scholarly journals The comparison of projectile impact resistance of ultra-high-performance fibre-reinforced concrete with various aggregates

2021 ◽  
Vol 250 ◽  
pp. 06007
Author(s):  
Martina Drdlová ◽  
Martin Šperl
Keyword(s):  
Reinforced Concrete ◽  
High Speed ◽  
High Performance ◽  
Structural Integrity ◽  
Impact Load ◽  
Impact Resistance ◽  
Fibre Reinforced Concrete ◽  
Projectile Impact ◽  
The Impact ◽  
High Performance Fibre

In order to apply the ultra-high-performance fibre-reinforced concrete (UHPFRC) in the constructions of ballistic protective structures, the impact resistance of UHPFRC has been investigated experimentally by conducting the high-speed projectile penetration tests. 5 mixtures with basalt and corundum aggregates with various grain size have been prepared and subjected to the quasi-static and 7.62 x 54R B32 API projectile impact load using the striking velocity of 850 m/s. The influence of the strength, size and material of the aggregate on the projectile impact resistance represented by differential efficiency factor (DEF), structural integrity and area and height of impact crater has been evaluated. The superior projectile resistance of UHPFRC with corundum has been observed. Regarding the size of the aggregates, the incorporation of coarser aggregates brings better projectile impact resistance.

scholarly journals Impact response of various concretes at 2.8-second drop shaft

2021 ◽  
Vol 352 ◽  
pp. 00005
Author(s):  
Radoslav Sovják ◽  
Josef Fládr ◽  
Jiří Šťástka ◽  
Michal Frydrýn
Keyword(s):  
Reinforced Concrete ◽  
High Speed ◽  
High Performance ◽  
Experimental Testing ◽  
Maximal Velocity ◽  
Fibre Reinforced Concrete ◽  
Drop Shaft ◽  
Before And After ◽  
The Impact ◽  
High Performance Fibre

This paper presents experimental testing of various types of concrete under impact loading by using a 2.8-second drop shaft. The drop shaft is located in the Josef Underground Laboratory and allows dropping a projectile from 40 meters that results in a maximal velocity of 100 km/h. Three basic types of concrete were used in the framework of this study. This was normal strength concrete, fibre-reinforced concrete, and high-performance fibre-reinforced concrete. The slabs were constructed 1700 mm × 500 mm × 70 mm in size and the clear span of the impacted slab was 1500 mm. Damage of the slab was recorded and the velocity of the projectile was measured with the high-speed camera before and after the impact. It was demonstrated that high-performance fibre-reinforced concrete has a higher ability to absorb and dissipate the kinetic energy of the impact that their lower strength counterparts.

scholarly journals LABORATORY STUDY ON THE INFLUENCE OF CASTING ON PROPERTIES OF ULTRA-HIGH PERFORMANCE FIBRE REINFORCED CONCRETE (UHPFRC) SPECIMENS

2014 ◽  
Vol 20 (3) ◽  
pp. 380-379 ◽  
Author(s):  
Adam Zofka ◽  
Miglė Paliukaitė ◽  
Audrius Vaitkus ◽  
Dominika Maliszewska ◽  
Ramandeep Josen ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Fibre Orientation ◽  
Compact Tension ◽  
Fibre Reinforced Concrete ◽  
X Ray ◽  
Fracture Testing ◽  
Physical Changes ◽  
The Impact ◽  
High Performance Fibre

This paper presents a study on the effects of casting procedure and resulting fibre orientation on the properties of Ultra-High Performance Fibre Reinforced Concrete (UHPFRC). To investigate the impact of fibre orientation in the UHPFRC specimens, three approaches were employed. First, densities were measured from the top, middle and bottom zones of the cylinders to observe physical changes as the function of cylinder height. Secondly, two engineering fracture tests were performed in both compression and tension, and a comparison of fracture energies was conducted between different cylinder zones. While previous studies have explored the influence of steel fibres on the UHPFRC performance, the Semi-Circular Bending (SCB) and Disc Compact Tension (DCT) experimental setups have not yet been used in the UHPFRC fracture testing. Lastly, samples from different zones were scanned using X-ray computer tomography (X-ray CT). Both visual and digital image analysis of the X-ray scans were conducted in order to observe fibre orientation pattern changes within different zones. Although density calculations showed insignificant differences between different zones, fracture testing exhibited significant differences through the testing process as well as through fracture energy computations. Furthermore, X-ray CT demonstrated considerable differences in spatial fibre orientation with respect to two uniquely defined angles.

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 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.

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