Search Results (4,808)

The binary blend of poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) has emerged as the primary base material combination for biodegradable mulch films because of their favorable processability and biodegradability, offering a viable route to replace conventional polyethylene films in agricultural applications. However, the PBAT/PLA binary system suffers from thermodynamic incompatibility, limiting simultaneous achievement of mechanical, barrier, and optical properties. This study introduces poly(propylene carbonate) (PPC) as the third component and investigates its content (0–20%) on the microstructure and performance of PBAT/PLA/PPC ternary films. At PPC ≤ 10%, the system maintains an amorphous homogeneous structure, and PPC enriches the surface and improves interfacial adhesion. When the PPC content is 10%, the blend exhibited a transverse tensile strength of 43.3 MPa, an elongation at break of 338%, and a 29.8% reduction in water vapor permeability versus the neat blend. At 15% PPC, the compatibility threshold is exceeded, causing severe phase separation, a sharp drop in melt strength, and deteriorated mechanics. At 20%, phase separation induces PBAT/PLA crystallization, further enhancing barrier performance but reducing thermal stability and transparency. Differential scanning calorimetry and dynamic rheological analysis confirm the compatibility threshold, while X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy reveal abrupt changes in surface chemistry, crystal structure, and morphology. Overall, 10% PPC offers the best balanced properties. This work elucidates structure and property relationships, providing a basis for the rational formulation design of biodegradable mulch film. Further field weathering and biodegradation tests are required to validate their practical agricultural performance. Full article

Person-overboard detection from maritime unmanned aerial vehicle (UAV) imagery is challenging because the targets occupy very few pixels, sea-surface clutter is severe, human appearance varies substantially, and real-time processing is required. Existing detectors therefore struggle to meet the demands of practical maritime search and rescue. This paper presents HPSNet, an accuracy- and recall-oriented detector designed for maritime UAV imagery. HPSNet uses YOLOv11 as its baseline and introduces three complementary modifications. A channel transposed attention (CTA) module is embedded in the backbone to improve the discrimination of target features from complex sea-surface interference. A Giraffe feature pyramid network (GFPN) replaces the original feature-fusion network to strengthen multiscale information exchange and preserve cues from extremely small targets. A Dynamic Head (DyHead) adapts the predictions to variations in target scale, location, and appearance. HPSNet is evaluated against 12 representative detectors on the public Person Detection in Water and AFO datasets, and ablation experiments examine the contribution of each component. On Person Detection in Water, HPSNet achieves 78.2% mAP@50, 37.5% mAP@50:95, and 67.2% recall, improving the YOLOv11 baseline by 2.7, 2.2, and 4.2 percentage points, respectively. On AFO, it achieves 88.4% mAP@50 and 59.4% mAP@50:95, with gains of 0.7 and 1.9 percentage points over the baseline. The model contains 4.18 M parameters, requires 9.6 GFLOPs, and processes an image in 13.4 ms on an RTX 4090. These results demonstrate improved detection of small and visually weak maritime targets relative to YOLOv11 while maintaining a moderate model scale, providing a foundation for future deployment and optimization on embedded maritime UAV platforms. Full article

National soil-carbon assessments often emphasize carbon density without fully integrating soil depth and spatial extent. Here, we quantified the soil organic carbon (SOC) stock represented by the complete 1 km CSDLv2 raster domain across mainland China using six depth layers spanning 0–5, 5–15, 15–30, 30–60, 60–100, and 100–200 cm. Across 13,810,230 valid grid cells, the 0–200 cm soil profile stored 215.82 Pg C, of which 57.72 Pg C occurred in the upper 0–30 cm and 158.09 Pg C in the 30–200 cm subsoil. Although 73.2% of the total stock occurred below 30 cm, this large contribution primarily reflected the greater cumulative thickness of the subsoil interval; thickness-normalized SOC storage was substantially higher in the surface layer than in the subsoil (20.34 vs. 9.83 kg C m⁻² m⁻¹). Northwest China contained the largest integrated SOC stock (90.79 Pg C), whereas Northeast China exhibited the highest mean profile carbon density (33.17 kg C m⁻²), revealing a clear regional reversal between carbon density and total stock. Surface–subsoil decoupling and relative subsoil-carbon distance (CSD) further characterized regional differences in vertical SOC organization. Cross-dataset evaluation against an independent 2010–2024 SOC compilation comprising 17,990 depth intervals from 5870 profiles yielded an original-scale RMSE of 4.73 kg C m⁻², a mean bias of 0.44 kg C m⁻², and a Pearson correlation of 0.44. Replacing the 1 km layers with 90 m layers changed the national stock estimate by only 0.02%, while alternative DI thresholds and CSD reference quantiles affected screening magnitudes but preserved the broad regional patterns. These results highlight pronounced regional differences in the amount and vertical organization of soil carbon and support differentiated management priorities, including deep-carbon conservation in Northeast China, profile-structure diagnosis in North China and the Loess Plateau, water–soil coordination in Southern China, context-dependent water–carbon management in Northwest China, and disturbance avoidance and natural recovery in Southwest China and Tibet. Full article

