scholarly journals Experimental and Numerical Investigation on the Size Effect of Ultrahigh-Performance Fibre-Reinforced Concrete (UHFRC)

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5714
Author(s):  
Andreas Lampropoulos ◽  
Demetris Nicolaides ◽  
Spyridon Paschalis ◽  
Ourania Tsioulou
Keyword(s):  
Reinforced Concrete ◽  
Size Effect ◽  
Numerical Models ◽  
Tensile Tests ◽  
Tensile Behaviour ◽  
Fibre Reinforced Concrete ◽  
Direct Tension ◽  
Flexural Tests ◽  
Direct Tensile ◽  
Efficiency And Reliability

In the last few years, there has been increasing interest in the use of Ultrahigh-Performance Fibre-Reinforced Concrete (UHPFRC) layers or jackets, which have been proved to be quite effective in strengthening applications. However, to facilitate the extensive use of UHPFRC in strengthening applications, reliable numerical models need to be developed. In the case of UHPFRC, it is common practice to perform either direct tensile or flexural tests to determine the UHPFRC tensile stress–strain models. However, the geometry of the specimens used for the material characterization is, in most cases, significantly different to the geometry of the layers used in strengthening applications which are normally of quite small thickness. Therefore, and since the material properties of UHPFRC are highly dependent on the dimensions of the examined specimens, the so called “size effect” needs to be considered for the development of an improved modelling approach. In this study, direct tensile tests have been used and a constitutive model for the tensile behaviour of UHPFRC is proposed, taking into consideration the size of the finite elements. The efficiency and reliability of the proposed approach has been validated using experimental data on prisms with different geometries, tested in flexure and in direct tension.

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.

scholarly journals Mechanical Optimization of Concrete with Recycled PET Fibres Based on a Statistical-Experimental Study

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 240
Author(s):  
Alejandro Meza ◽  
Pablo Pujadas ◽  
Laura Montserrat Meza ◽  
Francesc Pardo-Bosch ◽  
Rubén D. López-Carreño
Keyword(s):  
Reinforced Concrete ◽  
Aspect Ratio ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Superior Performance ◽  
Fibre Reinforced Concrete ◽  
Marine Fauna ◽  
Recycled Pet ◽  
Pet Bottles ◽  
Fibre Aspect Ratio

Discarded polyethylene terephthalate (PET) bottles have damaged our ecosystem. Problems of marine fauna conservation and land fertility have been related to the disposal of these materials. Recycled fibre is an opportunity to reduce the levels of waste in the world and increase the mechanical performance of the concrete. PET as concrete reinforcement has demonstrated ductility and post-cracking strength. However, its performance could be optimized. This study considers a statistical-experimental analysis to evaluate recycled PET fibre reinforced concrete with various fibre dose and aspect ratio. 120 samples were experimented under workability, compressive, flexural, and splitting tensile tests. The results pointed out that the fibre dose has more influence on the responses than its fibre aspect ratio, with statistical relation on the tensional toughness, equivalent flexural strength ratio, volumetric weight, and the number of fibres. Moreover, the fibre aspect ratio has a statistical impact on the tensional toughness. In general, the data indicates that the optimal recycled PET fibre reinforced concrete generates a superior performance than control samples, with an improvement similar to those reinforced with virgin fibres.

scholarly journals Fracture and Size Effect of PFRC Specimens Simulated by Using a Trilinear Softening Diagram: A Predictive Approach

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3795
Author(s):  
Fernando Suárez ◽  
Jaime C. Gálvez ◽  
Marcos G. Alberti ◽  
Alejandro Enfedaque
Keyword(s):  
Reinforced Concrete ◽  
Size Effect ◽  
A Priori ◽  
Plain Concrete ◽  
Specimen Size ◽  
Bending Test ◽  
Orientation Factor ◽  
Fibre Reinforced Concrete ◽  
Softening Function ◽  
Three Point Bending

The size effect on plain concrete specimens is well known and can be correctly captured when performing numerical simulations by using a well characterised softening function. Nevertheless, in the case of polyolefin-fibre-reinforced concrete (PFRC), this is not directly applicable, since using only diagram cannot capture the material behaviour on elements with different sizes due to dependence of the orientation factor of the fibres with the size of the specimen. In previous works, the use of a trilinear softening diagram proved to be very convenient for reproducing fracture of polyolefin-fibre-reinforced concrete elements, but only if it is previously adapted for each specimen size. In this work, a predictive methodology is used to reproduce fracture of polyolefin-fibre-reinforced concrete specimens of different sizes under three-point bending. Fracture is reproduced by means of a well-known embedded cohesive model, with a trilinear softening function that is defined specifically for each specimen size. The fundamental points of these softening functions are defined a priori by using empirical expressions proposed in past works, based on an extensive experimental background. Therefore, the numerical results are obtained in a predictive manner and then compared with a previous experimental campaign in which PFRC notched specimens of different sizes were tested with a three-point bending test setup, showing that this approach properly captures the size effect, although some values of the fundamental points in the trilinear diagram could be defined more accurately.

