scholarly journals Cracking Diagnosis in Fiber-Reinforced Concrete with Synthetic Fibers Using Piezoelectric Transducers

Fibers ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Maristella E. Voutetaki ◽  
Maria C. Naoum ◽  
Nikos A. Papadopoulos ◽  
Constantin E. Chalioris
Keyword(s):  
Reinforced Concrete ◽  
Damage Detection ◽  
Mechanical Impedance ◽  
Harmonic Excitation ◽  
Fiber Reinforced Concrete ◽  
Repeated Loading ◽  
Fiber Reinforced ◽  
Damage Diagnosis ◽  
Promising Alternative ◽  
Synthetic Fibers

The addition of short fibers in concrete mass offers a composite material with advanced properties, and fiber-reinforced concrete (FRC) is a promising alternative in civil engineering applications. Recently, structural health monitoring (SHM) and damage diagnosis of FRC has received increasing attention. In this work, the effectiveness of a wireless SHM system to detect damage due to cracking is addressed in FRC with synthetic fibers under compressive repeated load. In FRC structural members, cracking propagates in small and thin cracks due to the presence of the dispersed fibers and, therefore, the challenge of damage detection is increasing. An experimental investigation on standard 150 mm cubes made of FRC is applied at specific and loading levels where the cracks probably developed in the inner part of the specimens, whereas no visible cracks appeared on their surface. A network of small PZT patches, mounted to the surface of the FRC specimen, provides dual-sensing function. The remotely controlled monitoring system vibrates the PZT patches, acting as actuators by an amplified harmonic excitation voltage. Simultaneously, it monitors the signal of the same PZTs acting as sensors and, after processing the voltage frequency response of the PZTs, it transmits them wirelessly and in real time. FRC cracking due to repeated loading ad various compressive stress levels induces change in the mechanical impedance, causing a corresponding change on the signal of each PZT. The influence of the added synthetic fibers on the compressive behavior and the damage-detection procedure is examined and discussed. In addition, the effectiveness of the proposed damage-diagnosis approach for the prognosis of final cracking performance and failure is investigated. The objectives of the study also include the development of a reliable quantitative assessment of damage using the statistical index values at various points of PZT measurements.

Flexural Performance Evaluation of Fiber-Reinforced Concrete Incorporating Multiple Macro-Synthetic Fibers

2018 ◽  
Vol 2672 (27) ◽  
pp. 1-12 ◽  
Author(s):  
Michael Dopko ◽  
Meysam Najimi ◽  
Behrouz Shafei ◽  
Xuhao Wang ◽  
Peter Taylor ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Residual Strength ◽  
Performance Enhancement ◽  
Construction Material ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Test Beam ◽  
Synthetic Fibers ◽  
Flexural Performance ◽  
Strength And Toughness

Fiber-reinforced concrete (FRC) is a promising construction material mainly because of the crack-controlling mechanisms that discrete fibers can impart to inherently brittle concrete. Macrofibers, in particular, have been proven effective for providing post-crack ductility and toughness, while synthetic fibers are a promising solution to avoid corrosion-related durability issues. To assess the performance enhancement provided by macro-synthetic concrete fibers, this study performs flexural tests on FRC beams containing three different types of macro-synthetic fibers. The selected fibers include polypropylene (PP), polyvinyl alcohol (PVA), and alkali-resistant glass (ARG) macrofibers mixed at volume fractions of 0.5%, 1.0%, and 1.5%. Static and dynamic fresh properties are monitored using the vibrating Kelly ball (VKelly) test. Beam specimens are then placed under a third point bending configuration, as per ASTM C1609 Standard, to measure load versus mid-span deflection. Strength and toughness parameters are derived from the load–deflection data to assess the flexural performance of the FRC composite systems under consideration. The parameters of interest include first peak strength (pre-crack flexural strength) and post-crack residual strength and toughness provided by fiber addition. Of the mixtures tested, ARG fiber mixtures show the highest residual strength and toughness values, followed by PP and PVA fiber mixtures. ARG fibers produce the most workable mixtures at all fiber volumes, while PVA fibers show a tendency to encounter dispersion issues at higher volume doses. The outcome of this study is expected to facilitate the selection of fibers by giving insight into their relative contribution to fresh and hardened flexural properties of FRC.