Red mud, an alkaline industrial by-product of alumina refining generated in enormous volumes worldwide, poses a persistent environmental disposal challenge; using it as a partial cement replacement offers a promising route toward more sustainable concrete, but the resulting compressive strength is governed by complex, nonlinear interactions among the mix constituents that conventional empirical and regression-based models struggle to capture accurately. To address this challenge, the present study develops and compares four machine learning and deep learning models, namely the Deep Gradient Boosting Machine (DGBM), the Differentiable Neural Decision Tree (DNDT), Long Short-Term Memory (LSTM), and the Monte Carlo Dropout Neural Network (MCDNN), for the accurate and uncertainty-aware prediction of the compressive strength of red mud concrete. A dataset of 183 data points, compiled from the literature and supplemented with experimental results, was used to capture the influence of red mud content, curing period, and other mix parameters, including cement dosage, water content, and admixture proportions. The data were pre-processed prior to model training, and predictive performance was evaluated using R², RMSE, MAE, and WMAPE, among other indicators. The results show that the deep learning models outperformed the tree-based models: LSTM achieved the highest accuracy (R² = 0.942 on the testing dataset), while MCDNN additionally provided reliable uncertainty estimates alongside comparable prediction accuracy; DNDT and DGBM were comparatively less effective. Global sensitivity analysis identified fly ash and water content as the most influential contributors to strength development. By combining rigorous data-driven modeling with sensitivity and uncertainty analysis, this study contributes to the literature a validated, uncertainty-aware deep learning framework for sustainable concrete strength prediction, and offers practical value to the construction industry by providing engineers with a reliable, data-driven tool for optimizing red mud content in concrete mix design, thereby supporting the safe and wider industrial utilization of this problematic waste stream. Full article

Per- and polyfluoroalkyl substances (PFAS) coatings are widely used to impart water repellency to textiles, but their drawbacks, including the lack of biodegradability and potential effects on human health, underscore the need for fluorine-free alternatives. Current replacement products, such as PTFE (polytetrafluoroethylene) layers and wax applications, experience durability issues and require reapplication. In this study, a dual-surfactant coating comprising pentanoic acid (C5) and octadecylamine (C18) was developed to impart hydrophobicity to woven nylon 6,6 fabrics. The proposed mechanism involves thermal treatment after exposure to pentanoic acid to create carboxylate-rich surface sites, followed by electrostatic association of octadecylamine to form a non-polar monolayer. Process conditions were optimized by varying heating time, temperature, and pentanoic acid soaking time. Pristine nylon showed a water contact angle of 60.6°, whereas the fully coated fabric had a water contact angle of 118.8°. ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared), FESEM (Field Emission Scanning Electron Microscope), and XPS (X-ray Photoelectron Spectroscopy) demonstrated successful coating on the nylon surface. Weight and color analysis indicated near-surface alkyl enrichment with minimal visible change to the fabric. The short-term durability has been confirmed by measuring water contact angle after aging and laundry cycles. These results present a simple fluorine-free strategy for producing hydrophobic nylon 6,6 textiles. Full article

