Search Results (2,215)

The mechanical properties and real-time damage evolution of sustainable concrete (SC) containing 100% recycled concrete aggregate (RCA) under the combined action of hybrid steel and polyolefin fibers were studied. Inspired by solving the massive effects on the environment from construction waste, as well as to improve the lower mechanical performance of lower-grade RCA, the effect of combining high-stiffness hooked-end steel fibers and flexible macro-polyolefin fibers within RCA was investigated. Six different mix designs were considered: plain, single-fiber (100% steel and 100% polyolefin) and three hybrid composites with varying fractions of the steel/polyolefin fibers (25/75, 50/50, and 75/25). Compressive, tensile and flexural strengths were determined by mechanical testing. During compressive testing, the damage evolution was monitored using low-cost acoustic emission (AE) as a non-destructive technique. Cumulative hits analysis, amplitude distributions, and the statistical b-value parameter were used for damage characterization. The results show that steel fiber significantly increased compressive strength (an increase of up to 13.8%), and the 50/50 hybrid mix showed a high synergistic effect, yielding the highest tensile (4.86 MPa) and flexural (25.54 MPa) strengths. AE analysis identified different damage fingerprints: Based on amplitude analysis, steel-fiber composites exhibited high-amplitude events (which may be attributable to fiber pull-out); polyolefin-fiber composites generated medium-amplitude events (may have resulted from distributed microcracking); and hybrid mixes displayed a mixed amplitude distribution. The b-value analysis provided insight into progressive damage and revealed that the hybrid fibers induce stable, diffuse damage that prevents the brittle failure of plain recycled aggregate concrete (RAC). The results show that hybrid fiber reinforcement can be a reliable approach to enhance the mechanical performance and crack resistance of RAC. Furthermore, low-cost acoustic emission (AE) serves as an effective non-destructive method for monitoring damage progression within the material. Full article

The rapid growth in the use of carbon fiber-reinforced polymers (CFRPs) and fused-deposition-modeled (FDM) polylactic acid (PLA) has generated substantial non-biodegradable and thermoplastic waste streams, creating urgent needs for scalable recycling and valorization strategies. This study develops and evaluates an integrated route that chemically recovers carbon fibers (CFs) from CFRP waste and converts them into high-performance reinforcements for recycled PLA matrices. CFRP fragments were pre-swollen in acetic acid (120 °C, 1 h), then depolymerized by means of oxidation with 1 M KMnO₄ (100 °C, 2 h), washed, dried (100 °C, 24 h), and size-reduced by means of cryogenic milling. Recycled CFs (treated) and untreated CFRP fragments were blended with 3D-printing PLA waste at 10, 20 and 30 wt.% via melt mixing (175 °C, 5 min, 70 rpm) and molded into ASTM D638 dog-bone specimens. Materials were characterized via XRD, FTIR, Raman, SEM and mechanical testing. XRD and Raman confirmed retention of the graphitic backbone after treatment; FTIR and Raman revealed oxygen-containing surface functionalization consistent with oxidation, while SEM showed effective removal of epoxy and improved fiber surface cleanliness. Compared with neat PLA (tensile strength 45.4 MPa; modulus 2.6 GPa; elongation 6.3%), composites reinforced with chemically recycled CFs exhibited marked mechanical enhancement: at 30 wt.% treated CF, the tensile strength increased to 102.6 MPa (+126%), elastic modulus to 11.7 GPa (+350%), and toughness to 250.3 MPa, while ductility decreased to 2.9%. Equivalent composites with untreated CFRP exhibited smaller gains (30 wt.%: tensile 87.3 MPa; modulus 10.3 GPa), highlighting the benefit of epoxy removal and surface activation for fiber–matrix adhesion. The proposed chemical recycling pathway is operationally simple and cost-effective, produces reusable CFs with preserved graphitic structure and enhanced surface chemistry, and enables the fabrication of high-performance, waste-derived PLA composites suitable for structural and engineering applications. This work demonstrates a viable waste-to-value approach that advances circularity for both CFRP and 3D-printing polymer waste streams. Full article

