@inproceedings{HerzSigruenerMuscatetal.2023, author = {Herz, Jonas and Sigr{\"u}ner, Michael and Muscat, Dirk and Str{\"u}bbe, Nicole}, title = {Co-extruded polymer fibers for concrete reinforcement}, series = {Proceedings of the 37th International Conference of the Polymer Processing Society (PPS-37)}, volume = {2884}, booktitle = {Proceedings of the 37th International Conference of the Polymer Processing Society (PPS-37)}, number = {1}, doi = {10.1063/5.0168511}, year = {2023}, abstract = {Corrosion of steel reinforcements in concrete constructions is a big topic for the building industry. Polymeric materials are a possible alternative due to their ability to withstand corrosion. To replace steel reinforcements, fibers with high mechanical properties and a good bonding ability between fiber and concrete are needed. Today different approaches for concrete reinforcement by polymer fibers have been investigated. The bonding ability of the fibers can be increased by mechanical anchoring, e.g. crimped or embossed fibers, as well as by a chemical bonding between concrete and fiber surface. To realize the requirements of high mechanical properties and a good bonding behavior, a fiber that is drawn from a co-extruded filament shall be produced and tested. The filament owns an innovative core-shell-structure. The core maintains the fiber-stiffness and the tensile strength while the shell allows using another material to affect the bonding behavior of the fiber. This study shows the usage of fibers with differing shell materials to examine their influence on the mechanical properties of the fiber in total and the adhesion abilities to concrete. As core material, an unfilled polypropylene (PP) is used. The shell materials are varied using different polymers e.g. polypropylene or ethylene acrylic acid copolymer, as well as two PP based compounds filled with wood particles and calcium carbonate blended with a maleic anhydride based coupling agent. The mechanical properties of the fibers are tested by fiber tensile tests to compare the younǵs modulus and the tensile strength. The influence of the shell phase on the bonding ability to concrete is evaluated by the interfacial shear strength calculated from single fiber pull-out tests. Microscopy is used to interpret changes before and after pull-out. The results depict incredible positive effects and allow new insights in possible materials for fiber reinforced concrete constructions.}, language = {en} } @article{HerzMuscatStruebbe2025, author = {Herz, Jonas and Muscat, Dirk and Str{\"u}bbe, Nicole}, title = {The Influence of Fillers on the Reinforcement Capabilities of Polypropylene Based Mono-Material and Core-Shell Fibers in Concrete, a Comparison}, series = {Polymers}, volume = {17}, journal = {Polymers}, number = {13}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/polym17131781}, pages = {24}, year = {2025}, abstract = {Noncorrosive concrete reinforcement, such as polymer fibers, is needed to overcome the current issues caused by corroded steel reinforcements. Fibers made of polypropylene show a low bonding behavior in concrete. Fillers can help to overcome this issue but often lead to reduced mechanical properties. Core-shell fibers, which split the mechanical properties and the bonding behavior between the core and the shell component, could be a solution. This study investigates mono-material and core-shell fibers produced with calcium carbonate and bentonite fillers and compares their behavior in tensile tests, density measurements, contact angle measurements, topography measurements, single fiber pull-out tests, reflected light microscopy, and thermogravimetric analysis. The fillers caused an increased drawability, resulting in higher mechanical properties. Further, in the core-shell fibers, the calcium carbonate increased the surface roughness, which led to a better anchoring of the fiber in concrete, which was also visible in the deformation during pull-out observed in reflected light microscopy pictures. The thermogravimetric analysis showed a delay in onset of degradation for fibers containing bentonite.}, language = {en} } @techreport{HerzKazmiStruebbeetal.2022, author = {Herz, Jonas and Kazmi, Monis and Str{\"u}bbe, Nicole and Muscat, Dirk and Schuster, Jens and Hunger, Martin and Lanyi, Franz J.