Fiber-reinforced Concrete Slabs Research Articles

Performance of fiber-reinforced concrete link slabs with embedded steel and GFRP rebars

Expansion joints in bridge superstructures are often difficult to maintain, leading to the problems associated with water leakage and debris accumulation. As a potential solution, link slabs can be placed at the expansion joints, providing a continuous deck system. Despite the promise of such a system, there have been standing questions on the materials of choice and structural configurations appropriate for link slabs, especially in their transition zone from the bridge deck to their debonded region. This motivated the current study to investigate various reinforcement alternatives using full-scale laboratory tests and numerical simulations. To achieve a satisfactory crack resistance, a fiber-reinforced concrete (FRC) mixture was developed for the tested link slabs. In addition, two rebar alternatives, i.e., steel and GFRP rebars, were evaluated to ensure a proper transfer of stresses induced by negative bending moments (due to continuity) and to limit the width of cracks on the top surface of the link slabs, where they are directly exposed to water and deleterious agents. The full-scale performance was examined under increasing vertical loads applied to the midpoint of two individual spans connected by a link slab. This included an investigation of various structural response measures, such as strains in the FRC and embedded rebars. The study was then extended by performing a set of finite-element simulations to understand the effects of reinforcement details. The outcome of this study provided holistic information on how flexible link slabs can be utilized for jointless bridge superstructures, addressing the concerns regarding their performance and durability.

Numerical Modeling and Analysis of Concrete Slabs in Interaction with Subsoil

This article focuses on the analysis and numerical modeling of a concrete slab interacting with subsoil. This is a complex task for which a number of factors enter into the calculation, including the scope or dimension of the model, the non-linear solution approach, the choice of input parameters, and so forth. The aim of this article is to present one possible approach, which is based on a non-linear analysis and a three-dimensional computational model. Five slabs were chosen for modeling and analysis. The experiments involved slabs of 2000 × 2000 mm and a thickness of 150 mm, which were tested using specialized equipment. The slabs included a reinforced concrete slab, a standard concrete slab, and three fiber-reinforced concrete slabs. The fiber-reinforced slabs had fiber volume fractions of 0.32%, 0.64%, and 0.96%, which corresponded to fiber dosages of 25, 50, and 75 kg/m3. A reinforced concrete slab was chosen for the calibration model and the initial parametric study. The numerical modeling itself was based on a detailed evaluation of experiments, tests, and recommendations. The finite element method was used to solve the three-dimensional numerical model, where the fracture-plastic material of the model was used for concrete and fiber-reinforced concrete. In this paper, the performed numerical analyses are compared and evaluated, and recommendations are made for solving this problem.

Variability of Seismic Loading over the Surface of a Concrete Slab in Interaction with the Subsoil

This article is aimed at the analysis of the behavior of a fiber-reinforced concrete slab in contact with subsoil during dynamic loading in close proximity. The properties of such slabs are important for evaluating their dynamic response, though the properties of the subsoil environment through which the vibrations propagate must also be taken into account. The analysis itself was performed on the basis of the results obtained from experimental measurements during seismic excitation with a calibrated impact. There were three concrete slabs tested, with varying amounts of fiber. The standard Vistec seismic instrumentation was used for measuring the dynamic response. The results of the experiment were processed in both the amplitude and frequency domains, and a graphic comparison in the waveform and frequency fields was made. The results acquired from this experimental research may support a more objective approach during the evaluation of dynamic impacts ranging from anthropogenic impacts to building structures.

Cracking of composite fiber-reinforced concrete foundation slabs due to shrinkage

Industrial concrete floors made directly on the ground are concrete slabs reinforced with structural reinforcement and often additionally reinforced with dispersed reinforcement in the form of polypropylene or steel fibers. More often than not, these floors are not separated from the reinforced concrete slab; they form a monolithic whole with it. Due to high variable loads and additional pressure of groundwater, in the case of foundation slabs in underground garages, floors ought to be subject to precise static and strength calculations. However, the load from concrete shrinkage is often neglected, as it is considered to appear temporarily in concrete care phase and to disappear gradually when the slab is normally exploited. In the recipe of the concrete mix itself, the composition of aggregate, plasticizing additives, the amount of mixing water and the addition of dispersed reinforcement should be carefully selected in order to minimize concrete shrinkage. The quality of the flooring also has a huge impact upon the course of shrinkage and the distribution of tensile stresses in the floor. The article presents the main errors related to the appearance of excessive cracking caused by shrinkage stress.