The influence of natural and synthetic fibers on mixed mode I/II fracture behavior of cement concrete materials

2019 ◽  
Vol 46 (12) ◽  
pp. 1081-1089 ◽  
Author(s):  
Hossein Karimzadeh ◽  
Ali Razmi ◽  
Reza Imaninasab ◽  
Afshin Esminejad
Keyword(s):  
Fracture Toughness ◽  
Reinforced Concrete ◽  
Mixed Mode ◽  
Fiber Reinforced Concrete ◽  
Bending Test ◽  
Synthetic Fiber ◽  
Mode I ◽  
Fiber Reinforced ◽  
Synthetic Fibers ◽  
Natural And Synthetic

This paper evaluated mixed mode I/II fracture toughness of fiber-reinforced concrete using cracked semi-circular bend (SCB) specimens subjected to three-point bending test. Additionally, a comparison was made between the experimental results and the estimations made by different theoretical criteria. Natural and synthetic fibers at various concentrations were used in this study. After producing cracks in SCB specimens at different inclination angles to induce different mixed mode loading conditions (from pure mode I to II), the fracture toughness of SCB specimens was determined. Furthermore, the compressive, splitting tensile, and flexural strength of natural and synthetic fiber-reinforced concrete were measured after 7 and 28 days of curing. While there is an increase in the aforementioned strengths with fiber content increase, 0.3% was found to be the optimum percentage regarding fracture toughness for both fibers. Also, the comparison between the experimental and theoretical results showed that generalized maximum tangential stress criterion estimated the experimental data satisfactorily.

Constitutive Behaviour of Lateral Ties Confined Polyolefin Fibre Reinforced Concrete under Monotonic Axial Compression

2012 ◽  
Vol 253-255 ◽  
pp. 367-375 ◽  
Author(s):  
S. Palanivel ◽  
M. Sekar
Keyword(s):  
Reinforced Concrete ◽  
Volume Fraction ◽  
Secondary Reinforcement ◽  
Fiber Reinforced Concrete ◽  
Constitutive Behaviour ◽  
Fiber Reinforced ◽  
Behavioral Differences ◽  
Synthetic Fibers ◽  
The Matrix ◽  
Low Modulus

In this investigation, the combined effect of spacing of lateral ties and volume fraction of polyolefin fibres was studied both experimentally and analytically from the point of deformability characteristics of concrete. Low modulus synthetic fibers such as polyolefin based fibers, it is shown that polyolefin fibers with sufficient tensile strength can successfully enhance the mechanical properties of concrete. The mechanism of delaying and arresting the progressive internal cracking from transition zone to the matrix by the fibres can be made use in passive confinement of concrete. Such concrete was termed as polyolefin fiber reinforced concrete (PFRC). In this study the confinement effectiveness of polyolefin fibres of volume fractions 0.3%,0.5%,0.7%,0.9% and 1.2% in addition to lateral ties of spacing 290mm, 145mm and 75mm on concrete prisms of size 150 ×150 ×300 mm were investigated. Such concrete is termed as confined polyolefin fiber reinforced concrete (CPFRC).This paper presents an analytical model(profile) for predicting the constitutive behaviour of CPFRC based on the experimental and analytical results. A total of seventy two prisms of size 150 ×150 ×300 mm were cast and tested under strain control rate of loading. The increase in strength and strain of CPFRC were used in formulating the constitutive relation. The results of the testing demonstrate the behavioral differences between plain and CPFRC and the ability of the synthetic macro fiber to be used as secondary reinforcement in seismic resistance applications.

scholarly journals Design Aspects of Proposed Alternative Solutions for Tertiary Irrigation Canal

2019 ◽  
Vol 4 (5) ◽  
pp. 139-147
Author(s):  
Mohamad Farouk Abd-elmagied ◽  
Fahmy Salah Abd-elhaleem
Keyword(s):  
Reinforced Concrete ◽  
Ground Level ◽  
Fiber Reinforced Concrete ◽  
Concrete Lining ◽  
Irrigation Canal ◽  
Fiber Reinforced ◽  
Promising Alternative ◽  
Concrete Pipe ◽  
Level 3 ◽  
Concrete Section

This study presents a five alternative systems for the protection of old lined mesqas. The main causes of damages were identified and the hydraulic calculations for mesqas were carried out. The suggested technical alternatives for old lined mesqas were; 1- U-shape reinforced concrete section under the ground level; 2- U-shape reinforced concrete section above the ground level; 3- Reinforced concrete pipe mesqa; 4- Fiber reinforced concrete lined mesqa; and 5- Grouted stone pitched lined mesqa. The design aspects of these five alternatives were analyzed and deliberated. The most promising alternative for protecting old lined mesqas is fiber reinforced concrete lining. Also, the grouted stone pitched lined mesqas economically recommended.

scholarly journals Exploration of Characteristics of Steel Fiber Reinforced Concrete and Its Influence on Regular Concrete

2020 ◽  
Vol 9 (2) ◽  
pp. 209-212
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Natural Fibers ◽  
Plain Concrete ◽  
Fiber Content ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Synthetic Fibers

Concrete is the most widely used product in the construction sector mainly because of its properties and its capability to be moulded to any size. Plain concrete has low tensile strength and forms internal micro cracks. It has been proven that with the addition of natural fibers and synthetic fibers in concrete, it helps in the durability and functionality of structure. The steel fibers are added to the concrete in very low volume doses and it has been effective in decreasing the plastic shrinkage in cracking and also acting as a crack arrestor. In this journal, experimental analysis on steel fiber reinforced concrete is done on M30 and M50 mix with 0.5%, 1%, 1.5% and 2% volume fraction of steel fiber content and is compared with samples of 0% steel fiber content and these samples are investigated on their compressive, split tensile and flexural strengths.