This study investigates the effect of waste cement dust (CD) and rock wool (RW) inorganic fiber on the tribological performance of brake friction composite materials. Five formulations were fabricated by varying CD from 65 to 45 wt.% and RW from 5 to 25 wt.% and evaluated for tribological properties on a Chase friction testing machine in accordance with IS 2742 test procedures. The results show that composites containing higher CD and lower RW exhibited higher coefficients of friction, lower friction variability, and improved fade resistance. In contrast, composites containing higher RW and lower CD showed improved recovery characteristics and substantially enhanced wear resistance. The performance coefficient of friction decreased from about 0.521 to 0.442 as the formulation shifted from CD-rich to RW-rich compositions, while the variability coefficient increased from about 0.364 to 0.516. The highest wear was recorded for the composite containing 65 wt.% CD and 5 wt.% RW inorganic fiber, whereas the lowest friction fluctuations were obtained for the composite containing 55 wt.% CD and 15 wt.% RW inorganic fiber. Finally, a simple ranking process-based decision-making technique was employed to evaluate the overall performance of all the composites, suggesting 55 wt.% CD as the optimal content. These findings confirm the potential of waste CD as a viable functional constituent in brake friction composites when combined with RW inorganic fiber in an optimized manner. Full article

Food industry by-products represent an abundant and underexploited source of bioactive compounds, dietary fibers and proteins with significant potential for functional food development. Recent studies estimate that up to 30 to 50% of processed raw materials are discarded as by-products, while food waste contributes approximately 8–10% of global greenhouse gas emissions, equivalent to nearly 3.3 billion tons of CO₂ annually. This review critically evaluates advances (2015–2026) in the valorization of food industry by-products, with a focus on technological efficiency, health-related evidence, and environmental impact. Specifically, it addresses the following research question: to what extent do current valorization strategies provide measurable technological, nutritional, and environmental advantages over conventional food production systems? Emerging extraction technologies including ultrasound- and microwave-assisted extraction (20–40 kHz, 30–60 °C), supercritical fluid extraction (200–350 bar, 35–60 °C), enzymatic hydrolysis, and fermentation demonstrated improvements in extraction yields (up to 20–50% increases compared to conventional methods) and higher purity in the recovered compounds. These approaches enable the isolation of compounds such as pectins from citrus peels, polyphenols from grape pomace, galacto-oligosaccharides from dairy whey, and collagen from fish by-products. From an environmental perspective, valorization strategies can reduce waste disposal and associated emissions by up to 30%, depending on the scale and type of by-product processing. Furthermore, these approaches contribute directly to circular economy models and support multiple Sustainable Development Goals, particularly SDG 12 (responsible consumption and production) and SDG 13 (climate action). However, challenges remain, including variability in raw material composition, scalability limitations, and the limited availability of high-quality clinical evidence supporting health benefits. By integrating nutritional potential, technological feasibility, and sustainability indicators, this review provides a comprehensive and critical assessment of the current state of by-product valorization and identifies key gaps for future research. Full article

In this study, the effect of substituting waste glass aggregate and recycled concrete aggregate (RCA) at different ratios (20%, 40%, 60%, 80%, 100%) on the compressive strength performance of geopolymer concretes reinforced with tire-derived textile fibers (TDTF) was investigated. A total of 22 different mixtures were prepared, and their 7-day and 28-day compressive strengths, water absorption rates, and ultrasonic pulse velocity (UPV) were determined. The results showed that TDTF improved compressive strength in both waste aggregate series, with a more pronounced contribution at 28 days. Increasing the waste glass aggregate content reduced 28-day compressive strength by 16–31% compared with the control mixture, whereas RCA mixtures showed only 1–4% strength loss up to 60% replacement and 17–19% loss at higher replacement levels. Glass aggregate mixtures generally exhibited higher early-age strength, while RCA mixtures performed better at 28 days. TDTF addition increased the 28-day compressive strength by approximately 25–30%, depending on aggregate type and replacement level. The lowest water absorption value was obtained in the fiber-reinforced glass aggregate series, whereas the highest value was measured in the RCA series, mainly due to the porous adhered mortar on RCA particles. Based on the compressive strength, water absorption, and UPV results, RCA replacement levels up to 60% and glass aggregate replacement levels of 40–60% may be considered suitable for the mixtures examined in this study. Full article

