Search Results (33)

This paper reviews the applications and performance advantages of ultra-high-performance concrete (UHPC), engineered cementitious composite (ECC), and recycled aggregate concrete (RAC) in composite flexural members. UHPC is characterized by its ultra-high strength, high toughness, excellent durability, and microcrack self-healing capability, albeit with high costs and complex production processes. ECC demonstrates superior tensile, flexural, and compressive strength and durability, yet it exhibits a lower elastic modulus and greater drying shrinkage strain. RAC, as an eco-friendly concrete, offers cost-effectiveness and environmental benefits, although it poses certain performance challenges. The focus of this review is on how to enhance the load-bearing capacity of composite beams or slabs by modifying the interface roughness, adjusting the thickness of the ECC or UHPC layer, and altering the cross-sectional form. The integration of diverse concrete materials improves the performance of beam and slab elements while managing costs. For instance, increasing the thickness of the UHPC or ECC layer typically enhances the load-bearing capacity of composite beams or plates by approximately 10% to 40%. Increasing the roughness of the interface can significantly improve the interfacial bond strength and further augment the ultimate load-bearing capacity of composite components. Moreover, the optimized design of material mix proportions and cross-sectional shapes can also contribute to enhancing the load-bearing capacity, crack resistance, and ductility of composite components. Nevertheless, challenges persist in engineering applications, such as the scarcity of long-term monitoring data on durability, fatigue performance, and creep effects. Additionally, existing design codes inadequately address the nonlinear behavior of multi-material composite structures, necessitating further refinement of design theories. Full article

Psychology is a core discipline in understanding why and how individuals choose to engage in sustainable action. This paper uses social representations theory to explore the rising use of eco/green prefixes for psychology concepts through a critical analysis of the concept of eco/green fatigue. It argues that this term, which originated in the world of popular online news media, has typically been treated in academic psychology discussions using existing psychology concepts in the same way as eco-anxiety and eco-grief, which hides important features of the phenomenon that need to be better understood. The paper presents an analysis of eco-fatigue based on a critical review of the existing psychology literature, qualitative online archival analyses, and an exploratory quantitative survey study. The survey study was conducted with a sample of 182 students and non-students and analysed using principal components and cluster analysis. The paper provides evidence that simply adding an eco/green prefix to an existing psychology concept without a systematic empirical investigation into the phenomenon can result in overly simplistic conceptual frameworks that do not lead to sound practical conclusions. A preliminary empirical examination of the social representation of eco-fatigue in the public arena suggested that inappropriate sustainability messaging and bad business behaviour may be more of a barrier to sustainability action than the beliefs or attitudes held by individuals. Full article

This review explores the evolving landscape of sustainable textile manufacturing, with a focus on rubber-based materials for various industrial applications. The textile and rubber industries are shifting towards eco-friendly practices, driven by environmental concerns and the need to reduce carbon footprints. The integration of sustainable textiles in rubber-based products, such as tires, conveyor belts, and defense products, is becoming increasingly prominent. This review discusses the adoption of natural fibers like flax, jute, and hemp, which offer biodegradability and improved mechanical properties. Additionally, it highlights sustainable elastomer sources, including natural rubber from Hevea brasiliensis and alternative plants like Guayule and Russian dandelion, as well as bio-based synthetic rubbers derived from terpenes and biomass. The review also covers sustainable additives, such as silica fillers, nanoclay, and bio-based plasticizers, which enhance performance while reducing environmental impact. Textile–rubber composites offer a cost-effective alternative to traditional fiber-reinforced polymers when high flexibility and impact resistance are needed. Rubber matrices enhance fatigue life under cyclic loading, and sustainable textiles like jute can reduce environmental impact. The manufacturing process involves rubber preparation, composite assembly, consolidation/curing, and post-processing, with precise control over temperature and pressure during curing being critical. These composites are versatile and robust, finding applications in tires, conveyor belts, insulation, and more. The review also highlights the advantages of textile–rubber composites, innovative recycling and upcycling initiatives, addressing current challenges and outlining future perspectives for achieving a circular economy in the textile and rubber sectors. Full article

