Search Results (66)

The use of recycled materials and locally sourced alternative binders in 3D concrete printing (3DCP) has significant potential to reduce carbon emissions in concrete construction. This study examines the effect of sugarcane bagasse ash (SCBA), a byproducts from the sugarcane industry, as a sustainable binder in 3DCP. SCBA was oven-dried at 105 °C, sieved to 250 µm, and used to replace up to 25% of the total binder by weight in a supplementary cementitious material (SCM) blended system. The impact of polypropylene (PP) and steel (ST) microfibres on SCBA-based mixes was also investigated. The fresh properties of the mortar were evaluated using the flow table, Vicat needle, shape retention, buildability, and rheometer tests. The mortar was 3D printed using a small-scale robotic setup with a RAM extruder. Mechanical properties were then tested, including compressive and flexural strengths, and interlayer bonding, along with microstructure analysis. The results showed that increasing the SCBA content led to greater slump and improved flowability, as well as a slower rate of static yield stress development, with up to a 90 percent reduction compared to the control mix. The addition of PP fibres doubled the static yield stress in the mixes containing 20 percent SCBA. The 10 percent SCBA mix achieved the highest mechanical strength, both in compression and flexure, due to its denser microstructure and enhanced pozzolanic reaction. Full article

This study investigates the synergistic influence of multi-walled carbon nanotubes (MWC-NTs), nanosilica powder (NSP), and polypropylene fiber waste (PFW) on the mechanical performance of mortar incorporating demolished concrete waste aggregates (DCWA). The replacement of natural aggregates with DCWA typically results in strength reductions and weak interfacial transition zones; therefore, the combined use of nanomaterials and microfibers is proposed as a mitigation strategy. A Taguchi Design of Experiments (DOE) approach was employed to optimize mix parameters, including MWCNT dosage, NSP content, PFW volume fraction, and DCWA replacement level. Mortar mixtures were prepared with MWCNTs (0–0.1% by binder weight), NSP (0–2% by binder weight), PFW (0–0.3% by volume), and DCWA (0–20% replacement of fine sand). Mechanical performance was assessed through compressive and flexural strength tests. A combined statistical approach using the Pareto chart and ANOVA identified the most influential parameters and their respective contributions to the response variable. The innovative aspect of this research lies in the synergistic integration of MWCNTs, NSP, demolished concrete waste, and polypropylene fiber waste within the mortar matrix, with the incorporation of nanomaterials specifically intended to compensate for the strength reduction typically induced by the use of demolition concrete waste aggregates. Although a potential nano-scale synergy between MWCNTs and NSP was initially considered, the experimental results indicated that the most relevant synergistic effects occurred among broader mix parameters rather than specifically between the two nanomaterials. Even so, when assessed individually, both nanomaterials contributed to improving the mechanical characteristics of the mortar—particularly nanosilica, which demonstrated a more pronounced effect—yet these individual enhancements did not translate into a distinct synergistic interaction between MWCNTs and NSP. The Taguchi DOE proved to be an efficient tool for multiple factor analysis, enabling reliable identification of the most influential parameters with a minimum number of tests. Its application facilitated the development of mortar mixtures that effectively integrate demolition waste while achieving enhanced mechanical performance through nano- and micro-scale reinforcement. Full article

This research examines the electrochemical polymerization of 3-Methyl-4-phenylpyrrole on carbon microfibers and compares its electrode performance with similar structures utilizing Poly-pyrrole and Poly-3-Phenylpyrrole on carbon microfibers. For technological considerations, going beyond a rate of 90 mV/s for the electrochemical deposition of the 3-Methyl-4-phenylpyrrole polymer is not advisable. By examining the Nyquist diagram, it is noted that the highest phase angle, exceeding 80°, occurs for the carbon–polymer structure created at a deposition rate of 70 mV/s, displaying the most pronounced capacitive behavior. Similar results at a deposition rate of 70 mV/s regarding SEM and AFM images were noted, revealing a structure that resembles the shape of the deposited polymer granules as “droplets” with a reduced average roughness level, at under 60 nm, and achieving a layer thickness of over 0.7 μm. Considering the results from cyclic voltammetry and electrochemical impedance, it was observed that the carbon micro-fiber structure coated with 3-Methyl-4-phenylpyrrole polymer shows superior capacitive behavior when compared to similar structures using pyrrole and 3-Phenyl-pyrrole polymers. 3-Methyl-4-phenylpyrrole also showed a lower admittance value than 3-Phenyl-pyrrole, and presented the highest capacitance, leading to a maximum increase of +27.3% in relation to pyrrole, emphasizing the significance of studying this PPy derivative for energy storage applications. Full article