Asphalt mixing plant recycled powder (RP) is a solid waste generated during asphalt mixture production, and its efficient resource utilization is urgently needed. This study investigates the feasibility of utilizing RP as a cement replacement material in C30 concrete. The effects of RP on the workability, mechanical properties, drying shrinkage, hydration kinetics, and microstructure of concrete were systematically evaluated at replacement ratios ranging from 0% to 28%. The results indicate that RP incorporation reduces the fluidity of fresh concrete, with a maximum slump reduction of 21.1%. Both compressive and splitting tensile strengths decrease continuously with increasing replacement ratio. The higher relative early-age strength gain of RP mixtures in compressive strength mainly stems from their much lower absolute strength rather than accelerated hydration; isothermal calorimetry further revealed that RP retards hydration and reduces both the peak and cumulative heat release, while the dilution effect suppresses the formation of hydration products (C-S-H gel), thereby inhibiting strength development. Consequently, the 28-day compressive strength fails to meet the C30 design standard at a 28% replacement ratio. In addition, RP exacerbates drying shrinkage owing to its high water absorption. Pore structure analysis showed that moderate RP increased the proportion of gel pores while concurrently increasing mesopores and macropores; the pore-structure evolution at replacement ratios beyond 14% requires further investigation. Considering workability, mechanical performance, and volume stability, 14% is recommended as the maximum replacement ratio that satisfies the engineering acceptance requirements. Within this limit, RP demonstrates viability as a cement replacement material, offering a promising pathway for the high-value utilization of asphalt-related industrial solid waste and contributing to the low-carbon development of the concrete industry. Full article

The substitution of conventional materials with alternative resources is a significant approach for enhancing the engineering performance and sustainability of foamed concrete (FC). While supplementary cementitious materials, volcanic materials, and waste-derived materials have been extensively investigated, the use of obsidian as an alternative aggregate in FC systems remains largely unexplored, and the combined, systematic comparative use of obsidian, waste ceramic powder (WCP), and recycled concrete powder (RCP) within a unified experimental framework has not been previously investigated. This paper evaluates the use of obsidian, WCP, and RCP as alternative aggregates in hydroxypropyl methylcellulose (HPMC)-stabilized FC by replacing standard sand at 25%, 50%, and 100% levels. The thermal, durability and mechanical characteristics of the mixtures were assessed through density, compressive strength (CS), ultrasonic pulse velocity (UPV), water absorption (WA), elevated temperature resistance (200 °C, 400 °C, 600 °C and 800 °C), freeze–thaw performance, thermal conductivity (TC), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS) and X-ray diffraction (XRD) analyses. The results showed that the 28-day CS increased from 0.545 MPa in the control mixture to a maximum value of 2.590 MPa in the obsidian-based FC. Moreover, WA decreased markedly from 117.7% to 46.9% in the obsidian-based FC. The UPV varied from 1355 to 1795 m/s due to the incorporation of RCP, WCP and obsidian at different replacement ratios in the mixture designs. The lowest TC of 0.08185 W/(m·K) was recorded in the obsidian-based FC at 50% substitution level. Under elevated-temperature exposure, the mixture with 100% obsidian replacement retained a compressive strength of 0.5936 MPa at 800 °C. To conclude, the use of obsidian, WCP and RCP as alternative aggregates in FC shows promising potential for the development of durable, thermally efficient, and sustainable lightweight construction materials. Full article

Drinking water is essential for humans; its quality determines the health and proper functioning of the body. In order to obtain drinking water in accordance with the legislation in force, the performance of the technology applied for water treatment and the infrastructure for transport and distribution to the consumer are equally important. Particular importance to this last aspect was given by the introduction of European Directive 2020/2184. Infrastructure can significantly influence water quality due to the fact that there are periods when water stagnates in the pipe and electro-corrosion processes, and salt deposits or degradation/corrosion of the pipes can occur, or periods when water circulates under pressure, when deposits but also particles from the pipes are mechanically detached and transported to the consumer. In this article, we aim to present the behavior of asbestos-cement pipes, AC, special steel for pipes OLT 37, galvanized steel, OLT 37.1, and high-density polyethylene, HDPE, in contact with drinking water. The study was conducted in Calarasi city, Calarasi county, Romania, where some of the old pipes were replaced. A comparative study of new pipes of the same type with pipes in use for more than 20 years, up to 46 years, was conducted, and at the same time the changes that the pipes (which have not yet been replaced) have on the quality of drinking water for street consumers were also analyzed. Following the analyses performed, it can be stated that the water quality is within the maximum permissible limits, but the micropollutants that appear can accumulate in the body (such as AC microfibers, microplastics, metallic zinc, zinc ions, iron ions, manganese, aluminum) with effects that can be evident after a long period of consumption through bioaccumulation. Full article

