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1
Manis, Frank, Georg Stegschuster, Jakob Wölling, and Stefan Schlichter. "Influences on Textile and Mechanical Properties of Recycled Carbon Fiber Nonwovens Produced by Carding." Journal of Composites Science 5, no. 8 (August 6, 2021): 209. http://dx.doi.org/10.3390/jcs5080209.
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Nonwovens made of recycled carbon fibers (rCF) and thermoplastic (TP) fibers have excellent economic and ecological potential. In contrast to new fibers, recycled carbon fibers are significantly cheaper, and the CO2 footprint is mostly compensated by energy savings in the first product life cycle. The next step for this promising material is its industrial serial use. Therefore, we analyzed the process chain from fiber to composite material. Initially, the rCF length at different positions during the carding process was measured. Thereafter, we evaluated the influence of the TP fibers on the processing, fiber shortening, and mechanical properties. Finally, several nonwovens with different TP fibers and fiber volume contents between 15 vol% and 30 vol% were produced, consolidated by hot-pressing, and tested by four-point bending to determine the mechanical values. The fiber length reduction ranged from 20.6% to 28.4%. TP fibers cushioned the rCF against mechanical stress but held rCF fragments back due to their crimp. The resulting bending strength varied from 301 to 405 MPa, and the stiffness ranged from 16.3 to 30.1 GPa. Design recommendations for reduced fiber shortening are derived as well as material mixtures that offer better homogeneity and higher mechanical properties.
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Jamshaid, Hafsa, Rajesh Mishra, Muhammad Zeeshan, Bilal Zahid, Sikandar Abbas Basra, Martin Tichy, and Miroslav Muller. "Mechanical Performance of Knitted Hollow Composites from Recycled Cotton and Glass Fibers for Packaging Applications." Polymers 13, no. 14 (July 20, 2021): 2381. http://dx.doi.org/10.3390/polym13142381.
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This research deals with the development of knitted hollow composites from recycled cotton fibers (RCF) and glass fibers (GF). These knitted hollow composites can be used for packaging of heavy weight products and components in aircrafts, marine crafts, automobiles, civil infrastructure, etc. They can also be used in medical prosthesis or in sports equipment. Glass fiber-based hollow composites can be used as an alternative to steel or wooden construction materials for interior applications. Developed composite samples were subjected to hardness, compression, flexural, and impact testing. Recycled cotton fiber, which is a waste material from industrial processes, was chosen as an ecofriendly alternative to cardboard-based packaging material. The desired mechanical performance of knitted hollow composites was achieved by changing the tube diameter and/or thickness. Glass fiber-reinforced knitted hollow composites were compared with RC fiber composites. They exhibited substantially higher compression strength as compared to cotton fiber-reinforced composites based on the fiber tensile strength. However, RC fiber-reinforced hollow composites showed higher compression modulus as compared to glass fiber-based composites due to much lower deformation during compression loading. Compression strength of both RCF- and GF-reinforced hollow composites decreases with increasing tube diameter. The RCF-based hollow composites were further compared with double-layered cardboard packaging material of similar thickness. It was observed that cotton-fiber-reinforced composites show higher compression strength, as well as compression modulus, as compared to the cardboard material of similar thickness. No brittle failure was observed during the flexural test, and samples with smaller tube diameter exhibited higher stiffness. The flexural properties of glass fiber-reinforced composites were compared with RCF composites. It was observed that GF composites exhibit superior flexural properties as compared to the cotton fiber-based samples. Flexural strength of RC fiber-reinforced hollow composites was also compared to that of cardboard packaging material. The composites from recycled cotton fibers showed substantially higher flexural stiffness as compared to double-layered cardboard material. Impact energy absorption was measured for GF and RCF composites, as well as cardboard material. All GF-reinforced composites exhibited higher absorption of impact energy as compared to RCF-based samples. Significant increase in absorption of impact energy was achieved by the specimens with higher tube thickness in the case of both types of reinforcing fibers. By comparing the impact performance of cotton fiber-based composites with cardboard packaging material, it was observed that the RC fiber-based hollow composites absorb much higher impact energy as compared to the cardboard-based packaging material. The current paper summarizes a comparative analysis of mechanical performance in the case of glass fiber-reinforced hollow composites vis-à-vis recycled cotton fiber-reinforced hollow composites. The use of recycled fibers is a positive step in the direction of ecofriendly materials and waste utilization. Their performance is compared with commercial packaging material for a possible replacement and reducing burden on the environment.
3
Schneller, Anna, Wolfgang M. Mueller, Ramona Roessle, and Siegfried R. Horn. "Surface Modification of Recycled Carbon Fibers by Use of Plasma Treatment." Key Engineering Materials 742 (July 2017): 576–82. http://dx.doi.org/10.4028/www.scientific.net/kem.742.576.
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In this study, sized and thermally desized virgin carbon fibers (vCF) as well as recycled carbon fibers (rCF) from a thermal recycling process are plasma treated by a plasma-jet. The effect of two different process gases (nitrogen and dinitrogen monoxide) and the influence of the distance between the plasma source and the fiber surface are studied with the aim of increasing the oxygen and nitrogen concentration on the rCF surfaces. Higher surface coverage of oxygen-and nitrogen-containing functional groups is supposed to lead to a better adhesion between the carbon fiber and the epoxy resin matrix. The elemental compositions and functional groups of the treated carbon fiber surfaces are studied by x-ray photoelectron spectroscopy. The effect of plasma treatment on the fiber properties like tensile strength, tensile modulus and surface roughness is investigated.
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Reichert, Olaf, Larisa Ausheyks, Stephan Baz, Joerg Hehl, and Götz T. Gresser. "Innovative rC Staple Fiber Tapes - New Potentials for CF Recyclates in CFRP through Highly Oriented Carbon Staple Fiber Structures." Key Engineering Materials 809 (June 2019): 509–14. http://dx.doi.org/10.4028/www.scientific.net/kem.809.509.
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Increasing waste streams of carbon fibers (CF) and carbon fiber reinforced plastics (CFRP) lead to increasing need for recycling and to growing amounts of recycled carbon fibers. A main issue in current research for carbon fiber recycling is the reuse of regained fibers. Carbon staple fibers such as recycled fibers hold big potential for mechanical properties of lightweight parts, if used properly. Applying recycled CF (rCF) as milled reinforcement fibers or as nonwoven in carbon fiber reinforced plastic leads to a poor yield of mechanical proper due to low fiber orientation, limitations in fiber volume content or due to short fiber length. The rC staple fiber tape presents a more efficient approach. Recycled carbon fibers are blended with 50 wt. % thermoplastic nylon 6 fibers and processed through a roller card to a sliver, which is a linear fibrous intermediate. The sliver is continuously drawn, formed, heated and consolidated to the thermoplastic rC staple fiber tape. The tape is similar to common carbon fiber tapes or to continuous tows but has different positive properties, such as high fiber orientation, homogeneous blend of fiber and matrix and suitability for deep drawing.
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Wilson, Peter, Alon Ratner, Gary Stocker, Frank Syred, Kerry Kirwan, and Stuart Coles. "Interlayer Hybridization of Virgin Carbon, Recycled Carbon and Natural Fiber Laminates." Materials 13, no. 21 (November 4, 2020): 4955. http://dx.doi.org/10.3390/ma13214955.
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To meet sustainability objectives in the transport sector, natural fiber (NF) and recycled carbon fiber (RCF) have been developed, although they have been typically limited to low to medium performance components. This work has considered the effect of interlayer hybridization of woven NF and non-woven RCF with woven virgin carbon fibers (VCF) on the mechanical and damping performance of hybrid laminates, produced using double bag vacuum infusion (DBVI). The mean damping ratio of the pure laminates showed a trend of NF>RCF>VCF, which was inversely proportional to their modulus. The tensile, flexural and damping properties of hybrid laminates were dominated by the outermost ply. The VCF-RCF and VCF-NF hybrid laminates showed a comparatively greater mean damping ratio. The results of this work demonstrate a method for the uptake of alternative materials with a minimal impact on the mechanical properties and improved damping performance.
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Vaidya, Uday, Mark Janney, Keith Graham, Hicham Ghossein, and Merlin Theodore. "Mechanical Response and Processability of Wet-Laid Recycled Carbon Fiber PE, PA66 and PET Thermoplastic Composites." Journal of Composites Science 6, no. 7 (July 7, 2022): 198. http://dx.doi.org/10.3390/jcs6070198.