Single-molecule detection (SMD) has reformed analytical science by enabling the direct observation of individual molecular events, thus overcoming the limitations of ensemble-averaged measurements. This review presents a comprehensive analysis of the principles, devices, and emerging materials that have shaped the current landscape of SMD. We explore a wide range of sensing mechanisms, including surface plasmon resonance, mechanochemical transduction, transistor-based sensing, optical microfiber platforms, fluorescence-based techniques, Raman scattering, and recognition tunneling, which offer distinct advantages in terms of label-free operation, ultrasensitivity, and real-time responsiveness. Each technique is critically examined through representative case studies, revealing how innovations in device architecture and signal amplification strategies have collectively pushed the detection limits into the femtomolar to attomolar range. Beyond the sensing principles, this review highlights the transformative role of advanced nanomaterials such as graphene, carbon nanotubes, quantum dots, MnO₂ nanosheets, upconversion nanocrystals, and magnetic nanoparticles. These materials enable new transduction pathways and augment the signal strength, specificity, and integration into compact and wearable biosensing platforms. We also detail the multifaceted applications of SMD across biomedical diagnostics, environmental monitoring, food safety, neuroscience, materials science, and quantum technologies, underscoring its relevance to global health, safety, and sustainability. Despite significant progress, the field faces several critical challenges, including signal reproducibility, biocompatibility, fabrication scalability, and data interpretation complexity. To address these barriers, we propose future research directions involving multimodal transduction, AI-assisted signal analytics, surface passivation techniques, and modular system design for field-deployable diagnostics. By providing a cross-disciplinary synthesis of device physics, materials science, and real-world applications, this review offers a comprehensive roadmap for the next generation of SMD technologies, poised to impact both fundamental research and translational healthcare. Full article

The automation of concrete constructions through 3D printing (3DP) has been increasingly developed and adopted in civil engineering due to its promising advantages over traditional construction methods. However, widespread implementation is hindered by uncertainties in quality control, homogeneity, and interlayer bonding, as well as the uniqueness of each printed component. Building upon our prior work in developing 3D-printable self-sensing cementitious materials by incorporating graphite powder and carbon microfibers into a cementitious matrix to enhance its piezoresistive properties, this study aims at enabling condition assessment of cementitious 3DP by integrating the self-sensing materials as sensing nodes within conventional components. Three different 3D-printed strip patterns, consisting of one, two, and three strip lines that mimic the pattern used in fabricating foil strain gauges were investigated as conductive electrode designs to impart strain sensing capabilities, and characterized from a series of quasi-static and dynamic tests. Results demonstrate that the three-strip design yielded the highest sensitivity (${\lambda }_{\mathrm{stat}}$ of 669, ${\lambda }_{\mathrm{dyn}}$ of 630), whereas the two-strip design produced the highest signal quality (SNR_stat = 9.5 dB, SNR_dyn = 10.8 dB). These findings confirm the feasibility of integrating 3D-printed self-sensing cementitious materials through hybrid manufacturing, enabling monitoring of print quality, detection of load path changes, and identification of potential defects. Full article

Addressing the urgent need for robust and sustainable catalysts to detoxify nitroaromatic pollutants, this study introduces a novel approach for synthesizing cobalt oxide nanocomposites via pyrolysis of cobalt benzene-1,3,5-tricarboxylate. By integrating porous carbon (PC) and nano silica (NS) supports with Co₃O₄ to form (Co₃O₄/PC) and (Co₃O₄/NS), we achieved precise morphological control, as evidenced by SEM and TEM analysis. SEM revealed 80–500 nm Co₃O₄ microspheres, 300 nm Co₃O₄/PC microfibers, and 2–5 µm Co₃O₄/NS spheres composed of 100 nm nanospheres. TEM further confirmed the presence of ~15 nm nanoparticles. Additionally, FTIR spectra exhibited characteristic Co–O bands at 550 and 650 cm⁻¹, while UV–Vis absorption bands appeared in the range of 450–550 nm, confirming the formation of cobalt oxide structures. Catalytic assays toward p-nitrophenol reduction revealed exceptional kinetics (k = 0.459, 0.405, and 0.384 min⁻¹) and high turnover numbers (TON = 5.1, 6.7, and 6.3 mg 4-NP reduced per mg of catalyst), outperforming most of the recently reported systems. Notably, both supported catalysts retained over 95% activity after two regeneration cycles. These findings not only fill a gap in the development of efficient, regenerable cobalt-based catalysts, but also pave the way for practical applications in environmental remediation. Full article