}, title = {Holz-Kunststoff-Hybrid-Gewebe/Gelege - Grundlagenuntersuchung zur Entwicklung eines innovativen Holz-Kunststoff-Hybrid-Gewebes/Geleges f{\"u}r den Ersatz von Stahlbewehrungen im Bau (Machbarkeitsstudie) : Schlussbericht zum Verbundvorhaben : Laufzeit: 01.06.2020 bis 28.02.2022}, doi = {10.2314/KXP:1860061346}, year = {2022}, language = {de} } @misc{HerzHefenbrockLorenzetal.2024, author = {Herz, Jonas and Hefenbrock, Sophia and Lorenz, Katharina and Muscat, Dirk and Str{\"u}bbe, Nicole}, title = {Polyketone-Polypropylene Core-Shell Fibers for Concrete Reinforcement}, series = {Proceedings of the 39th International Conference of the Polymer Processing Society (PPS-39)}, journal = {Proceedings of the 39th International Conference of the Polymer Processing Society (PPS-39)}, editor = {Ediciones Uniandes,}, doi = {10.51573/Andes.PPS39.GS.FF.1}, pages = {167 -- 177}, year = {2024}, abstract = {Corrosion of the commonly used steel reinforcements weakens the structural strength of concrete. To oppose this issue, concrete reinforcements in the form of polymer fibers are investigated. These polymer fibers need a good bonding ability to concrete and good mechanical properties. This study investigates core-shell fibers produced from polyketone and polypropylene mixed with a compatibilizer. The core-shell fibers were produced by coextrusion and drawing. The fibers were analyzed by tensile tests, a single fiber pull-out test, contact angle measurements, scanning electron microscopy and thermogravimetric analysis.}, language = {en} } @inproceedings{HerzSigruenerKrekemeyeretal.2021, author = {Herz, Jonas and Sigr{\"u}ner, Michael and Krekemeyer, Markus and Kazmi, Monis and Schuster, Jens and Muscat, Dirk and Str{\"u}bbe, Nicole}, title = {INVESTIGATION OF AN INNOVATIVE WOOD-PLASTIC HYBRID LAID FABRIC FOR THE REPLACEMENT OF STEEL REINFORCEMENTS IN CONSTRUCTIONS}, series = {SAMPE Europe 2021 Conference, Baden/Z{\"u}rich, 29. - 30. Sept. 2021}, booktitle = {SAMPE Europe 2021 Conference, Baden/Z{\"u}rich, 29. - 30. Sept. 2021}, year = {2021}, language = {en} } @inproceedings{HerzSigruenerWalteretal.2022, author = {Herz, Jonas and Sigr{\"u}ner, Michael and Walter, David and Muscat, Dirk and Str{\"u}bbe, Nicole}, title = {Coextruded Polymeric Bicomponent Fibers for Concrete Reinforcements}, series = {SAMPE Europe Conference Proceedings 2022, Hamburg, 15. - 17. Nov. 2022}, booktitle = {SAMPE Europe Conference Proceedings 2022, Hamburg, 15. - 17. Nov. 2022}, year = {2022}, language = {en} } @article{HerzSchusserMuscatetal.2025, author = {Herz, Jonas and Schusser, Verena and Muscat, Dirk and Str{\"u}bbe, Nicole}, title = {Cold-Drawn Wood-Filled Polybutylene Succinate Macro-Fibers as a Reinforcing Material for Concrete}, series = {Polymers}, volume = {17}, journal = {Polymers}, number = {3}, publisher = {MDPI}, address = {Basel}, doi = {https://doi.org/10.3390/polym17030403}, pages = {21}, year = {2025}, abstract = {The corrosive behavior of steel reinforcements causes issues in the concrete industry. To overcome this issue, alternative noncorrosive reinforcements such as polymer fibers could be used. However, as environmental protection becomes more important, sustainability must also be considered in the solution. An alternative to polymers based on raw oil is bio-based polymers. This study investigates the suitability of polymer fibers produced from polybutylene succinate together with cellulose and wood fillers as concrete reinforcements. Different mixtures of polybutylene succinate, cellulose, and wood fillers were created, and fibers were produced using a multiple drawing process. The fibers were tested using tensile tests, a single-fiber pull-out test, contact angle measurements, reflected light microscopy, density measurements, and thermogravimetric analysis. The fillers were shown to decrease the mechanical properties as the particle size and filler amount increased, resulting in a reduction in Young's modulus and tensile strength of 55\% and 70\%, respectively, while adhesion to concrete increased with particle size from 0.31 ± 0.02 N/mm2 without filler to 0.90 ± 0.10 N/mm2 for the best-performing material combination. Reflected light microscopy images show changes in the fiber surface before and after pull-out. The fiber density decreased from 1.26 ± 0.05 g/cm3 to 0.91 ± 0.04 g/cm3 with an increasing filler amount and particle size for a compound with 10 weight percent of wood filler 1. The fiber thermal stability decreased slightly with the addition of filler. The greatest effect was a reduction in the temperature to ≈58 °C at 1\% weight loss when 10 weight percent of wood was added. This study proves the possibility of using bio-based materials as concrete reinforcements.