Single fibre pullout tests on auxetic polymeric fibres

By adding fibres to concrete mix the objective is to bridge discrete cracks providing for some control to the fracture process and increase the fracture energy. Fibres become active mainly when cracking starts and deformation of the fibre occurs. Pullout tests with four types of fibres with different orientation, embedment lengths, and concrete strengths are performed to simulate the bridging process. Fibre pullout behaviour is analysed for relatively small slippage displacement to keep it close to real designing situations. The test results show significant effect of fibre type on pullout behaviour, nevertheless the effect is intangible on fibres inclined at 30 degrees or more. An effective displacement is introduced, derived from experimental force-slip curves, when fibre becomes involved in bridging. Based on the effective displacement and simplified average force-slip curves a numerical model is proposed to analyse the tensile stresses transferred by fibres crossing a crack.

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Micromechanical Tests on Natural Fibre Composites with Enzymatically Enhanced Fibre–Matrix Adhesion

Materials Circular Economy ◽

10.1007/s42824-021-00040-4 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Hanna M. Brodowsky ◽

Anne Hennig

Keyword(s):

Shear Strength ◽

Single Fibre ◽

Natural Fibre ◽

Interfacial Shear ◽

Frictional Stress ◽

Reinforced Composites ◽

Fragmentation Test ◽

Fibre Pullout ◽

Fibre Matrix ◽

Fibre Reinforced Composites

Abstract Natural fibre–reinforced composites are more sustainable than other composites with respect to the raw materials. Their properties are attractive due to high specific properties, and especially so wherever high damping is valued. As the interphase between fibre and matrix is the region of highest stresses, a strong bond between fibre and matrix is essential for any composites’ properties. The present study compares two methods of determining the interfacial shear stress in natural fibre–reinforced composites: the single fibre fragmentation test and the single fibre pullout test. The studied composites are flax fibre reinforced epoxy. For a variety of fibre–matrix interaction, the fibres are treated with a laccase enzyme and dopamine, which is known to improve the fibre–matrix shear strength. In the observed samples, single fibre fragmentation test data, i.e. of fracture mode and fragment length, scatter when compared to pullout data. In single fibre pullout tests, the local interfacial shear strength showed a 30% increase in the laccase-treated samples, compared to the control samples. The method also permitted an evaluation of the frictional stress occurring after surface failure.

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On the single fibre pullout and pushout problem: Effect of fibre anisotropy

Zeitschrift für angewandte Mathematik und Physik ◽

10.1007/bf00948488 ◽

1993 ◽

Vol 44 (4) ◽

pp. 769-775 ◽

Cited By ~ 16

Author(s):

Li-Min Zhou ◽

Yiu-Wing Mai

Keyword(s):

Single Fibre ◽

Fibre Pullout

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Evaluation of locally available synthetic macro fibres in a single-fibre pullout test in concrete

Journal of the South African Institution of Civil Engineering ◽

10.17159/2309-8775/2018/v60n1a3 ◽

2018 ◽

Vol 60 (1) ◽

pp. 21-30

Author(s):

C. M. Odendaal ◽

A. J. Babafemi ◽

R. Combrinck ◽

W. I. de Villiers

Keyword(s):

Pullout Test ◽

Single Fibre ◽

Fibre Pullout

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Experimental, Analytical and Numerical Studies of Interfacial Bonding Properties between Silane-Coated Steel Fibres and Mortar

Buildings ◽

10.3390/buildings11090398 ◽

2021 ◽

Vol 11 (9) ◽

pp. 398

Author(s):

Yong Yao ◽

Hui Zhang ◽

Xin Zhang ◽

Feifan Ren ◽

Yaqi Li ◽

...