The global outbreak and prolonged presence of Coronavirus Disease 2019 (COVID-19) have resulted in a substantial accumulation of discarded masks, posing serious environmental challenges. This study proposes an eco-friendly and low-carbon strategy to repurpose discarded DMFM fibers as a key component in fiber-reinforced self-compacting recycled aggregate concrete (FRSCRAC). The mechanical and environmental performance of FRSCRAC was systematically evaluated by investigating the effects of recycled coarse aggregate (RCA) replacement ratios (0%, 50%, 100%), discarded DMFM fiber material (DMFM) contents (0%, 0.1%, 0.2%, 0.3%), and fiber lengths (2 cm, 3 cm, 4 cm) on axial compression failure mode and stress–strain behavior. The results demonstrated that DMFM fibers significantly enhanced concrete ductility and peak stress via the fiber-bridging effect. Based on fiber influence, modified stress–strain and shrinkage models for SCRAC were established. To further understand the fiber fixation mechanism, X-ray computed tomography (X-CT) and scanning electron microscopy (SEM) analyses were conducted. The findings revealed a stable random distribution of fibers and strong interfacial bonding between fibers. These improvements contributed to enhanced mechanical performance and the effective immobilization of polypropylene microfibers, preventing further microplastics release into the air. This innovative approach provides a sustainable solution for recycling and effectively immobilizing discarded DMFM fibers in concrete over long curing periods, while also enhancing its properties. Full article

Fast fashion is a rapidly expanding sector characterized by high production volumes, low costs, and short product lifecycles. While recent efforts have focused on improving sustainability within supply chains, consumer behavior remains a critical yet underexplored driver of environmental impacts. This study presents a web-based calculator tool designed to estimate both the carbon and plastic footprints associated with individual fast fashion consumption, with a particular focus on shopping behaviors, garment disposal, and laundry habits. Adopting a geographical perspective, the analysis explicitly considers the spatial dynamics of consumption and logistics within the urban context of Milan (Italy), a dense metropolitan area representative of high fashion activity and mobility. By incorporating user-reported travel patterns, logistics routes, and localized emission factors, the tool links consumer habits to place-specific environmental impacts. By involving over 360 users, the tool not only quantifies emissions and plastic waste (including microfibers) but also serves an educational function, raising awareness about the hidden consequences of fashion-related choices. Results reveal high variability in environmental impacts depending on user profiles and behaviors, with online shopping, frequent use of private vehicles, and improper garment disposal contributing significantly to emissions and plastic pollution. Our findings highlight the importance of integrating consumer-focused educational tools into broader sustainability strategies. The tool’s dual function as both calculator and awareness-raising platform suggests its potential value for educational and policy initiatives aimed at promoting more sustainable fashion consumption patterns. Full article

Electroactive biomaterials are a key emerging technology for the treatment of neural damage. Conducting polymer-coated carbon microfibers are particularly useful for this application because they provide directional support for cell growth and tissue repair and simultaneously allow for ultrasensitive recording and stimulation of neural activity. Here, we report in vitro experiments investigating the biology of Schwann cells (SCs), a major player in peripheral nerve regeneration, on electroconducting microfibers. The optimal molecular composition of the cell substrate and cell culture medium was studied for SCs dissociated from rat and pig peripheral nerves. The substrate molecules were then attached to carbon microfibers coated with poly (3,4-ethylenedioxythiophene) doped with poly [(4-styrenesulfonic acid)-co-(maleic acid)] (PCMFs), which served as an electroactive scaffold for culturing nerve explants. Biphasic electrical stimulation (ES) was applied through the microfibers, and its effects on cell proliferation and migration were assessed in different cell culture media. Rodent and porcine SCs avidly migrated on PCMFs functionalized with a complex of poly-L-lysine, heparin, basic fibroblast growth factor, and fibronectin. Serum and forskolin/heregulin increased, by two-fold and four-fold, the number of SCs on PCMFs, respectively, and ES further doubled cell numbers without favoring fibroblast proliferation. ES additionally increased SC migration. These results provide a baseline for using biofunctionalized PCMFs in peripheral nerve repair. Full article