EVALUATION OF COMPRESSIVE STRENGTH OF SYNTHETIC FIBER REINFORCED CONCRETE

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Saman Hedjazi ◽  
Daniel Castillo
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Fiber Reinforced Concrete ◽  
Synthetic Fiber ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Synthetic Fibers

This paper evaluates the effect of discrete fibers in concrete on the pulse velocity and mechanical properties of FRC. Two different type of synthetic fibers consisting of Polypropylene and Nylon were investigated. The effect of concrete mix proportions such as types of fiber, volume fraction of fiber, water-to-cement ratio (w/c), and curing conditions were examined. An experimental program was designed and conducted on 100 mm x 200 mm cylindrical specimens to evaluate the properties of FRC. The compressive strength obtained from the Compression Test Machine (CTM) was compared to those calculated from UPV. The difference between two types of synthetic fibers on concrete properties were investigated. Results show that the highest compressive strength of Polypropylene Fiber Reinforced Concrete (PFRC) was achieved at 0.5% fiber volume fraction, whereas for Nylon Fiber Reinforced Concrete (NFRC) the highest compressive strength was obtained at 1.0% fiber volume fraction. Additionally, results show that the available equations relating UPV to compressive strength of concrete need modifications when used for different fibers. Therefore, either new or modified empirical equations are needed for better estimation of mechanical properties of FRC.

Mixing of High Ductile Mortar (HDM) in Concrete Mixers

2019 ◽  
Vol 1 ◽  
pp. 1-10
Author(s):  
Tek Raj Gyawali
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Poly Vinyl Alcohol ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Synthetic Fibers ◽  
Reinforcing Fibers ◽  
History Of

Plain concrete is strong in compression, but very weak in tension. Tensile strength of plain concrete is about10 to 15% of the compressive strength depending upon the grade of concrete. Another limitation of plain concrete is that it is brittle in failure. Fiber-reinforced concrete (FRC) is the concrete made primarily of hydraulic cements, aggregates, and discrete reinforcing fibers. Fibers suitable for reinforcing concrete are produced from steel, glass, and organic polymers (synthetic fibers). Author hereby has attempted to develop the High Ductile Mortar (HDM) using Poly Vinyl Alcohol (PVA) fibers. HDM may replace the steel fibers to increase the flexural strength and deflection. It also lightens the structure than steel fiber reinforced concrete (SFRC). This paper gives the brief history of HDM development results which were mixed in small mortar mixer of 10 liter capacity. Then, it presents the results of HDM mixed in two different concrete mixers of 100 liter capacity using different PVA fibers and sands.

scholarly journals Fiber-reinforced concrete for the flat bottom of silos

2020 ◽  
Vol 24 (4) ◽  
pp. 274-279
Author(s):  
Rodrigo A. Constantino ◽  
José P. Lopes Neto ◽  
Marcilene V. da Nóbrega ◽  
José W. B. do Nascimento ◽  
Jefferson H. G. da Silva
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Mechanical Performance ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Flat Bottom ◽  
Fiber Concentration ◽  
Synthetic Fibers ◽  
Concrete Matrix

ABSTRACT The use of synthetic fibers as reinforcement for concrete replacing the steel reinforcement has been diffused worldwide in several applications, gaining prominence in the application for industrial floors, tunnel linings, road pavements, etc., i.e., continuous structures in contact with soil that require performance in the elastic medium. The present study investigated the applicability of concrete reinforced with synthetic fibers in the bottom slab of silos supported directly on the ground, being composed of an experimental study and a case study. The experimental study consisted of the analysis of the mechanical behavior of this concrete by testing three concentrations of synthetic fibers (3.0, 4.5 and 6.0 kg m-3) in a conventional simple concrete matrix. The case study consisted of the design of this part in conventional reinforced concrete and concrete reinforced with synthetic fibers with the objective of performing an economic comparison between the two projects. The experimental results showed that the fiber concentration that contributed to a better mechanical performance of the concrete matrix was 3.0 kg m-3. The case study showed that the most economical design was the one made with fiber-reinforced concrete.

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