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The interest in recycled carbon fiber (rCF) is growing rapidly and the supply chain for these materials is gradually being established. However, the processing routes, material intermediates and properties of rCF composites are less understood for designers to adopt them into practice. This paper provides a practical pathway for rCFs in conjunction with low cost and, for the most part, commodity thermoplastic resins, namely polyethylene (PE), polyamide 66 (PA66) and polyethylene terephthalate (PET). Industrially relevant wet-laid (WL) process routes have been adopted to produce mats using two variants of WL mats, namely (a) high speed wet-laid inclined wire to produce broad good ‘roll’ forms and (b) 3DEPTM process patented by Materials Innovation Technologies (MIT)-recycled carbon fiber (RCF), now Carbon Conversions, which involves mixing fibers and water and depositing the fibers on a water-immersed mold. These are referred to as ‘sheet’ forms. The produced mats were evaluated for their processing into composites as ‘fully consolidated mats’ and ‘non-consolidated’ as-produced mats. Comprehensive mechanical data in terms of tensile strength, tensile modulus and impact toughness for rCF C/PE, C/PA66 and C/PET are presented. The work is of high value to sustainable composite designers and modelers.
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Montava-Jordà, Sergi, Sergio Torres-Giner, Santiago Ferrandiz-Bou, Luis Quiles-Carrillo, and Nestor Montanes. "Development of Sustainable and Cost-Competitive Injection-Molded Pieces of Partially Bio-Based Polyethylene Terephthalate through the Valorization of Cotton Textile Waste." International Journal of Molecular Sciences 20, no. 6 (March 19, 2019): 1378. http://dx.doi.org/10.3390/ijms20061378.
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This study presents the valorization of cotton waste from the textile industry for the development of sustainable and cost-competitive biopolymer composites. The as-received linter of recycled cotton was first chopped to obtain short fibers, called recycled cotton fibers (RCFs), which were thereafter melt-compounded in a twin-screw extruder with partially bio-based polyethylene terephthalate (bio-PET) and shaped into pieces by injection molding. It was observed that the incorporation of RCF, in the 1–10 wt% range, successfully increased rigidity and hardness of bio-PET. However, particularly at the highest fiber contents, the ductility and toughness of the pieces were considerably impaired due to the poor interfacial adhesion of the fibers to the biopolyester matrix. Interestingly, RCF acted as an effective nucleating agent for the bio-PET crystallization and it also increased thermal resistance. In addition, the overall dimensional stability of the pieces was improved as a function of the fiber loading. Therefore, bio-PET pieces containing 3–5 wt% RCF presented very balanced properties in terms of mechanical strength, toughness, and thermal resistance. The resultant biopolymer composite pieces can be of interest in rigid food packaging and related applications, contributing positively to the optimization of the integrated biorefinery system design and also to the valorization of textile wastes.
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Kim, Kwan-Woo, Dong-Kyu Kim, Woong Han, and Byung-Joo Kim. "Comparison of the Characteristics of Recycled Carbon Fibers/Polymer Composites by Different Recycling Techniques." Molecules 27, no. 17 (September 2, 2022): 5663. http://dx.doi.org/10.3390/molecules27175663.
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In this study, three recycling methods, namely, mechanical grinding, steam pyrolysis, and the supercritical solvent process, which are used to acquire recycled carbon fibers (RCFs), were compared for their application in synthesizing polymer-matrix composites. RCF-reinforced polyethylene (PE) composites were prepared to compare the mechanical properties of the composites generated using the three recycling methods. The PE/RCF composites exhibited 1.5 times higher mechanical strength than the RCF-reinforced PE composites, probably because of the surface oxidation effects during the recycling processes that consequently enhanced interfacial forces between the RCF and the matrix. Further, the steam pyrolysis process showed the highest energy efficiency and can thus be applied on a large production scale in domestic recycled CF markets.
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Novotná, Jana, Martin Kormunda, Jakub Perner, and Blanka Tomková. "Comparison of the Influence of Two Types of Plasma Treatment of Short Carbon Fibers on Mechanical Properties of Epoxy Composites Filled with These Treated Fibers." Materials 15, no. 18 (September 9, 2022): 6290. http://dx.doi.org/10.3390/ma15186290.
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The interfacial interface between fibers and matrix plays a key role for epoxy matrix composites and short recycled randomly arranged fibers. This study used short recycled carbon fiber (RCF) as a filler. Plasma treatment was used for carbon fiber surface treatment. This treatment was performed using radio (RF) and microwave (MW) frequencies at the same pressure and atmosphere. Appropriate chemical modification of the fiber surfaces helps to improve the wettability of the carbon fibers and, at the same time, allows the necessary covalent bonds to form between fibers and the epoxy matrix. The effect of the plasma treatment was analyzed and confirmed by X-ray photoelectron spectroscopy, Raman microscopy, scanning electron microscopy, transmission electron microscopy and wettability measurements. Composite samples filled with recycled carbon fibers with low concentrations (1 wt%, 2.5 wt% and 5 wt%) and high concentrations (20 wt% and 30 wt%) were made from selected treated fibers. The mechanical properties (impact toughness, 3PB) were analyzed on these samples. It was found that the modulus of elasticity and bending stress increase with the increasing content of recycled carbon fibers. A more significant change in impact strength occurred in samples with low concentration.
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Omar, Nur’ain Wahidah Ya, Norshah Aizat Shuaib, Mohd Haidiezul Jamal Ab Hadi, Azwan Iskandar Azmi, and Muhamad Nur Misbah. "Mechanical and Physical Properties of Recycled-Carbon-Fiber-Reinforced Polylactide Fused Deposition Modelling Filament." Materials 15, no. 1 (December 28, 2021): 190. http://dx.doi.org/10.3390/ma15010190.
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Carbon-fiber-reinforced plastic materials have attracted several applications, including the fused deposition modelling (FDM) process. As a cheaper and more environmentally friendly alternative to its virgin counterpart, the use of milled recycled carbon fiber (rCF) has received much attention. The quality of the feed filament is important to avoid filament breakage and clogged nozzles during the FDM printing process. However, information about the effect of material parameters on the mechanical and physical properties of short rCF-reinforced FDM filament is still limited. This paper presents the effect of fiber loading (10 wt%, 20 wt%, and 30 wt%) and fiber size (63 µm, 75 µm, and 150 µm) on the filament’s tensile properties, surface roughness, microstructure, porosity level, density, and water absorptivity. The results show that the addition of 63 µm fibers at 10 wt% loading can enhance filament tensile properties with minimal surface roughness and porosity level. The addition of rCF increased the density and reduced the material’s water intake. This study also indicates a clear trade-off between the optimized properties. Hence, it is recommended that the optimization of rCF should consider the final application of the product. The findings of this study provide a new manufacturing strategy in utilizing milled rCF in potential 3D printing-based applications.
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Goergen, C., D. May, and P. Mitschang. "Integration of rCF in resin transfer pressing process." Journal of Reinforced Plastics and Composites 39, no. 9-10 (February 23, 2020): 361–72. http://dx.doi.org/10.1177/0731684420906879.
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A new composite manufacturing process, resin transfer pressing, is introduced in this paper. In this process, nonwoven fabrics made of recycled carbon fibers are oversaturated with thermoset resin, i.e. they contain excess resin. The oversaturated nonwoven fabrics are prefabricated and used as resin carrier in a press process, where they are placed in a heated mold together with a dry textile-based preform. During pressing, the resin is pressed out and transferred from the nonwoven into the non-impregnated preform and hence impregnates the whole reinforcement. This study examines the oversaturation of nonwoven fabrics, the resin transfer pressing laminate manufacturing and the surface quality of the laminates. The ability of a nonwoven fabric to be oversaturated with resin is defined by the saturation degree, which was determined as up to 12 for glass fiber nonwoven fabrics and up to 60 for recycled carbon fiber nonwoven fabrics. Different laminates are manufactured by resin transfer pressing, and the impregnation quality is evaluated. With an optimized stacking sequence, a pore content <1% was achieved. The use of recycled carbon fiber nonwovens in the resin transfer pressing process leads to a less wavy surface compared to a wet compression molding manufactured laminate, showing a decrease of waviness Wz25 of 11% minimum.
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Goergen, Christian, Stephan Baz, Peter Mitschang, and Götz T. Gresser. "Recycled Carbon Fibers in Complex Structural Parts - Organic Sheets Made of rCF Staple Fiber Yarns." Key Engineering Materials 742 (July 2017): 602–9. http://dx.doi.org/10.4028/www.scientific.net/kem.742.602.
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In order to sustainably establish carbon fiber reinforced polymer composites (CFRPC) in the market on an industry scale, solutions on how to recycle these new materials have to be developed. Quasi-continuously aligned carbon staple fiber structures in organic sheets made of recycled carbon are one approach which will be dealt with in this article. The process chain as well as the mechanical properties will be presented. Moreover, the specific feature of staple fiber yarns to be able to plastically deform under process temperature, enabling new degrees of deep-drawing of CFRPC organic sheets in the thermoforming process, will be highlighted.
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Belli, Alberto, Alessandra Mobili, Tiziano Bellezze, Francesca Tittarelli, and Paulo Cachim. "Evaluating the Self-Sensing Ability of Cement Mortars Manufactured with Graphene Nanoplatelets, Virgin or Recycled Carbon Fibers through Piezoresistivity Tests." Sustainability 10, no. 11 (November 2, 2018): 4013. http://dx.doi.org/10.3390/su10114013.