This study investigates multi-scale reinforcement of Ultra-High-Performance Concrete through targeted modifications of its mechanical and fracture-resistant properties via carbon microfibers and carbon nanotubes. The research employed comprehensive characterization techniques including workability tests, mercury porosimetry for microscale porosity analysis, and X-ray tomography for macro-scale pore evaluation. Mechanical performance was assessed through compression strength, tensile strength, and fracture energy measurements. Results demonstrated significant performance enhancements testing UHPC samples with 6 mm carbon microfibers (9 kg/m³) and varying carbon nanotubes dosages (0.11–0.54 wt%). The addition of carbon microfibres improved compressive strength by 12%, while incorporating 0.54 wt% carbon nanotubes further increased strength by 24%. Remarkably, the combined reinforcement strategy yielded a 313% increase in tensile strength compared to the reference mixture. The synergistic effect of carbon fibers and carbon nanotubes proved particularly effective in enhancing concrete performance. This multi-scale reinforcement approach presents a promising alternative to traditional steel fiber reinforcement, offering superior mechanical properties and potential advantages in corrosive environments. Full article

This study investigated silicone composites with distributed boron nitride platelets and carbon microfibers that are oriented electrically. The process involved homogenizing and dispersing nano/microparticles in the liquid polymer, aligning the particles with DC and AC electric fields, and curing the composite with IR radiation to trap particles within chains. This innovative concept utilized two fields to align particles, improving the even distribution of carbon microfibers among BN in the chains. Based on SEM images, the chains are uniformly distributed on the surface of the sample, fully formed and mature, but their architecture critically depends on composition. The physical and electrical characteristics of composites were extensively studied with regard to the composition and orientation of particles. The higher the concentration of BN platelets, the greater the enhancement of dielectric permittivity, but the effect decreases gradually after reaching a concentration of 15%. The impact of incorporating carbon microfibers into the dielectric permittivity of composites is clearly beneficial, especially when the BN content surpasses 12%. Thermal conductivity showed a significant improvement in all samples with aligned particles, regardless of their composition. For homogeneous materials, the thermal conductivity is significantly enhanced by the inclusion of carbon microfibers, particularly when the boron nitride content exceeds 12%. The biggest increase happened when carbon microfibers were added at a rate of 2%, while the BN content surpassed 15.5%. The thermal conductivity of composites is greatly improved by adding carbon microfibers when oriented particles are present, even at BN content over 12%. When the BN content surpasses 15.5%, the effect diminishes as the fibers within chains are only partly vertically oriented, with BN platelets prioritizing vertical alignment. The outcomes of this study showed improved results for composites with BN platelets and carbon microfibers compared to prior findings in the literature, all while utilizing a more straightforward approach for processing the polymer matrix and aligning particles. In contrast to current technologies, utilizing homologous materials with uniformly dispersed particles, the presented technology reduces ingredient consumption by 5–10 times due to the arrangement in chains, which enhances heat transfer efficiency in the desired direction. The present technology can be used in a variety of industrial settings, accommodating different ingredients and film thicknesses, and can be customized for various applications in electronics thermal management. Full article

This paper explores the development of 3D-printed self-sensing Ultra-High Performance Concrete (UHPC) by incorporating graphite (G) powder, milled carbon microfiber (MCMF), and chopped carbon microfiber (CCMF) as additives into the UHPC matrix to enhance piezoresistive properties while maintaining workability for 3D printing. Percolation curves were established to identify optimal filler inclusion levels, and a series of compressive tests, including quasi-static cyclic, dynamic cyclic, and monotonic compressive loading, were conducted to evaluate the piezoresistive and mechanical performance of 29 different mix designs. It was found that incorporating G powder improved the conductivity of the UHPC but decreased compressive strength for both mold-cast and 3D-printed specimens. However, incorporating either MCMF or CCMF into the UHPC resulted in the maximum 9.8% and 19.2% increase in compressive strength and Young’s modulus, respectively, compared to the plain UHPC. The hybrid combination of MCMF and CCMF showed particularly effective in enhancing sensing performance, achieving strain linearity over 600 $\mu \epsilon$. The best-preforming specimens (3G250M250CCMF) were fabricated using 3 wt% of G, 0.25 wt% of MCMF, and 0.25 wt% of CCMF, yielding a maximum strain gauge factor of 540, a resolution of 68 $\mu \epsilon$, and an accuracy of 4.5 $\mu \epsilon$ under axial compression. The 3D-printed version of the best-performing specimens exhibited slightly diminished piezoresistive and mechanical behaviors compared to their mold-cast counterparts, yielding a maximum strain gauge factor of 410, a resolution of 99 $\mu \epsilon$, and an accuracy of 8.6 $\mu \epsilon$. Full article

