Steel fibre spacing in self-compacting concrete precast walls by X-ray computed tomography

Ponikiewski, Tomasz; Katzer, Jacek; Bugdol, Monika; Rudzki, Marcin

doi:10.1617/s11527-014-0444-y

Cited by 34 publications

(16 citation statements)

References 31 publications

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“…Usually (depending on mix design and rheological characteristics) fibre distribution of SFR-SCC is impaired on a much greater scale than in ordinary SFRC. This phenomenon was noted and described in previous publications [36,38] dealing with SFR-SCC slab and wall elements. To get accurate relationship between fibre volume and mechanical parameters of a given SFR-SCC element, XCT procedures were used to calculate the density of fibres (q F ) for each fracture surface.…”

Section: Discussionsupporting

confidence: 70%

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X-ray computed tomography of fibre reinforced self-compacting concrete as a tool of assessing its flexural behaviour

Ponikiewski

Katzer

2015

Mater Struct

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The aim of the presented research programme was to investigate the flexural behaviour of steel fibre reinforced self-compacting concrete beams. The tested beams were reinforced with two types of crimped steel fibres. Fibres were added in volumes of 0.5, 1.0 and 1.5 %. The experimental tests were conducted on specimens cut from 1.2 m long elements. Before destructive mechanical testing the specimens were subjected to medical X-ray computed tomography (XCT) procedures. Results of XCT allowed to determine the distribution of fibres. The flexural behaviour of the beams was tested according to the RILEM TC 162-TDF recommendation. A comparison of non-destructive results and mechanical behaviour of tested specimens proved a very strong dependence. XCT also made it possible to assess the uniformity of fibre distribution throughout the tested elements. The influence of the location of concrete casting on fibre distribution was determined. The influence of mixture flow on fibre orientation was also analysed.

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Section: Discussionsupporting

confidence: 70%

“…The mix design has not been adjusted (as proposed by Ferrara et al [14]) to account for the incorporation of larger volumes of fibre. In this way the compliance with previous research programmes [36][37][38]43] was maintained and full comparison of achieved results is enabled.…”

Section: Materials and Mixture Compositionmentioning

confidence: 85%

X-ray computed tomography of fibre reinforced self-compacting concrete as a tool of assessing its flexural behaviour

Ponikiewski

Katzer

2015

Mater Struct

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“…As a condition of fulfilling the self-compaction ability a value of D max = 55.0 cm of slump-flow test was acquired. This condition was thoroughly described and discussed by Ponikiewski [12,13,14]. The addition of all three (basalt, polypropylene and basalt) types of fibre deteriorates mixes' workability.…”

Section: Achieved Results and Discussionmentioning

confidence: 99%

Fresh Mix Characteristics of Self-Compacting Concrete Reinforced by Fibre

Ponikiewski

Katzer

2016

Period. Polytech. Civil Eng.

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An analysis of influence of different types of fibre and fibre content on properties of self-compacting concrete is the main subject of the paper. Presented study is focused on the effect of steel, basalt and polypropylene fibres with different geometrical parameters on workability and self-compacting abilities of fresh mixes. Keywords SCC , self-compacting, cement, rheology, fibre, steel, basalt, polypropylene IntroductionThe current state-of-the-art of concrete technology is not sufficient to effectively shape the workability of self-compacting concrete (SCC) with the addition of fibre. Further research is needed, especially taking into account the impact of variable physicochemical properties of cement type and mineral additions (e.g. fly ash, silica fume, lime fume) on such concrete mixes.The influence of fibre addition on properties of fresh and hardened concrete mixes was thoroughly described in multiple previous publications [1,2,3,4,5]. In general, the higher the volume of fibre (V f ) added to concrete mix the better the mechanical properties of the hardened composite are. At the same time increasing fibre volume in concrete causes the loss of workability of fresh mixes and problems with casting and forming [6]. Currently, fibre plays a very important and rapidly growing role in modern concrete technology. Harnessing fibre as concrete reinforcement allows to enhance its mechanical properties and obtaining significant economic benefits. Fibre quickly becomes an important element of sustainable development of construction industry [7]. As far as technology of fibre reinforced self-compacting concrete (FRSCC) is concerned the main problem is the technical difficulty of its preparation and implementation processes during casting. There is a real need to examine and describe the true nature of FRSCC workability and determine the effect of added fibre on multiple phenomena occurring in fresh mix and hardened SCC composite.According to numerous researchers [8, 9] a fresh concrete mix under loading behaves like viscoplastic Bingham body. It basically behaves as a rigid body at low stresses but flows as a viscous fluid at high stresses.Rheological parameters yield point (g) and plastic viscosity (h) are material constants, characterizing the properties of a fresh concrete mix. Once the stresses exceed the yield point, the mixture will flow at a rate proportional to plastic viscosity. The smaller the plastic viscosity of the mixture, the greater the speed of the flow at a given load. Workability-wise, the yield point parameter is the most essential for shaping workability of both ordinary and SCC fresh mixes. In case of ordinary concrete mixes (which are traditionally compacted by vibration),

