiber reinforcement, providing a theoretical basis for optimizing fiber parameters and improving the crack-resistance performance of asphalt pavement. Full article

To improve the rutting resistance and low-temperature cracking performance of polymer-modified asphalt under extreme conditions, hierarchically structured ZnO-loaded porous activated carbon (ZnO/PAC) nanosheets were introduced as a synergistic reinforcing agent for SBS-modified asphalt. The ZnO/PAC hybrids were synthesized via template-assisted carbonization followed by hydrothermal growth, and their effects were evaluated by microscopic characterization and rheological tests, including temperature sweeps, multiple stress creep and recovery (MSCR), and bending beam rheometer (BBR) analyses. ZnO was successfully anchored onto the PAC, forming a three-dimensional flower-like nanostructure. Among the investigated samples, ZPS3 with 3 wt.% ZnO/PAC showed the best overall performance. At 64 °C, the rutting factor increased from 4.2 kPa for the SBS-modified asphalt to 6.8 kPa for ZPS3, representing a ~62% enhancement and indicating markedly improved high-temperature deformation resistance. MSCR results further confirmed the superior rutting resistance of ZPS3, which exhibited the highest recovery and the lowest non-recoverable creep compliance. In addition, BBR results showed that the low-temperature performance grade improved from −12 °C for conventional the SBS-modified asphalt to −18 °C for the ZnO/PAC-modified system. These results demonstrate that ZnO/PAC nanosheets can effectively enhance both the high-temperature rutting resistance and low-temperature cracking resistance of SBS-modified asphalt. Full article

Warm-mix asphalt (WMA) technology and basalt fiber modification have been increasingly applied in road engineering. However, conventional basalt fibers often disperse unevenly and tend to agglomerate. In this study, basalt fiber powder (BFP) was incorporated into a Sasobit-based WMA system and systematically compared with matrix asphalt, Sasobit-modified WMA, conventional basalt fiber-modified WMA, and styrene butadiene styrene (SBS)-modified asphalt. Multiscale characterization—including dynamic shear rheometry (DSR), bending beam rheometry (BBR), scanning electron microscopy (SEM), and nanoindentation—was conducted to elucidate rheological behavior and interfacial micromechanical responses. The corresponding Asphalt Concrete-13 (AC-13) mixtures were further evaluated through rutting tests, low-temperature bending tests, and moisture susceptibility tests. Results demonstrate that micronized BFP achieves more homogeneous dispersion within the asphalt matrix and may promote a more effective reinforcing morphology, significantly enhancing high-temperature deformation resistance while partially mitigating the low-temperature stiffness increase induced by Sasobit. Compared with conventional basalt fiber systems, BFP shows better stress relaxation capacity and interfacial mechanical response under the tested conditions. At the mixture level, the BFP–Sasobit system showed the best overall performance, with the dynamic stability increasing by 242.2% relative to the base asphalt mixture and the residual Marshall stability reaching 92.3%, while the low-temperature flexural strain increased by 33.3%. Overall, the findings suggest that morphology-controlled micronization provides a morphology-guided enhancement strategy for Sasobit-based warm-mix asphalt by promoting coordinated improvements across the rheological, micromechanical, and mixture scales. Full article

This study investigates the synergistic effects of combining polyphosphoric acid (PPA) and styrene–butadiene–styrene (SBS) as modifiers in asphalt binders to enhance their performance. The research focuses on optimizing the concentrations of PPA and SBS to improve the resistance to permanent deformation, cracking at intermediate and low temperatures, and resistance to aging. A series of empirical and rheological tests, including penetration, softening point, elastic recovery, dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), and bending beam rheometer (BBR), were conducted to evaluate the rheological and engineering properties of the modified binders. The results indicate that PPA can partially replace SBS, offering comparable improvements in high-temperature performance and creep resistance. The MSCR test revealed a statistically significant synergistic effect between PPA and SBS, resulting in improved recovery and reduced non-recoverable compliance. However, PPA alone shows limited effectiveness at low temperatures and in properties that are governed by elastic response. This study highlights the potential for optimizing asphalt modifiers by leveraging the complementary properties of PPA and SBS in hybrid systems, particularly regarding high-temperature properties and dynamic loading. Full article

Biopolymer-based packaging films possess outstanding performances and are being developed as the alternatives to traditional petroleum-based plastic packaging films with many non-ignorable shortcomings. In this study, chitosan, succinylated pullulan (SP), and berberine (BBR) were combined to fabricate novel biopolymer-based composite films (CSSPB) via the layer-by-layer assembly method. The effects of the incorporation of BBR on the physicochemical properties of the film were investigated. It was found that after BBR was added, the tensile strength (TS), elongation at break (EAB), hydrophobicity, and antioxidant capacities of the film were enhanced. The chemical bonding, crystalline properties, elemental composition, and thermal stability of the films were also characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA), respectively. The in vitro antifungal tests revealed the antifungal activities of the films with a relatively high BBR content against Colletotrichum gloeosporioides (CG). In the preservation experiments, the CSSPB films exhibited preservation effects on fresh-cut apples, which manifested as delaying browning, weight loss, an increase in the soluble solids content, and a decrease in hardness. The new CSSPB composite films were opined to hold application potential in the field of food packaging. Full article

The restricted availability of raw materials underscores the significance of recycling asphalt materials that have reached the end of their service life, facilitating their reuse with additives for economic and sustainability benefits. The study includes both empirical investigations and numerical analyses. Empirical studies were conducted in four stages to evaluate the binder and mixture. First, the rheological properties of binders obtained from various sources were assessed in both unmodified and modified states. Second, the binders were subjected to different levels of aging. Third, the presence of additives in the binders was investigated. In the final stage, the analysis of asphalt pavement layers was conducted using the finite element method (FEM) for both modified and unmodified binders. Performance tests were carried out to evaluate the binder’s properties, and physical examinations were conducted to compare these properties. The binders were tested under both unaged and aged conditions using linear amplitude sweep (LAS), frequency sweep (FS), multiple stress creep recovery (MSCR), and bending beam rheometer (BBR) tests. The results indicated that aging increased the stiffness of the binders, regardless of their source. Additionally, the introduction of a rejuvenator reduced the binder’s stiffness, particularly at low temperatures. Findings showed that the growth rate (GR) and rutting parameters increased with binder aging, while the frequency decreased. The R² value of 0.92 demonstrates a strong correlation between the parameters. Polymer-modified binders demonstrated superior deformation resistance and higher stiffness stability. Overall, aging reduced asphalt flexibility, whereas modified binders improved long-term pavement deformation performance. Full article