scholarly journals Plain and Fiber-Reinforced Concrete Subjected to Cyclic Compressive Loading: Study of the Mechanical Response and Correlations with Microstructure Using CT Scanning

2019 ◽  
Vol 9 (15) ◽  
pp. 3030 ◽  
Author(s):  
Jesús Mínguez ◽  
Laura Gutiérrez ◽  
Dorys C. González ◽  
Miguel A. Vicente
Keyword(s):  
Mechanical Response ◽  
High Performance Concrete ◽  
Compressive Strain ◽  
Compressive Loading ◽  
Fiber Reinforced Concrete ◽  
Mechanical Parameters ◽  
Fiber Reinforced ◽  
High Resolution Computed Tomography ◽  
Internal Damage ◽  
Number Of Cycles

The response ranges of three principal mechanical parameters were measured following cyclic compressive loading of three types of concrete specimen to a pre-defined number of cycles. Thus, compressive strength, compressive modulus of elasticity, and maximum compressive strain were studied in (i) plain, (ii) steel-fiber-reinforced, and (iii) polypropylene-fiber-reinforced high-performance concrete specimens. A specific procedure is presented for evaluating the residual values of the three mechanical parameters. The results revealed no significant variation in the mechanical properties of the concrete mixtures within the test range, and slight improvements in the mechanical responses were, in some cases, detected. In contrast, the scatter of the mechanical parameters significantly increased with the number of cycles. In addition, all the specimens were scanned by means of high resolution computed tomography, in order to visualize the microstructure and the internal damage (i.e., internal micro cracks). Consistent with the test results, the images revealed no observable internal damage caused by the cyclic loading.

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.

Behaviour of Uniaxial Reinforced Concrete Columns Strengthened with Ultra-High Performance Concrete and Fiber Reinforced Polymers

2021 ◽  
Vol 28 (2) ◽  
pp. 54-72
Author(s):  
Abd-al-Salam Al-Hazragi ◽  
Assim Lateef
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Columns ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced Polymers ◽  
Tension Zone ◽  
Fiber Reinforced ◽  
Group A ◽  
Group B

This article investigates the behaviour of strengthened concrete columns using jacketing ultra-high-performance fiber reinforced concrete (UHPFRC) and carbon fiber-reinforced polymer (CFRP) under uniaxial loaded. The jacket was connected to the column core using shear connectors and (CFRP) fixed as a strip on the tension zone between the column cores and the jacketing. Seven column samples of square cross-section (120 x120) mm at the midsection with overall length of 1250 mm were cast using normal strength concrete (NSC) and having similar longitudinal and transverse reinforcement. The samples were made and tested under axial load at eccentricity equal to 120 mm up to failure. Test parameters were the thickness of jackets (25 and 35) mm and the width of CFRP (0,8, and 12) cm. Column specimens were tested, one of them was reference without any strengthening, and the other specimens divided into two groups (A, and B), and each group included three specimens based on the parameters. Group (A) has UHPFRC jacket thickness 25 mm and CFRP width (0,8, and 12) cm respectively, and group (B) has UHPFRC jacket thickness 35 mm and CFRP width (0,8, and 12) cm respectively. The outcomes of the article show that increasing the thickness of jacket, and width of CFRP lead to increase in the load carrying capacity about (110.5%,168.4%, and 184.2%) for group A, and (157.9%,226.3%, and 263.2%) for group B compared with the reference column due to delay in the appearance of cracks and their distribution. The mid-height lateral displacement of columns was decreased about (66.6%,42.3%, and 35.9%) for group A, and (46.15%,38.46%, and 32.3%) for group B, also the axial deformation of specimens decreased about (71.7%,60.86%, and 55.86%) for group A, and (65.5%,60.5%, and 53.4) for group B compared with the reference column. The ductility of columns that were strengthened with UHPFRC jacket only was increased about (13.67%,19.66%) for thickness(25,35) mm respectively, because of that UHPFRC jacket was contented on steel fibers, and the percentage decrease of ductility was about (5.1%,and 12%) for group (A), (1%,and 9.4%) for group (B) when bonded CFRP in the tension zone with width (8 ,and 12) cm respectively. The results show improvement in the initial and secant stiffness when, increased the thickness of jacket, and width of CFRP because of increase in the size of columns and improvement in the modulus of elasticity. The toughness increase was about (273.97%,301.55%, and 304.5%) for group A, and (453.69%,511.93%, and 524.28%) for group B compared with the reference column because of increase in the size of specimens and delay the appearance of cracks.