This research utilized recycled acetate fibers from discarded cigarette butts (CBs) as reinforcing materials, reducing solid waste and enhancing the properties of bitumen. The surface properties of the fibers significantly impacted the binder characteristics. The treatment of CB fibers with anhydrous ethanol was employed to remove the plasticizer glycerol triacetate (GTA), enabling the better homogeneity of the fibers in the binder. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to assess the effectiveness of the fiber treatment. A dynamic shear rheometer (DSR) was used to explore the properties of bitumen with varying CB contents (0%, 0.25%, 0.75%, and 1.25% by weight). A whole life cycle analysis further confirmed the eco-efficiency of CB binders. The results show that the pretreatment effectively removed GTA, leading to a more homogeneous dispersion of fibers in the binder. Adding CBs can significantly improve bitumen properties, but this effect does not increase with higher dosages; when the CB content exceeded 1.25%, a reduction in fatigue resistance was observed. Among the tested dosages, the optimal amount was 0.75%, which improved the high-temperature performance of the binder by 2.7 times, the medium-temperature fatigue life by 1.78 times, and the low-temperature performance by 1.08 times. In terms of ecological benefits, the addition of CB fibers to bitumen pavement reduced carbon emissions by two-thirds compared to traditional bitumen pavement, resulting in a significant decrease in carbon emissions. This study provides valuable insights into the construction of sustainable transportation infrastructure. Full article

The smart capsule bubble tile (SCBT) is an innovative flooring solution that combines acupressure-based reflexology with electromagnetic wave stimulation to enhance well-being. Designed for smart buildings and healthcare applications, SCBT integrates traditional construction techniques with advanced healing technologies to create a health-conscious, eco-friendly flooring system. For durability and thermal performance, SCBT tiles are manufactured using conventional concrete methods, enhanced with aluminum oxide (Al₂O₃). Each tile contains multiple pressure point capsules featuring a copper cap that emits electromagnetic waves when exposed to sunlight. This dual-function mechanism stimulates acupressure points on the feet, promoting better blood circulation, reducing stress, and enhancing relaxation. The heat release from the copper caps further improves thermal comfort and energy flow in the body, reinforcing the benefits of reflexology. The performance of SCBT tiles was extensively tested, demonstrating impressive physical and functional properties. They exhibit a flexural strength of 4.6 N/mm², a thermal emissivity of 0.878, a solar reflectance of 0.842, and a water absorption rate of 8.12%. In biomechanical assessments, SCBT showed significant benefits for balance and posture correction. Users experienced a 70.8% reduction in lateral stance ellipse area with eyes open and a 50.5% reduction with eyes closed, indicating improved stability and proprioception. By integrating acupressure and electromagnetic stimulation into flooring design, SCBT promotes a holistic approach to health. This technology supports energy efficiency in smart buildings and contributes to preventive healthcare by enhancing musculoskeletal health and reducing fatigue. SCBT represents a significant step in creating built environments supporting human well-being, merging traditional healing principles with modern material science. Full article

In addition to the widely recognized benefits of reducing carbon emissions and protecting the environment, the authors believe that bus electrification has potential advantages in enhancing driving safety, improving passenger comfort, and reducing driver fatigue—areas that have not yet been sufficiently studied and emphasized. Safety and comfort are fundamental objectives in the continuous development of transportation systems. They are directly and closely related to both passengers and drivers and are among the top priorities when individuals choose their mode of transportation. Therefore, these aspects deserve broader and more in-depth attention and research. This study aims to identify the potential advantages of route bus electrification in terms of safety and comfort. The results of a passive experiment on the speed profile of buses operating on actual routes are presented here. Firstly, we focus on the acceleration/deceleration at the starting/stopping stops, specifically for regular-route buses, and obtain the following information: I. Starting acceleration from a bus stop is particularly strong in the second half of the acceleration process, being suitable for motor-driven vehicles. II. The features of the stopping deceleration at a bus stop are “high intensity” and “low dispersion”, with the latter enabling the refinement of regenerative settings and significantly lowering electricity economy during electrification. And we compare the speed profile of an electric bus with those of a diesel bus and obtain the following information: III. Motor-driven vehicles offer the advantages of “high acceleration performance” and “no gear shifting”, making them particularly suitable for the high-intensity acceleration required when route buses depart from stations. This not only simplifies driving operations but also enhances lane-changing safety. And by calculating and analyzing the jerk amount, we could quantitatively demonstrate the comfortable driving experience while riding on this type of bus where there is no shock due to gear shifting. IV. While the “high acceleration performance” of motor-driven vehicles produces “individual differences in the speed change patterns”, this does not translate to “individual differences in electricity consumption”, owing to the characteristics of this type of vehicle. With engine-driven vehicles, measures such as “slow acceleration” and “shift up early” are strongly encouraged to realize eco-driving, and any driving style that deviates from these measures is avoided. However, with motor-driven vehicles, the driver does not need to be too concerned about the speed change patterns during acceleration. This characteristic also suggests a benefit in terms of the electrification of buses. Full article

