scholarly journals ULTRA-HIGH-PERFORMANCE FIBRE-REINFORCED CONCRETE UNDER HIGH-VELOCITY PROJECTILE IMPACT. PART I. EXPERIMENTS

2018 ◽  
Vol 58 (4) ◽  
pp. 232 ◽  
Author(s):  
Sebastjan Kravanja ◽  
Radoslav Sovják
Keyword(s):  
Significant Influence ◽  
Impact Loading ◽  
High Velocity ◽  
High Performance ◽  
Fibre Volume ◽  
Fibre Reinforced Concrete ◽  
Volumetric Fraction ◽  
Projectile Impact ◽  
High Performance Fibre ◽  
Area And Volume

A series of cratering experiments were performed where the response of the Ultra-High-Performance Fibre-Reinforced Concretes with various fibre volume fractions to the high- velocity projectile impact loading was investigated. It was found that the increment of the fibre volumetric fraction did not have a significant influence on the depth of the penetration, but it was very effective in reducing the crater area and volume.

scholarly journals ULTRA-HIGH-PERFORMANCE FIBRE-REINFORCED CONCRETE UNDER HIGH-VELOCITY PROJECTILE IMPACT - PART 2. APPLICABILITY OF PREDICTION MODELS

2018 ◽  
Vol 58 (6) ◽  
pp. 355-364 ◽  
Author(s):  
Sebastjan Kravanja ◽  
Radoslav Sovják
Keyword(s):  
Reinforced Concrete ◽  
High Velocity ◽  
High Performance ◽  
Prediction Models ◽  
Analytical Models ◽  
Fibre Reinforced Concrete ◽  
Depth Of Penetration ◽  
Projectile Impact ◽  
Mass Ejection ◽  
High Performance Fibre

Semi-infinite targets of Ultra-High-Performance Fibre-Reinforced Concrete with various fibre volume fractions were subjected to the high-velocity projectile impact using in-service bullets. In this study, a variety of empirical and semi-analytical models for prediction of the depth of penetration and mass ejection were evaluated with respect to the experimental results. Models for the depth of penetration and spalling mass ejection were revisited and applied both with deformable and nondeformable projectiles parameters. The applicability of the prediction models was assessed through a statistical comparison of values from models with experimental results. The evaluation of the applicability was made through the newly proposed measure of a relative prediction accuracy for model selection and model estimation, which was verified with established statistical accuracy evaluations, such as accuracy ratio, logarithmic standard deviation and correlation coefficient. The best fit to the experimental readings was provided by newer semi-analytical models, which are incorporating additional concrete parameters beside compressive strength while the majority of older models failed to provide sufficient accuracy.

scholarly journals Fibre Distribution Characterization of Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) Plates Using Magnetic Probes

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5064
Author(s):  
Lufan Li ◽  
Jun Xia ◽  
Chee Chin ◽  
Steve Jones
Keyword(s):  
Reinforced Concrete ◽  
Volume Content ◽  
High Performance ◽  
Fibre Orientation ◽  
Orientation Angle ◽  
Fibre Volume ◽  
Fibre Reinforced Concrete ◽  
Fibre Distribution ◽  
Fibre Orientation Angle ◽  
High Performance Fibre

Ultra-high performance fibre reinforced concrete (UHPFRC) is an innovative cement-based engineering material. The mechanical properties of UHPFRC not only depend on the properties of the concrete matrix and fibres, but also depend on the interaction between these two components. The fibre distribution is affected by many factors and previous researchers had developed different approaches to test the fibre distribution. This research adopted the non-destructive C-shape ferromagnetic probe inductive test and investigated the straight steel fibre distribution of the UHPFRC plate. A simplified characterization equation is introduced with an attenuation factor to consider the different plate thicknesses. The effective testing depth of this probe was tested to be 24 mm. By applying this method, fibre volume content and the fibre orientation angle can be calibrated for the entire plate. The fibre volume content generally fulfilled the design requirement. The fibre orientation angle followed a normal distribution, with a mean value of 45.60°. By testing small flexural specimens cut from the plates, it was found out that the mechanical performance (peak flexural strength) correlates with the product of fibre volume content and cosine fibre orientation angle.

