Search Results (169)

High-content crumb rubber composite modified asphalt (HRCMA), which combines crumb rubber with a styrene–butadiene–styrene (SBS) modifier, offers excellent mechanical performance and environmental benefits, yet its high viscosity requires elevated production and construction temperatures that may accelerate thermo-oxidative aging and impair its durability and self-healing capability. In this study, the self-healing behavior of HRCMA under virgin, Thin Film Oven Test (TFOT)-aged, and Pressure Aging Vessel (PAV)-aged conditions was systematically investigated and compared with that of conventional SBS modified asphalt (SBSMA) using fatigue–healing–fatigue tests. The effects of damage degree, healing interval time, and healing temperature were evaluated, and a comprehensive self-healing index (HI) integrating the recovery of initial mechanical properties and the recovery of damage evolution characteristics was proposed. The results show that increasing the damage degree significantly reduces the self-healing capability of both binders, and thermal aging further intensifies this deterioration; two-way analysis of variance (ANOVA) confirmed that these effects are statistically significant. Extending the healing interval time and raising the healing temperature improve the self-healing performance, although the enhancement weakens after severe aging owing to the reduction in molecular mobility. Compared with SBSMA, HRCMA exhibits higher self-healing capability under all aging conditions, indicating stronger resistance to aging-induced damage. The proposed HI provides a more comprehensive evaluation of asphalt self-healing behavior, and the findings provide theoretical support for the durability assessment and engineering application of highly modified asphalt materials. Full article

This study developed a composite rejuvenator comprising recycled polyethylene wax (PREW), waste cooking oil (WCO), and epoxidized soybean oil (ESO) activated by the tertiary amine catalyst BDMA to improve the intermediate-temperature rejuvenation of aged SBS-modified asphalt binder. The binder was subjected to combined rolling thin-film oven and pressure aging vessel aging. Conventional tests, rotational viscosity, bending beam rheometer, multiple stress creep recovery, fluorescence microscopy, and Fourier transform infrared spectroscopy were used to evaluate macroscopic, rheological, and microstructural properties. Aging hardened and embrittled the binder, increased softening point and viscosity, reduced penetration and ductility, and disrupted the polymer-rich phase. PREW reduced flow resistance and retained relatively high-temperature structural stability, whereas WCO improved flexibility and flowability, although excessive softening impaired high-temperature stability. ESO/BDMA treatment was accompanied by changes in oxygen-containing functional group-related absorption regions and improved apparent connectivity of the SBS-rich phase. Among the tested temperatures, 120 °C provided the best overall balance among the evaluated properties, satisfying low-temperature stress-relaxation requirements while limiting high-temperature creep deformation. These results identify 120 °C as the preferred treatment temperature for the PREW/WCO/ESO-BDMA rejuvenation system. Full article

Pectin is a naturally occurring biopolymer extensively used for applications in the pharmaceutical, biotechnology, and food industries, and is abundantly present in lemon by-products. Although lemon peels represent a highly promising raw material, the structure of pectin is strongly influenced by extraction and drying processes, and the resulting attributes remain insufficiently understood. The present study systematically investigates the impact of conventional hot acid extraction using three different acidifying agents (citric, sulphuric, and hydrochloric) in combination with two drying techniques (oven-drying and freeze-drying) on the physicochemical, structural, thermal, and viscosity–shear rate properties of pectin obtained from lemon by-products (Citrus limon, Portuguese Eureka variety) following the prior recovery of bioactive compounds (essential oils and phenolic compounds). The results demonstrated that citric acid extraction followed by freeze-drying yielded the highest pectin recovery, at approximately 26.7%, highlighting the suitability of this approach for efficient by-product valorisation. Oven-dried pectins exhibited higher moisture contents (8.5–10%) and lower lightness values (L* = 57.02–65.67), indicating darker colouration compared to freeze-dried pectins (L* = 78.82–83.75). All extracted pectins presented a degree of esterification (DE ≥ 50%), classifying them as high-methoxyl pectins. The galacturonic acid (GalA) content ranged from 37.6 to 48.9% for oven-dried samples and increased to 44.1–58.6% for freeze-dried samples. Furthermore, pectin obtained from lemon by-products exhibited a well-defined structural organisation and enhanced thermal stability, especially for freeze-dried pectin samples, and suitable rheological properties, with no statistically significant variations observed between different acids or drying conditions, supporting its technological suitability for applications in the food, cosmetic, and pharmaceutical industries. Full article

