scholarly journals Experimental Tests and Reliability Analysis of the Cracking Impact Resistance of UHPFRC

Fibers ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 74
Author(s):  
Hussain A. Jabir ◽  
Sallal R. Abid ◽  
Gunasekaran Murali ◽  
Sajjad H. Ali ◽  
Sergey Klyuev ◽  
...  
Keyword(s):  
High Performance ◽  
Steel Fiber ◽  
Impact Resistance ◽  
High Strength ◽  
Experimental Tests ◽  
Fiber Reinforced Concrete ◽  
Fiber Types ◽  
Impact Performance ◽  
High Performance Fiber ◽  
The Impact

Ultra-high performance (UHP) concrete is a special type of fibrous cementitious composite that is characterized by high strength and superior ductility, toughness, and durability. This research aimed to investigate the resistance of ultra-high performance fiber-reinforced concrete (UHPFRC) against repeated impacts. An adjusted repeated drop mass impact test was adopted to evaluate the impact performance of 72 UHPFRC disc specimens. The specimens were divided into six mixtures each of 12 discs. The only difference between the mixtures was the types of fibers used, while all other mixture components were the same. Three types of fibers were used: 6 mm micro-steel, 15 mm micro-steel, and polypropylene. All mixtures included 2.5% volumetric content of fibers, however with different combinations of the three fiber types. The test results showed that the mixtures with the 15 mm micro-steel fiber absorbed a higher number of impact blows until cracking compared to other mixtures. The mixture with pure 2.5% of 15 mm micro-steel fiber exhibited the highest impact resistance, with percentage increases over the other mixtures ranging from 25 to 140%. In addition, the Weibull distribution was used to investigate the cracking impact resistance of UHP at different levels of reliability.

scholarly journals Impact Performance of Steel Fiber-Reinforced Self-Compacting Concrete against Repeated Drop Weight Impact

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 91
Author(s):  
Sallal R. Abid ◽  
Murali Gunasekaran ◽  
Sajjad H. Ali ◽  
Ahmed L. Kadhum ◽  
Thaar S. Al-Gasham ◽  
...  
Keyword(s):  
Steel Fiber ◽  
Impact Resistance ◽  
High Strength ◽  
Steel Fibers ◽  
Test Results ◽  
Fiber Reinforced ◽  
Self Compacting Concrete ◽  
Impact Performance ◽  
Free Falling ◽  
The Impact

The self-compacting concrete (SCC) was invented to overcome the compaction problems in deep sections, owing to its perfect workability characteristics. Steel fibers when used with SCC would affect the required fluidity characteristics but improve its impact resistance. In this research, an experimental work was conducted to evaluate the impact response of micro-steel fiber-reinforced SCC, under flexural impact. A 5.47 kg free-falling mass was dropped repeatedly from 100 mm height on the top center of 270 mm-length beam specimens. Eight mixtures with two design grades of 30 and 50 MPa were prepared to distinguish the normal and high-strength SCCs. The distinguishing variable for each design grade was the fiber content, where four volumetric contents of 0%, 0.5%, 0.75%, and 1.0% were used. The test results showed that the impact resistance and ductility were significantly improved due to the incorporation of micro-steel fibers. The percentage improvements were noticeably higher at failure stage than at cracking stage. For the 30 MPa mixtures, the maximum percentage improvements at cracking and failure stages were 543% and 836%, respectively. Weibull’s linear correlations with R2 values of 0.84 to 0.97 were obtained at the failure stage, which meant that the impact failure number followed the Wiebull distribution.

Effect of Placement Method on Projectile Impact Resistance of UHPFRC

2016 ◽  
Vol 722 ◽  
pp. 316-321
Author(s):  
Romana Lovichová ◽  
Michal Mára ◽  
Jindřich Fornůsek
Keyword(s):  
Experimental Investigation ◽  
High Performance ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Projectile Impact ◽  
Placement Method ◽  
High Performance Fiber ◽  
Vertical Casting ◽  
The Impact ◽  
Penetration Depths

This paper presents the results of an experimental investigation of the impact resistance of UHPFRC slabs. The influence of horizontal and vertical casting of thin slabs against penetration by a projectile is described. The resistance of penetration by a projectile was investigated using projectile with lead core. The results indicate different penetration depths and crater diameters in the target specimens for both kind of casting. Which points on a different arrangement of fibers for horizontal and vertical casting slabs. However, the protective ability is guaranteed in both placement method. Based on the present findings the slabs from ultra-high performance fiber-reinforced concrete casted vertically appear to be most efficient in protection against projectile impact.

scholarly journals Effects of Steel Fiber Percentage and Aspect Ratios on Fresh and Harden Properties of Ultra-High Performance Fiber

2021 ◽  
Vol 2 (3) ◽  
pp. 501-515
Author(s):  
Rajib Kumar Biswas ◽  
Farabi Bin Ahmed ◽  
Md. Ehsanul Haque ◽  
Afra Anam Provasha ◽  
Zahid Hasan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
High Performance ◽  
Steel Fiber ◽  
Setting Time ◽  
Fiber Reinforced Concrete ◽  
Future Research ◽  
Manufacturing Cost ◽  
Aspect Ratios ◽  
High Performance Fiber