Geometrical and Material Nonlinear Finite Analysis of Fiber Reinforced Concrete Slabs

Geometrical nonlinearity arises from the continuous change of shape under increasing loads on thin or long span members, and the materials nonlinearity due to the nonlinear behavior of the materials composing the structural element. In this study the finite element method is used to analyze fibrous reinforced concrete slabs, material and geometric nonlinearities were considered. Concrete is represented by degenerate quadratic thick shell element. Concrete behavior in compression is modeled by elastic perfectly plastic or strain hardening plasticity. A tensile strength criterion is used to follow crack initiation and propagation. A parabolic stress degradation function, which is based on the fracture energy concept, is used to model the tension stiffening effect of steel fibers. The reinforcement is considered as smeared within the concrete layers, and assumed as either an elastic perfectly plastic material or as an elastic-plastic material with linear strain hardening. Von Karman assumptions which is based on the total Lagrangian approach is used for the geometric nonlinearity. The numerical results using for both normal and lightweight fiber reinforced concrete slabs were predicted satisfactorily. The average predicted failure load of the investigated cases to the experimental failure load was 0.899 with a standard deviation of 0.092.

Effect of Stirrups on Lateral Cyclic Behavior of Interior Glass Fiber-Reinforced Polymer-Reinforced Concrete Slab- Column Connections

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Flexural Behavior of Composite Concrete Slabs Made with Steel and Polypropylene Fibers Reinforced Concrete in the Compression Zone.

The paper presented aimed at examining the effect of a fiber-reinforced concrete layer in the compressed zone on the mechanical properties of composite fiber-reinforced concrete slabs. Steel fibers (SF) and polypropylene fibers (PP) in the amount of 1% in relation to the weight of the concrete mix were used as reinforcement fibers. The mixture compositions were developed for the reference concrete, steel fiber concrete and polypropylene fiber concrete. The mechanical properties of the concrete obtained from the designed mixes such as compressive strength, bending strength, modulus of elasticity and frost resistance were tested. The main research elements, i.e., slabs with a reinforced compression zone in the form of a 30 mm layer of concrete with PP or SF were made and tested. The results obtained were compared with a plate made without a strengthening layer. The bending resistance, load capacity and deflection tests were performed on the slabs. A scheme of crack development during the test and a numerical model for the slab element were also devised. The study showed that the composite slabs with fiber-reinforced concrete with PP in the upper layer achieved 12% higher load capacity, with respect to the reference slabs.

Response of low-percentage FRC slabs under impact loading: Experimental, numerical, and soft computing methods

Application of fiber reinforced concrete (FRC) has been increased in the past decade due to its enhanced structural performance. Therefore, it is important to fully characterize its static and dynamic behavior under different loading scenarios. In this paper, the effects of low-percentage steel fibers with four different fiber volume is investigated on the dynamic responses of concrete slabs. First, a series of experimental tests are conducted. Next, the results are used to validate a nonlinear finite element model under impact loading. Finally, a large dataset of numerical simulations are developed using appropriate design of experiments, and four soft computing techniques are used to predict the target responses.The findings show that application of low-percentages fiber increases the acceleration response of the concrete slabs subjected to impact load, on the average of 102%. The slab’s stiffness increases with an increase in fiber percentage. The dominant frequency, the damping ratio, as well as the slab’s cracking pattern, and the failure modes indicate that FRC slabs are stiffer than conventional RC specimen. The numerical simulations reasonably estimate the maximum acceleration. Outcome of the predictive meta-models can be used to estimate the dynamic behavior of similar slabs with no additional experimental and numerical costs.