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This paper presents the resistivity and piezoresistivity behavior of cement-based mortars manufactured with graphene nanoplatelet filler (GNP), virgin carbon fibers (VCF) and recycled carbon fibers (RCF). GNP was added at 4% of the cement weight, whereas two percentages of carbon fibers were chosen, namely 0.05% and 0.2% of the total volume. The combined effect of both filler and fibers was also investigated. Mortars were studied in terms of their mechanical properties (under flexure and compression) and electrical resistivity. Mortars with the lowest electrical resistivity values were also subjected to cyclic uniaxial compression to evaluate the variations in electrical resistivity as a function of strain. The results obtained show that mortars have piezoresistive behavior only if they are subjected to a prior drying process. In addition, dry specimens exhibit a high piezoresistivity only when loaded with 0.2 vol.% of VCF and 0.4 wt.% of GNP plus 0.2 vol.% RCF, with a quite reversible relation between their fractional change in resistivity (FCR) and compressive strain.
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Attahu, C. Y., J. Yang, KH Wong, and C. K. Thein. "Flexural and shear strength properties of unidirectional carbon fiber reinforced polymer composite interleaved with recycled carbon fiber and short virgin aramid fiber non-woven mats." IOP Conference Series: Materials Science and Engineering 1225, no. 1 (February 1, 2022): 012005. http://dx.doi.org/10.1088/1757-899x/1225/1/012005.
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Abstract Carbon fiber reinforced polymer composites (CFRPs) are one of the most widely used composite types and wastes associated with them (CFRPs) get generated through either their manufacturing or end-of-service-life. Predominately due to environmental concerns and governmental regulations, recycling these CFRPs is needed and to make use of the recycled carbon fibers (rCFs), a wet paper-making technique was used to convert the rCFs into a 60 g/m2non-woven mat. For comparison purposes, the same technique was used to convert short virgin aramid fibers (vAFs) into a 60 g/m 2 non-woven mat. Each mat was sandwiched with two resin films and then interleaved with 12-ply unidirectional (UD) prepreg tapes (carbon/epoxy). The assemblage was molded into composite laminates using a vacuum bagging assisted compression molding technique, and the samples for the tests were cut using a waterjet machine accordingly. Compared with the control, the results indicate an increment in the flexural modulus, and the specific flexural modulus for the CFRPs with non-woven mats: the flexural modulus increased by approximately 8.2% and 12.0% for the CFRP with rCF and vAF mats, respectively; the specific flexural modulus increased around 9.5% and 13.3%, respectively for the CFRP with rCF and vAF mats. On the other hand, the shear strength approximately decreased by 6.4% and 6.0% for the CFRP with rCF and vAF mats, respectively. The negative shear strength performances of the composite laminates with non-woven mats reflected on their flexural strength performances: the flexural strength increased about 1.1% and decreased by approximately 7.9% for the CFRP with vAF and rCF mats, respectively. To resolve the negative shear strength performances, it is recommended that the surfaces of the mats be treated with a coupling agent to improve their interfacial adhesions.
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Hofmann, Marcel, Dirk Wenzel, Bernd Gulich, Heike Illing-Günther, and Daisy Nestler. "Development of Nonwoven Preforms Made of Pure Recycled Carbon Fibres (rCF) for Applications of Composite Materials." Key Engineering Materials 742 (July 2017): 555–61. http://dx.doi.org/10.4028/www.scientific.net/kem.742.555.
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For the development of an efficient and economic recycling process of carbon fibers (CF) still many technological challenges have to be mastered. One of them is the removal of all extraneous natural and synthetic fibres, e.g. polyester sewing threads. The objective of the research was to develop an in-line process for the removal of those extraneous fibres, which result from mechanical processes such as tearing. A promising approach for the removal of extraneous fibres from cut-off carbon-fibre material (CF) has been identified, getting recycled carbon fibres (rCF). For that purpose, the use of modern laser technologies is particularly promising. However, the focus was not the development of new laser systems, but the adaptation of existing technologies and their integration into textile processing steps for carbon fibre recycling. In addition to the removal of the extraneous fibres, the degree of CF losses and quality degradation due to fibre damage have been analysed and compared with optimum fibre characteristics. The separation has been experimented and corresponding laser parameters have been defined. Finally, the obtained carbon-fibre material has been tested with regard to its processability in textile manufacturing processes (dry non-woven fabric production) up to carbon fibre reinforced plastics (CFRP). For the evaluation of the material for potential applications, test plates from irradiated and non-irradiated material have been used. The performed tensile and flexural tests have proved that the irradiated material has similar properties compared to the non-exposed one.
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Hengstermann, M., MMB Hasan, A. Abdkader, and Ch Cherif. "Development of a new hybrid yarn construction from recycled carbon fibers (rCF) for high-performance composites. Part-II: Influence of yarn parameters on tensile properties of composites." Textile Research Journal 87, no. 13 (August 20, 2016): 1655–64. http://dx.doi.org/10.1177/0040517516658511.
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This article reports the successful manufacturing of hybrid yarns from virgin staple CF (40 or 60 mm) or recycled staple CF (rCF) by mixing with polyamide 6 (PA 6) fibers of defined length. The hybrid yarns are produced using an optimized process route of carding, drawing, and flyer machine. Furthermore, the influence of CF length, CF type (i.e. virgin or rCF), CF volume content, and twist of the yarn are also investigated regarding the tensile properties of unidirectionally laid (UD) thermoplastic composites. The results show that CF length, yarn twist, and CF content of composites play a big role on the tensile properties of thermoplastic composites. From the comparison of tensile strength of UD composites produced from 40 and 60 mm virgin staple CF, it can be seen that the increase of yarn twist decreases the tensile strength. However, the effect of twist on the tensile properties of UD composites manufactured from 40 mm virgin staple CF is insignificant. The tensile strength of UD thermoplastic composites manufactured from the hybrid yarn with 40 and 60 mm virgin staple CF and rCF is found to be 771 ± 100, 838 ± 81, and 801 ± 53.4 MPa, respectively, in the case of 87 T/m containing 50 volume% CF.
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Szpieg, M., K. Giannadakis, and LE Asp. "Viscoelastic and viscoplastic behavior of a fully recycled carbon fiber-reinforced maleic anhydride grafted polypropylene modified polypropylene composite." Journal of Composite Materials 46, no. 13 (October 21, 2011): 1633–46. http://dx.doi.org/10.1177/0021998311423858.
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The effect of maleic anhydride grafted polypropylene (MAPP) coupling agents on properties of a new composite made of recycled carbon fibers and recycled polypropylene (rCF/[rPP + MAPP]) was studied experimentally. This new material presented significantly improved properties, compared to the previous generation, without the addition of MAPP (Giannadakis K, Szpieg M and Varna J. Mechanical performance of recycled carbon fibre/PP. Exp Mech 2010; published online.). This was mostly attributed to improvement of the fiber/matrix interface. The inelastic and time-dependent behavior of the MAPP modified composite material in tension was analyzed. A series of quasi-static tensile and creep tests were performed to identify the material model, which accounts for: (a) damage-related stiffness reduction, (b)development of stress and time-dependent irreversible strains described as viscoplasticity, (c) nonlinear viscoelastic behavior. The damage-related stiffness reduction was found to be less than 10%. Although damage-dependent stiffness was not the main source of nonlinearity, it was included in the inelastic material model. In creep tests, it was found that the time and stress dependence of viscoplastic strains follows a power law, which makes the determination of the parameters in the viscoplasticity model relatively simple. The viscoelastic response of the composite was found to be linear in the investigated stress domain. The material model was validated in constant stress rate tensile tests.
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Donatelli, A., G. Casciaro, T. Marcianò, and F. Caretto. "Grinding, Melting and Reshaping of EoL Thermoplastic Polymers Reinforced with Recycled Carbon Fibers." Journal of Materials and Applications 10, no. 2 (November 15, 2021): 53–62. http://dx.doi.org/10.32732/jma.2021.10.2.53.
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This article assesses the technical feasibility of a recycling process based on grinding, melting and re-shaping of carbon fibers (CFs) reinforced thermoplastic polymers, in order to obtain new products that can be introduced in different markets, depending on mechanical properties retained. The idea at the basis of our study is that this kind of recycling process lies at the edge of the stages of recycling and re-use of materials, considering that the latter is preferable when considering the waste management hierarchy. Lower cost and similar mechanical strength of virgin CFs allowed the spread of recycled CFs in the automotive sector in the form of composite materials. Taking into account the Directive 2000/53/EC that sets out measures to prevent and limit waste from end-of-life (EoL) vehicles and their components, and ensures that where possible this is reused, recycled or recovered, we considered worth to investigate the recyclability of composite materials made with recycled CFs when they will reach the state of EoL materials. Considering this premise, an additional scope of this paper is therefore to provide some useful information about the possibility to perform a multiple closed loop recycling of rCF thermoplastic composites. Experiments carried out demonstrated that re-shaping of composites is technically feasible. Some square plates were produced without any setback. The mass balance of the recycling process demonstrated that about 88% of the EoL material can be recovered. Calculation of energy consumption showed that approximately 16 MJ are necessary in the treatment of 1 kg of EoL composites.