Wetlands support fisheries and other livelihoods but can also bring people into close contact with crocodilians. Human–crocodile conflict has been documented across Africa, Asia, Australia and the Americas, yet indirect economic costs, including damage to fishing gear, remain less studied than attacks on people or livestock. We analysed questionnaire data from 379 respondents in purposively selected crocodile-exposed fishing communities in the southern Sudd Wetlands, South Sudan. The study quantified seasonal patterns of Nile crocodile (Crocodylus niloticus) damage to fishing gear, reporting pathways, conflict-resolution perceptions, responses to damaged gear and likely annual damaged-net categories. Reporting pathways were defined as the social and institutional channels through which respondents said gear-damage incidents were communicated; handling responses were defined as actions taken after gear was damaged. As expected from seasonal variation in floodplain use, the water level and fishing activity, reported damage was concentrated from July to December, with September the being most frequently selected main damage month (157 respondents; 41.4%). Quarterly ordinal responses differed among seasons (Friedman test: ${\chi }^2=721.54$, df = 3, $p<0.001$). Cumulative link models that included both quarters and the broader survey area showed the largest odds-ratio contrasts for July–September and October–December, whereas broader-area contrasts were smaller, and their confidence intervals overlapped one. Reporting was dominated by informal and community pathways: fishing-camp leadership, family members and other fishers each reached 100% agreement, whereas wildlife authorities received no affirmative reporting. Respondents also expressed little confidence in formal conflict resolution: 100% agreed that crocodile-related gear-damage conflicts were difficult to resolve, and 0% agreed that government would compensate for damaged gear. Damaged nets were mainly abandoned and replaced; repair was rare (1.6%). The most likely annual damaged-net category was 1–5 nets/year/participant (275 respondents; 72.6%). Because the survey was purposive, the results should be interpreted as patterns among sampled respondents and locations, not as prevalence estimates for all fishers in the Sudd Wetlands or South Sudan. The findings indicate that seasonal gear damage, weak formal reporting to wildlife institutions and limited institutional confidence should be central considerations in crocodile-conflict management. Full article

The construction industry’s dependence on ordinary Portland cement (OPC) makes low-carbon binder systems an urgent priority; yet, the nonlinear interactions among multiple supplementary cementitious materials (SCMs) and nanomaterials complicate rational mix design. This study fuses explainable artificial intelligence (XAI) with a hierarchy of closed-form mathematical formalisms and an experimental durability programme for a quaternary sustainable concrete in which OPC is partially replaced by sugarcane bagasse ash (SCBA, 40 kg/m³), ground granulated blast furnace slag (GGBS, 60 kg/m³), natural zeolite (20 or 40 kg/m³) and nano-silica (0–20 kg/m³) at a constant water–binder ratio of 0.45. Thirteen mixes were tested for compressive and flexural strength, rapid chloride penetration (RCPT) and sulfuric acid resistance at 7, 28 and 56 days. The optimum blend (12 kg/m³ nano-silica) reached 45.0 MPa at 28 days, 49.5% above the control, while reducing chloride charge by 70% and acid mass loss by 65%. Information theoretic discrimination among three competing hydration kinetics laws selects the hyperbolic rate model with an Akaike weight of 1.000 (ΔAIC_c > 32), showing the blend raises the ultimate strength ceiling by 46% while delaying half-strength by only two days. Within this mix series, effective binder (k-value) analysis indicates that, at low dosage, one kilogram of nano-silica contributes 28-day strength broadly comparable to that of several tens of kilograms of OPC (a dataset-specific, dose-dependent estimate rather than a general mass equivalence), and three independent estimators—the experimental peak, the response surface stationary point (12.8 kg/m³) and the marginal efficiency zero (13.2 kg/m³)—converge on an optimum nano-silica dosage of 3.0–3.3% of binder. Principal component analysis compresses the six-dimensional strength–durability response into a single latent statistical axis (interpreted as an indicator of pore connectivity) carrying 91.5% of the variance, and a Fickian error function solution seeded by Berke–Hicks conversion of RCPT charge projects a 3.4-fold extension of the chloride-initiation service life (36.7 versus 10.8 years at 50 mm cover). Six machine learning models were benchmarked; extremely randomized trees performed best (R² = 0.9905, RMSE = 0.920 MPa; leave-one-out R² = 0.986; bootstrap 95% CI on R² [0.981, 0.996]), and SHAP force plot attributions were triangulated with Sobol global sensitivity indices (curing age 75.4%, nano-silica 23.1% of output variance) and response surface significance tests. The optimized mixes cut embodied CO₂ by 26–32% and improve eco-strength efficiency 2.1-fold; grey relational analysis over six strength, durability and carbon criteria ranks the 12 kg/m³ nano-silica mixes first. The framework demonstrates how interpretable machine learning, information theoretic model selection, diffusion theoretic service-life projection and experimental durability evidence can be unified into a transparent, physically validated basis for sustainable concrete mix design. Full article