Infrastructure expansion in Indonesia has increased demand for paving blocks, raising concerns over cement production costs and environmental impact. This study investigates the comparative effectiveness of pineapple leaf fiber (PALF, Ananas comosus) and sisal fiber (Agave sisalana) as reinforcements in paving blocks, evaluating water absorption and 28-day compressive strength at fiber contents of 0%, 1%, 3%, 5%, and 7% by cement volume. A full-factorial two-way ANOVA with post-hoc Tukey HSD was employed. A dosage of 3% for both fiber types resulted in compressive strengths of 14.5 MPa (PALF, +59% vs. control) and 15.2 MPa (sisal, +67% vs. control), both of which met the requirements of SNI 03-0691-1996 Class B. Sisal fiber demonstrated superior compressive performance, consistent with its higher stiffness and tensile strength as reported in the literature. Water absorption increased monotonically with fiber content for both types, with SNI Class D compliance (≤10%) maintained only at 0% for PALF and 0–1% for sisal, a known consequence of the inherently hydrophilic nature of plant-based natural fibers. A statistically significant interaction term (F = 3.697, p = 0.012) confirmed that the two fibers respond differently to dosage increases, providing nuanced practical guidance beyond what single-factor studies can offer. These findings demonstrate the promising compressive strength of agricultural waste fiber-reinforced paving blocks, warranting further investigation of abrasion resistance, flexural strength, and long-term durability before practical deployment. Such utilization supports circular economy principles in the construction industry. Full article

This paper develops foamed mixture lightweight soil (FMLS) using dredged soil for ecological floating landscapes applications, focusing on key performance indices including dry density, compressive strength, splitting tensile strength, water absorption, and fluidity. Orthogonal experiments determined the optimal mix ratio, while CaO expansion agent, MgO expansion agent, polypropylene fiber (PPF), and basalt fiber (BF) were employed to modify material properties. The microstructural mechanisms of FMLS before and after modification were characterized by scanning electron microscopy (SEM). The results show that FMLS achieves optimal comprehensive performance at a cement-to-sand ratio of 0.4, foam content of 10%, and water-to-sand ratio of 0.35, with all parameters conforming to technical specifications. The optimal dosage for both CaO and MgO expansion agents is 5%, PPF is 0.3% and BF is 0.5%, respectively. MgO expansion agent and PPF demonstrate superior suitability for floating landscapes due to enhanced pore-filling efficiency and crack-bridging effects by SEM. Finally, correlation analysis further indicates that the water–binder ratio critically governs the strength characteristics of FMLS. This paper not only provides a new direction to promote the effective use of dredged soil resources, but also provides new ideas for carrier materials for ecological floating landscapes. Full article

There is renewed interest in local sourcing, regional supply chains, and the rebuilding of fiber-to-fashion systems. However, limited attention has been paid to the upstream role of fiber farmers and the infrastructure that enables or constrains regional textile economies. This study investigates the opportunities and challenges of fiber farming in West Virginia and explores the motivations that drive participation in this sector. Using a qualitative approach, semi-structured interviews were conducted with 16 fiber farmers across West Virginia. The findings revealed five interconnected themes: heterogeneous actants, the translation of wool, regional network breakdown, festivals and social media as network hubs, and institutional gaps and network fragility. The results indicate that fiber farming persists through strong community networks, adaptive entrepreneurial strategies, and deep attachments to place. However, its economic viability is constrained by declining processing infrastructure, labor shortages, weakened institutional support, and fragmented supply chains. These challenges also have important sustainability implications. Most notably, wool is often discarded because processing and transportation costs exceed its market value, resulting in the waste of a renewable and biodegradable fiber that could otherwise remain in productive use. This study contributes to the literature on local sourcing, rural entrepreneurship, and sustainable and circular economies by highlighting the relational infrastructures required to rebuild regionally embedded textile systems in Appalachia and beyond. Full article

The valorization of agro-industrial byproducts is attracting attention due to its potential to support circular bioeconomy development in food systems. Dragon fruit (Selenicereus spp.) peel, representing approximately one-third of total fruit mass, is an underutilized biomass that is high in pectin content. Unlike standardized commercial citrus and apple pectins, pectin from dragon fruit peel exhibit variability in their galacturonic acid content, degree of esterification, molecular weight, and rhamnogalacturonan-I branching structure, which are dependent on how the pectin is extracted. These structural attributes influence the solubility, rheological properties, gelation mechanisms, emulsifying capacity, and water-holding properties. There is emerging evidence that rhamnogalacturonan-I-enriched fractions promote the growth of beneficial microorganisms and may also increase the in vitro production of short-chain fatty acid, thereby exhibiting potential prebiotic activity. In addition, low methoxyl pectin has been shown to provide excellent properties for the calcium-mediated encapsulation of probiotics, as well as for pH-sensitive release in the gastrointestinal tract, thus supporting the synbiotic concept. The purpose of the current paper is to provide an overview of recent findings related to extraction technologies, structural characterization, structure–function relationship, fermentation behavior, potential delivery of probiotics, and the regulatory requirements for using dragon fruit peel pectin in the development of functional foods. Full article