Modern smart kitchen automation requires reliable vision-based tools to provide user-advisory decision support during domestic culinary processes. However, standard deep learning models utilizing closed-set Softmax classifiers typically misclassify unknown or Out-of-Distribution (OOD) kitchen objects with high confidence, posing safety and reliability risks. To address this problem without clous dependency, this study introduces a localized open-set metric learning framework based on a modified MobileNetV2 architecture. The conventional Softmax classification layer is replaced with a feature embedding layer evaluated via Cosine Similarity and a calibrated decision threshold. This architecture tracks targeted food items across four operational stages—counter-raw, in-oven-raw, in-oven-cooked, and counter-cooked—while identifying and rejecting OOD objects. To ensure reproducibility, comprehensive experimental validations were conducted on a dedicated internal dataset, providing direct baseline comparisons against mainstream backbones (ResNet50, EfficientNet-B0, and Vision Transformers) stripped of their Softmax layers and evaluated under identical metric constraints. The results demonstrate that the proposed framework achieves a Macro F1-score 92.6% and ultra-low inference latency of 11.5 ms, ensuring an optimized trade-off between Macro $F_1$-score and inference speed on edge computing environments. This framework establishes a robust, self-contained solution for open-set object recognition in localized smart home appliances. Full article

Sulforaphane (SF), the renowned hydrolysis product of glucoraphanin from broccoli, is known to undergo thermal degradation to 3-butenyl isothiocyanate (3-BITC) during gas chromatography–mass spectrometry (GC-MS) analysis. In this study, the effects on SF degradation associated with exposure to oven temperature during column transit, passage through the split/splitless injector, and through the transfer line to the mass spectrometer were investigated. Massive degradation was observed during column transit when the oven temperature exceeded 150 °C. Degradation during the passage through the injector increased with temperature, from 150 °C to 250 °C, and with decreasing split ratio, from 100:1 to 20:1. Conventional splitless conditions with the injector temperature set at 250 °C resulted in a degradation > 60%. Operating the GC-MS system with oven temperature below 150 °C prior to SF elution, an injector at 225 °C and a split ratio of 20:1, SF degradation was reduced to less than 1%. Under these optimized analytical conditions, the concentration of free SF in two broccoli-based dietary supplements was estimated based on external calibration and using 2,6-dimethylphenyl isothiocyanate as an internal standard. The GC-MS method proved to be a valuable tool for the quality evaluation of SF-labeled supplements integrated with the official EU ISO 9167:2019 HPLC-PDA glucosinolates analysis. Full article

Biopolymer-based porous materials are attracting increasing interest as sustainable alternatives to conventional thermal insulation foams; however, achieving low thermal conductivity together with adequate mechanical performance and fire response remains challenging. Building on previous formulation screening, this study investigates alginate-expanded perlite xerogel foams modified with chitosan and glycerol for thermal insulation applications. Foams were prepared via in situ CO₂ foaming and Ca²⁺ crosslinking, followed by mild oven drying. The effects of expanded perlite (9–12%), glycerol (0–10%), and chitosan (0–1%) were systematically investigated. All formulations exhibited low thermal conductivity (0.0467–0.0525 W m⁻¹ K⁻¹) and UL-94 V-0 self-extinguishing behavior. Incorporation of dispersed chitosan significantly enhanced compressive strength, reaching 263 kPa at 10% strain, within the range of commercial polymer foams. Image analysis and SEM showed that chitosan suppressed bubble coalescence, reduced large-pore fractions, and improved particle coverage, yielding structurally coherent matrices. Glycerol primarily acted as a plasticizer, improving the dimensional stability, but contributing less to pore refinement. The developed foams combine competitive thermal insulation performance, self-extinguishing behavior, and mechanical properties suitable for self-supporting insulation applications through a simple, water-based manufacturing route, highlighting their potential as sustainable alternatives to conventional fossil-based insulation materials for building applications. Full article