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Jalilifar, Hasan, Fatholla Sajedi, and Sadegh Kazemi. "Investigation on the Mechanical Properties of Fiber Reinforced Recycled Concrete." Civil Engineering Journal 2, no. 1 (January 1, 2016): 13–22. http://dx.doi.org/10.28991/cej-2016-00000009.
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The flexural strength of conventional concrete material is known to be enhanced by incorporating a moderate volume-fraction of randomly distributed fibers. However, there is limited information on describing the influence of fiber volume-fraction on the compressive and flexural strength of recycled coarse aggregate concrete (RCA-C) material. This paper reports on experimental test results of the RCA-C material replaced with 0, 30, 50 and 100% recycled aggregate and 0, 0.5, 1 and 1.5% steel fiber volume fraction. Three-point flexural tests of notched prism specimens were completed. The mechanical properties in compression were characterized using cube specimens. Significant improvement in compressive and flexural strength of RCA-C was found as fiber content increased from 0 to 1.5%. The experimental test results of RCA-C were further evaluated to investigate the influence of fiber content on flexural toughness. According to test results, the addition of steel fibers to RCA-C material appreciably increased the flexural toughness.
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Faure, Alexandre, Olivier Mantaux, Arnaud Gillet, and Gilles Cazaurang. "New Intelligent Semi-Products based on Recycled Carbon Fibres." IOP Conference Series: Materials Science and Engineering 1226, no. 1 (February 1, 2022): 012102. http://dx.doi.org/10.1088/1757-899x/1226/1/012102.
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Abstract The carbon fibre recycling industry is not yet able to operate at full capacity. This lack of potential is a repercussion of a low demand for recycled carbon fibres (rCF) to manufacture new composite materials. As a matter of fact, few semi-products containing recycled carbon fibres are available on the market. Moreover, rCF semi-products available do not allow to manufacture high performances composite parts. The MANIFICA project, based on highly realigned carbon fibres after steam thermolysis, aims at producing new semi-products from recycled carbon fibres for high performance composites. In this article we introduce the I2M/Université de Bordeaux re-alignment process producing continuous tapes made of highly aligned long discontinuous fibres. These tapes are then used to manufacture new intelligent rCF semi-products. In the first part, the mechanical properties of rCF composites based on different semi-products are compared. In the second part, several semi products based on realigned fibres tapes are presented. This work demonstrates that high performance products can be targeted with recycled carbon fibres, thanks to the development of these intelligent semi-products.
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Haji Badri, Khairiah, Mariana Mohd Zaini, Ahmad Zhafreen Reza Ahmad Redfzi, and Muhammad Syukri Ngah. "Recycled Carbon Fiber as Flame Retardant in Palm-Based Polyurethane Composite." Advanced Materials Research 1087 (February 2015): 251–56. http://dx.doi.org/10.4028/www.scientific.net/amr.1087.251.
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The effect of recovered carbon fiber (rCF) to the burning property of polyurethane composites was investigated. The carbon fiber reinforced polymer (CFRP) in mat form was first glycolysed at 190-200 oC and characterized by FTIR, TGA, DSC and SEM analyses. The rCF was added at 0, 0.5, 1.0 and 1.5% (w/w). The polyurethane filled with recovered carbon fiber composites (PU-rCF) have also undergone burning test. The TGA analysis of PU-rCF indicated the percentage of weight loss decreased from 95.6% to 91.4% as rCF content increased. The DSC showed the glass transition temperature, Tg of PU-rCF increased with increasing addition of rCF from 56.7 to 63.0oC. The burning rate of the PU-rCF decreased from 6.1 mm∙s-1 to 2.8 mm∙s-1 with increasing rCF. The FTIR analysis confirmed that there was no chemical interaction between the rCF and PU. The addition of rCF to PU has improved the burning property of the composite.
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Rahim, Mustaqqim Abdul, Omi Yanti Pohan, Mohd Badrul Hisyam Ab Manaf, Ahmad Nur Aizat Ahmad, Shahiron Shahidan, Zuhayr Md. Ghazaly, Nor Faizah Bawadi, et al. "Characteristics of Steel Fiber Reinforced Concrete With Recycled Coarse Aggregate." Journal of Civil Engineering, Science and Technology 9, no. 2 (October 3, 2018): 1. http://dx.doi.org/10.33736/jcest.987.2018.
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Steel is one of the fibers used in fiber reinforced concrete technology. Steel fibers in concrete help to improve flexural strength and crack resistance. Today, there are critical shortages of natural resources. In this research, waste concrete is being used to produce recycled aggregate. The Recycled Coarse Aggregate (RCA) is partially replaced with the natural coarse aggregate (NCA) in concrete to analyze the mechanical properties of steel fiber reinforced concrete (SFRC). Several tests were conducted, such as compression and flexural tests. Five batches (A, B, C, D and E) of concrete cube and prism samples with different proportions of RCA (0%, 25%, 50%, 75% & 100%) and 1.5% volume fraction of steel fiber were tested, together with one control sample which used 100% NCA and 0% volume fraction of steel fiber. As a result, the control sample achieved 27.32 MPa in compression strength and 0.90 MPa for flexural strength while batch A managed to achieve 48.60 MPa and 1.10 MPa respectively. The cube and prism samples of all batches (A, B, C, D, E) showed decreasing compressive and flexural strength with increasing proportion of RCA in the concrete. Four samples fully achieved more than 20 MPa of compression strength and optimum flexural strength.
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Altun, Muhammet Gökhan, and Meral Oltulu. "Improving the impact resistance of recycled aggregate concretes with different types of fibers." Challenge Journal of Structural Mechanics 5, no. 1 (March 12, 2019): 19. http://dx.doi.org/10.20528/cjsmec.2019.01.003.
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In this study, the aim was to use different types of fibers to improve the impact resistance of recycled aggregate concrete (RAC) that normally shows poor performance against mechanical impacts compared to normal concrete (NC). For this purpose, 18 groups of concrete were cast using different parameters. The study examined different types of concrete mixtures where the proportion of RCA (recycled coarse aggregate) used was 30% and 50% respectively, and where steel fiber-reinforcement was used in proportions of 1% and 2%, and polypropylene fiber-reinforcement was used in proportions of 0.1%. While the material performance of RAC compared to NC is analyzed in existing published literature, there is no evidence on whether the use of RCA and hybrid fibers affect the impact properties of concrete. Drop weight impact testing was conducted on test specimens and the impact resistance of these specimens was studied at 28 days. It was observed that the increasing use of RCA reduced the impact resistance. The use of 30% RCA does not significantly influence the strength of concrete. According to the results, the performance of both the NC and RAC was increased with an increase in the volume fractions of steel fiber used. In addition, hybrid fiber-reinforced concretes showed the best results of all the concrete groups.
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Chin, Kai-Yen, Angus Shiue, Yi-Jing Wu, Shu-Mei Chang, Yeou-Fong Li, Ming-Yuan Shen, and Graham Leggett. "Studies on Recycling Silane Controllable Recovered Carbon Fiber from Waste CFRP." Sustainability 14, no. 2 (January 9, 2022): 700. http://dx.doi.org/10.3390/su14020700.
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During the production process of commercial carbon fiber reinforced polymers (CFRPs), a silane coupling agent is added to the carbon fiber at the sizing step as a binder to enhance the product’s physical properties. While improving strength, the silane coupling agent results in a silane residue on recovered carbon fibers (rCF) after recycling, which is a disadvantage when using recovered carbon fibers in the manufacture of new materials. In this study, the rCF is recovered from waste carbon fiber reinforced polymers (CFRPs) from the bicycle industry by a microwave pyrolysis method, applying a short reaction time and in an air atmosphere. Moreover, the rCF are investigated for their surface morphologies and the elements present on the surface. The silicon element content changes with pyrolysis temperature were 0.4, 0.9, and 0.2%, respectively, at 450, 550, and 650 °C. Additionally, at 950 °C, silicon content can be reduced to 0.1 ± 0.05%. The uniformity of microwave pyrolysis recycle treatment was compared with traditional furnace techniques used for bulk waste treatment by applying the same temperature regime. This work provides evidence that microwave pyrolysis can be used as an alternative method for the production of rCFs for reuse applications.
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Guo, Wenjian, Shuxin Bai, Yicong Ye, and Li’an Zhu. "Recycling carbon fiber-reinforced polymers by pyrolysis and reused to prepare short-cut fiber C/C composite." Journal of Reinforced Plastics and Composites 38, no. 7 (January 7, 2019): 340–48. http://dx.doi.org/10.1177/0731684418822144.