While the individual effects of sustainable fillers on cementitious systems are widely known, their combined tribological and fracture behaviors within a polymer concrete matrix remain largely unexplored. Addressing this gap, this study experimentally investigates the physical, mechanical, and tribological characteristics of polyester-based polymer concrete (PC). In addition to reference specimens produced with polyester resin and silica sand, modified mixtures were developed by replacing the silica sand with ground granulated blast-furnace slag (GGBS) and recycled waste concrete aggregate (WC) at various substitution ratios (0%, 5%, 10%, 15%, 20%, and 25%). To evaluate the performance of the developed PCs, parameters including unit weight, water absorption capacity, flexural and compressive strengths, Shore D hardness, surface roughness, acid resistance, Bohme abrasion resistance, and fracture energy were analyzed. Furthermore, temperature variations on the friction surfaces were monitored in real time using a thermal camera during the Bohme abrasion tests. To elucidate the fracture mechanisms, the fractured surfaces were examined via digital microscopy. The quantitative findings indicate that a 25% GGBS replacement optimizes mechanical performance, increasing the compressive and flexural strengths by 21.2% (108.30 MPa) and 30.6% (35.29 MPa), respectively, alongside a 27% improvement in Bohme abrasion resistance. However, this modification significantly increases material brittleness, reducing the fracture energy by 53.3% compared to the reference. Conversely, although incorporating WC offers sustainability advantages, it limits mechanical performance, leading to decreases of up to 9.9% (80.46 MPa) in compressive strength and 15% (22.97 MPa) in flexural strength at a 20% substitution rate. Regarding fracture energy, while the W20 series absorbed more energy than the B25 series, it still remained 47.8% lower than the reference. Additionally, the GGBS-incorporated series demonstrated higher susceptibility to sulfuric acid attack compared to the WC-incorporated series. Full article

The use of phase change materials (PCMs) in cementitious mortars is a promising strategy for passive thermal regulation and thermal energy storage (TES) in buildings, but its practical implementation remains constrained by PCM leakage and its effects on physical and mechanical performance. This study investigates the use of recycled clay brick waste as a dual-function component in eco-efficient mortars, serving as a partial replacement for fine aggregate and as a porous carrier for paraffin-based PCM. The experimental program comprised three stages: selection of an eco-efficient reference mortar, impregnation of recycled ceramic aggregates using thermal and vacuum-assisted procedures, and evaluation of PCM-modified mortars through fresh-state, physical, mechanical, thermophysical, direct thermal exposure, thermoregulation, and infrared thermography tests. Thermal impregnation at 15 wt% PCM provided the most favorable balance between PCM incorporation and stability against surface accumulation and mass loss and was selected for mortar production. Compared with REFeco, PCM incorporation reduced water absorption by approximately 10% and caused compressive and flexural strength losses below 10%. PCM15 exhibited the most favorable thermophysical balance, increasing volumetric specific heat by 14.9% and thermal inertia by 8.5%, while reducing thermal diffusivity by 10.8%. Under direct flame exposure, PCM25 produced the greatest thermal buffering effect, delaying the attainment of 200 °C on the rear face by approximately 4 min and reducing maximum estimated heat flux by approximately 16% relative to REFeco. Overall, recycled clay brick waste demonstrated potential as a PCM carrier for eco-efficient cementitious mortars with thermal energy storage functionality. Full article

