Application Of Fiber Reinforced Concrete Research Articles

Investigating interphase bond behavior of waste badminton string fiber in composite matrix

ABSTRACT Recently moving towards the usage of sustainable and renewable construction materials, the badminton strings are identified as alternate material for commercial fibers. These recycled badminton strings once discarded from the racquets become a waste and cannot be reused. Hence investigation of the interphase bond behavior of these fibers with the cement and epoxy polymer matrix plays a major role. Therefore, the pullout mechanism between the fibers with the epoxy matrix is examined using the photoelasticity technique with a 40 mm embedment length. Whereas the pullout mechanism between the fibers with the cementitious matrix is examined for a single string of fiber using a pullout test with varied embedment lengths of 10, 20, 30, 40, 50, 60, 70, and 80 mm. From the study, the minimum and maximum bond stress between the fiber and epoxy interface is 3.23 MPa and 11.59 MPa respectively. Whereas between the fiber and cementitious interface, the minimum and maximum bond stress is 1.02 MPa and 2.15 MPa respectively. The experimental results are validated by the Weibull modulus approach which shows less variability. Thus, the results of the pullout test in composite matrix recommend the usage of waste badminton strings in fiber-reinforced concrete applications.

A New Insight into the Design Compressive Strength of Ultra-High Performance Concrete

Compressive strength is one of the most critical mechanical properties of various types of concrete and is the main input variable for structural concrete design. Recently, with the advances in concrete technology, applications of fiber-reinforced concrete (FRC), including ultra-high performance concrete (UHPC), have grown rapidly. These new types of concrete are well known to exhibit superior mechanical characteristics such as compressive strength, fracture toughness, and durability compared to conventional concrete and thus are popularly used in urgent repair jobs where compressive strength is an important parameter to determine the required curing time until open to the public. Considering the importance of compressive strength in practice, this study aims to evaluate the effect of age and maturity on the compressive strength characteristics of three different types of concrete, namely UHPC with micro and macro steel fibers, FRC, and plain concrete, and to propose a new design strength criterion for UHPC. To this end, 180 concrete cube specimens were tested at 12 different ages between 3 and 126 days. The results indicated that irrespective of the type and presence of fibers, UHPC gained more than 90% of their ultimate compressive strength after only 21 days, while FRC and plain concrete specimens required a longer time (i.e., 28 days) to achieve 90% of their ultimate strength. Therefore, UHPC may adopt a 21-day compressive strength as a design input instead of a 28-day compressive strength commonly required for structural concrete specified by many codes of practice. Moreover, the obtained experimental results were compared with existing compressive strength predictive models in the codes of practice.

Mechanical performance evaluation of steel fiber-reinforced concrete (FRC) based on multi-mechanical indicators from split hopkinson pressure bar (SHPB) test

Fiber-reinforced concrete (FRC) is a new composite material composed of various fibers and a cement matrix that has been widely used and developed in the construction engineering field. In this paper, split Hopkinson pressure bar (SHPB) tests are carried out with the aim of investigating the mechanical properties and failure characteristics of FRC containing different types and dosages of steel fibers. The main findings are as follows: At a fiber content of 0 %–3.5 %, the strength of FRC shows two trends: continuously increasing and then decreasing. The ductility of hooked-end steel fiber-reinforced concrete (HFRC) is better than that of hybrid steel fiber-reinforced concrete (HSFRC) and straight steel fiber-reinforced concrete (SFRC) under static loads, whereas the ductility of HSFRC is better than that of SFRC and HFRC under dynamic loads. Straight steel fibers (SF) are better than hooked-end steel fibers (HF) in improving tensile toughness but worse than HF in improving compressive toughness. In terms of the degree of failure, NFRC and HFRC were the most severely fragmented, whereas SFRC and HSFRC exhibited better integrity. Finally, based on the multi-mechanical indicators of the FRC, a comprehensive performance evaluation method and optimization suggestions for the FRC are proposed. This provides theoretical support for the application of FRC as seismic-resistant materials in reinforced structures (i.e., anti-slide piles, retaining walls, and beam structures) of rocky landslides in strong seismic areas, which have important engineering significance.