Objective: This study aims to investigate the structural and functional characteristics of walnut protein hydrolysates (WPHs) with different molecular weights prepared using protease from Dregea sinensis Hemsl, as well as the anti-fatigue effects of low-molecular-weight walnut protein hydrolysates (LWPs) and their impact on the cecal microbiota and faecal metabolism of mice. Methods: The anti-fatigue activity of WPHs with different molecular weights was evaluated, and the LWPs were analyzed in a centralized manner. A 28-day gavage study was conducted to assess LWP’s anti-fatigue benefits in mice, supplemented by metabolomic analysis to explore its impact on metabolic pathways. Results: Our findings revealed that LWP significantly outperformed unhydrolyzed walnut protein (WP) in terms of water retention, lipid retention, emulsifying properties, and foaming capacity. Notably, differential protein expression associated with LWP highlighted pathways related to antioxidant activity. In vivo studies showed that LWP markedly enhanced glycogen storage in the muscles and liver of mice, while reducing serum levels of serum urea nitrogen, lactate dehydrogenase, blood lactic acid, and creatine kinase. Furthermore, the levels of Superoxide Dismutase and Glutathione were significantly elevated, alongside a reduction in Malondialdehyde, indicating that LWP’s anti-fatigue effect is closely linked to improved oxidative stress resistance. Additionally, LWP promoted beneficial increases in microbial populations such as Akkermansia, Alistipes, Eubacterium, and Muribaculum, which are associated with enhanced fatigue resistance. Metabolomic analysis indicated significant enrichment in glycerophospholipid metabolism and amino acid biosynthesis, identifying key metabolites including palmitoylethanolamide and 4-methyl-5-thiazoleethanol, both of which are integral to health maintenance. Conclusions: LWP demonstrates a robust anti-fatigue effect, supported by its accessibility, straightforward preparation, and eco-friendly characteristics. These attributes suggest that LWP has promising potential for inclusion in health products aimed at enhancing vitality and combating fatigue. Full article

Epoxy composites play a crucial role in modern materials technologies, with their exceptional properties such as high strength and thermal and chemical resistance, making them ideal for a wide range of industrial applications, including aerospace, automotive, construction, and energy. This review article provides a comprehensive overview of the current trends and advancements in epoxy composites, focusing on mechanical properties and their optimization. Attention is given to technological innovations, including the use of nanotechnologies, hybrid reinforcement, and eco-friendly materials, which are key to enhancing the performance and sustainability of these materials. The analysis shows that the introduction of nanomaterials, such as graphene, titanium dioxide, and silicon dioxide, can significantly improve the strength, fatigue resistance, and electrical properties of epoxy composites, opening new possibilities in advanced technologies. Another significant contribution is the development of hybrid composites, which combine different types of fibers, such as carbon, aramid, and glass fibers, enabling the optimization of key properties, including interlayer strength and delamination resistance. The article also highlights the importance of environmental innovations, such as bio-based resins and self-healing mechanisms, which enable more sustainable and long-term effective use of composites. The combination of theoretical knowledge with practical applications provides valuable guidance for designing materials with precisely defined properties for future industrial use. This text thus offers a comprehensive view of the possibilities of epoxy composites in the context of increasing demands for performance, reliability, and environmental sustainability. Full article

This study examines how the green marketing mix—comprising green product, price, place, and promotion—affects consumers’ environmental attitudes and green purchase intentions, incorporating environmental knowledge as a moderating factor, focusing on a sample of 334 environmentally conscious consumers from second- and third-tier cities in China. Structural equation modeling (SEM) was used to analyze the data collected through SPSS 24 and AMOS 26. The results indicate that green promotion, price, and place significantly influenced environmental attitude, while green products did not show a significant effect. Both green products and promotions positively affected green purchase intention, whereas price and place had no notable impact. Environmental attitude strongly influenced green purchase intention, emphasizing its critical role in shaping consumer behavior. Interestingly, higher levels of environmental knowledge weakened the link between environmental attitude and green purchase intention, potentially due to increased skepticism toward environmental claims and the onset of “green fatigue”. By analyzing data from consumers in China’s second- and third-tier cities, this study provides valuable insights into the unique dynamics of green consumer behavior in emerging markets, offering strategic guidance for companies to develop more effective and environmentally responsible marketing approaches. It offers insights for policymakers to promote a sustainable, eco-conscious society. Full article

