Micromechanical performance of interfacial transition zone in fiber-reinforced cement matrix

Zacharda, Vojtěch; Němeček, Jiří; Štemberk, Petr

doi:10.1088/1757-899x/246/1/012018

Cited by 7 publications

(5 citation statements)

References 14 publications

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“…On the other hand, steel fibres can enhance drying shrinkage as pores are connected and water permeability increases [ 17 ]. The increased porosity in the contact zone of cement matrix and steel fibres [ 16 ] can even enhance this effect.…”

Section: Resultsmentioning

confidence: 99%

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Influence of Rapid Heat Treatment on the Shrinkage and Strength of High-Performance Concrete

2021

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Resource-efficient precast concrete elements can be produced using high-performance concrete (HPC). A heat treatment accelerates hardening and thus enables early stripping. To minimise damages to the concrete structure, treatment time and temperature are regulated. This leads to temperature treatment times of more than 24 h, what seems too long for quick serial production (flow production) of HPC. To overcome this shortcoming and to accelerate production speed, the heat treatment is started here immediately after concreting. This in turn influences the shrinkage behaviour and the concrete strength. Therefore, shrinkage is investigated on prisms made from HPC with and without steel fibres, as well as on short beams with reinforcement ratios of 1.8% and 3.1%. Furthermore, the flexural and compressive strengths of the prisms are measured directly after heating and later on after 28 d. The specimens are heat-treated between 1 and 24 h at 80 °C and a relative humidity of 60%. Specimens without heating serve for reference. The results show that the shrinkage strain is pronouncedly reduced with increasing temperature duration and rebar ratio. Moreover, the compressive and flexural strength decrease with decreasing temperature duration, whereby the loss of strength can be compensated by adding steel fibres.

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Section: Resultsmentioning

confidence: 99%

“…Furthermore, calcium hydroxide crystals grow on the surface of the fibres, what loosens the structure of the concrete matrix [ 13 ]. Moreover, the contact zone between concrete and fibres shows lower amounts of clinker, which increases the porosity [ 16 ]. This facilitates moisture penetration and affects drying shrinkage.…”

Section: Introductionmentioning

confidence: 99%

Influence of Rapid Heat Treatment on the Shrinkage and Strength of High-Performance Concrete

2021

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“…Steel fiber-reinforced cementitious composite (SFRCC) has become one of the most widely used building materials in the last few decades due to its excellent reinforcing effects. The crack bridging efficiency of a single fiber usually depends on its embedded length, radius, geometry, orientation, material properties and interfacial characteristics (Abbas and Iqbal Khan, 2016; Abu-Lebdeh et al., 2011; Aslani and Nejadi, 2012; Bao and Song, 1993; Cunha et al., 2010; Deng et al., 2018; Leung and Shapiro, 1999; Lin and Li, 1997; Zacharda et al., 2017). Among others, it is generally recognized that the crack bridging effect is substantially influenced by the bond properties of the fiber/matrix interface.…”

Section: Introductionmentioning

confidence: 99%

“…The stress transfer from the matrix to the fibers is achieved through the shear stress (or rather, the bond) at the fiber/matrix interface. The role of fibers in the composite is to delay the occurrence of cracks and restrain their propagation through fiber bonding, debonding and pullout processes, thus greatly improving the mechanical properties such as the bearing capacity, energy dissipation capacity (or rather, ductility), toughness and impact resistance (Aslani and Nejadi, 2012;Cunha et al, 2010;Lee et al, 2010;Moradi et al, 2020;Xu et al, 2011Xu et al, , 2012Yang et al, 2020;Zacharda et al, 2017;Zhang et al 2013). This is the so-called crack bridging effect, the main mechanism of fiber reinforcement.…”

Section: Introductionmentioning

confidence: 99%

A micromechanical crack bridging model considering the slip-softening interface with the residual shear stress for SFRCC

Wei

Zhu

Chen

et al. 2022

International Journal of Damage Mechanics

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Characterizing the bond properties of the steel fiber/matrix interface plays an important role in describing the crack bridging effect in steel fiber-reinforced cementitious composites (SFRCC). In this paper, a new interface law considering the residual shear stress is proposed to interpret the slip-softening effects of the steel fiber/matrix interface. Accordingly, a micromechanical crack bridging model for SFRCC is formulated by combining the single steel fiber pullout model with the image analysis-based fiber orientation distribution. Comparisons with the experimental data and the existing models show that the proposed model can well predict SFRCC’s tensile softening behavior. Meanwhile, the decrease rate of the bridging stress, the composite fracture energy, the peak bridging stress and the corresponding peak crack opening displacement (COD) are employed to quantitatively evaluate the crack bridging curves. Finally, the effects of the residual shear stress ratio, the interfacial softening coefficient and the fiber orientation distribution on the crack bridging relation are discussed with the proposed framework.

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“…Im Gegensatz dazu werden erhöhte Dehnungen infolge Trocknungsschwinden festgestellt, da Stahlfasern unter anderem die Porenräume im Beton verbinden, was zu einer erhöhten Wasserdiffusion führt [10]. Außerdem weisen die Kontaktzonen zwischen Fasern und Betonmatrix eine größere Porosität auf [11], was zu Feuchtetransporten führen kann und damit das Schwindverhalten beeinflusst.…”

Section: Introductionunclassified

Experimente zur Schwindreduktion von hochfesten Betonbauteilen durch Wärmebehandlung

Stindt

Forman

Mark

2021

Beton und Stahlbetonbau

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Im Beitrag wird die Reduktion des Schwindens von hochfestem Beton durch eine Wärmebehandlung untersucht. Betone werden wärmebehandelt, um die Erhärtung zu beschleunigen und ein frühes Ausschalen zu ermöglichen. Durch eine geeignete Wahl der maximalen Behandlungstemperatur, der Aufheiz‐ und Abkühlrate sollen Schädigungen des Betongefüges minimiert werden. Dies führt zu Wärmebehandlungsdauern von mehr als 24 h, was für eine serielle Fertigung von Betonfertigteilen zu lange ist. Für eine minimal kurze Wärmebehandlung wird auf eine Vorlagerungszeit sowie eine reglementierte Aufheizrate verzichtet, sodass das Aufheizen direkt nach dem Betonieren beginnt. Diese Verkürzung hat Einfluss auf das Schwindverhalten. Es wird hier an Prismen mit und ohne Stahlfasern sowie an Balken mit einem Stabstahlbewehrungsgrad von 1,8 % und 3,1 % untersucht. Alle Proben werden bei 80 °C und 60 % rel. Luftfeuchte für 1, 2, 4, 6 und 24 h wärmebehandelt. Proben ohne Wärmebehandlung dienen als Referenz. Die Ergebnisse zeigen, dass mit zunehmender Wärmebehandlungsdauer die Schwinddehnung deutlich reduziert wird. Sie wird zudem mit zunehmendem Bewehrungsgrad geringer. Um das Schwindverhalten in Abhängigkeit von der Wärmebehandlung zu prognostizieren, werden datenbasierte Antwortflächen abgeleitet und validiert. Dabei steigt die Vorhersagequalität mit zunehmendem Betonalter.

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Micromechanical performance of interfacial transition zone in fiber-reinforced cement matrix

Cited by 7 publications

References 14 publications

Influence of Rapid Heat Treatment on the Shrinkage and Strength of High-Performance Concrete

Influence of Rapid Heat Treatment on the Shrinkage and Strength of High-Performance Concrete

A micromechanical crack bridging model considering the slip-softening interface with the residual shear stress for SFRCC

Experimente zur Schwindreduktion von hochfesten Betonbauteilen durch Wärmebehandlung

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