Three-dimensional concrete printing (3DPC) offers geometric versatility for fabricating complex artificial coral reef structures; however, how regional differences in binder composition affect mechanical anisotropy, water absorption, and alkali leaching remains insufficiently characterized. This study compares two regional formulations: Mix_Vn (Vietnam, 40% fly ash) and Mix_Cn (China, 30% fly ash + 20% ground granulated blast-furnace slag, GGBS). Compressive strength was evaluated in three orthogonal orientations, water absorption was measured in tap and seawater, and pH evolution was monitored under four immersion regimes. Mix_Cn exhibited higher and more isotropic strength, reduced water absorption, and slower alkali release compared with Mix_Vn. In particular, GGBS substitution improved pore connectivity and stabilized pH near 9.0 under renewed seawater, whereas Mix_Vn exceeded pH 10.5 within two days in static tap water. These findings demonstrate that the GGBS-containing regional formulation (Mix_Cn) exhibited more favorable short-term performance across all evaluated metrics under the investigated laboratory conditions, contributing to low-carbon concrete construction through substantial Portland cement replacement by industrial by-products. Full article

Reducing asphalt mixture production temperatures and partially replacing virgin aggregates with industrially derived materials are potential pathways toward more sustainable pavement technologies. This study evaluated the effects of steel slag (SS) aggregate and air-cooled blast furnace slag (ACBFS) aggregate on the properties of asphalt concrete for pavement binder courses produced as warm-mix asphalt (WMA) using water-foamed bitumen. The reference hot-mix asphalt (HMA) and WMA mixtures were compared with WMA variants in which 20% or 40% of the virgin aggregate was replaced by SS or ACBFS. The slag aggregates were characterized by physical and mechanical properties, surface morphology, and local elemental composition. Mixture performance was evaluated based on air voids content, indirect tensile strength, water and freeze–thaw resistance, dynamic modulus, and rutting resistance, followed by statistical analysis. Slag type and replacement level affected the properties differently. Increasing slag content increased air voids content, whereas slag-containing mixtures showed a lower relative loss of tensile strength after conditioning than the reference mixtures. Compared with SS, ACBFS resulted in lower dynamic modulus and poorer rutting resistance. The mixture containing 20% SS satisfied all adopted technical requirements. The results support the use of SS at this replacement level, whereas ACBFS mixtures require further optimization. Full article

Chloride ingress is a critical durability concern for cement-based construction materials exposed to marine environments and other chloride-containing conditions, as it can accelerate material degradation and reduce service life. To improve the chloride ingress resistance of mortar containing pre-wetted porous fine aggregate, the effects of internal curing provided by the porous fine aggregate and ion adsorption by calcined layered double hydroxides (CLDHs) on mortar performance were investigated. Compressive strength, pore structure, water-soluble chloride profiles, X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS) were employed to analyze chloride transport and fixation in mortars with different porous fine aggregate replacement ratios and CLDHs contents. The results showed that the pre-wetted porous fine aggregate was beneficial to later-age strength development, which may be associated with its internal water storage and release characteristics, although its effect varied with the replacement ratio. At a replacement ratio of 10%, the pore structure of the mortar remained relatively stable, and the increase in water-soluble chloride content relative to the reference mortar was mainly confined to the near-surface region. By contrast, higher replacement ratios increased the total porosity and the proportions of larger pores and pore throats, thereby promoting chloride migration into the intermediate and deeper regions. CLDHs did not significantly improve the overall pore structure of the mortar, but may have reduced the water-soluble chloride content through structural reconstruction and interlayer fixation. Among the investigated mixtures, the mortar containing 3% CLDHs exhibited the lowest water-soluble chloride content at all tested depths. The pre-wetted porous fine aggregate primarily regulated the pore structure and chloride transport conditions, whereas CLDHs mainly reduced water-soluble chloride content and may contribute to chloride binding. Their combined contributions helped retard chloride migration into the mortar and improve its resistance to chloride ingress. Full article