In North America and Europe, asphalt shingle waste created during the installation of roofing membranes and tear-off shingles retrieved at the end of the membrane’s life cycle are two major sources of municipal solid waste. Since almost 15–35% of recycled asphalt shingles (RAS) consist of an asphalt binder, the effective recycling of RAS into asphalt mixtures could also allow a reduction in the consumption of non-renewable resources such as asphalt binders. In this context, several studies investigating the use of RAS in asphalt mixtures can be found in the literature, although they exhibit widespread and sometimes conflicting information about the investigated materials, the mix preparation and testing methodologies and the experimental findings. Given this background, this review paper aims at summarizing the existing information and research gaps, providing a synthetic and rational picture of the current literature, where similar attempts cannot be found. In particular, different research studies show that the use of RAS in asphalt mixtures is an economical as well as an eco-friendly option. RAS with up to 20% by weight of binder or 5% by weight of aggregate/mixtures (eventually in combination with 15% reclaimed asphalt pavement aggregate) were found to be relatively suitable to improve the performance properties of asphalt mixtures, both in the laboratory and in the field. Adding RAS to asphalt mixtures could enhance their stiffness, strength and rutting resistance (i.e., high-temperature properties), while negatively affecting the mixtures’ fatigue and thermal cracking resistance. However, the addition of specific biomaterials (e.g., bio-binders, bio-oils) or additives to asphalt mixtures can mitigate such issues, resulting in lower brittleness and shear susceptibilities and thus improving the anti-cracking performance. On the other hand, the literature review revealed that several aspects still need to be studied in detail. As an example, RAS-modified porous asphalt mixtures (fatigue, rutting, moisture susceptibility and thermal cracking) need specific research, and there are no comprehensive research studies on the effects of the RAS mixing time, size and mixing temperature in asphalt mixtures. Moreover, the addition of waste cooking/engine oils (biomaterials) as asphalt binder rejuvenators in combination with RAS represents an attractive aspect to be studied in detail. Full article

In recent decades, in order to replace traditional synthetic polymer composites, engineering research has focused on the development of new alternatives such as green biocomposites constituted by an eco-sustainable matrix reinforced by natural fibers. Such innovative biocomposites are divided into two different typologies: random short fiber biocomposites characterized by low mechanical strength, used for non-structural applications such as covering panels, etc., and high-performance biocomposites reinforced by long fibers that can be used for semi-structural and structural applications by replacing traditional materials such as metal (carbon steel and aluminum) or synthetic composites such as fiberglass. The present research work focuses on the high-performance biocomposites reinforced by optimized sisal fibers. In detail, in order to contribute to the extension of their application under fatigue loading, a systematic experimental fatigue test campaign has been accomplished by considering four different lay-up configurations (unidirectional, cross-ply, angle-ply and quasi-isotropic) with volume fraction V_f = 70%. The results analysis found that such laminates exhibit good fatigue performance, with fatigue ratios close to 0.5 for unidirectional and angle-ply (±7.5°) laminates. However, by passing from isotropic to unidirectional lay-up, the fatigue strength increases significantly by about four times; higher increases are revealed in terms of fatigue life. In terms of damage, it has been observed that, thanks to the high quality of the proposed laminates, in any case, the fatigue failure involves the fiber failure, although secondary debonding and delamination can occur, especially in orthotropic and cross-ply lay-up. The comparison with classical synthetic composites and other similar biocomposite has shown that in terms of fatigue ratio, the examined biocomposites exhibit performance comparable with the biocomposites reinforced by the more expensive flax and with common fiberglass. Finally, appropriate models, that can be advantageously used at the design stage, have also been proposed to predict the fatigue behavior of the laminates analyzed. Full article

This study investigates the transformative effects of incorporating Trinidad Lake asphalt (TLA), crumb rubber modifier (CRM), and the warm mix additive leadcap (LC) into petroleum-based asphalt binder PG 64-22. Our results show that LC significantly reduces binder viscosity, leading to easier application and lower energy consumption, especially when combined with TLA and CRM. The addition of TLA and CRM enhances rutting resistance, with notable improvements in both pre- and post-aging conditions, particularly in formulations combining PG 64-22, 20% TLA, and 10% CRM. These formulations exhibit superior performance metrics, such as increased percentage recovery (% rec) and reduced non-recoverable creep compliance (J_nr), indicating improved flexibility and deformation resistance. Furthermore, LC balances increased rigidity and susceptibility to fatigue cracking from higher TLA and CRM levels, respectively. These modifications also promote environmental sustainability by reducing energy usage and emissions during production and paving. This study highlights LC’s critical role in advancing high-performance, eco-friendly warm mix asphalt binders, offering valuable insights for sustainable pavement engineering and setting a new benchmark for advanced asphalt technologies. Full article