Effect of Fiber Diameter on Fatigue Strength of Fiber Reinforced Concrete and its Design

2011 ◽  
Vol 138-139 ◽  
pp. 810-815 ◽  
Author(s):  
Pang Jo Chun ◽  
Mitao Ohga
Keyword(s):  
Reinforced Concrete ◽  
Theoretical Model ◽  
Fiber Diameter ◽  
Design Method ◽  
Fatigue Behavior ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Stress Degradation ◽  
Fatigue Rupture ◽  
Number Of Cycles

This paper describes the effect of fiber diameter of fiber reinforced concrete (FRC) under fatigue behavior and its design method. Some researchers showed that the fatigue behavior of FRC is mainly governed by the bridging stress degradation, but little information is still available so far. We conducted fatigue tensile experiments of the FRC under constant strain amplitude first and the degradation of bridging stress was measured experimentally. Then, the micromechanics-based theoretical model is also developed, and the model is verified by the test results. The model accounts for the loss of fatigue ruptured fibers of which fatigue rupture is based on S-N relationships. The parametric study from the micromechanics-based theoretical model indicates that the best fiber diameter varies according to the number of cycles and strain level applied to the FRC specimen. The result suggests that we need to design FRC with considering the application and its loading conditions to utilize the capacity of FRC.

Influence of Different Mechanical Properties to the Concrete Penetration Resistance

2014 ◽  
Vol 982 ◽  
pp. 119-124 ◽  
Author(s):  
Tomáš Vavřiník ◽  
Jan Zatloukal
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
High Speed ◽  
High Performance ◽  
High Performance Concrete ◽  
Penetration Resistance ◽  
Fiber Reinforced Concrete ◽  
Experimental Program ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete

This paper describes influence of different mechanical properties to the concrete penetration resistance. The resistance is evaluated on the basis of the presented experimental program. In the experiment, non-deformable ogive-nose projectiles with diameter of 7.92 mm and mass of 8 g with impact velocity of about 700 m/s were hitting center of the specimens. Determination of the concrete penetration resistance was than based on projectile residual velocity obtained from high-speed camera record. The specimens were made from high strength concrete, steel fiber-reinforced concrete, ultra-high performance concrete and ultra-high performance fiber-reinforced concrete with different fiber content. The concrete penetration resistance was evaluated on total 32 specimens. Influence of mechanical properties, addition of coarse aggregate and steel fibers were discussed. Mechanical properties of the tested materials were investigated on total 125 specimens. Data from the measurements were used for creation of new RHT concrete models in Autodyn. In order to confirm experiment's setup and results, numerical analysis was performed in Autodyn. Results of the numerical simulations were compared to the experimental program.

scholarly journals Effect of Strengthening Methods on Two-Way Slab under Low-Velocity Impact Loading

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5603
Author(s):  
Sun-Jae Yoo ◽  
Tian-Feng Yuan ◽  
Se-Hee Hong ◽  
Young-Soo Yoon
Keyword(s):  
Reinforced Concrete ◽  
High Performance Concrete ◽  
Impact Load ◽  
Reaction Force ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Low Velocity Impact ◽  
Fiber Reinforced ◽  
Reinforced Concrete Slabs ◽  
The Impact

In this study, the performance of reinforced concrete slabs strengthened using four methods was investigated under impact loads transferred from the top side to bottom side. The top and bottom sides of test slabs were strengthened by no-slump high-strength, high-ductility concrete (NSHSDC), fiber-reinforced-polymer (FRP) sheet, and sprayed FRP, respectively. The test results indicated that the test specimens strengthened with FRP series showed a 4% increase in reaction force and a decrease in deflection by more than 20% compared to the non-strengthened specimens. However, the specimen enhanced by the NSHSDC jacket at both the top and bottom sides exhibited the highest reaction force and energy dissipation as well as the above measurements because it contains two types of fibers in the NSHSDC. In addition, the weight loss rate was improved by approximately 0.12% for the NSHSDC specimen, which was the lowest among the specimens when measuring the weight before and after the impact load. Therefore, a linear relationship between the top and bottom strengthening of the NSHSDC and the impact resistance was confirmed, concluding that the NSHSDC is effective for impact resistance when the top and bottom sides are strengthened. The results of the analysis of the existing research show that the NSHSDC is considered to have high impact resistance, even though it has lower resistance than the steel fiber reinforced concrete and ultra-high-performance-concrete, it can be expected to further studies on strengthening of NSHSDC.

scholarly journals Enhancing Damage-Sensing Capacity of Strain-Hardening Macro-Steel Fiber-Reinforced Concrete by Adding Low Amount of Discrete Carbons

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 938 ◽  
Author(s):  
Duy-Liem Nguyen ◽  
Dong-Joo Kim ◽  
Duc-Kien Thai
Keyword(s):  
Strain Hardening ◽  
Carbon Fibers ◽  
Mechanical Response ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Damage Sensing ◽  
Softening Behavior ◽  
Multi Walled Carbon Nanotubes

