Fiber-Reinforced Cement Composites and Geopolymers: Mechanics and Durability

A special issue of Fibers (ISSN 2079-6439).

Deadline for manuscript submissions: 15 September 2026 | Viewed by 4806

Editors


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Guest Editor
Department of Civil Engineering, Wrocław University of Environmental and Life Sciences, pl. Grunwaldzki 24, 50-356 Wrocław, Poland
Interests: beam and slab deformation; steel fiber-reinforced concrete; mechanical properties of high-strength fiber-reinforced concrete; creep and shrinkage of concrete; calculation methods of beams and plates
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Guest Editor
Department of Civil Engineering, Wrocław University of Environmental and Life Sciences, pl. Grunwaldzki 24, 50-356 Wrocław, Poland
Interests: concrete technology; supplementary cementitious materials; sustainable building materials; recycling; durability; thermal properties; heat and mass transfer; Monte Carlo simulation

Special Issue Information

Dear Colleagues,

Fibres are one of the established methods of modifying and enhancing cement-based composites and geopolymers. They improve selected properties of materials with a brittle matrix—particularly, though not exclusively, their tensile strength. Fibres are introduced both in loose form and as bundles, meshes, or even technical textiles.

The resulting changes in the properties of such modified composites, and the extent of those changes, are the subject of numerous studies. This includes the durability of the fibres themselves in environments that are often unfavourable to certain types of them, as well as methods to improve their performance under such conditions. Equally important is the impact of fibres on the deformability and strain behaviour of materials, especially under various loading conditions.

Given these factors, research into the use of fibres in cementitious composites and geopolymers remains a relevant and evolving scientific field, where many knowledge gaps still exist and there is room for further innovation. A relatively underexplored area of study is the use of recycled fibres, particularly in the context of their performance and durability in concrete and geopolymer matrices. Undoubtedly, other such areas can also be identified.

The aims of this Special Issue are to gather researchers working in this field and to collect new findings and recent advances concerning the use of fibres in cementitious composites and geopolymers, their influence on the mechanical, physical, durability, and deformation-related properties of such materials, the mechanisms of interaction between fibres and the matrix and how these can be improved, the degradation of certain types of fibres (especially organic ones) and ways to mitigate such effects, as well as other topics falling within the broad thematic scope of this Issue.

Dr. Maciej Kaźmierowski
Dr. Roman Jaskulski
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-anonymized peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fibers is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • fibres for the modification of cementitious composites
  • fibre-reinforced geopolymers
  • cement concrete
  • cement mortar
  • mechanical properties
  • material deformability and strain behaviour
  • shrinkage
  • thermal properties
  • durability parameters
  • material structure
  • fibre–matrix interaction in cementitious and geopolymer systems
  • degradation of fibres (especially organic ones)
  • application of recycled fibres
  • durability of materials in aggressive environments

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Published Papers (3 papers)