Agricultural production in arid regions is strongly constrained by water stress, making timely evaluation of crop water conditions increasingly important. However, conventional measurements of plant moisture content (PMC) primarily rely on destructive oven-drying methods, which are not only labor-intensive and time-consuming but also constrained by limited sample size and spatial coverage. These shortcomings make it difficult to capture the spatial heterogeneity of crop water status across large agricultural regions, thereby restricting regional-scale water diagnosis and precision irrigation decision-making. Focusing on silage maize cultivated in the arid region of Gansu Province, China, this work develops a regional PMC estimation approach by combining multi-source remote sensing data. High-resolution unmanned aerial vehicle (UAV) observations were integrated with Sentinel-2 and Sentinel-3 imagery, while radiometric and temperature corrections were applied to improve data consistency. A set of spectral, textural, and thermal features was derived from multispectral, visible, and thermal infrared datasets. Feature selection based on Pearson correlation was then carried out, followed by the construction of three models, namely Random Forest (RF), Support Vector Machine (SVM), and Partial Least Squares Regression (PLSR). Among them, the RF model performed more reliably, achieving a validation R² of 0.92 with relatively low prediction error. In addition, calibration using UAV data led to a clear improvement in satellite-based estimates, with R² increasing from 0.52–0.62 to 0.71–0.74. The generated PMC maps captured both the temporal decline during the growing season and the spatial variability across the study area. Overall, the proposed approach offers a practical option for large-scale monitoring of crop water status and can support irrigation management in water-limited environments. Full article

Flexible base layers can improve deformation compatibility and reduce reflective cracking in asphalt pavements, but conventional graded crushed stone is limited by weak interparticle bonding, poor water stability, and insufficient resistance to permanent deformation. Solution Road Soilfix (SRX) is a water-based polymer stabilizer used to improve the engineering performance of graded crushed stone by enhancing interparticle bonding. This study investigated the effects of SRX dosage, aggregate gradation, degree of compaction, and curing conditions on the load-bearing capacity and pavement performance of SRX-stabilized graded crushed stone. The results showed that SRX stabilization significantly improved the California bearing ratio (CBR), water stability, and permanent deformation resistance of the graded crushed stone mixture, although its permeability decreased due to polymer coating and void filling. At an SRX dosage of 0.50% by dry aggregate mass, the CBR values exceeded 300%, while further dosage increases provided only limited additional improvement. Among the three gradations, the 26.5 mm gradation exhibited the best overall performance due to its balanced coarse aggregate distribution and stable interlocking skeleton. CBR was highly sensitive to the degree of compaction, and a field compaction degree of at least 98% is recommended. Oven curing at 50 °C accelerated moisture evaporation and SRX film formation; the 6-day CBR exceeded 80% of the 30-day reference strength and correlated well with long-term strength. Overall, the recommended parameters are 0.50% SRX dosage, 26.5 mm maximum aggregate size, compaction degree ≥ 98%, and oven curing at 50 °C for 6 days before laboratory CBR evaluation. Full article

With the increased application of porous asphalt, the recycling and reutilization of aged materials have become a critical issue for sustainable pavement engineering. This study investigates the evolution of the performance characteristics of porous asphalt mixtures under high-temperature heating conditions, with the aim of providing a theoretical basis for hot in-place recycling (HIR) technology in the rehabilitation of porous asphalt pavements. The heating states of asphalt, mortar and mixtures in HIR were simulated using controlled oven heating. Their microscopic, mechanical and thermal properties were evaluated under different aging conditions and with the incorporation of different rejuvenators. The results show that asphalt aging intensifies with the increasing heating temperature and time. The incorporation of bio-based rejuvenators significantly alleviates aging effects and demonstrates superior performance compared to conventional rejuvenators. Furthermore, aggregates and rejuvenators enhance the thermal conductivity of materials, while aging reduces the thermal conductivity coefficient and increases the risk of temperature gradient diseases. The rheological properties of asphalt are closely related to the degree of aging. While aging mitigation improves low-temperature cracking resistance and acoustic damping performance, it may compromise high-temperature deformation resistance. In conclusion, to achieve an optimal balance between performance recovery and aging control, it is recommended that the HIR of porous asphalt pavements be conducted at a heating temperature of 180 °C for 5 min, with the addition of 3% bio-based rejuvenator. Full article

This study investigates the electrical properties of gold mine tailings from the Soweto mining region to assess their potential as a low-cost and sustainable backfill material for grounding systems. Samples were collected from historical mine dumps, oven-dried at 70 °C for 24 h to determine dry density and baseline moisture content, and reconstituted to controlled moisture levels of 5–25% by mass. Bulk electrical resistivity was measured using the Wenner four-electrode method in accordance with ASTM G57-06. The results reveal a strong inverse correlation between moisture content and resistivity. At low moisture content (≈5%), resistivity exceeded measurable limits, indicating poor ionic conduction, whereas increasing moisture content led to a substantial reduction in resistivity, reaching an average value of approximately 10 Ω at 25% moisture due to improved pore water continuity and ionic mobility. These findings demonstrate that moisture-conditioned gold mine tailings can achieve electrical performance comparable to that of conventional grounding enhancement materials while offering notable economic and environmental benefits. Owing to their local availability and waste re-utilisation potential, the tailings present a technically feasible and environmentally responsible solution for improving earthing performance in high-resistivity soils. Further work should examine long-term field performance, corrosion effects, and leaching behaviour. Full article