Feasibility study of using waste badminton string fibers in con-crete by morphological, microstructural and tensile characteristics

As the strings are cut off from the badminton racquet system, the whole string will be replaced with a new one and there is no other alternative. Hence those cut-off strings are considered as waste and cannot be recycled, tons of waste are retained as debris. Among many research on recycled synthetic fiber, this application of waste material is a new context in sustainable construction. Here five different samples are examined based on wide usage, recycled Waste Badminton String Fiber (WBSF) is characterized and physically examined using a Scanning Electron Microscope, Fourier Transform Infrared Spectroscopy, and X-ray diffraction to use it as a recycled synthetic fiber in various fiber reinforced concrete applications. The diameter and cross-sectional area of WBSF are studied using the Scanning Electron Microscope imaging technique and Image J application, which shows that the fiber is highly engineered with 3 layers namely elasticity outer, outer layer, and core fiber with the mean diameter and net cross-sectional area is 777.6 µm and 5,05,959 µm2 respectively. The surface roughness of fiber is analyzed using ImageJ application which varies between 16-32 nm. The fiber samples are subjected to tensile loading the average tensile stress lies between 544.34 - 639.94 MPa. From the above examinations, the accurate diameter, net cross-sectional area, and voided area of the WBSF are calculated. The structural property and polymer relationship of the fiber are investigated using the X-ray diffraction technique and Fourier transform infrared spectroscopy, this reveals that the WBSF is of polyamide 6,6 form. The superior tensile stress compared to other recycled nylon fibers. So, the use of waste badminton string fiber in concrete is a new merging idea for fiber-reinforced concrete applications like pavements, pipes, tunnel lining, and other structural elements.

Ensaio DEWS simplificado para caracterização do concreto reforçado com fibras de aço

Abstract Fibre Reinforced Concrete (FRC) is internationally recognised as a structural material in the fib Model Code 2010 and at a national level in the recently published ABNT standard NBR 16935, which establishes the structural design procedure based on post-cracking parameters. This publication should foster an increase in the number of applications of FRC in Brazil in the next years. In this context, many researchers have investigated the use of the DEWS test for the FRC characterisation as an alternative to the three-point bending test (3PBT) usually recommended by standards. The DEWS test is conducted by applying a compressive load on specimens with triangular grooves that induce a pure mode‑I tensile fracture. Despite the advantages of the test, such as a smaller specimen and simpler testing procedure to obtain the anisotropic/orthotropic material properties, it still requires transducers to measure crack opening and generate the triangular grooves in the specimen, which is more complex, and labour demanding. This study addresses these issues by proposing a simplified test method and preparation consisting of removing the transducers (correlating the machine stroke and the crack opening) and generating the triangular groves during the casting instead of sawing afterwards. These modifications made the testing procedure much easier to perform. The experimental program assesses the modifications in the DEWS test setup and their influence on the post-cracking characterisation of FRC. Additionally, the effective fibre content and orientation were assessed by performing the inductive test. The results show that FRC characterisation can be successfully conducted using a simpler configuration of the DEWS test. This alternative test presents some advantages in comparison with the 3PBT test for FRC quality control, especially the lower volume of material and the test control by machine displacement.

Structural response of a fibre reinforced concrete pile-supported flat slab: full-scale test

The total substitution of traditional reinforcement in the form of steel bars by fibres can be mainly found in elements with favourable boundary conditions and subjected to low-moderate load levels. However, the rigorous study of fibre reinforced concrete (FRC) and its potential fields of application over the last decades permitted this material to face structural application with greater responsibility in terms of structural integrity and mechanical capacity – construction of FRC flat slabs. This promising technology was used in a dozen buildings with recognition of positive outcomes with respect to the optimization of resources, reduction of execution time, and environmental impacts. Despite these achievements, the application of FRC in flat slabs is still limited in the building sector because of certain concerns of the material capacities, and existence of some aspects related both to service and ultimate limit states, which are still unclear. With this in mind, an extensive experimental programme was carried out and focused on the construction of a full-scale FRC flat slab and its loading protocol in order to analyse both crack and deflection patterns. Likewise, the structure was led to failure, which also allowed assessing both the bearing and deformability capacities as well as the fibre distribution and orientation. The results derived from this experimental program are expected to increase the confidence of designers and practitioners on the use of FRC as structural material for column-supported flat slabs.

Systematic Review on the Creep of Fiber-Reinforced Concrete.