}, language = {en} } @inproceedings{HerzLorenzMuscatetal.2024, author = {Herz, Jonas and Lorenz, Katharina and Muscat, Dirk and Str{\"u}bbe, Nicole}, title = {Polymeric core-shell and mono-material fibers for concrete reinforcement}, series = {AIP Conference Proceedings}, volume = {3158}, booktitle = {AIP Conference Proceedings}, number = {1}, organization = {38th International Conference of the Polymer Processing Society (PPS-38)}, doi = {10.1063/5.0204946}, year = {2024}, abstract = {A reinforcement of concrete structures is needed because of the low tensile strength of concrete. Corrosion of the usually used steel reinforcments cause issues during time. Therfore, alternative reinforcements produced from non-corosive materials - like polymer fibers - become more interesting. A polymer fiber has to reach high mechanical properties and a good bonding ability to concrete. Both properties can be influenced by the selection of polymer and the used production process. Two polymers, polypropylene and aliphatic polyketone are tested within this study. First mono-material fibers of each material are produced and tested, later the materials are combined in a core-shell fiber. All fibers are produced by standard extrusion or coextrusion and a later drawing process. The mechanical properties are determined by tensile tests. The calculation of interfacial shear strength from single fiber pull-out tests allows an evaluation of the bonding ability. Additionally, fiber surface before and after pull-out is examined using reflected light microscopy. Contact angle measurements are done to evaluate possible influences of the surface energy and polarity. Density measurements are used to compare weight potential of the different mono-material and core-shell fibers. The results show good mechanical properties for all fiber materials. The interfacial shear strength is ≈ 2-3 times higher for fibers with polyketone compared to the ones with polypropylene at the fibers surface, which can be explained by higher surface energy and polarity of the polyketone compared to polypropylene and different surface deformation during pull-out. Lower densities are reached by fibers containing polypropylene.}, language = {en} } @article{SigruenerHueskenPirskawetzetal.2023, author = {Sigr{\"u}ner, Michael and H{\"u}sken, G{\"o}tz and Pirskawetz, Stephan and Herz, Jonas and Muscat, Dirk and Str{\"u}bbe, Nicole}, title = {Pull-out behavior of polymer fibers in concrete}, series = {Journal of Polymer Science}, volume = {61}, journal = {Journal of Polymer Science}, number = {21}, doi = {10.1002/pol.20230264}, pages = {2708 -- 2720}, year = {2023}, abstract = {The bond between polymer fibers and the surrounding cementitious matrix is essential for the development of concrete reinforcement. The single fiber pull-out test (SFPT) is the standard characterization technique for testing the bond strength. However, the different phases of debonding cannot be distinguished by the SFPT. This study investigates the debonding of different polymer fibers from the surrounding cementitious matrix with a modified SFPT and proposes methods to change the SFPT setup to generate more valuable information on the debonding mechanism. The SFPT was equipped with linear variable differential transformers (LVDT), digital image correlation (DIC) and acoustic emission (AE) analysis. The results demonstrate that the modified SFPT allows a better understanding of the different phases of debonding during fiber pull-out. Furthermore, bond strength values calculated by different methods reveal that the chemical bond of the investigated polymers is not different as reported by previous studies. Deformation measurements performed using LVDTs and DIC are suitable measuring techniques to characterize the debonding mechanism in SFPT. A correlation between recorded AE and debonding phases was not found.}, language = {en} }