Hydrogen-rich shaft furnaces operated with coke oven gas (COG) represent an important low-carbon ironmaking route. Conventional porous-medium CFD models, however, do not explicitly resolve geometry-dependent burden descent or downward advection of solid sensible heat in variable-cross-section moving beds. To address this gap, a user-defined-scalar (UDS)-based pseudo-fluid moving-bed dual-temperature CFD framework is developed in this study. The framework couples geometry-dependent pseudo-solid kinematics, UDS-based transport of pseudo-solid species and sensible enthalpy, and a 12-step reduction-reforming-carbon reaction network on a fixed Eulerian mesh. It is applied to a 0.5 Mt·a⁻¹ industrial reactor through one reference case and three parametric groups covering solid descent velocity, cooling-side back pressure, and CH₄ content. Mesh-independence and mass-conservation checks indicate that the medium mesh is adequate for the intended trend-level assessment; the fine-to-medium deviations are 0.54% for DRI metallization, 0.23% for DRI outlet temperature, and 0.20% for top-gas temperature, with a net global mass residual of 1.53 × 10⁻⁶ kg·s⁻¹; the baseline DRI metallization (96.3%), carbon content (1.1%), and combined H₂ + CO utilization (29.45%) all fall within the reported ranges of the HBIS demonstration line and Energiron-ZR projects. As the descent velocity increases from 2.88 to 6.72 × 10⁻⁴ m·s⁻¹, DRI metallization drops from 98.0% to 79.4% and the outlet temperature rises from 313.3 to 719.4 K. Increasing the cooling-gas outlet back pressure from 60 to 100 kPa reduces the cooling-outlet excess flow from 1.49 to 0.11 kg·s⁻¹, indicating a dynamic gas-seal control between the two gas circuits, whereas raising the inlet CH₄ fraction from 10 to 23 vol% lowers the apparent CH₄ conversion from 29.5% to 18.5% and broadens the carbon-deposition zone. The framework offers a continuum basis for proof-of-concept and trend-level analysis of variable-cross-section hydrogen-rich moving-bed shaft furnaces. Full article

Waste plastics have attracted widespread attention in asphalt modification because of their environmental and economic benefits. However, the incorporation of waste plastics may weaken asphalt–aggregate interfacial adhesion, thereby increasing the risk of moisture damage in asphalt pavements. Although liquid anti-stripping agents have been widely used in conventional asphalt systems, their effectiveness and performance evolution in waste plastic-modified asphalt (WPA) remain insufficiently understood. To address this gap, this study systematically investigated the effects of two liquid anti-stripping agents, AJ-1 and AMR-II, on the adhesion, rheological properties, and aging behavior of WPA. Specifically, asphalt–aggregate adhesion was evaluated using water-boiling and binder bond strength tests, rheological properties were characterized by dynamic shear rheometer and bending beam rheometer tests, and aging behavior was analyzed through rolling thin-film oven test, pressurized aging vessel, and Fourier transform infrared spectroscopy. The results show that waste plastics reduce the adhesion performance at the asphalt-aggregate interface, whereas anti-stripping agents compensate for this loss. Compared with AJ-1, AMR-II showed stronger adhesion enhancement, increasing the asphalt residual coating ratio by approximately 1.5%–3.5% and the pull-off tensile strength by 17.4%–28.1%, while the corresponding improvements for AJ-1 were approximately 1.3%–2.7% and 13.0%–25.0%, respectively. As the dosage of both anti-stripping agents increased, the penetration index decreased, the temperature susceptibility increased, the softening point generally decreased, and the ductility increased markedly. Temperature sweep results show that both AJ-1 and AMR-II reduce the high-temperature performance of WPA. According to the bending beam rheometer results, AMR-II also enhances the low-temperature performance of WPA. Aging test results indicate that both anti-stripping agents increase the aging sensitivity of WPA to some extent, but the adverse effect of AMR-II on aging resistance is smaller than that of AJ-1, and AMR-II better preserves the low-temperature ductility and adhesion performance after aging. Overall, this study provides a binder scale evaluation showing that 0.4% AMR-II may offer a more balanced strategy for improving the adhesion and service performance of WPA. Full article