Fiber-reinforced concrete (FRC) is increasingly used in structural applications owing to its benefits in terms of toughness, durability, ductility, construction cost and time. However, research on the creep behavior of FRC has not kept pace with other areas such as short-term properties. Therefore, this study aims to present a comprehensive and critical review of literature on the creep properties and behavior of FRC with recommendations for future research. A transparent literature search and filtering methodology were used to identify studies regarding creep on the single fiber level, FRC material level, and level of structural behavior of FRC members. Both experimental and theoretical research are analyzed. The results of the review show that, at the single fiber level, pull-out creep should be considered for steel fiber-reinforced concrete, whereas fiber creep can be a governing design parameter in the case of polymeric fiber reinforced concrete subjected to permanent tensile stresses incompatible with the mechanical time-dependent performance of the fiber. On the material level of FRC, a wide variety of test parameters still hinders the formulation of comprehensive constitutive models that allow proper consideration of the creep in the design of FRC elements. Although significant research remains to be carried out, the experience gained so far confirms that both steel and polymeric fibers can be used as concrete reinforcement provided certain limitations in terms of structural applications are imposed. Finally, by providing recommendations for future research, this study aims to contribute to code development and industry uptake of structural FRC applications.

Structural performance of optimised spirally deformed steel fibre

The capability of steel fibres in stress transferring across the cracked sections (bridging effect) could be employed to enhance the concrete role (especially in tension zones) in the overall load bearing capacity of Reinforced Concrete (RC) members. However, the structural applications of Fibre Reinforced Concrete (FRC) is limited mainly due to the poor performance of existing fibres on the market (softening response). The continuous pullout load decay, i.e. softening response, cannot result in a major contribution of fibres to the ultimate load bearing capacity of RC members. In this paper, the structural contribution of an optimised spirally deformed steel fibre engineered by the authors possessing hardening response in normal concrete is examined experimentally. To this end, a structural testing programme consists of two sets of RC beams, i.e. shear-critical and flexure-critical, is designed such that the shear and flexural contribution of the spiral fibre can be assessed individually. Various experiment parameters are considered in the testing programme. The test results reveal that such a fibre could be employed as partial/full replacement for conventional reinforcement in RC beams. A shear design equation for RC beams incorporating the new fibre is also proposed.

Strength development and microstructure characteristics of artificial concrete pillar considering fiber type and content effects

The artificial concrete pillar (ACP) replacement technique is a safe and reliable method to safely mine orebody pillar in room and pillar mining. In contrast to traditional ore pillar, artificial pillar has recently received significant attention due to its applicability, stability and cost benefits. This study deals the influence of fiber type and content on uniaxial compressive strength (UCS) and microstructure characteristics of fiber-reinforced concrete (FRC) considered as an effective artificial pillar. A total of 3 non-FRC (NFRC) and 27 FRC samples reinforced with glass, polypropylene (PP), and polyacrylonitrile (PAN) fibers at a content of 0 wt%, 0.4 wt%, 0.8 wt% and 1.2 wt% were manufactured for examining their strength properties. After UCS testing, some microstructure tests including computed tomography scan and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy were done to better explore the morphology of FRC. Results illustrate that: (1) The UCS values of all FRC samples first increase and then decrease with increasing fiber content. The UCS increment ratio in FRC steadily decreases as the fiber content increases. (2) PP fiber was more effective than both glass and PAN fibers in increasing peak strain and strength performance. This was mainly because of an improved bonding quality within the matrix which allows to decrease the water absorption of FRC. Overall, the peak strain increases linearly with increasing fiber content. Finally, the findings of this study can offer a substantial reference in design and application of FRC to be used as artificial pillar in underground mines.

Application of fiber-reinforced concrete in high-rise construction

In this research, we study the use of fiber-reinforced concrete, including steel fiber-reinforced concrete in the construction of outrigger floors of a high-rise building. The definition and classification of fiber-reinforced concrete as a construction material, the methodology for calculating high-rise buildings using fiber-reinforced concrete, the advantages and disadvantages of this composite material, and the specifics of its use are formulated. The domestic and foreign experience in use of fiber-reinforced concrete is analyzed. The rationale for its use on the experience of construction of residential building in seismically active regions is given. A comparative analysis of concrete and fiber concrete use in the outrigger floors’ construction is carried out.

Study on application of fiber-reinforced concrete in sluice gates

A sluice gate is a primary hydraulic structure in water discharge and storage facilities. Steel sluice gates are often stolen when global metal prices are high. Thus, this study proposed using fiber-reinforced concrete to fabricate sluice gates. The material mechanical properties and durability of the fiber-reinforced concrete sluice gates were tested, and field test and feasibility tests were subsequently performed. The compressive strength, flexural strength, and elastic modulus of the concrete used to construct the gates were respectively 99.3 MPa, 18.2 MPa, and 40.0 GPa. In the concrete, the depth of wear by hyperconcentrated flow was 0.5 mm h−1 mm−2; the chloride diffusion coefficient was 2.25 × 10−12 m2 s−1; and the weight loss in the soundness test was 1.02%.The results of the field testing suggested that the size and weight of the fiber-reinforced concrete sluice gates met operational needs and that the gates maintained their watertight seals and functioned normally during and after several tropical cyclones. Monthly observations revealed no noticeable cracks or rust stains on the gate surfaces. And the difference of properties of fiber-reinforced concrete before and after one year exposure is within ±6%. The fiber-reinforced concrete sluice gates were estimated to be one-tenth cheaper to produce than stainless steel gates and one-fifth cheaper than cast iron gates. The concrete sluice gates can be employed in low-head areas and drainage basins.

