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Fibers, Volume 12, Issue 2 (February 2024) – 6 articles

Cover Story (view full-size image): The mechanical properties of carbon fiber (CF) reinforced polymers (CFRPs) rely heavily on the quality of the fiber-matrix interface. This interface's integrity is influenced by CF surface functionalization and resin type. Recently, research has shifted towards investigating CF sizing—a protective coating traditionally used to shield CFs from environmental damage and ease handling—as a determining factor in enhancing the fiber-matrix interface, particularly with incorporating nanomaterials. This study is dedicated to establishing a pilot-scale CF sizing line, including the design, installation, and operational phases. By experimenting with various sizing solutions containing nanomaterials, our objective is to optimize conditions and to ensure a uniform and robust coating, leading to improved mechanical properties of CFRPs. View this paper

Nanomaterial-Enhanced Sizings: Pilot Fibre Sizing Line Design and Optimization

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30 pages, 14678 KB

Open AccessArticle

Repairing of One-Way Solid Slab Exposed to Thermal Shock Using CFRP: Experimental and Analytical Study

by Mousa Shhabat, Ahmed Ashteyat and Mu’tasim Abdel-Jaber

Fibers 2024, 12(2), 18; https://doi.org/10.3390/fib12020018 - 19 Feb 2024

Cited by 7 | Viewed by 2350

Abstract

This research was conducted to investigate, experimentally, theoretically, and numerically, the use of CFRP materials for repairing a reinforced concrete one-way solid slab exposed to thermal shock. Nine slabs, measuring 1800 mm in length, 500 mm in width, and 100 mm in depth, were cast. Seven of these slabs underwent thermal shock at a temperature of 600 °C, rapidly cooled by immersion in water for 15 min. Three primary parameters were examined: the type of CFRP (rope, strip, and sheet), spacing (100 and 200 mm), and the number of sheet layers (one and two). The experimental results revealed a significant decrease of approximately 45.4% in the compressive strength of the concrete after exposure to thermal shock. The thermally shocked RC slab showed a reduction in ultimate capacity by 15.4% and 38.5% in stiffness compared to the control slab. The results underscored the efficacy of CFRP materials, with all repair configurations exhibiting a substantial increase in maximum load capacity and stiffness. Capacity enhancement ranged from 23.7% to 53.4%, while stiffness improvement ranged from 27.6% to 57.1%. Notably, all repair configurations effectively minimized the maximum deflection. This reduction in deflection ranged from 5.2% to 26% compared to the control slab. Numerical results demonstrated strong concurrence with experimental results for both capacity and deflection. The enhancement in capacity ranged from 0.7% to 10.4%, while deflection decreased within a range from 0.95% to 14.16% compared to experimental results. Full article

(This article belongs to the Special Issue Fiber-Reinforced Polymers and Fiber-Reinforced Cement-Based Mortars in Repair/Strengthening Methods of Masonry and Reinforced Concrete Structural Members)

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29 pages, 16673 KB

Open AccessReview

Utilization of Novel Basalt Fiber Pellets from Micro- to Macro-Scale, and from Basic to Applied Fields: A Review on Recent Contributions

by Tasnia Ahmed, Ahmed Bediwy, Ahmed Azzam, Riham Elhadary, Ehab El-Salakawy and Mohamed T. Bassuoni

Fibers 2024, 12(2), 17; https://doi.org/10.3390/fib12020017 - 5 Feb 2024

Cited by 7 | Viewed by 3003

Abstract

Fiber-reinforced cementitious composites (FRCC) are one of the leading engineering materials in the 21st century, as they offer proficiency in enhancing strength, ductility, and durability in structural engineering applications. Because the recently developed basalt fiber pellets (BFP) offer combined strands of fibers encased in a polymer matrix, they are being prevalently studied to explore new possibilities when used in brittle materials such as mortar and concrete. Hence, this paper synthesizes the intensive research efforts and contributions to this novel class of fibers conducted by the authors. Specifically, it reviews the fresh, mechanical, and durability properties of FRCC incorporating single BFP or hybrid with polyvinyl alcohol fibers and modified with slag/fly ash and nano-materials and its suitability for different field applications. In addition, the nano- and meso-scale modeling of such matrices are described. BFP significantly contributes to improving post-cracking flexural behavior by toughening the cementitious matrix and minimizing strength losses when exposed to harsh environments. All results show promising progress in the development of high-performance FRCC comprising BFP, with potential success for structural and pavement applications. Full article

(This article belongs to the Collection Review Papers of Fibers)

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18 pages, 8299 KB

Open AccessArticle

Nanomaterial-Enhanced Sizings: Design and Optimisation of a Pilot-Scale Fibre Sizing Line

by Dionisis Semitekolos, Ioannis Papadopoulos, Stavros Anagnou, Behnam Dashtbozorg, Xiaoying Li, Hanshan Dong and Costas A. Charitidis