This article proposes a sustainable approach to producing eco-friendly paper from fibers derived from water hyacinth (Eichhornia crassipes), an invasive aquatic species with potential high lignocellulose content. The research evaluated the possibility of using its biomass as a non-wood raw material for papermaking through an industrial-oriented processing framework. About 10 groups of water hyacinth samples were analyzed by separating their components (roots, leaves, and stems) to determine moisture content, dry biomass yield, fiber distribution, and performance in papermaking. Mechanical pulping and mild alkaline treatment with sodium hydroxide were compared to evaluate their effects on fiber behavior and paper quality. The results showed a high moisture content in the biomass, averaging approximately 88%, while the remaining dry matter represented the usable fibrous material fraction. After fiber classification, it was revealed that the long fibers predominated over the short fibers and the fine fibers (waste), favoring the hydrogen bonding and structural anchoring during sheet formation. Mechanical quality analyses were conducted using the Corrugating Medium Test (CMT), Concora Crush Test (CCT), Ring Crush Test (RCT), and Short Compression Test (SCT). Untreated water hyacinth paper demonstrated mechanical properties comparable to those of an industrial reference paper, including consistent compression resistance and corrugating performance. In contrast, the alkaline-treated sample showed greater structural uniformity but lower mechanical strength due to fiber fragmentation and increased fine production. Overall, the findings showed that Eichhornia crassipes represents a viable and sustainable alternative to non-wood fibers for paper production, offering potential environmental benefits by serving as an invasive species and reducing dependence on wood-based raw materials. Full article

Polymeric geosynthetics serve as fundamental components of engineered composite liners in waste containment facilities. The interface shear behavior between a coextruded textured geomembrane (GMTC) and a bentonite–polymer composite geosynthetic clay liner (BPC-GCL) was investigated under both dry and hydrated conditions, with varying polymer content (0%, 3.5%, and 5.5%), using large-scale direct shear tests. Hydration of BPC-GCL was found to significantly reduce GMTC/BPC-GCL interface shear strengths, with the magnitude of reduction increasing with normal stress. For the BPC-GCL with 3.5% polymer content, the peak strength at 400 kPa decreased by 36% from 272 kPa (dry) to 175 kPa (hydrated), which was attributed to bentonite softening and reduced frictional resistance. Polymer content non-linearly influenced shear behavior. At 400 kPa, the 3.5% BPC-GCL exhibited an 18% higher peak strength than the conventional GCL, while the 5.5% BPC-GCL showed a 9% reduction compared to the 3.5% specimen, attributed to internal structural damage and interfacial lubrication. Visual post-shear inspections revealed that dry conditions promoted interfacial friction-dominated failure, while hydration induced significant internal BPC-GCL damage, including fiber break and bentonite extrusion. The failure mode shifted with polymer content, and conventional GCL failed through internal bentonite deformation, while BPC-GCL exhibited a composite mechanism combining internal reinforcement and interfacial friction, with the 3.5% BPC-GCL demonstrating a more favorable composite effect than the 5.5% BPC-GCL. The study underscored the critical roles of hydration conditions and polymer modification in governing the shear mechanisms and strength at the GMTC/BPC-GCL interface. Full article

New partially bio-based, waste-derived composites are manufactured from date palm surface fibers (DPSF), waste coffee filters (CFP), and disposable medical isolation gowns (MIG). These three disposable raw materials fill landfills and create an environmental problem. Therefore, the objective of this current study is to use such materials in creating promised thermal insulation and sound absorption boards. Six hybrid composites with different compositions were made using Polyvinyl acetate (PVA) wood adhesive as a binder. Three of them were made of DPSF and MIG, and the other three were composed of DPSF and the CFP. Different tests were performed on the developed composites, such as thermal conductivity measurements, sound absorption and noise reduction determination, surface morphology image analysis, thermogravimetric analysis, and three-point bending tests. The results showed that the thermal conductivity coefficients for the hybrids DPSF + MIG and DPSF + CFP are in the ranges 0.0493–0.0613 W/(m·K) and 0.052–0.065 W/(m·K), respectively, over the temperature range 24–82 °C. The sound absorption coefficient (SAC) is greater than 0.4 for all composites at frequency bands greater than 500 Hz. The noise reduction coefficient (NRC) is ≥0.45 for all composites. Surface morphology images of the composites were also reported. The results also show that the composites are thermally stable at temperatures up to 258.3 °C. The flexural modulus ranges between 5.0 and 8.46 MPa for the medical isolation gown composites and 2.49 and 5.57 MPa for the coffee filter paper composites. The hybrid composites have a lower moisture content of 0.51% to 2.5%. These promising results support the use of these composites for thermal insulation and sound absorption in building construction as alternatives to conventional thermal insulations derived from crude fuels. Full article