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A new idea of reusing carbon fiber recycled from carbon fiber-reinforced epoxy resin (CF/EP) composite to fabricate short-cut fiber C/C composite by moulding was proposed. The recycled carbon fiber (rCF) maintains comparable properties to virgin carbon fiber (vCF) except for a small amount of pyrolytic carbon attached to it. The wettability of rCF-furfural acetone resin (FA), vCF-FA and pyrolytic carbon-FA is nearly the same by sessile drop method. The obtained rCF was subsequently fabricated into C/C composite by moulding. The density of the prepared rCF C/C composite is 1.51 g·cm−3 which is slightly higher than that of vCF C/C composite of 1.48 g·cm−3. The flexural strength of rCF C/C composite is 34.2 MPa, which is slightly lower than that the vCF C/C composite of 38.8 MPa. However, the vCF C/C composite exhibits pseudo-ductile fracture behavior, while the rCF C/C composite presents a brittle fracture behavior after reaching the maximum value. The reason can be attributed to the cluster structure of rCF resulting in its dispersion lower than that of vCF. Destruction of cluster structure and dispersion of rCF are vital for improving the mechanical properties of short-cut rCF C/C composite.
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El-Hassan, Hilal, Jamal Medljy, and Tamer El-Maaddawy. "Properties of Steel Fiber-Reinforced Alkali-Activated Slag Concrete Made with Recycled Concrete Aggregates and Dune Sand." Sustainability 13, no. 14 (July 18, 2021): 8017. http://dx.doi.org/10.3390/su13148017.
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Reutilizing industrial by-products and recycled concrete aggregates (RCA) to replace cement and natural aggregates (NA) in concrete is becoming increasingly important for sustainable development. Yet, experimental evidence is needed prior to the widespread use of this sustainable concrete by the construction industry. This study examines the performance of alkali-activated slag concrete made with RCA and reinforced with steel fibers. Natural coarse aggregates were replaced with RCA. Steel fibers were added to mixes incorporating RCA at different volume fractions. Desert dune sand was used as fine aggregate. The mechanical and durability properties of plain and steel fiber-reinforced concrete made with RCA were experimentally examined. The results showed that the compressive strength did not decrease in plain concrete mixes with 30 and 70% RCA replacement. However, full replacement of NA with RCA resulted in a 20% reduction in the compressive strength of the plain mix. In fact, 100% RCA mixes could only be produced with compressive strength comparable to that of an NA-based control mix in conjunction with 2% steel fiber, by volume. In turn, at least 1% steel fiber, by volume, was required to maintain comparable splitting tensile strength. Furthermore, RCA replacement led to higher water absorption and sorptivity and lower bulk resistivity, ultrasonic pulse velocity, and abrasion resistance. Steel fiber incorporation in RCA-based mixes densified the concrete and improved its resistance to abrasion, water permeation, and transport, thereby enhancing its mechanical properties to exceed that of the NA-based counterpart. The hardened properties were correlated to 28-day cylinder compressive strength through analytical regression models.
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Gao, Danying, Yongming Yan, Yuyang Pang, Jiyu Tang, Lin Yang, and Zhiqiang Gu. "Effects of Groove and Steel Fiber on Shear Properties of Concrete with Recycled Coarse Aggregate." Materials 13, no. 20 (October 13, 2020): 4537. http://dx.doi.org/10.3390/ma13204537.
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In this paper, a series of shear specimens with or without groove were manufactured to mainly analyze the effects of grooves (or shear section height) and steel fibers on the shear properties of concrete with recycled coarse aggregate through double-side direct shear test. In addition, the relationship between the shear strength and the compressive strength and splitting tensile strength of steel fiber reinforced concrete with recycled coarse aggregate (SFRCAC) was also discussed. The experimental results showed that the peak load, deformation corresponding to the peak load and calculated shear strength of the specimens with grooves were lower than those of the specimens without grooves. The steel fiber and recycled coarse aggregate (RCA) had a significant effect on the shear properties of SFRCAC. As the volume content of steel fibers increased, the shear strength of SFRCAC and the corresponding deformation increased gradually. With the replacement ratio of RCA increasing, the shear strength of SFRCAC decreased but the corresponding deformation increased gradually. Finally, the formula for calculating the shear strength of SFRCAC was proposed by analyzing and fitting the test results and the data of related literature.
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Bachmann, Jens, Martin Wiedemann, and Peter Wierach. "Flexural Mechanical Properties of Hybrid Epoxy Composites Reinforced with Nonwoven Made of Flax Fibres and Recycled Carbon Fibres." Aerospace 5, no. 4 (October 10, 2018): 107. http://dx.doi.org/10.3390/aerospace5040107.
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Can a hybrid composite made of recycled carbon fibres and natural fibres improve the flexural mechanical properties of epoxy composites compared to pure natural fibre reinforced polymers (NFRP)? Growing environmental concerns have led to an increased interest in the application of bio-based materials such as natural fibres in composites. Despite their good specific properties based on their low fibre density, the application of NFRP in load bearing applications such as aviation secondary structures is still limited. Low strength NFRP, compared to composites such as carbon fibre reinforced polymers (CFRP), have significant drawbacks. At the same time, the constantly growing demand for CFRP in aviation and other transport sectors inevitably leads to an increasing amount of waste from manufacturing processes and end-of-life products. Recovering valuable carbon fibres by means of recycling and their corresponding re-application is an important task. However, such recycled carbon fibres (rCF) are usually available in a deteriorated (downcycled) form compared to virgin carbon fibres (vCF), which is limiting their use for high performance applications. Therefore, in this study the combination of natural fibres and rCF in a hybrid composite was assessed for the effect on flexural mechanical properties. Monolithic laminates made of hybrid nonwoven containing flax fibres and recycled carbon fibres were manufactured with a fibre volume fraction of 30% and compared to references with pure flax and rCF reinforcement. Three-point bending tests show a potential increase in flexural mechanical properties by combining rCF and flax fibre in a hybrid nonwoven.
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Ahmad, Jawad, Osama Zaid, Carlos López-Colina Pérez, Rebeca Martínez-García, and Fernando López-Gayarre. "Experimental Research on Mechanical and Permeability Properties of Nylon Fiber Reinforced Recycled Aggregate Concrete with Mineral Admixture." Applied Sciences 12, no. 2 (January 6, 2022): 554. http://dx.doi.org/10.3390/app12020554.
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Plain concrete’s major two drawbacks are its low tensile strength and high carbon footprint. Joint adding of fibers and recycled/waste materials in concrete might assist to resolve these problems. In the present study, a novel technique is planned to improve the recycled aggregate concrete (RAC) mechanical behavior and durability performance by joint incorporation of silica fume (SF) and nylon fibers (NF). In this research paper, different properties of concrete samples are examined for example flexural strength, compressive strength, split tensile strength, penetration of chloride ions, acid resistance, and water absorption. It was noted that adding nylon fibers as individual components enhances the recycled aggregate concrete mechanical characteristics and resistance to acid exposure. The inclusion of nylon fibers improved the behavior of the recycled aggregate concrete; however, it also increased the chloride penetration and water absorption by only 18% and 8% respectively. Up to 26% of mechanical strength of concrete was improved when silica fume was added in comparison to reference concrete, silica fume also assisted in controlling the loss of durability because of adding recycled aggregate concrete and nylon fibers. Silica fume improved the bond between binder matrix and nylon fibers. The study revealed that the combination of 50% RCA, 0.5% nylon fibers and 20% silica fume are optimum for the joint incorporation into concrete that can assist in developing sustainable, durable, and ductile recycled aggregate fiber reinforced concrete.
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Gao, Danying, Lijuan Zhang, Michelle Nokken, and Jun Zhao. "Mixture Proportion Design Method of Steel Fiber Reinforced Recycled Coarse Aggregate Concrete." Materials 12, no. 3 (January 25, 2019): 375. http://dx.doi.org/10.3390/ma12030375.
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Steel fiber reinforced recycled coarse aggregate concrete (SFRCAC) is an impact minimisation building material. Mixture proportion design method of SFRCAC is developed in this paper to obtain concrete with target strength and workability, which can be used in structural members. Four key parameters of mixture proportioning, steel fiber content, water-cement ratio, water content and sand ratio are discussed through the mixture design tests. The formula for calculating the four key parameters of mixture proportions for SFRCAC are established through the statistical analysis of test results, which mainly consider the influences of recycled coarse aggregate (RCA) replacement ratio and steel fiber characteristic coefficient. The detailed procedure by using the new mixture proportion design method is illustrated with examples. The formulas established have the simple form, reflect the properties of RCA and steel fibers, enhance the mixture proportion design accuracy, and provide the reference for the mix proportion design of SFRCAC.
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Ismail, Sallehan, Wan Nur Syazwani Wan Mohammad, and Mahyuddin Ramli. "Diversified Production of Recycled Aggregate Concrete Mixture with the Addition of Single and Hybrid Fibers." International Journal of Engineering & Technology 7, no. 3.11 (July 21, 2018): 147. http://dx.doi.org/10.14419/ijet.v7i3.11.15950.
