scholarly journals A New Method to Determine the Steel Fibre Content of Existing Structures—Test Setup and Numerical Simulation

2022 ◽  
Vol 12 (2) ◽  
pp. 561
Author(s):  
Simon Cleven ◽  
Michael Raupach ◽  
Thomas Matschei
Keyword(s):  
Steel Fibre ◽  
Fibre Content ◽  
Fibre Reinforced Concrete ◽  
Missing Information ◽  
Concrete Composition ◽  
Test Setup ◽  
Steel Fibre Reinforced Concrete ◽  
Additional Information ◽  
Existing Structures ◽  
Laboratory Investigations

The diagnostics of constructions built with steel fibre reinforced concrete are extremely difficult to conduct because, typically, no information on the actual amount and orientation of the fibres is available. Therefore, it is of great interest to engineers to have the possibility to determine the steel fibre content and, at best, also the orientation of the fibres in existing structures. For this purpose, an easy-to-use test setup was developed and tested, in the course of laboratory investigations. This method can be used for cylinders, for example drilling cores, that can later be taken of existing structures, to determine both the fibre content and orientation. Based on these results, a model for cylindrical specimens was derived, which can be used for varying concrete compositions with steel fibre contents of up to 80 kg/m3. In the case of missing information concerning the concrete composition, it allows an initial estimation for the fibre content. In case additional information about the concrete composition is available, a much higher accuracy of the projected steel fibre content and therefore, an assessment of the building’s condition is possible.

scholarly journals A New Method to Determine the Steel Fibre Content of Existing Structures—Evaluation and Validation

2022 ◽  
Vol 12 (1) ◽  
pp. 454
Author(s):  
Simon Cleven ◽  
Michael Raupach ◽  
Thomas Matschei
Keyword(s):  
Reinforced Concrete ◽  
Steel Fibre ◽  
Concrete Structures ◽  
Test Method ◽  
Fibre Content ◽  
New Method ◽  
Fibre Reinforced Concrete ◽  
Steel Fibre Reinforced Concrete ◽  
Existing Structures ◽  
Non Destructive

The in-situ measurement of the content and orientation of steel fibres in concrete structures is of great importance for the assessment of their specific mechanical properties, especially in the case of repair. For existing structures, the actual fibre content as well as the orientation of the fibres, which is based on many factors such as casting or compacting direction, is typically unknown. For structural maintenance or rehabilitation, those factors have to be determined in order to apply meaningful structural design calculations and plan necessary strengthening methods. For this reason, a new method based on the analysis of drilling cores of concrete structures has been established. The newly developed non-destructive test setup used in this research consists of a framework for cylindrical specimens in combination with an LCR meter to determine the electrical resistance of the fibre reinforced concrete. In combination with a suitable FEM model, concretes with fibre contents up 80 kg/m3 were analysed to derive a first model to assess the actual fibre content of steel fibre reinforced concretes. After a calibration of the literature’s equation by use of an adjusted aspect ratio for the analysis of drilling cores, the estimation of the fibre content is possible with high accuracy for the tested material combination. The results show that the newly developed test method is suitable for the rapid and non-destructive structural diagnosis of the fibre content of steel fibre reinforced concrete based on drilling cores using electrical resistivity measurements.

scholarly journals Electrical Resistivity of Steel Fibre-Reinforced Concrete—Influencing Parameters

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3408
Author(s):  
Simon Cleven ◽  
Michael Raupach ◽  
Thomas Matschei
Keyword(s):  
Electrical Resistivity ◽  
Literature Review ◽  
Steel Fibre ◽  
Plain Concrete ◽  
Fibre Content ◽  
Fibre Reinforcement ◽  
Concrete Composition ◽  
Steel Fibre Reinforced Concrete ◽  
Granulated Blast Furnace Slag ◽  
The Impact

This paper presents a systematic study of the electrical resistivity of different steel fibre-reinforced concretes with fibre contents from 0 kg/m3 to 80 kg/m3 in order to identify possible effects of interactions among concrete composition and fibre type and content regarding electrical resistivity. Based on a literature review, four parameters, w/c ratio, binder content, ground granulated blast-furnace slag (GGBS) and fineness of cement, which show a significant influence on the electrical resistivity of plain concrete, were identified, and their influence on the electrical resistivity as well as interaction effects were investigated. The results of the experiments highlight that the addition of fibres leads to a significant decrease in electrical resistivity, independent of all additional parameters of the concrete composition. Additionally, it was shown that a higher porosity of the concrete, e.g., due to a higher w/c ratio, also results in a lower electrical resistivity. These results are in agreement with the literature review on plain concrete, while the influence of the concrete composition on the electrical resistivity is weaker with the increase in fibre content. The influence of fibre reinforcement is thus not affected by changes in the concrete composition. In general, a higher fibre dosage leads to a decrease in electrical resistivity, but the impact on the electrical resistivity varies slightly with different types of steel fibres. Based on this study, the potential of determining the fibre content using electrical resistivity measurements could be clearly presented.