Fibers 2024, 12(2), 16; https://doi.org/10.3390/fib12020016 - 4 Feb 2024

Cited by 6 | Viewed by 3782

Abstract

This study focuses on the development of a pilot-scale sizing line, including its initial design and installation, operational phases, and optimization of key process parameters. The primary objective is the identification of critical parameters for achieving a uniform sizing onto the fibres and the determination of optimal conditions for maximum production efficiency. This investigation focused on adjusting the furnace desizing temperature for the removal of commercial sizing, adjusting the drying temperature, as well as optimizing the corresponding residence time of carbon fibres passing through the furnaces. The highest production rate, reaching 1 m sized carbon fibres per minute, was achieved by employing a desizing temperature of 550 °C, a drying temperature of 250 °C, and a residence time of 1 min. Furthermore, a range of sizing solutions was investigated and formulated, exploring carbon-based nanomaterial types with different surface functionalizations and concentrations, to evaluate their impact on the surface morphology and mechanical properties of carbon fibres. In-depth analyses, including scanning electron microscopy and contact angle goniometry, revealed the achievement of a uniform coating on the carbon fibre surface, leading to an enhanced affinity between fibres and the polymeric epoxy matrix. The incorporation of nanomaterials, specifically N₂-plasma-functionalized carbon nanotubes and few-layer graphene, demonstrated notable improvements in the interfacial shear properties (90% increase), verified by mechanical and push-out tests. Full article

(This article belongs to the Topic Advanced Composites Manufacturing and Plastics Processing)

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9 pages, 1062 KB

Open AccessArticle

Observation of Visible Upconversion Luminescence of Soft Glass Multimode Fibers

by Mario Ferraro, Fabio Mangini, Raffaele Filosa, Vincent Couderc, Yifan Sun, Pedro Parra-Rivas, Wasyhun A. Gemechu, Grzegorz Stepniewski, Adam Filipkowski, Ryszard Buczynski and Stefan Wabnitz

Fibers 2024, 12(2), 15; https://doi.org/10.3390/fib12020015 - 4 Feb 2024

Cited by 1 | Viewed by 2211

Abstract

This research investigates the visible upconversion luminescence which is induced by multiphoton absorption of soft glass fiber defects. The study of this phenomenon has thus far been restricted to standard silica fibers. We observed the emission of green and cyan light as a consequence of fiber material ionization. We investigate both the commercial ZBLAN step index and in-house-made tellurite nanostructured graded-index fibers. For the latter, the analysis of the luminescence signal permits us to determine the core and cladding refractive index difference. Upconversion luminescence is a powerful tool for characterizing soft glass fibers and a promising platform for innovative photonic technologies and mid-IR applications. Full article

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18 pages, 9296 KB

Open AccessArticle

Effect of Adding Phragmites-Australis Fiber on the Mechanical Properties and Volume Stability of Mortar

by Jamal Khatib, Rawan Ramadan, Hassan Ghanem and Adel Elkordi

Fibers 2024, 12(2), 14; https://doi.org/10.3390/fib12020014 - 30 Jan 2024

Cited by 14 | Viewed by 2600

Abstract

In this research, the investigation focuses on the influence of Phragmites-Australis (PA) fibers on the mechanical properties and volume stability of mortar. A total of four mixtures were employed with varying amounts of locally sourced PA fibers ranging from 0.5% to 2% (by volume). Testing includes flexural strength, compressive strength, chemical shrinkage, drying shrinkage, autogenous shrinkage, and expansion. The findings show that the use of PA fibers caused a reduction in compressive and flexural strength. However, beyond 3 days of curing, an increase in flexural strength ranging from 7 to 21% was observed at 1% PA fiber compared to the control sample. Furthermore, the addition of PA fibers up to 2% effectively mitigates the dimensional stability of mortar samples. A gradual decrease in chemical, autogenous, and drying shrinkage as well as expansion occurs in mortar samples when % of PA fibers increases. At 180 days, this reduction was 37, 19, 15 and 20% in chemical shrinkage, autogenous shrinkage, drying shrinkage, and expansion, respectively, for a mix containing 2% PA fiber. Additionally, a hyperbolic model is proposed to predict the variation of length change with time. Also, a strong relationship is observed between chemical shrinkage and other length change parameters. Consequently, the environmentally friendly utilization of PA fibers demonstrates its potential to significantly enhance mortar durability in construction applications. Full article

(This article belongs to the Special Issue Development of Eco-Friendly Concrete-, Mortar- and Fiber-Reinforced Composite Systems for Building Applications: Experimental and Theoretical Studies)

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15 pages, 5499 KB

Open AccessArticle

Cement-Based Mortars with Waste Paper Sludge-Derived Cellulose Fibers for Building Applications

by Francesco Bencardino, Pietro Mazzuca, Ricardo do Carmo, Hugo Costa and Roberta Curto

Fibers 2024, 12(2), 13; https://doi.org/10.3390/fib12020013 - 23 Jan 2024

Cited by 7 | Viewed by 2889

Abstract

This study assesses the mechanical properties of mortars incorporating waste paper sludge-derived cellulose fibers. Compression and flexural tests were carried out on specimens prepared with cellulose fibers at different proportions, ranging from 0% to 2% of the total weight of the solid mortar constituents (cement, sand, and lime). In addition, a comparative analysis was carried out to evaluate the influence of the preparation method on the mechanical properties of the mortars. To this end, two series of mortars were studied: one prepared following a rigorous control of the preparation parameters and the other made without systematic parameter control to simulate typical on-site conditions. Finally, the applicability of both traditional and eco-friendly mortars in the construction of small-scale masonry walls was assessed through compression tests. Overall, the mechanical properties of mortars with cellulose fibers were comparable to those with 0% waste material, regardless of the production process. Regarding the compressive behavior of masonry walls, experimental tests showed significant similarities between specimens made with traditional and eco-friendly mortar. In conclusion, incorporating cellulose fibers into cement-based mortar shows considerable potential for building applications, enhancing the environmental benefits without compromising the mechanical behavior. Full article

(This article belongs to the Special Issue Development of Eco-Friendly Concrete-, Mortar- and Fiber-Reinforced Composite Systems for Building Applications: Experimental and Theoretical Studies)

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