The Application of Fibre Reinforced Concrete for Protective Shelter from Auxiliary Material

The article deals with the application of fibre reinforced concrete for protective shelter from auxiliary material. It describes a basic structure element, a structure of the shelter, and a process of building.

Structural Applications of Fibre Reinforced Concrete in the Czech Republic

The paper presents improvement of function and performance of the precast structural members by using fibre reinforced concrete (FRC) instead of ordinary reinforced concrete and attempts to transfer innovative technologies from laboratory in academic sphere into real industrial production which is cost-effective and brings about savings of labour and material. Three examples of successful technology transfer are shown – application of FRC in an element without common rebar reinforcement, in the element with steel rebar reinforcement and SFRC pre-tensioned structural element. Benefits of FRC utilization are discussed.

Application of Fiber-reinforced Concrete in Tram Track Foundation

The use of polymer fiber-reinforced concrete is one of the most promising trends in tram track development. It was first successfully used as tram track foundation in 2010-2011. The analysis of such structures has shown a number of their advantages: reduced construction time, economic benefits in terms of reducing cost and labour, and construction technology simplification. Mathematical modelling of structure strength characteristics and field testing specifying the model parameters are required for the subsequent use of fiber-reinforced concrete as tram track foundation.

Seismic performance of fiber-reinforced concrete interior beam-column joints

Fiber-reinforced concrete (FRC), as an advanced alternative to normal concrete, has been increasingly used to construct beam-column joints which is one of the most congested parts of reinforcements in reinforced concrete (RC) structures because of its potentially beneficial properties. The present work aims to investigate the seismic performance of FRC beam-column joints experimentally and numerically. A total of eight beam-column joints, including both FRC beam-column joints and RC beam-column joint, were conducted to explore its seismically important features under quasi-static reversed cyclic load, mainly including the failure modes, hysteretic response, energy dissipation, stiffness degradation. It was found that the application of FRC can effectively improve the seismic performance of beam-column joints because it leads to higher load-carrying capacity and a greater deformation capability prior to the formation of the major diagonal cracks in the joint core zone. A numerical study, using the Open System for Earthquake Engineering Simulation (OpenSEES), was also conducted to study the seismic performance of beam-column joints deeply after its applicability and accuracy being validated with test data. The prediction from the proposed numerical model shows a good agreement with test data. Furthermore, a parametric study was generated to address and evaluate the effects on the seismic performance of FRC beam-column joints from different parameters, including the axial load ratios, transverse reinforcement ratios and FRC compressive strength. The results indicate that the increment of axial load ratios and FRC compressive strength can enhance the load-carrying capacity.

Improvement of impact-resistance of a nuclear containment building using fiber reinforced concrete

Since the act of terrorism that occurred in the USA on September 11, 2001, the protection of nuclear power plants against large commercial aircraft crashes has been an emerging issue. Besides the verification of the safety of nuclear power plants in operation or in design, efficient methods for improving the impact-resistance of these structures have been investigated. Fiber reinforced concrete (FRC) has been generally accepted as an effective material for this purpose. In particular, FRC has been developed to improve the tensile behavior of concrete such as tensile strength, ductility and toughness. One of the main fields of application of FRC can be found in blast-protective or blast-resistant concrete structures. It is expected, therefore, that safety-related structures in a nuclear power plant can also be effectively protected from external blast, aircraft crash, etc. by applying FRC. In order to analytically verify the effect on structural behavior of applying FRC, the particular material properties of FRC should be incorporated into the material modeling of a structural analysis program. This study investigates the mathematical modeling of FRC, which represents various aspects of material behavior. Two numerical examples are provided to show the improved impact-resistance of a nuclear containment building that is expected when applying FRC in comparison with ordinary concrete. The analysis results show that the displacement decreases by 43–67% while the impact-resistance increases by 40–82%, depending on a fiber type.