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Research

20 pages, 4094 KB  
Article
Effect of Copper Slag Content and Hybrid Steel Fiber Addition on the Mechanical Response of an Alkali-Activated Geopolymer Composite
by Maciej Kaźmierowski, Jakub Sławiński, Jarosław Rybak and Jolanta Dąbrowska
Fibers 2026, 14(6), 67; https://doi.org/10.3390/fib14060067 - 8 Jun 2026
Viewed by 446
Abstract
This study evaluated the effects of copper slag (CS), dosed relative to the mass of fly ash (FA; CS = 0, 7.5, 15, and 22.5%), and the volume fraction of hybrid steel fibers (Vf = 0.0, 0.5, and 1.0%) on the [...] Read more.
This study evaluated the effects of copper slag (CS), dosed relative to the mass of fly ash (FA; CS = 0, 7.5, 15, and 22.5%), and the volume fraction of hybrid steel fibers (Vf = 0.0, 0.5, and 1.0%) on the mechanical response of an alkali-activated geopolymer composite. The tests were performed using a two-factor CS × Vf design (4 × 3), with compressive strength (fc) and splitting tensile strength (fct.sp) determined as the response variables. Statistical analysis showed significant effects of CS, Vf, and CS × Vf on fc, and a significant CS × Vf interaction for fct.sp, confirming that the fiber effect depended on the CS content. The greatest increases in fc relative to fiber-free composites were obtained for CS = 7.5%: +73% (Vf = 0.5%) and +102% (Vf = 1.0%), and for CS = 22.5%: +75% (Vf = 1.0%). For fct.sp, a decrease was found at CS = 0% and Vf = 0.5% (−34%), whereas an increase was observed at CS = 22.5% and Vf = 1.0% (+49%). The interpretation of the mechanical response was extended by DIC-based strain analysis in compression and splitting tests, together with σct.spεx curves, indicating differences in strain/damage localization and post-cracking response. Full article
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15 pages, 2041 KB  
Article
Freeze–Thaw Durability and Damage Evolution of High-Strength Concrete Reinforced with Steel–Polypropylene Hybrid Fibers
by Yingying Tao, Yanmei Zhang, Chuan Zhao, Changlei Bu, Rui Zhang, Qikai Wang, Qingzhe Yi, Fuxin Wu, Yanchang Zhu and Yongxiang Fang
Fibers 2026, 14(3), 28; https://doi.org/10.3390/fib14030028 - 24 Feb 2026
Cited by 1 | Viewed by 1829
Abstract
High-strength concrete (HSC) is vital for large-scale tunnel infrastructure; however, its durability is often compromised by rigorous freeze–thaw cycles in cold-region environments. This study investigates the synergistic effects of incorporating hybrid steel fiber (SF) and polypropylene fiber (PPF) to enhance the frost resistance [...] Read more.
High-strength concrete (HSC) is vital for large-scale tunnel infrastructure; however, its durability is often compromised by rigorous freeze–thaw cycles in cold-region environments. This study investigates the synergistic effects of incorporating hybrid steel fiber (SF) and polypropylene fiber (PPF) to enhance the frost resistance of HSC. Experimental testing involved 125 freeze–thaw cycles across various fiber dosages and lengths, monitoring mass loss and the relative dynamic modulus of elasticity. Additionally, a concrete damage plasticity (CDP) model was utilized in numerical simulations to analyze thermal stress distribution and damage evolution under coupled freeze–thaw and axial loading. Results indicate that the hybrid fiber integration significantly improved durability, with Group A3 (35 kg/m3 SF and 1.5 kg/m3 of 18 mm PPF) achieving the highest performance. After 125 cycles, Group A3 maintained a relative dynamic modulus of 94.5% and restricted mass loss to 1.42%, a 41% improvement over the fiber-free control. Numerical simulations corroborated these findings, demonstrating that the dual-fiber system preserves load-bearing capacity, limiting compressive strength degradation to just 6.7%. These findings quantitatively validate the synergistic mechanisms of hybrid fibers, providing a robust reference for designing high-durability concrete in cold-climate engineering applications. Full article
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20 pages, 4299 KB  
Article
Mechanical Behavior and Modeling of Flax Fiber-Reinforced Geopolymers in Comparison with Other Natural Fiber Composites
by Sana Ullah, Salvatore Benfratello, Carmelo Sanflippo and Luigi Palizzolo
Fibers 2026, 14(2), 27; https://doi.org/10.3390/fib14020027 - 14 Feb 2026
Cited by 2 | Viewed by 1736
Abstract
The rising environmental concerns over cement-based construction materials have led to the development of sustainable alternatives. Among these, geopolymers represent a promising class of low-carbon binders offering environmental benefits and competitive mechanical properties; however, their intrinsic brittleness limits their tensile and post-cracking performance. [...] Read more.
The rising environmental concerns over cement-based construction materials have led to the development of sustainable alternatives. Among these, geopolymers represent a promising class of low-carbon binders offering environmental benefits and competitive mechanical properties; however, their intrinsic brittleness limits their tensile and post-cracking performance. This study investigates the adoption of flax fibers as natural reinforcement to enhance ductility and post-peak behavior of metakaolin-based geopolymers. The performance of metakaolin-based geopolymers with flax fibers (MKFLAX) was experimentally evaluated in terms of strength, stiffness, toughness, and failure behavior. The addition of flax fibers enhanced ductility, toughness, and post-peak load-carrying capacity while slightly improving stiffness due to the bridging of cracks and the fiber pull-out mechanism. In comparison with the available literature on sisal, flax, and jute fibers, flax fibers showed improved performance due to the better dispersion within the matrix and higher tensile modulus. These findings highlight that flax fiber-reinforced metakaolin geopolymers show enhanced post-cracking behavior at the laboratory scale and could be of interest for sustainable cementitious materials, subject to further validation at the structural scale. Furthermore, a nonlinear finite element model was adopted based on damage mechanics to simulate the damage localization, stress–strain response and post-peak behavior of geopolymer composites. The numerical results showed a reasonable agreement with the experimental trends, particularly in the elastic and early softening phases. The findings are limited to the studied material system, fiber content, and small-scale samples and should be viewed as trend-level observations rather than generalized performance claims. Full article
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