Steel fibers and their aspect ratios are important parameters that have significant influence on the mechanical properties of ultrahigh-performance fiber-reinforced concrete (UHPFRC). Steel fiber dosage also significantly contributes to the initial manufacturing cost of UHPFRC. This study presents a comprehensive literature review of the effects of steel fiber percentages and aspect ratios on the setting time, workability, and mechanical properties of UHPFRC. It was evident that (1) an increase in steel fiber dosage and aspect ratio negatively impacted workability, owing to the interlocking between fibers; (2) compressive strength was positively influenced by the steel fiber dosage and aspect ratio; and (3) a faster loading rate significantly improved the mechanical properties. There were also some shortcomings in the measurement method for setting time. Lastly, this research highlights current issues for future research. The findings of the study are useful for practicing engineers to understand the distinctive characteristics of UHPFRC.

scholarly journals Resistance of an Optimized Ultra-High Performance Fiber Reinforced Concrete to Projectile Impact

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 63
Author(s):  
Anna L. Mina ◽  
Michael F. Petrou ◽  
Konstantinos G. Trezos
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Depth Of Penetration ◽  
Projectile Impact ◽  
High Performance Fiber

The scope of this paper is to investigate the performance of ultra-high performance fiber reinforced concrete (UHPFRC) concrete slabs, under projectile impact. Mixture performance under impact loading was examined using bullets with 7.62 mm diameter and initial velocity 800 m/s. The UHPFRC, used in this study, consists of a combination of steel fibers of two lengths: 6 mm and 13 mm with the same diameter of 0.16 mm. Six composition mixtures were tested, four UHPFRC, one ultra-high performance concrete (UHPC), without steel fibers, and high strength concrete (HSC). Slabs with thicknesses of 15, 30, 50, and 70 mm were produced and subjected to real shotgun fire in the field. Penetration depth, material volume loss, and crater diameter were measured and analyzed. The test results show that the mixture with a combination of 3% 6 mm and 3% of 13 mm length of steel fibers exhibited the best resistance to projectile impact and only the slabs with 15 mm thickness had perforation. Empirical models that predict the depth of penetration were compared with the experimental results. This material can be used as an overlay to buildings or to construct small precast structures.

Strengthening Paudèze bridges decks using UHPFRC struts

2019 ◽  
Author(s):  
Philippe Menétrey ◽  
Lionel Moreillon ◽  
Maléna Bastien-Masse
Keyword(s):  
High Performance ◽  
Bridge Deck ◽  
Experimental Tests ◽  
Highway Bridges ◽  
Fiber Reinforced Concrete ◽  
Bending Moments ◽  
Box Girder ◽  
High Performance Fiber ◽  
Over 40 Years ◽  
Deck Slab

<p>Paudèze bridges are two 400‐m long parallel highway bridges located in Switzerland and opened to traffic in 1974. After over 40 years of service life, both bridges must be completely rehabilitated and strengthened while constantly maintaining 2 traffic lanes in both directions.</p><p>The bridge deck slab was strengthened using UHPFRC (Ultra‐High Performance Fiber Reinforced Concrete) struts. These inclined struts connect the end of the deck slab cantilever and the box girder web, forming a Warren truss. They thus reduce the bending moments in the deck slab and the existing steel reinforcement could be kept.</p><p>The joint between the prefabricated UHPFRC struts and the existing concrete web is done through a cast in‐ place UHPFRC beam, without any mechanical connection. Forces go through the joint and into the web by a combination of friction and compression forces.</p><p>Various experimental tests and numerical simulations confirmed the feasibility of this solution. In particular, the UHPFRC‐concrete web connection, the UHPFRC‐UHPFRC connection and the global behavior of the strut were tested and modelled.</p><p>The strengthening of the bridges decks took place between 2017 and 2019. The developed solution, using UHPFRC struts, was shown to be very effective to strengthen the deck and creates a rhythm in the structure.</p>

scholarly journals Implementation of Highly-Flowable Strain Hardening Fiber Reinforced Concrete in New RC Beam-Column Joints

2018 ◽  
Vol 147 ◽  
pp. 01003
Author(s):  
Wen-Cheng Liao ◽  
Wei-Ru Su
Keyword(s):  
Reinforced Concrete ◽  
Strain Hardening ◽  
Life Cycle Cost ◽  
High Performance ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Building Systems ◽  
Rc Building ◽  
High Performance Fiber

The purpose of New RC project was aimed to reduce the member sections and increase the available space of high rise buildings by using high strength concrete (f’c > 70 MPa) and high strength rebars (fy > 685 MPa). Material consumptions and member section sizes can be further reduced owing to the upgrade of strength. However, the nature of brittleness of high strength may also cause early cover spalling and other ductility issues. Addition of steel fibers is an alternative as transverse reinforcement. Highly flowable strain hardening fiber reinforced concrete (HF-SHFRC) has excellent workability in the fresh state and exhibits the strain-hardening and multiple cracking characteristics of high performance fiber reinforced cementitious composites (HPFRCC) in their hardened state. The objective of this study is to investigate the feasibility of implementing HF-SHFRC in New RC building systems, particularly for beam-column joints as an alternative of transverse reinforcements. Four full-scale exterior beam-column joints, including two specimens with intensive transverse reinforcements and two specimens made of HF-SHFRC without any stirrup, are tested. Test results show that the HF-SHFRC specimens perform as well as specimens with intensive transverse reinforcements regarding failure mode, ductility, energy dissipation and crack width control. Integration of New RC building systems and HF-SHFRC can assuring construction qualities and further diminish labor work and give infrastructure longer service life, and eventually lower the life-cycle cost.

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