Keyword(s):

Analytical Solutions ◽

Steel Fibre ◽

Single Fibre ◽

Systematic Investigation ◽

Interfacial Stress ◽

Bond Slip ◽

Steel Fibre Reinforced Concrete ◽

Concrete Members ◽

Pullout Tests ◽

Bonding Properties

A systematic investigation of the effects of silane coatings on steel fibre–mortar interfacial bond properties was conducted, combining pullout tests, analytical solutions, and meso-scale FE simulations. Nine silane coatings were tested, and their effects were evaluated by 30 single fibre pullout tests. They were found to increase the peak force and energy consumption up to 5.75 times and 2.48 times, respectively. Closed-form analytical solutions for pullout load, displacement, and interfacial stress distribution during the whole pullout process were derived based on a tri-linear bond-slip model, whose parameters were calibrated against the pullout tests. Finally, the calibrated bond-slip models were used to simulate the pullout tests and complex failure of multi-fibre specimens in mesoscale finite element models. Such an approach of combining pullout tests, analytical solutions, and mesoscale modelling provides a reliable way to investigate the effects of fibre–mortar interfacial properties on the mechanical behaviour of steel fibre reinforced concrete members in terms of structural strength, stiffness, ductility, and failure mechanisms.

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Interfacial Adhesion Characteristics of Kenaf Fibres Subjected to Different Polymer Matrices and Fibre Treatments

Journal of Composites ◽

10.1155/2014/350737 ◽

2014 ◽

Vol 2014 ◽

pp. 1-12 ◽

Cited By ~ 14

Author(s):

Umar Nirmal ◽

Saijod T. W. Lau ◽

Jamil Hashim

Keyword(s):

Interfacial Adhesion ◽

Single Fibre ◽

Polymer Matrices ◽

Alkaline Solutions ◽

Fibre Breakage ◽

Chemical Treatments ◽

Fibre Pullout ◽

Failure Morphology ◽

Interfacial Adhesion Strength ◽

Kenaf Fibres

This study is aimed at determining the interfacial adhesion strength (IAS) of kenaf fibres using different chemical treatments in hydrochloric (HCl) and sodium hydroxide (NaOH) with different concentrations. Single fibre pullout tests (SFPT) were carried out for both untreated and treated fibres partially embedded into three different polymer matrices; polyester, epoxy, and polyurethane (PU) as reinforcement blocks and tested under dry loading conditions. The study revealed that kenaf fibres treated with 6% NaOH subjected to polyester, epoxy, and PU matrices exhibits excellent IAS while poor in acidic treatment. The effect of SFPT results was mainly attributed to chemical composition of the fibres, types of fibre treatments, and variation in resin viscosities. By scanning electron microscopy examination of the material failure morphology, the fibres experienced brittle and ductile fibre breakage mechanisms after treatment with acidic and alkaline solutions.

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Microbond fibre bundle pullout technique to evaluate the interfacial adhesion of polyethylene and polypropylene self reinforced composites

Applied Adhesion Science ◽

10.1186/s40563-019-0121-z ◽

2019 ◽

Vol 7 (1) ◽

Cited By ~ 1

Author(s):

M. Sharan Chandran ◽

K. Padmanabhan

Keyword(s):

Composite Materials ◽

Interfacial Adhesion ◽

Interfacial Properties ◽

Pullout Test ◽

Single Fibre ◽

Interface Properties ◽

Reinforced Composites ◽

Adhesion Properties ◽

Fibre Pullout ◽

The Matrix

Abstract Self reinforced polymer composites possess a comparable shear and tensile strength unlike the glass or carbon fibre reinforced composites. Important deciding factors of overall efficiency of composite materials are the interfacial adhesion properties between the fibre and the matrix. Structural properties and processability of composite materials are also dependent on adhesion between the fibre and the matrix. Polypropylene and polyethylene self-reinforced composites are the systems investigated here for the purpose of analyzing the interfacial properties of these systems. Multiple fibre pullout test is an alternate method for single fibre pullout test with added advantages of more reliable statistically averaged data with less standard deviation and minimized chances for fibre breakage during testing. This test can also be verified for various volume fractions unlike single fibre pullout test. Micro bonds of matrix materials are cured on a bundle of fibres and by using a micro vise as an additional fixture, the interfacial strength and other interfacial properties are evaluated through fibre pullout. Surface tension between the fibre and the matrix plays an important role in this test. Thus from the contact angle and the frictional properties of the interface, the interface properties are evaluated. Interface properties obtained from this meso-mechanical semi empirical method are also compared with the properties evaluated from micromechanical formulations. Spectroscopic studies revealed the bonding characteristics during the interface formation and after failure. Fractography reveals the cause and nature of failure and substantiate the analysis.

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