scholarly journals Impact Response of Plates Under Drop Weight Impact Testing

1970 ◽  
Vol 7 (1) ◽  
pp. 1-11 ◽  
Author(s):  
S Elavenil ◽  
GM Samuel Knight
Keyword(s):  
Reinforced Concrete ◽  
Aspect Ratio ◽  
Energy Absorption ◽  
Steel Fibre ◽  
Impact Resistance ◽  
Impact Testing ◽  
Fibre Content ◽  
Fibre Reinforced Concrete ◽  
Steel Fibre Reinforced Concrete ◽  
Drop Weight

Concrete structures are often subjected to long term static and short term dynamic loads. Due to a relatively low tensile strength and energy dissipating characteristics, the impact resistance of concrete is poor. Research work carried out so far towards the development of concrete that exhibits improved impact resistance than conventional concrete showed that the steel fibre reinforced concrete has a good potential as a viable structural material for such applications. The overall objective of the study is to investigate the dynamic behaviour of steel fibre reinforced concrete plates under impact loading with respect to displacement, velocity and acceleration. In the drop weight test, eighteen plate specimens were tested with three different thicknesses of 20,25 and 30mm and with three different steel fibre contents of 0.5,0.75 and 1%.The edges of the plates were fixed on all sides. Displacement versus time, velocity versus time and acceleration versus time behaviour for all the plates tested were studied. It was found that when the aspect ratio of fibres is 50 and 75 there is a marginal increase in energy absorption for change in fibre content from 0.5 to 0.75%. There is a steep increase in energy absorption for a steel fibre content of 1% when the aspect ratio of fibre is 100.DOI: http://dx.doi.org/10.3329/diujst.v7i1.9580Daffodil International University Journal of Science and Technology Vol.7(1) 2012 1-11

Adding an expansive agent to increase the toughness of steel fibre reinforced concrete

2019 ◽  
Vol 26 (4) ◽  
pp. 197-208
Author(s):  
Leo Gu Li ◽  
Albert Kwok Hung Kwan
Keyword(s):  
Reinforced Concrete ◽  
Steel Fibre ◽  
The Other ◽  
Fibre Reinforced Concrete ◽  
Test Results ◽  
Compressive Properties ◽  
Shrinkage Cracking ◽  
Steel Fibre Reinforced Concrete ◽  
Expansive Agent ◽  
Concrete Matrix

Previous research studies have indicated that using fibres to improve crack resistance and applying expansive agent (EA) to compensate shrinkage are both effective methods to mitigate shrinkage cracking of concrete, and the additions of both fibres and EA can enhance the other performance attributes of concrete. In this study, an EA was added to fibre reinforced concrete (FRC) to produce concrete mixes with various water/binder (W/B) ratios, steel fibre (SF) contents and EA contents for testing of their workability and compressive properties. The test results showed that adding EA would slightly increase the superplasticiser (SP) demand and decrease the compressive strength, Young’s modulus and Poisson’s ratio, but significantly improve the toughness and specific toughness of the steel FRC produced. Such improvement in toughness may be attributed to the pre-stress of the concrete matrix and the confinement effect of the SFs due to the expansion of the concrete and the restraint of the SFs against such expansion.

Structural performance of steel fibre reinforced concrete — Part IV. Toughness properties

2014 ◽  
Vol 5 (2) ◽  
pp. 119-125
Author(s):  
I. Kovács
Keyword(s):  
Reinforced Concrete ◽  
Steel Fibre ◽  
Fibre Orientation ◽  
Reinforced Concrete Beams ◽  
Fibre Reinforcement ◽  
Fibre Reinforced Concrete ◽  
Flexural Toughness ◽  
Steel Fibre Reinforced Concrete ◽  
Set Up ◽  
Flexural Tests

The present paper of a series deals with the experimental characterisation of flexural toughness properties of structural concrete containing different volume of hooked-end steel fibre reinforcement (75 kg/m3, 150 kg/m3). Third-point flexural tests were carried out on steel fibre reinforced concrete beams having a cross-section of 80 mm × 85 mm with the span of 765 mm, hence the shear span to depth ratio was 3. Beams were sawn out of steel fibre reinforced slab elements (see Part I) in order to take into consideration the introduced privilege fibre orientation (I and II) and the position of the beam (Ba-a, Ba-b, Ba-c) before sawing (see Part I). Flexural toughness properties were determined considering different standard specifications, namely the method of the ASTM (American Standards for Testing Materials), the process of the JSCE (Japan Society of Civil Engineering), and the final proposal of Banthia and Trottier for the post cracking strength. Consequently, behaviour of steel fibre reinforced concrete was examined in bending taking into consideration different experimental parameters such as fibre content, concrete mix proportions, fibre orientation, positions of test specimens in the formwork, while experimental constants were the size of specimens, the type of fibre used and the test set-up and test arrangement.

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