Evaluation of hybrid fibre-reinforced concrete slabs in terms of punching shear

This study aims to investigate the influence of hybrid steel-polypropylene fibres in enhancing the capacity of punching shear with respect to concrete slab column connection. This paper adopted the experimental programme of studies to evaluate the influence of hybrid fibre on the punching shear as a key property of a concrete member. The experimental programme, supporting this investigation, involved samples of three mixtures in addition to a reference plain concrete mixture (PC). Fibre type and volume were the factors that have been used for determining these mixtures. The mixtures included single fibre concrete (SFC) mix with steel fibre volume of 0.5%, hybrid fibre-reinforced concrete mix (HFC1) with steel fibre volume of 0.5%, polypropylene fibre volume of 0.2%, hybrid fibre-reinforced concrete mix (HFC2) with steel fibre volume of 1.5%, and polypropylene fibre volume of 0.2%. The experimental programme adopted the use of 600 mm diameter circular slab specimens with overall depth of 75 mm to test the punching shear.The experimental study further investigated the influence of the hybrid fibres on other concrete properties including compressive and, flexural strength; 150-mm cubic specimens and 150 × 150 × 600 mm prismatic beams were used to measure the compressive and flexural strengths, respectively.The results of the study demonstrated a significant improvement in the punching shear capacity in hybrid fibre concrete mixes over plain and single fibre concrete mixes. This improvement has also been demonstrated in other concrete properties including compressive strength, flexural strength, cracking behaviour, ductility, and toughness. The improvement in the concrete properties was observed to be high in HFC2 mixture (0.2% PP, 1.5% SF), and on comparison with the plain concrete mixture a notable increase of 34% in punching sheer capacity was recorded.

Impact Response of Carbon Fiber Reinforced Concrete

Fiber reinforced concrete is becoming increasingly more important in the construction field due to its numerous applications and advantages. Fibre reinforced concrete (FRC) is composed of fibres and matrix. Fibres constitute the reinforcements and the main source of strength while the matrix ‘glues’ all the fibres together in shape and transfers the stress between the reinforcing fibres. Different types of fibres in use are steel, glass, carbon, basalt and aramid. Fibre reinforced concrete has many advantages such as improvement in the mechanical properties like modulus of elasticity, deflection, energy absorption and crack resistance. This paper discusses the experimental investigations carried out on carbon fiber reinforced concrete under impact loading. Mix design is carried out for M25 grade of concrete reinforced with carbon fibers in proportions of 0%, 0.75%, 1.00% and 1.25% by volume fraction. The test results show that there is an increase in compressive, split tensile and flexural strengths of carbon fiber reinforced concrete (not discussed in this paper). The inclusion of 1% carbon fibers showed the maximum enhancement in strength and it can be considered as optimum dosage. When compared to conventional concrete, the crack width also reduced in carbon fiber reinforced concrete. Extensometer test was conducted to determine the modulus of elasticity of concrete. The main aim of this study is to understand the dynamic behavior of carbon fiber reinforced concrete under impact loading. For carrying out the drop-weight tests, eight slab specimens were casted. The edges of the slab were fixed on all four sides. FRC slab with 1% addition of carbon fibres gave the best results. There was a decrease in displacement and an increase in impact energy for an the aspect ratio of fiber is 45.

Computational Analysis of Punching Shear Models of Steel Fiber Reinforced Concrete Slabs

A computational analysis is presented to predict the ultimate and cracking shear strength of steel fiber reinforced concrete slabs. Different models are suggested considering the effect of concrete compressive and tensile strength, amount of flexural reinforcements, yield strength of the reinforcement bars and steel fiber properties (volume percent, aspect ratio, and type of steel fibers). The predicted results are compared with the experimental data found in literature and found good agreement.

Flexural Behavior of Basalt Fiber–Reinforced Concrete Slab Strips with BFRP Bars: Experimental Testing and Numerical Simulation

AbstractThis study investigated the flexural behavior of a new one-way concrete slab system reinforced longitudinally with basalt fiber–reinforced polymer (BFRP) bars and cast with basalt fiber–rei...