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The low strength property of recycled concrete aggregates (RCAs) limits its widespread application in the production of high-strength recycled aggregate concrete (RAC). In this study, RCA properties were improved prior to its incorporation into an RAC mixture through surface treatment. This mixture was subsequently diversified considering the benefits of adding various fiber-reinforced systems to enhance RAC performance. Two types of short discrete synthetic fibers, namely, polyolefin and polypropylene, were added in single and hybrid forms. This study aimed to investigate the effectiveness of the diversified modification of RAC mixture production on the mechanical strength of the resulting RAC. Various properties of the modified RAC were analyzed. Although the modified RAC mixture using treated RCA significantly enhanced the mechanical strength of this RAC, the diversification of the RAC mixture with additional polyolefin and polypropylene fibers, particularly in the hybrid form, further optimized the RAC performance.
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Ahmed, Wisal, C. W. Lim, and Arslan Akbar. "Influence of Elevated Temperatures on the Mechanical Performance of Sustainable-Fiber-Reinforced Recycled Aggregate Concrete: A Review." Buildings 12, no. 4 (April 14, 2022): 487. http://dx.doi.org/10.3390/buildings12040487.
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In recent times, the applications of fiber-reinforced recycled aggregate concrete (FRAC) in practical engineering have gained greater popularity due to its superior mechanical strength and fracture properties. To apply FRAC in buildings and other infrastructures, a thorough understanding of its residual mechanical properties and durability after exposure to fire is highly important. According to the established research, the properties and volume fractions of reinforcing fiber materials, replacement levels of recycled concrete aggregate (RCA), and heating condition would affect the thermal–mechanical properties of FRAC. This review paper aims to present a thorough and updated review of the mechanical performance at an elevated temperature and post-fire durability of FRAC reinforced with various types of fiber material, specifically steel fiber (SF), polypropylene (PP) fiber, and basalt fiber (BF). More explicitly, in this review article the residual mechanical properties of FRAC, such as compressive strength, splitting tensile capacity, modulus of elasticity, mass loss, spalling, and durability after exposure to elevated temperatures, are discussed. Furthermore, this study also encompasses the relationship among the dosages of fibers, replacement levels of recycled aggregate, and the relative residual mechanical properties of FRAC that would help in the optimum selection of the fiber content. Conclusively, this study elaborately reviews and summarizes the relevant and recent literature on recycled aggregate concrete containing SF, PP fiber, and BF. The study further provides a realistic comparison of these fibers in terms of the residual mechanical performance and durability of FRAC that would help in their future enhancements and applications in practical engineering.
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Sauer, Michael, Jonas Feil, Frank Manis, Tobias Betz, and Klaus Drechsler. "Thermoplastic Multi-Material Nonwovens from Recycled Carbon Fibres Using Wet-Laying Technology." Key Engineering Materials 809 (June 2019): 210–16. http://dx.doi.org/10.4028/www.scientific.net/kem.809.210.
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In this study, multi-material nonwovens were produced using a wet laying nonwoven batch process. The aim of this work is to investigate and develop nonwoven material solutions that can be used for a substitution of pure glass fibre (GF)-applications and also provide a more cost-sensitive option compared to nonwovens purely made from recycled carbon fibres (rCF). The multi-material-nonwovens of this study consisted of the functional components rCF and GF as well as a thermoplastic matrix, built by the admixture of PA6-fibres. All three fibre types were mixed directly within the nonwoven manufacturing process, respectively in the course of the initial weighed portions. Six different material compositions with individual amounts of rCF and GF were produced, but a constant overall fibre volume content (FVC) as well as a uniform grammage was defined. A hot pressing technique was used to consolidate these multi-material-nonwoven layers. Subsequently, the sheet materials were examined using tensile and 4-point bending tests, as well as wet-chemical fibre volume content determinations and micrographic sections. With regard to the mechanical performance, a near-linear increase is observed for increased proportions of recycled carbon fibres. In this context a potential for the use of multi-material-nonwovens consisting of rCF and GF can be found. It is demonstrated that rCF might be an adequate substituent for classical GF-applications. The results contribute to broadening the performance spectrum of rCF and thus to its substantial recycling route.
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Kachouh, Nancy, Tamer El-Maaddawy, Hilal El-Hassan, and Bilal El-Ariss. "Shear Behavior of Steel-Fiber-Reinforced Recycled Aggregate Concrete Deep Beams." Buildings 11, no. 9 (September 21, 2021): 423. http://dx.doi.org/10.3390/buildings11090423.
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Results of an experimental investigation aimed at studying the effect of steel fibers on the shear behavior of concrete deep beams made with a 100% recycled concrete aggregate (RCA) are presented in this paper. The study comprised testing of seven concrete deep beam specimens with a shear span-to-depth ratio (a/h) of 1.6. Two beams were made of natural aggregates (NAs) without steel fibers, two beams were made of a 100% RCA without steel fibers, and three beams were made of RCA-based concrete with steel fibers at volume fractions (vf) of 1, 2, and 3%. Two of the beams without steel fibers included a minimum shear reinforcement. Test results showed that the beam with a 100% RCA without steel fibers exhibited a lower post-cracking stiffness, reduced shear cracking load, and lower shear capacity than those of the NA-based control beam. The detrimental effect of the RCA on the shear response was less pronounced in the presence of the minimum shear reinforcement. The addition of steel fibers significantly improved the shear response of the RCA-based beams. The post-cracking stiffness of the RCA-based concrete beams with steel fibers coincided with that of a similar beam without fibers containing the minimum shear reinforcement. The use of steel fibers in RCA beams at vf of 1 and 2% restored 80 and 90% of the shear capacity, respectively, of a similar beam with the minimum shear reinforcement. The response of the RCA specimen with vf of 3% outperformed that of the NA-based control beam with the minimum shear reinforcement, indicating that steel fibers can be used in RCA deep beams as a substitution to the minimum shear reinforcement. The shear capacities obtained from the tests were compared with predictions of published analytical models.
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El-Hassan, Hilal, Abdalla Hussein, Jamal Medljy, and Tamer El-Maaddawy. "Performance of Steel Fiber-Reinforced Alkali-Activated Slag-Fly Ash Blended Concrete Incorporating Recycled Concrete Aggregates and Dune Sand." Buildings 11, no. 8 (July 28, 2021): 327. http://dx.doi.org/10.3390/buildings11080327.
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This study evaluates the performance of alkali-activated slag-fly ash blended concrete made with recycled concrete aggregates (RCA) and reinforced with steel fibers. Two blends of concrete with ground granulated blast furnace slag-to-fly ash ratios of 3:1 and 1:1 were used. Natural aggregates were substituted with RCA, while macro steel fibers with 35 mm of length and aspect ratio of 65 were incorporated in RCA-based mixtures at various volume fractions. Fine aggregates were in the form of desert dune sand. Mechanical and durability characteristics were investigated. Experimental results revealed that RCA replacement decreased the compressive strength of plain concrete mixtures with more pronounced reductions being perceived at higher replacement percentages. Mixtures made with 30%, 70%, and 100% RCA could be produced with limited loss in the design compressive strength upon incorporating 1%, 2%, and 2% steel fibers, by volume, respectively. In turn, splitting tensile strength was comparable to the NA-based control while adding at least 1% steel fiber, by volume. Moreover, higher water absorption and capillary sorptivity and lower ultrasonic pulse velocity, bulk resistivity, and abrasion resistance were reported during RCA replacement. Meanwhile, incorporation of steel fibers densified the concrete and enhanced its resistance to abrasive forces, water permeation, and water transport. Analytical regression models were developed to correlate hardened concrete properties to the 28-day cylinder compressive strength.
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Rodríguez-Alloza, Ana María, Juan Gallego-Medina, José María Bermejo-Muñoz, and Leticia Saiz-Rodríguez. "EVALUATION OF SIEVE ANALYSIS METHODS FOR THE DETERMINATION OF FIBER CONTENT IN SAMPLES OF RUBBER POWDER." Rubber Chemistry and Technology 85, no. 4 (December 1, 2012): 661–68. http://dx.doi.org/10.5254/rct.12.88906.
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ABSTRACT The objective of this article is to study the validity of the test methods that are currently used to determine the fiber content in samples of rubber powder made from end-of-life tires: CEN/TS 14 243, ASTM D 5603-01, and XP T 47–758. For this purpose, rubber powder samples contaminated with one weight percent (wt%) of fiber were prepared and submitted to sieve analyses, with the weight of the sample and sieving time as the variable parameters. The materials used were rubber powder without fibers and polyester fibers from recycled waste tires, both generated during the shredding of the tires. It has been observed that the procedure of determining fiber content based on sieving and extraction of fabric balls does not manage to recover more than 41.00% of the fibers contained in the samples. This research demonstrates that even with different sample weights and sieving times, is not possible to recover 100% of the fiber with which the rubber sample was contaminated. This seems to indicate that it is necessary to develop a methodology that differs from the current practice of sieving and extracting fabric balls to correctly determine the fiber content in a sample of rubber powder.