As awareness of the impact of anthropogenic activities on climate change increases, the concepts of durability, resilience, and sustainability in concrete tend to be adopted more seriously in the concrete construction industry. In this sense, one of the concrete technologies that began in the 1980s and that significantly contributes to maximize the beneficial effect on all these concepts are the ultra-high-performance concretes, a very attractive technology because it presents ultra-high strength and durability performances far superior to those of conventional concretes, a performance that is leading to a permanent increased demand. However, the development of these concretes has been widely criticized due to their high ecological impact, which is mainly attributable to the high cement dosages required for their production (800–1000 kg/m³). To address this criticism in a comprehensive manner and thereby reduce the embodied carbon attributable exclusively to the material, this research was oriented to determine the effect of an industrial by-product of vitrified clay, as a partial or total substitution for cement, silica fume, and limestone aggregate, on the compressive strength, flexural toughness, and embodied CO₂. For the UHPC’s evaluated in this work with a dosage of 2% by volume of steel micro-fibers, the results evidence the feasibility that the following substitutions by mass: 30% of the Portland cement, 100% of the silica fume, and 30% of the limestone aggregate and powder, do not detract the fresh stage, the compressive strength, the static modulus of elasticity, and the flexural strength, leading to significant reductions of the embodied CO₂. Full article

The performance of high-performance concrete has been enhanced in the present study by incorporating non-metallic fibres without altering the binder content. The impact of these fibres on high-performance concrete flexural and compression characteristics and the arrangement of fibres within the composite were systematically analysed. Unlike conventional practices, the authors of the research introduce various non-metallic fibres, including alkali-resistant glass fibres, carbon microfibers, three types of polypropylene microfibers, and one type of polyvinyl alcohol fibre while maintaining an equal amount of binder. The research aims to comprehensively evaluate the fibre’s influence on cement composite properties. Various types of non-metallic fibres, highlighting differences in diameters and their physical-mechanical properties with a constant amount by volume, have been considered in the research. Alkali-resistant glass and carbon fibres exhibit low values of residual post-cracking force but polyvinyl alcohol fibres demonstrate the best post-cracking behaviour, with a residual post-cracking force value. This detailed examination of fibre distribution and composition sheds light on the nuanced effects on fresh and hardened concrete properties. Notably, this work diverges from existing research by maintaining a constant binder amount and considering the quantitative distribution of fibres in a unit volume of the cement matrix, along with their aspect ratio. These findings provide valuable insights for selecting the most suitable non-metallic fibres for enhancing high-performance concrete properties. Full article

Superhydrophobic strain sensors are highly promising for human motion and health monitoring in wet environments. However, the introduction of superhydrophobicity inevitably alters the mechanical and conductive properties of these sensors, affecting sensing performance and limiting behavior monitoring. Here, we developed an alkylated MXene–carbon nanotube/microfiber composite material (AMNCM) that is simultaneously flexible, superhydrophobic, and senses properties. Comprising a commercially available fabric substrate that is coated with a functional network of alkylated MXene/multi-walled carbon nanotubes and epoxy–silicone oligomers, the AMNCM offers high mechanical and chemical robustness, maintaining high conductivity and strain sensing properties. Furthermore, the AMNCM strain sensor achieves a gauge factor of up to 51.68 within a strain range of 80–100%, and exhibits rapid response times (125 ms) and long-term stability under cyclic stretching, while also displaying superior direct/indirect anti-fouling capabilities. These properties position the AMNCM as a promising candidate for next-generation wearable devices designed for advanced environmental interactions and human activity monitoring. Full article