Experimental procedure for determination of the energy dissipation capacity of ultra-high-performance fibre-reinforced concrete under localized impact loading

2019 ◽  
Vol 10 (2) ◽  
pp. 251-265 ◽  
Author(s):  
Petr Konrád ◽  
Radoslav Sovják
Keyword(s):  
Reinforced Concrete ◽  
Impact Loading ◽  
High Performance ◽  
Volume Fraction ◽  
Concrete Specimen ◽  
Basic Material ◽  
Fibre Reinforced Concrete ◽  
Significant Difference ◽  
The Impact ◽  
High Performance Fibre

Research presented in this article is aimed to investigate the ability of ultra-high-performance fibre-reinforced concrete to absorb and dissipate mechanical energy at elevated strain rate loading. Specimens made of ultra-high-performance fibre-reinforced concrete were subjected to the low-velocity impact using the new testing procedure where no fixed supports that hold the sample during the impact were applied. The fibre volume fraction of the ultra-high-performance fibre-reinforced concrete was set as the main test variable in the framework of this study and the volumetric fraction of fibres was ranging from 0.125% to 2%. A high-speed camera was used to measure velocities of the impactor and the ultra-high-performance fibre-reinforced concrete specimen before and after the impact. Consequently, the energy dissipated by the ultra-high-performance fibre-reinforced concrete specimen during the impact was calculated using a simple energy balance equation. To determine the basic material properties of ultra-high-performance fibre-reinforced concrete, quasi-static loading rate was applied and conventional methods were used. A significant difference between the values of dissipated energies for different loading rates and various fibre volumetric fractions was observed. It can be noted that the new procedure shows a reasonable approach for testing the fibre-reinforced cementitious composites under localized impact loading and is worthy of further optimization.

scholarly journals Optimizing the Mechanical Properties of Ultra-High-Performance Fibre-Reinforced Concrete to Increase Its Resistance to Projectile Impact

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5098
Author(s):  
Anna L. Mina ◽  
Konstantinos G. Trezos ◽  
Michael F. Petrou
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Fibre Reinforced Concrete ◽  
Direct Tension ◽  
Steel Fibres ◽  
Projectile Impact ◽  
Binder Ratio ◽  
High Performance Fibre

This study describes an extensive experimental investigation of various mechanical properties of Ultra-High-Performance Fibre-Reinforced Concrete (UHPFRC). The scope is to achieve high strength and ductile behaviour, hence providing optimal resistance to projectile impact. Eight different mixtures were produced and tested, three mixtures of Ultra-High-Performance Concrete (UHPC) and five mixtures of UHPFRC, by changing the amount and length of the steel fibres, the quantity of the superplasticizer, and the water to binder (w/b) ratio. Full stress–strain curves from compression, direct tension, and flexural tests were obtained from one batch of each mixture to examine the influence of the above parameters on the mechanical properties. The Poisson’s ratio and modulus of elasticity in compression and direct tension were measured. Additionally, a factor was determined to convert the cubic strength to cylindrical. Based on the test results, the mixture with high volume (6%) and a combination of two lengths of steel fibres (3% each), water to binder ratio of 0.16% and 6.1% of superplasticizer to binder ratio exhibited the highest strength and presented great deformability in the plastic region. A numerical simulation developed using ABAQUS was capable of capturing very well the experimental three-point bending response of the UHPFRC best-performed mixture.

scholarly journals RESPONSE OF HIGH-PERFORMANCE FIBRE REINFORCED CONCRETE REINFORCED BY TEXTILE REINFORCEMENT TO IMPACT LOADING

2016 ◽  
Vol 56 (4) ◽  
pp. 328-335 ◽  
Author(s):  
Filip Vogel ◽  
Ondřej Holčapek ◽  
Petr Konvalinka
Keyword(s):  
Impact Loading ◽  
High Performance ◽  
High Performance Concrete ◽  
Impact Force ◽  
Cement Composites ◽  
Fibre Reinforced Concrete ◽  
Impact Machine ◽  
Three Point Bending ◽  
The Impact ◽  
High Performance Fibre

Generally, cement composites like high-performance concrete (HPC) are very brittle. The resistance to the impact loading of the HPFRC and the HPFRC reinforced by the textile reinforcement are compared in this article. The samples (0.56 × 0.1 × 0.1 m) were experimentally tested in three-point bending, by using horizontal impact machine. The better resistance of the textile reinforced HPFRC is obvious from the collected data (impact force, acceleration of hammer and acceleration of the tested sample).

scholarly journals EFFECTIVE FRACTURE ENERGY OF ULTRA-HIGH-PERFORMANCE FIBRE-REINFORCED CONCRETE UNDER INCREASED STRAIN RATES

2014 ◽  
Vol 54 (5) ◽  
pp. 358-362 ◽  
Author(s):  
Radoslav Sovják ◽  
Jana Rašínová ◽  
Petr Máca
Keyword(s):  
Reinforced Concrete ◽  
Strain Rate ◽  
Fracture Energy ◽  
High Performance ◽  
Fibre Volume ◽  
Strain Rates ◽  
Fibre Reinforced Concrete ◽  
Volume Fractions ◽  
High Performance Fibre

<p>The main objective of this paper is to contribute to the development of ultra-high performance fibre reinforced concrete (UHPFRC) with respect to its effective fracture energy. Effective fracture energy was investigated in this paper considering different fibre volume fractions and different strain rates. It was concluded that the effective fracture energy is dependent on the strain rate. In addition, it was found that higher fibre volume fractions tend to decrease the sensitivity of the UHPFRC to increased strain rates.</p>

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