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Muscalu, Marius Teodor, Andrei Radu, Mihai Budescu, Nicolae Ţăranu, and Eugen Florescu. "Use of Recycled Materials in the Construction of Roller Compacted Concrete (RCC) Pavements." Advanced Materials Research 649 (January 2013): 262–65. http://dx.doi.org/10.4028/www.scientific.net/amr.649.262.
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This paper presents the results of laboratory studies, undertaken by the authors, in the frame of 4D-POSTDOC research program :"Innovative technologies and logistical solutions for the reuse of demolition and construction waste in the construction of cement concrete and fiber reinforced cement concrete pavements". After the presentation of the main objectives of this research program, and of the specific characteristics of the demolition wastes investigated in parallel with those of conventional construction materials, the possibility of using these materials for the preparation of the roller compacted concrete (RCC) is investigated. Finally, conclusions on the influence of recycled aggregates and recycled steel fibers on the mechanical performances of RCC and technical recommendations for the use of this more efficient material and of the involved technology for the construction of sustainable road infrastructures are formulated.
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Mobili, Alessandra, Gloria Cosoli, Nicola Giulietti, Paolo Chiariotti, Giuseppe Pandarese, Tiziano Bellezze, Gian Marco Revel, and Francesca Tittarelli. "Effect of Gasification Char and Recycled Carbon Fibres on the Electrical Impedance of Concrete Exposed to Accelerated Degradation." Sustainability 14, no. 3 (February 4, 2022): 1775. http://dx.doi.org/10.3390/su14031775.
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This paper aims to evaluate the effect of carbon-based conductive recycled additions, i.e., recycled carbon fibres (RCF) and gasification char (GCH), on the mechanical, electrical, and durability properties of concretes. The obtained results show that the compressive strength of concrete is not affected by conductive additions, whereas electrical impedance, measured according to Wenner’s method, is significantly reduced (6%, 30% and 74% with RCF, GCH, and their combination, respectively) to the advantage of self-sensing properties. As durability is concerned, conductive additions slightly increase capillary water absorption, whereas they decrease chloride ingress through diffusion and do not significantly modify carbonation resistance.
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Tse, Barbara, Xueli Yu, Hugh Gong, and Constantinos Soutis. "Flexural Properties of Wet-Laid Hybrid Nonwoven Recycled Carbon and Flax Fibre Composites in Poly-Lactic Acid Matrix." Aerospace 5, no. 4 (November 15, 2018): 120. http://dx.doi.org/10.3390/aerospace5040120.
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Recycling carbon fibre is crucial in the reduction of waste from the increasing use of carbon fibre reinforced composites in industry. The reclaimed fibres, however, are usually short and discontinuous as opposed to the continuous virgin carbon fibre. In this work, short recycled carbon fibres (rCF) were mixed with flax and poly-lactic acid (PLA) fibres acting as the matrix to form nonwoven mats through wet-laying. The mats were compression moulded to produce composites with different ratios of rCF and flax fibre in the PLA matrix. Their flexural behaviour was examined through three-point-bending tests, and their morphological properties were characterised with scanning electron and optical microscopes. Experimental data showed that the flexural properties increased with higher rCF content, with the maximum being a flexural modulus of approximately 14 GPa and flexural strength of 203 MPa with a fibre volume fraction of 75% rCF and 25% flax fibre. The intimate mixing of the fibres contributed to a lesser reduction of flexural properties when increasing the flax fibre content.
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Kachouh, Nancy, Tamer El-Maaddawy, Hilal El-Hassan, and Bilal El-Ariss. "Shear Response of Recycled Aggregates Concrete Deep Beams Containing Steel Fibers and Web Openings." Sustainability 14, no. 2 (January 14, 2022): 945. http://dx.doi.org/10.3390/su14020945.
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Replacement of natural aggregates (NAs) with recycled concrete aggregates (RCAs) in complex reinforced concrete (RC) structural elements, such as deep beams with openings, supports environmental sustainability in the construction industry. This research investigates the shear response of RC deep beams with openings made with 100% RCAs. It also examines the effectiveness of using steel fibers as a replacement to the minimum conventional steel stirrups in RCA-based deep beams with web openings. A total of seven RC deep beams with a shear span-to-depth ratio (a/h) of 0.8 were constructed and tested. A circular opening with an opening height-to-depth ratio (h0/h) of 0.3 was placed in the middle of each shear span. Test parameters included the type of the coarse aggregate (NAs and RCAs), steel fiber volume fraction (vf = 1, 2, and 3%), and presence of the minimum conventional steel stirrups. The deep beam specimens with web openings made with 100% RCAs exhibited 13 to 18% reductions in the shear capacity relative to those of their counterparts made with NAs. The inclusion of conventional steel stirrups in RC deep beams with openings was less effective in improving the shear response when 100% RCAs was used. The addition of steel fibers remarkably improved the shear response of the tested RCA-based beams. The gain in the shear capacity of the RCA-based beams caused by the inclusion of steel fibers was in the range of 39 to 84%, whereas the use of conventional steel stirrups resulted in 18% strength gain. The use of 1% steel fiber volume fraction in the RCA-based beam with openings without steel stirrups was sufficient to restore 96% of the original shear capacity of the NA-based beam with conventional steel stirrups. The shear capacities obtained from the tests were compared with predictions of published analytical models. The predicted-to-measured shear capacity was in the range of 0.71 to 1.49.
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Lu, Dong, Hui Cao, Qiangru Shen, Yue Gong, Cheng Zhao, and Xiaohui Yan. "Dynamic Characteristics and Chloride Resistance of Basalt and Polypropylene Fibers Reinforced Recycled Aggregate Concrete." Advances in Polymer Technology 2020 (June 2, 2020): 1–9. http://dx.doi.org/10.1155/2020/6029047.
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Fiber polymer has been extensively used to improve the mechanical properties and durability of concrete. However, the studies of the effect of fiber polymer on the dynamic performance of recycled aggregate concrete (RAC) is still very limited. In this study, we prepared two types of RAC formulations: RAC reinforced with basalt fibers (BFs) and RAC reinforced with polypropylene fibers (PPs), and compared the effects of fiber types and contents on the air void content, workability (slump), mechanical properties (compressive and flexural strength), dynamic characteristics (dynamic modulus of elasticity and damping ratio), and chloride resistance of RAC. The experimental results showed that the air void content and slump value decreased with the increase of replacement percentage of RCA and fiber contents. Adding PPs provided a more negative effect on the slump of RAC than BFs. The mixtures containing 0.2% PPs and BFs both obtained the highest flexural strength. The addition of PPs was more effective than BFs in improving the damping ratio of RAC, and the mixtures containing 0.3% PPs and BFs both obtained the highest damping ratio. Compared to the RAC without addition of fiber, the charge passed of specimen with addition of PPs approximately increased by 45%, while the specimen with addition of BFs approximately increased by 30%, when the fiber content was 0.3%. This study demonstrates the potential of using fiber to promote the dynamic properties of RAC.
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Jahandari, Soheil, Masoud Mohammadi, Aida Rahmani, Masoumeh Abolhasani, Hania Miraki, Leili Mohammadifar, Mostafa Kazemi, Mohammad Saberian, and Maria Rashidi. "Mechanical Properties of Recycled Aggregate Concretes Containing Silica Fume and Steel Fibres." Materials 14, no. 22 (November 21, 2021): 7065. http://dx.doi.org/10.3390/ma14227065.
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In this study, the impact of steel fibres and Silica Fume (SF) on the mechanical properties of recycled aggregate concretes made of two different types of Recycled Coarse Aggregates (RCA) sourced from both low- and high-strength concretes were evaluated through conducting 60 compressive strength tests. The RCAs were used as replacement levels of 50% and 100% of Natural Coarse Aggregates (NCA). Hook-end steel fibres and SF were also used in the mixtures at the optimised replacement levels of 1% and 8%, respectively. The results showed that the addition of both types of RCA adversely affected the compressive strength of concrete. However, the incorporation of SF led to compressive strength development in both types of concretes. The most significant improvement in terms of comparable concrete strength and peak strain with ordinary concrete at 28 days was observed in the case of using a combination of steel fibres and SF in both recycled aggregate concretes, especially with RCA sourced from high strength concrete. Although using SF slightly increased the elastic modulus of both recycled aggregate concretes, a substantial improvement in strength was observed due to the reinforcement with steel fibre and the coexistence of steel fibre and SF. Moreover, existing models to predict the elastic modulus of both non-fibrous and fibrous concretes are found to underestimate the elastic modulus values. The incorporation of SF changed the compressive stress-strain curves for both types of RCA. The addition of steel fibre and SF remarkably improved the post-peak ductility of recycled aggregates concretes of both types, with the most significant improvement observed in the case of RCA sourced from a low-strength parent concrete. The existing model to estimate the compressive stress-strain curve for steel fibre-reinforced concrete with natural aggregates was found to reasonably predict the compressive stress-strain behaviour for steel fibres-reinforced concrete with recycled aggregate.