The effects of adding micro-carbon fibers on the electro-mechanical response of macro-steel fiber-reinforced concretes (MSFRCs) under tension were investigated. Two MSFRCs were investigated and they had identical mortar matrix but different fiber contents: MSFRC1 and MSFRC2 contained 1.0 and 1.5 vol.% fibers, respectively. The volume contents of added micro-carbon fibers were 0 to 1.5 vol.% in MSFRC1 and 0 to 0.75 vol.% in MSFRC2, respectively. The addition of 0.5 vol.% micro-carbon fibers, in both MSFRC1 and MSFRC2, produced significantly enhanced damage-sensing capability and still retained their strain-hardening performance together with multiple micro cracks. However, when the content of carbon fibers was more than 0.5 vol.%, the MSFRCs generated tensile strain-softening behavior and reduced damage-sensing capability. Furthermore, the effects of temperature and humidity on the electrical resistivity of MSFRCs were investigated, as were the effects of adding multi-walled carbon nanotubes on the damage-sensing capability of MSFRCs.

scholarly journals Influence of Cracking on Oxygen Transport in UHPFRC Using Stainless Steel Sensors

2019 ◽  
Vol 10 (1) ◽  
pp. 239
Author(s):  
Ana Martínez-Ibernón ◽  
Marta Roig-Flores ◽  
Josep Lliso-Ferrando ◽  
Eduardo J. Mezquida-Alcaraz ◽  
Manuel Valcuende ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Oxygen Availability ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced ◽  
Ultra High Performance Concrete ◽  
Cracking Behavior

Reinforced concrete elements frequently suffer small cracks that are not relevant from the mechanical point of view, but they can be an entrance point for aggressive agents, such as oxygen, which could initiate the degradation processes. Fiber-Reinforced Concrete and especially Ultra High Performance Concrete increase the multi-cracking behavior, reducing the crack width and spacing. In this work, the oxygen availability of three types of concrete was compared at similar strain levels to evaluate the benefit of multi-cracking in the transport of oxygen. The types of concrete studied include traditional, High-Performance, and Ultra-High-Performance Fiber-Reinforced Concrete with and without nanofibers. To this purpose, reinforced concrete beams sized 150 × 100 × 750 mm3 were prepared with embedded stainless steel sensors that were located at three heights, which have also been validated through this work. These beams were pre-cracked in bending up to fixed strain levels. The results indicate that the sensors used were able to detect oxygen availability due to the presence of cracks and the detected differences between the studied concretes. Ultra High Performance Concrete in the cracked state displayed lower oxygen availability than the uncracked High Performance Concrete, demonstrating its potential higher durability, even when working in cracked state, thanks to the increased multi-cracking response.

scholarly journals Performance of active porcelain enamel coated fibers for fiber-reinforced concrete : the performance of active porcelain enamel coatings for fiber-reinforced concrete and fiber tests at the University of Louisville

2021 ◽  
Author(s):  
Charles Weiss ◽  
William McGinley ◽  
Bradford Songer ◽  
Madeline Kuchinski ◽  
Frank Kuchinski
Keyword(s):  
Reinforced Concrete ◽  
High Performance Concrete ◽  
Phase 1 ◽  
Small Diameter ◽  
Ceramic Coatings ◽  
Fiber Reinforced Concrete ◽  
Market Potential ◽  
Fiber Reinforced ◽  
University Of Louisville ◽  
The University

A patented active porcelain enamel coating improves both the bond between the concrete and steel reinforcement as well as its corrosion resistance. A Small Business Innovation Research (SBIR) program to develop a commercial method for production of porcelain-coated fibers was developed in 2015. Market potential of this technology with its steel/concrete bond improvements and corrosion protection suggests that it can compete with other fiber reinforcing systems, with improvements in performance, durability, and cost, especially as compared to smooth fibers incorporated into concrete slabs and beams. Preliminary testing in a Phase 1 SBIR investigation indicated that active ceramic coatings on small diameter wire significantly improved the bond between the wires and the concrete to the point that the wires achieved yield before pullout without affecting the strength of the wire. As part of an SBIR Phase 2 effort, the University of Louisville under contract for Ceramics, Composites and Coatings Inc., proposed an investigation to evaluate active enamel-coated steel fibers in typical concrete applications and in masonry grouts in both tension and compression. Evaluation of the effect of the incorporation of coated fibers into Ultra-High Performance Concrete (UHPC) was examined using flexural and compressive strength testing as well as through nanoindentation.

scholarly journals Mechanical and Durability Properties of Hybrid Fiber Reinforced High Performance Concrete using Multiple Mineral Admixtures

2021 ◽  
pp. 359-364
Author(s):  
V. Hemavathi ◽  
Mr. S. Rathna Swamy
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Glass Fibers ◽  
Fiber Reinforced Concrete ◽  
Mineral Admixtures ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Asbestos Fibers ◽  
Durability Properties ◽  
Multiple Mineral

A study has been made for the high performance concrete of grade M70, where two mineral admixtures like GGBS and Metakaolin has been used with the two fibers, one B glass fibers and asbestos fibers. If two fibers are used in the concrete then we are call is having a fiber reinforced concrete the asbestos fibers percentage was kept constant of about 0.33% and glass fibers % have been changed from 0.25, 0.75 and 1.0%. The cubes are casted for different water cement ratios which is 0.25,0.30 and 0.35. there cubes are tested for the strength teste and durability zero.

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