Mechanical Properties of Steel-polypropylene Fibre Reinforced Concrete Under Elevated Temperature

Fibre reinforced concrete (FRC) has been found to improve strength, ductility, toughness, and durability of the structures. The application of FRC includes tunnel lining, ground slab, façade and many more. However, when exposing them to high temperature such as fire, there is still little information on the impact on its mechanical properties. The main objective of the study is to understand the fundamental behaviour of FRC when it is exposed to elevated temperature. However, rather than relying on one type of fibre, this study proposed of mixing two different types of fibre in concrete which will then be exposed to elevated temperature at normal temperature i.e. 27°C (room temperature), 200°C, and 400°C. The two types of fibres i.e. steel and propylene has different characteristics. The study is mainly focused on the experimental work. The fibre dosage will also be varied with percentage of steel-to-propylene of (100-0), (75-25), (50-50), (25-75) and (0-100) at 1.5% of fibres proportion from the volume of the concrete. Therefore this research is expected to answer the fundamental question whether if one type is vulnerable to fire, the other one will take place to avoid catastrophic failure of the whole structure. Experimental work will be carried out to study the impact of elevated temperature on the compressive strength, tensile strength, and flexural strength.

Diseño óptimo de dovelas de hormigón reforzado con fibras para el revestimiento de túneles

The use of fibre reinforced concrete (FRC) in precast segments for tunnel support is an increasing practice. However, although the suitability of this material seems to be proven at a technical and economic level, there is still some reluctance towards the natural implementation of this material. In fact, in those cases in which fibres were added to concrete, the structural contribution was not taken into account in the design. This is mainly due to the lack of specific regulations to deal with this, as well as other aspects related to the control, production and design of FRC structures. Fortunately, at national level, Annex 14 of the Spanish EHE-08 already proposes guidelines as regards these aspects, and the new Model Code 2010 also considers the FRC as a structural material. This paper aims, on the one hand, to analyse the most important applications of FRC in tunnel linings worldwide and, on the other hand, presents a design methodology which enables the reinforcement configuration of fibre reinforced concrete in precast segments to be optimised. Furthermore, three real examples of application in which this method has been applied are described.

Development of a 1200-mm-Diameter Round Panel Test for Post-Crack Assessment of Fiber-Reinforced Concrete

AbstractThe ASTM C1550 round panel test is now used widely to assess the post-crack performance of fiber-reinforced concrete (FRC) and fiber-reinforced shotcrete (FRS) and is firmly established as the most repeatable means of post-crack performance assessment available for these materials. However, the 75-mm standard specimen thickness for this test method has limited its application to relatively thin-walled structures such as FRS linings in mines and tunnels. The performance characteristics of FRC in bending depend on the thickness of a member, and thus a specimen with a thickness close to that in the intended application should be used for representative performance assessment. For this reason, tests such as ASTM C1609/C1609M, based on a 150-mm-deep beam, are typically used for thick-walled applications such as FRC tunnel linings and pre-cast elements. Unfortunately, the high single-operator variability characteristic of performance parameters obtained using beam tests has burdened the construction industry with unnecessarily expensive FRC designs, because the resulting margin between target performance and design requirements becomes excessively large. In response to this, demand has arisen for an enlarged version of the 75-mm-thick ASTM C1550 panel that can be used as a quality assurance tool for thick-walled FRC applications. The present paper describes the development of a version of the ASTM C1550 round panel 150 mm thick and 1200 mm in diameter with specific emphasis on developing thickness correction factors and characterizing the single-operator variability for these large test specimens. It also establishes a correlation between residual strengths measured using ASTM C1609/C1609M beams and using 1200-mm-diameter round panels at comparable crack widths.

The application of pseudo-ductile cementitious composites in the anchorage zone of post-tensioned concrete members

In China, fiber reinforced concrete (FRC) has been employed in practice for many years. In this paper, after a brief introduction to the current status of FRC applications in China, we will focus on recent research related to the use of pseudo-ductile cementitious composites (PDCC) to resist tensile splitting at the anchorage zone of post-tensioned concrete members. To simulate the situation at the anchorage zone, rectangular concrete columns were loaded under concentrated compression. Tests were performed on members made with (i) plain concrete, (ii) plain concrete and steel stirrups, as well as (iii) concrete with PDCC at the anchorage zone. According to the test results, PDCC is effective in improving the ultimate load under concentrated compression as long as failure is governed by tensile splitting. In some cases, it is found to be more effective than the steel stirrups. However, when the PDCC compressive strength is much lower than that of the concrete, compressive crushing failure may occur instead of tensile splitting, and the load capacity will then be decreased. For members that fail in splitting, a simple design method is proposed and the predicted failure load provides a close estimate of the experimental value. Based on the present study, the use of PDCC to replace all or part of the steel stirrups in the anchorage zone is proved to be feasible.