Tile adhesive mortars are industrialized products used for installing ceramic coverings and are classified according to the Brazilian standard ABNT NBR 14081/2012 on the basis of tensile adhesion performance under different curing conditions. Their formulation directly affects both technical performance and manufacturing competitiveness, while conventional product development remains slow, costly and strongly dependent on trial-and-error laboratory testing. This study evaluates whether historical industrial formulation data can support the retrospective prediction of approval or failure of tile adhesive mortars under ambient, oven, immersed and open-time curing conditions. A dataset comprising 6031 individual pull-off observations collected between 2021 and 2023 by a European multinational company in the construction materials sector was used to train and compare Logistic Regression, Random Forest, Boosted Decision Tree and Support Vector Machine models in R and Azure. The study was designed as an industrial-data modelling investigation rather than as a prospective optimization experiment. The results show that ensemble tree-based models, particularly Boosted Decision Tree and Random Forest, achieved the strongest predictive performance, whereas Logistic Regression remained more suitable for inferential interpretation of formulation variables. Model performance was uneven across curing conditions: prediction was more reliable for oven and immersed curing, whereas ambient curing and open time were affected by strong class imbalance and low failure prevalence. The findings indicate that Machine Learning can support formulation screening and quality-oriented decision-making for tile adhesive mortars, provided that its use remains restricted to the formulation ranges represented in the historical dataset and is complemented by prospective experimental validation before deployment in new product development. Full article

This study evaluates the performance of hyperspectral imaging (HSI) as a non-contact method for assessing railroad ballast fouling. A severely degraded ballast sample was collected from a derailment site. Conventional fouling indices were measured, indicating extreme ballast deterioration and fouling. To establish a quantitative baseline for degradation severity, hyperspectral reflectance data in the Visible–Near Infrared (VNIR) and Near Infrared (NIR) ranges were acquired for field samples under fouled-wet (as-received), fouled-dry (oven-dried), and clean-dry (oven-dried and sieved) conditions. Field spectra were compared with laboratory-fabricated ballast mixtures containing clay and coal fouling agents to ensure the results were not skewed due to the sampling procedure. Spectral similarity analysis using the Spectral Angle Mapper (SAM) was employed to quantify differences across ballast conditions. The maximum SAM angle reached approximately 0.45 radians between the as-received and clean-dry states in the NIR range, reflecting the combined effects of fouling and moisture. Comparisons between field and laboratory-fabricated samples showed moderate similarity, with SAM angles below 0.30 radians, indicating general agreement between field and laboratory spectra while capturing differences related to fouling agents, moisture retention, and compositional variability. Full article

Standard laboratory protocols for simulating short-term asphalt aging, including the Thin-Film Oven Test (TFOT) and Rolling Thin-Film Oven Test (RTFOT), are widely adopted but frequently lack sensitivity to the distinct thermo-oxidative kinetics of high-viscosity and polymer-modified systems. This study evaluates a severity-graded aging matrix incorporating the Pressure Aging Vessel (PAV) at variable durations (2, 5, and 10 h at 163 °C/2.1 MPa) as a potential alternative to conventional thin-film methods. Three binder systems BA-70 (PG 64-22), SBS-modified, and compatibilized functional thermoplastic (CFT)-modified asphalt were subjected to TFOT, RTFOT, and PAV variants. Comprehensive rheological characterization (DSR frequency/temperature sweeps, rutting parameter, MSCR) and SARA fractionation were employed to quantify oxidative stiffening, permanent deformation resistance, and compositional evolution. An Aging Severity Index (ASI) was developed to normalize multi-parameter responses and establish quantitative protocol equivalence thresholds. BA and SBS-modified binders exhibited pronounced protocol-dependent stiffening, with PAV-5h vs. RTFOT ASI gaps of 30.0% and 33.0%, respectively, confirming distinct aging severity under the tested conditions. Conversely, the CFT-modified binder demonstrated a compressed aging signature, maintaining stable complex modulus, minimal non-recoverable compliance escalation, and near-complete elastic recovery across all protocols. The ASI gap between PAV-5h and RTFOT for CFT was 6.0%, falling within the pre-defined ≤7% equivalence threshold established from combined rheological test uncertainty, specification-aligned engineering tolerance, and empirical gap clustering. SARA analysis corroborated these findings, showing CFT retained higher aromatic/resin fractions while limiting asphaltene accumulation compared to BA-70 and SBS. Importantly, the observed interchangeability between PAV-5h and RTFOT is strictly limited to the specific CFT-modified binder formulation tested under laboratory conditions. Broader specification adoption requires targeted validation across diverse modifier chemistries, dosages, and field-aged binders before generalization. Full article