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“…X-ray Computed Tomography (CT) scans have been also widely employed in the last decade: as a matter of fact, they allow effective 3D visualization of the fiber network inside a FRC specimen [13,39,[54][55][56][57][58][59][60][61][62], also in the case of non-conductive fibers [63], for which electrical methods cannot be applied. Limits on the specimen size and the need of an image analysis software for the quantitative processing of the collected data are so far the main concern in promoting the method for wider use, especially at the industrial scale.…”

Section: Non-destructive Monitoring Of Fiber Dispersionmentioning

confidence: 99%

Structural elements made with highly flowable UHPFRC: Correlating computational fluid dynamics (CFD) predictions and non-destructive survey of fiber dispersion with failure modes

Ferrara

Cremonesi

Faifer

et al. 2017

Engineering Structures

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Structural design with highly flowable Fibre Reinforced Concrete has to duly take into account the preferential alignment of fibers, which can be governed through the rheological properties of the fluid mixture and the casting process and by the geometry of the structure. The possibility of predicting the fiber alignment, by tailoring the casting process, and of non-destructively monitoring it, can foster more efficient structural applications and design approaches. Focusing on UHPFRC slabs with pre-arranged casting defects, the flowinduced alignment of the fibers has been predicted by means of a suitable CFD modelling approach and hence monitored via a non-destructive method based on magnetic inductance properties of the fiber reinforced composite. The comparison between the assessed data on the fibre orientation and the crack patterns as visualized by image analysis supports the effectiveness of casting flow modelling and non-destructive fiber dispersion monitoring in supporting the structural design of elements made with highly flowable fiber reinforced cementitious composites. Response to the reviewers of the manuscript ENGSTRUCT D-16-00912Structural elements made with highly flowable UHPFRC:can Computational Fluid Dynamics (CFD) and non-destructive survey of fiber dispersion complement structural design in predicting failure modes? submitted for publication to Engineering StructuresThe authors thank the reviewers for the time they have dedicated to read their manuscript and for the insightful comments they have made and for the overall evaluation of the manuscript.The authors have taken in high consideration all the comments, mainly made by the second reviewers, and have addressed them in the revised version of the manuscript, which is now resubmitted.In detail:RESPONSE TO REVIEWER 1 -The authors agree that citing "structural design" in the title may rise some expectations in the reader which the paper does not fully address. In view of this the tile has been modified as follows Structural elements made with highly flowable UHPFRC: correlating Computational FluidDynamics (CFD) predictions and non-destructive survey of fiber dispersion with failure modes? (see also response to 1st general remark of reviewer 2) -The thickness of the slab (30 mm) has been declared -Reference [93] (which has now become reference [94]) contains details about the test set-up and the mechanical test results with elaboration of the digital image correlation measurements of the cracks, which in this paper are taken as reference and simply compared with CFD predictions and ND fiber dispersion monitoring. -The citation by Svec has been added. As for the other reference cited by the reviewer, the authors are doubtful whether to cite or not since it is likely an internal publication which is not indexed nor widely available. -With reference to the slab with the defect at 1/3 of the side it is not true that the defect does not affect the crack pattern; even in the major crack does not develop along the casting defect line, the...

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Steel fibre spacing in self-compacting concrete precast walls by X-ray computed tomography

Cited by 34 publications

References 31 publications

X-ray computed tomography of fibre reinforced self-compacting concrete as a tool of assessing its flexural behaviour

X-ray computed tomography of fibre reinforced self-compacting concrete as a tool of assessing its flexural behaviour

Fresh Mix Characteristics of Self-Compacting Concrete Reinforced by Fibre

Structural elements made with highly flowable UHPFRC: Correlating computational fluid dynamics (CFD) predictions and non-destructive survey of fiber dispersion with failure modes

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