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Manis, Frank, Jakob Wölling, and Klaus Drechsler. "Damage Behaviour of Fibre Reinforced Materials Induced by High Temperature Oxidation for Optimisation of Thermal Recycling Routes." Materials Science Forum 825-826 (July 2015): 1088–95. http://dx.doi.org/10.4028/www.scientific.net/msf.825-826.1088.
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This study summarizes different characterisation methods performed with new carbon fibres(vCF - virgin carbon fibres) for structural applications as carbon fiber reinforced plastic (CFRP)as well as fiber samples which have been treated under different conditions. These parameters consistof combinations of temperature (400-600 C) and dwell time (30 - 60 min) in an oxidising atmospherein order to provide a fundamental basis for the definition of possible recycling processes to regain thehigh value raw material, i.e. the carbon fibre, after the use-phase of the initial CFRP-structure. The investigationsthat were performed on vCF and secondary fibres (rCF - recycled CF) show in very goodagreement, that below 500 C almost no degradation of the fibre is visible, between 500 and 600 C arapid decrease in different physical and mechanical properties occurs and above 600 C a recovery ofthe fiber in terms of a secondary use in high performance structural context seems not to be feasible.The investigations that were performed consist of optical microscopy for the measurement of the fibrediameter, the deformation of the cross section and a statistical analysis. The second method appliedwas the characterization of the monofilament density, alongside to the breaking force and elongation,leading to the calculation of tensile strength and Youngs Modulus and further statistical analysis ofWeibull Modulus and its decrease over temperature.
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Yuan, Hanquan, Lihua Zhu, Xiaopeng Wang, and Hongtao Yang. "Effect of Microstructure on the Mechanical Properties of Steel Fiber-Reinforced Recycled Concretes." Materials 15, no. 11 (June 6, 2022): 4018. http://dx.doi.org/10.3390/ma15114018.
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A steel fiber-reinforced recycled concrete (SFRRC) is a porous material, and its macromechanical properties are affected by its microstructure. To elucidate the change rules and internal mechanisms of the mechanical properties of SFRRCs, the mechanical properties and failure modes of SFRRCs were studied at different water–cement ratio, replacement rate of recycled concrete aggregate (RCA), and steel fiber content. Moreover, the microstructures of the interface transition zones (ITZ) of the SFRRC specimens were tested by scanning electron microscopy and mercury intrusion, and the effect of the microscopic pore structure on the macromechanical properties of SFRRC was analyzed. The research results showed that an appropriate amount of steel fibers could reduce the size and number of cracks in the ITZ and improve the pore structure of an SFRRC. Based on the fractal dimension, porosity and other factors, the quantitative relationship between the macromechanical properties and microscopic pore structure parameters of SFRRCs was established.
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Manis, Frank, Maren Schmieg, Michael Sauer, and Klaus Drechsler. "Properties of Second Life Carbon Fibre Reinforced Polymers." Key Engineering Materials 742 (July 2017): 562–67. http://dx.doi.org/10.4028/www.scientific.net/kem.742.562.
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In this study different materials made out of cut-off as well as reclained carbon fibres (rCF) are described and compared. For this benchmark nonwovens, compounds, SMC, BMC, as well as standard lightweight materials like high alloy steels, aluminium and magnesium are taken into account. Specific mechanical properties like modulus and tensile strength are used to show the lightweight potential of recycled carbon fibre materials in ashby charts. It is shown that rCF products can substitute glass fibre applications and are also comparable to metals and alloys.
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Rabe, David, Eric Häntzsche, and Chokri Cherif. "Recycling of Carbon Fibres and Subsequent Upcycling for the Production of 3D-CFRP Parts." Materials 15, no. 14 (July 20, 2022): 5052. http://dx.doi.org/10.3390/ma15145052.
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Carbon fibres (CF) are used in CF reinforced plastic (CFRP) components. However, waste from CF yarn trim, CFRP and the end of life (EOL) CFRP structures will cause a recycling challenge in the next decades because of strict environmental regulations. Currently, recycling is carried out almost entirely by the use of pyrolysis to regain CF as a valuable resource. This high temperature process is energy consuming, and the resulting fibres are brittle. Hence, they are not suitable for processing of textiles into yarns or new reinforcement structures. To enable grave to cradle processing, a new approach based on a solvolysis recovery of CF and subsequent yarn spinning to obtain hybrid yarns suitable for textile processing, especially by weft knitting, was the focus of the international research project IGF/CORNET 256EBR. For the first time, it was possible to process hybrid yarns made of rCF on a weft knitting machine to produce biaxial reinforced structures to form CFRP from recycled carbon fibres. Therefore, various modifications were done on the textile machinery. In this way, it was possible to process the rCF and to get out a reproducible textile structure for the production of 3D recycled CFRP (rCFRP) parts.
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Wang, Qiao-Huan, Jiong-Feng Liang, Chun-Feng He, and Wei Li. "Axial Compressive Behavior of Steel Fiber-Reinforced Recycled Coarse Aggregate Concrete-Filled Short Circular Steel Columns." Advances in Materials Science and Engineering 2021 (April 3, 2021): 1–9. http://dx.doi.org/10.1155/2021/5516893.
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This paper attempts to explore the effects of recycled coarse aggregate content, steel fiber content, and concrete strength on the axial compressive behavior of steel fiber-reinforced recycled coarse aggregate (RCA) concrete-filled circular steel stub columns. A total of 14 short columns are tested. The results show that using RCA in concrete will reduce the bearing capacity of short columns, but the increase in steel fiber content and concrete strength can eliminate this shortcoming. Not only that, the concrete strength has a great influence on the ductility and stiffness of the specimen.
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Alamri, Hatem, and It Meng Low. "Characterization and Properties of Recycled Cellulose Fibre- Reinforced Epoxy-Hybrid Clay Nanocomposites." Materials Science Forum 654-656 (June 2010): 2624–27. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.2624.
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In this paper, epoxy eco-composites reinforced with recycled cellulose fiber (RCF) and nano-fillers such as nano-clay platelets (30B) and halloysite nanotubes (HNTs), have been fabricated and investigated. The influences of RCF/nano-filler dispersion on the microstructure, physical and mechanical characteristics have been characterized. Results indicate that flexural strength decreased for the majority of study samples due to the poor dispersion of nano-fillers and the existence of voids within the samples. In contrast, impact toughness and fracture toughness were improved for all reinforced samples. The effect of water absorption was positive in terms of enhancing the impact toughness of the composites. Addition of nanoclay was found to increase the porosities of all nanocomposites.
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Ismail, Sallehan, and Mahyuddin Ramli. "Resistance to Chloride Penetration of Recycled Aggregate Concrete Modified Using Treated Coarse Recycled Concrete Aggregate and Fibres." Materials Science Forum 991 (May 2020): 101–8. http://dx.doi.org/10.4028/www.scientific.net/msf.991.101.
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This paper presents a study that aimed to assess the chloride penetration depth of recycled aggregate concrete (RAC) modified by using treated coarse recycled concrete aggregate (RCA), adding polyolefin (PO) or polypropylene (PP) fibre and comparing with normal concrete. The coupling effects of the treated RCA and fibres on the chloride penetration of RAC were analysed after two different curing regimes (i.e. normal and seawater) and tested at different curing ages (i.e. 90, 180 and 300 days). Results showed that the inclusion of treated coarse RCA can reduce porosity, thereby decreasing the chloride penetration of RAC. However, the coupling effects of treated coarse RCA and fibre, especially on the use of PO fibre, can enhance the results.
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Raza, A., B. Ali, F. U. Haq, M. Awais, and M. S. Jameel. "Influence of fly ash, glass fibers and wastewater on production of recycled aggregate concrete." Materiales de Construcción 71, no. 343 (August 17, 2021): e253. http://dx.doi.org/10.3989/mc.2021.15120.
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To encounter the issues of waste materials, low tensile strength of concrete and environmental impacts of cement production, research is needed to develop a sustainable concrete. This study has endeavored to investigate the effects of using recycled coarse aggregates (RCA), various types of wastewater effluents, fly ash, and glass fibers on the mechanical and durability behavior of recycled aggregate concrete (RAC) incorporating with fly ash and glass fibers (FGRAC). Six different kinds of wastewater effluents for the mixing of concrete, 100% replacing the natural coarse aggregates with RCA, and 30% replacement of cement with fly ash were used for the development of concrete. The experimental measurement portrayed that the textile factory effluent presented the highest compressive and tensile strengths of concrete. Fertilizer factory effluent portrayed the highest water absorption, mass loss due to acid attack, and chloride penetration to concrete.