This perspective focuses on the field of solid waste recovery and resource utilization for end-of-life (EoL) wind turbine blades. Wind energy plays a central role in the global transition toward low-carbon energy systems owing to its technological maturity, scalability, and widespread resource availability. As global installed wind power capacity exceeded 1000 GW in 2024, improving the life-cycle energy efficiency and resource productivity of wind energy systems has become increasingly important. In this context, wind turbine blades (WTBs), the most material-intensive components with high embodied energy, are approaching large-scale end-of-life replacement, with global EoL blade waste projected to reach 2–4 million tons by 2030. Although blades may reach the end of their structural service life, they contain substantial quantities of reinforcing fibers and polymeric matrices that embody significant material and manufacturing energy. Integrating blade recycling into the wind energy value chain represents a critical opportunity to reduce dependence on energy-intensive virgin materials and lower life-cycle energy consumption and associated carbon emissions. However, the realization of energy-efficient circular utilization remains constrained by several challenges, including inefficient heat and mass transfer during blade depolymerization, limited valorization of resin-derived products, and performance degradation of recovered fibers. This perspective examines the material characteristics of blades from a life-cycle energy utilization standpoint, assesses existing recycling pathways, and identifies key technological and system-level bottlenecks. Emphasis is placed on process intensification, product upgrading, and design-for-circularity strategies to support the long-term sustainability of wind power systems. Full article

Wine production is one of the most important agricultural activities worldwide, and generates significant amounts of organic by-products, particularly grape pomace. Traditionally, this was seen as waste, but currently, this residue has been reanalyzed from the perspective of the principles of the bioeconomy and circular economy, demonstrating its potential as a rich source of bioactive compounds with great potential for valorization. Its heterogeneous composition accumulates a variety of polyphenols, dietary fibers, flavonoids, phenolic acids, and other secondary metabolites that confer important biological properties, including antioxidant, anti-inflammatory, and antimicrobial activities. The chemical composition of grape pomace varies substantially according to variety, winemaking method, and extraction conditions, directly impacting its potential application. Extraction methods have progressed from traditional procedures to more advanced techniques such as ultrasound, supercritical fluids, and natural solvents, enabling the selective separation of high-value compounds. This review provides a comprehensive and critical overview of grape pomace valorization, emphasising its composition, green extraction and current industrial applications. In addition, regulatory frameworks and sustainability strategies supporting the integration of grape pomace into value-added production chains are discussed. Overall, grape pomace valorization supports waste reduction and the production of new functional products that balance economic efficiency and environmental responsibility. Full article

Microplastic contamination in wetland ecosystems is an escalating environmental threat, compromising ecosystem services, biogeochemical cycling and biodiversity conservation. This study assessed the occurrence, distribution and physicochemical characteristics of microplastics in the Ramsar-designated Pallikaranai wetland, southern India. Six representative subsamples were collected from spatially distinct locations and analyzed using density separation, followed by polymer identification via Raman spectroscopy and energy-dispersive X-ray spectroscopy (EDS). Microplastics were ubiquitously detected across both sediment and water matrices, with significantly higher abundances in sediments, indicating their role as a major sink. The dominant polymer types, polyethylene (PE), polypropylene (PP) and polystyrene (PS), along with prevalent morphotypes such as fragments, fibers, beads and foams, reflect diverse and persistent anthropogenic inputs. The compositional profile strongly implicates mismanaged domestic and urban waste as the primary source. The widespread presence and accumulation of microplastics in this ecologically sensitive wetland raise concerns over potential impacts on trophic interactions, habitat quality and long-term ecosystem resilience. These findings underscore the urgent need for targeted waste management strategies, pollution mitigation frameworks and continuous monitoring to safeguard the ecological integrity of the Pallikaranai wetland and similar Ramsar-listed ecosystems. Full article