With the increasing stringency of the Energy Efficiency Design Index (EEDI) requirements, improving the efficiency of the propeller has emerged as a significant challenge in the development of eco-friendly ships. Cavitation inevitably occurs, and it reduces the hydrodynamic performance of the propeller and erodes the blade surface, leading to increased fuel consumption. Therefore, reducing cavitation is crucial for ships to meet the EEDI requirement. This paper investigates the fatigue life and hydrodynamic performance of the propeller under different cavitation numbers and speeds. The relationship between propeller fatigue life and propulsion efficiency under cavitation conditions is explored. In simulation, the Schnerr–Sauer theoretical model is employed as the cavitation model. The nominal stress method (S-N method) is used to calculate the blade fatigue strength. The KP957 propeller is taken as the research object. The hydrodynamic performance of the propellor under different cavitation numbers is studied by means of the finite volume method. The surface pressure and wall shear stress of the blade within the cycle are calculated, and they are conveniently loaded in the dynamic process to calculate the stress and strain of the propeller using the finite element method. Subsequently, the fatigue life of the propeller is determined based on the S-N curve of the blade material. The validity of the study is established by comparing the cavitation results with the experimental results from the Korean Ocean Engineering Research Institute (KORDI) for the KS1295 ship at a speed of 15.7 knots, where the cavitation number in the wake field is 2.5553, and a good consistency is obtained. The findings emphasize the significant impact of cavitation on blade service life and vibration. Full article

This research study aims to investigate the feasibility of incorporating high-density polyethylene waste (HDPEW) into bitumen applications. Two conventional conditions of bitumen, namely, aged bitumen (AB) and virgin bitumen (VB), are rejuvenated and modified, respectively, using post-consumer HDPEW sourced out of bottle crates. The outcome (Pyro oil, PO-HDPEW) of the pyrolysis thermochemical process is used by 10, 20, and 30% to rejuvenate AB, while the fine-ground granules (FG) (FG-HDPEW) are used by 2, 3, 4, and 5% to modify the VB with different percentages. Physical and rheological characterization testing, including penetration, softening point temperature, and rotational viscosity (RV), is conducted to evaluate the performance of the HDPEW-rejuvenated and -modified binders and optimize both rejuvenator and modifier percentages. In addition, physical and chemical tests, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) are conducted to analyze the composition, distribution of surface contaminants, and the molecular structure of the bitumen, based on their respective wavelengths. Moreover, advanced mechanical and rheological tests, including dynamic shear rheometer (DSR), multiple stress creep and recovery (MSCR), and linear amplitude sweep (LAS) tests, are conducted to investigate the susceptibility of the rejuvenated and modified bitumen with HDPEW to rutting and fatigue cracking. The testing results demonstrate that the addition of PO-HDPEW to AB and FG-HDPEW modification of VB can enhance the physical, chemical, mechanical, and rheological properties of bitumen; however, this study recommends further research on the aging performance of the PO-HDPEW-rejuvenated bitumen. This research provides insights into using HDPEW as a cost-effective and eco-friendly rejuvenator and modifier on bitumen properties, which can aid in the longevity and performance of pavements. Full article

Environmental sustainability and eco-efficiency stand as imperative benchmarks for the upcoming era of materials. The use of sustainable plant fiber composites (PFCs) in structural components has garnered significant interest within industrial community. The durability of PFCs is an important consideration and needs to be well understood before their widespread application. Moisture/water aging, creep properties, and fatigue properties are the most critical aspects of the durability of PFCs. Currently, proposed approaches, such as fiber surface treatments, can alleviate the impact of water uptake on the mechanical properties of PFCs, but complete elimination seems impossible, thus limiting the application of PFCs in moist environments. Creep in PFCs has not received as much attention as water/moisture aging. Existing research has already found the significant creep deformation of PFCs due to the unique microstructure of plant fibers, and fortunately, strengthening fiber-matrix bonding has been reported to effectively improve creep resistance, although data remain limited. Regarding fatigue research in PFCs, most research focuses on tension-tension fatigue properties, but more attention is required on compression-related fatigue properties. PFCs have demonstrated a high endurance of one million cycles under a tension-tension fatigue load at 40% of their ultimate tensile strength (UTS), regardless of plant fiber type and textile architecture. These findings bolster confidence in the use of PFCs for structural applications, provided special measures are taken to alleviate creep and water absorption. This article outlines the current state of the research on the durability of PFCs in terms of the three critical factors mentioned above, and also discusses the associated improvement methods, with the hope that it can provide readers with a comprehensive overview of PFCs’ durability and highlight areas worthy of further research. Full article