scholarly journals Tensile Behaviour of FRCM Composites for Strengthening of Masonry Structures—An Experimental Investigation

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3626
Author(s):  
Łukasz Hojdys ◽  
Piotr Krajewski
Keyword(s):  
Tensile Stress ◽  
Strain Curve ◽  
Tensile Tests ◽  
Tensile Failure ◽  
Tensile Behaviour ◽  
Masonry Structures ◽  
Stress Strain ◽  
Flexural Tensile Strength ◽  
Cracking Pattern ◽  
Direct Tensile

This paper presents the results of direct tensile tests performed on six different FRCM (fabric reinforced cementitious matrix) strengthening systems used for masonry structures. The emphasis was placed on the determination of the mechanical parameters of each tested system and a comparison of their tensile behaviour in terms of first crack stress, ultimate stress, ultimate strain, cracking pattern, failure mode and idealised tensile stress-strain curve. In addition to the basic mechanical tensile parameters, accidental load eccentricities, matrix tensile strengths, and matrix modules of elasticity were estimated. The results of the tests showed that the tensile behaviour of FRCM composites strongly depends on the parameters of the constituent materials (matrix and fabric). In the tests, tensile failure of reinforcement and fibre slippage within the matrix were observed. The presented research showed that the accidental eccentricities did not substantially affect the obtained results and that the more slender the specimen used, the more consistent the obtained results. The analysis based on a rule of mixtures showed that the direct tensile to flexural tensile strength ratio of the matrixes used in the test was 0.2 to 0.4. Finally, the tensile stress–strain relationship for the tested FRCMs was idealised by a bi- or tri-linear curve.

Les bétons renforcés de fibres d'acier et la multifissuration

2000 ◽  
Vol 27 (4) ◽  
pp. 774-784 ◽  
Author(s):  
Benoît Bissonnette ◽  
Yves Therrien ◽  
Richard Pleau ◽  
Michel Pigeon ◽  
François Saucier
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Intrinsic Property ◽  
Tensile Tests ◽  
Experimental Program ◽  
Fibre Reinforcement ◽  
Fibre Reinforced Concrete ◽  
Restrained Shrinkage ◽  
Test Results ◽  
Multiple Cracking

This paper presents the results of an investigation aimed at establishing if multiple cracking can be an intrinsic property of steel fibre reinforced concrete (SFRC) in the hardened state and identifying the conditions to obtain it systematically. For this purpose, uniaxial restrained shrinkage tests and tensile tests were performed on large-scale SFRC specimens. The parameters studied in the experimental program were the fibre content (0-100 kg/m3), the fibre geometry, and the water to cement ratio of the concrete matrix (w/c = 0.40-0.80). The test results tend to indicate that multiple cracking is not a property of SFRC as such, at least within the range of concrete matrices and fibre contents investigated and that were intended to be compatible with practical considerations. While it does not mean that fibre reinforcement is not effective in terms of crack control, it is important to be careful in the analysis of test results where the effect of the restraining and exposure conditions might have been significant.Key words: cracking, drying shrinkage, fibre-reinforced concrete, multiple cracking, repairs, restrained shrinkage, steel fibres, tension.

Tensile and Cracking Behaviors of Strain-Hardening Cement Composite (SHCC) with Fluosilicate Based Shrinkage-Reducing Agent (SRA)

2014 ◽  
Vol 525 ◽  
pp. 473-477 ◽  
Author(s):  
Seung Ju Han ◽  
Seok Joon Jang ◽  
Zhong Jie Yu ◽  
Hyun Do Yun
Keyword(s):  
Strain Hardening ◽  
Volume Fraction ◽  
Cement Composite ◽  
Tensile Tests ◽  
Reducing Agent ◽  
Direct Tension ◽  
Direct Tension Test ◽  
Rich Mixture ◽  
Direct Tensile ◽  
Shrinkage Reducing Agent

This paper provides the results of direct tensile tests for strain-hardening cement composite (SHCC) to investigate the influence of fluosilicate based shrinkage-reducing agent (SRA) on the tensile and cracking behaviors of SHCC material under direct tension. The specified compressive strength of the SHCC material is 50MPa. The adding ratio of fluosilicate based SRA for SHCC material is 2.5 and 5.0%. Two mixitures of SHCC with 2.2% polyvinyl alcohol (PVA) fibers at the volume fraction were mixed; two mixtures with SRA and one mixture of conventional SHCC material. To evaluate the tensile and cracking behaviors of SHCC materials, two dumbbell-shaped tensile specimens for each mixture were manufactured and tested in direct tension. Test results show that the addition of fluosilicate based SRA improved direct tensile and cracking behaviors of SHCC materials with rich mixture. This phenomenon is noticeable for SHCC with higher volume of SRA.

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