Evaluation of Organizational and Technological Aspects of Construction of Elevated Steel Fibre Reinforced Concrete Slabs

Evaluation of Organizational and Technological Aspects of Construction of Elevated Steel Fibre Reinforced Concrete Slabs

강섬유보강 콘크리트를 이용한 콘크리트궤도 패널의 휨성능 평가

강섬유보강 콘크리트를 이용한 콘크리트궤도 패널의 휨성능 평가

Composite Binders for Concretes with Improved Impact Endurance

The chemical engineering principles of optimization of the physical and mechanical properties and performance characteristics of dispersed reinforced composite materials are proposed which consist in the integrated effect of a composite binder consisting of jointly ground Portland cement, rice husk ash, a complex of inert fillers, and a hyperplasticizer on the processes of structure formation of cement stone. Here, the effect of increasing the impact endurance increases up to sixfold. It is found that dispersed reinforced concretes with an increased ratio of static tensile strength to static compressive strength Rtens/Rcompr and ductility possess the best endurance to dynamic action. It is proved that this ratio can be increased by using dispersed reinforcement of concretes (so-called fibrous concretes). In experimental studies on penetration of both unreinforced and fiber-reinforced concrete slabs, it is noted that samples of unreinforced concrete are completely fractured into large and small pieces, while samples of fiber-reinforced concrete are not completely fractured, and only through penetration at the impact site was observed; that is, fibrous concrete possesses better impact resistance. These results can be applied to the design of various special structures, such as defense structures of civil defense and emergency situations, fortifications of the Russian Ministry of Defense, and concrete structures of nuclear power plants.

Experimental Studies on Flexural Behavior of Waste Plastic Fiber Reinforced Concrete Slab

Plastic disposal is challenging issue across the globe. The use of plastic in concrete will overcome the disposal problem. In this paper, we study the possibility of disposing waste in concrete. The effect of fiber is been studied for varying percentages of fiber 0.5% to 3.0% by weight of cement, with a variation of 0.5 % interval. The effect of fiber is been studied for two types of dispersion of fiber 1.Dispersed both in tension and compression zone 2.Dispersed only in tension zone. The flexural strength of slab with fiber reinforced concrete for nine point loading is been studied, the grade of concrete considered is M20. The results are compared with conventional concrete. It is been found that with the addition of fiber the strength of concrete considerably increases. Addition of plastic fiber of 1.5% shows the maximum increase in strength of concrete. The addition of plastic fiber increases the strength maximum at first crack level compared to ultimate load level. The number of cracks developed in fiber reinforced concrete is very less compared to conventional concrete.

Punching Shear in Steel Fiber-Reinforced Concrete Slabs with or without Traditional Reinforcement

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Impact Mechanical Properties of Fiber Reinforced Concrete Slab with Alkali-Resistant Glass Fiber of High Zirconium

This paper studied the impact resistance of high zirconium alkali-resistant glass fiber reinforced full-scale concrete slabs from the perspective of dynamics by the drop hammer test, and compared with macro-polypropylene and steel fiber. The effects of fiber type and fiber volume fractions on the impact resistance of concrete slabs were investigated, the concrete slab acceleration and the support reaction force time-history curve were measured, and the dynamic test results and failure mode of specimens were comparative analysis. All fiber reinforced concrete slabs show ductility failure, as the increase in fiber volume fractions, the impact resistance of specimens was improved more significantly, and the impact resistance of slabs exhibits secondary strengthening properties and experienced elastic-plastic phase. When the volume fraction was 0.45%, the first impact resistance of macro-polypropylene fiber and glass fiber reinforced concrete slab was similar, while when the volume fraction was 0.75%, the impact resistance of macro-polypropylene fiber reinforced concrete slab was better. With the same volume fraction, the second impact resistance of macro-polypropylene fiber reinforced concrete slab was better than that of glass fiber. Although the impact toughness and energy dissipation performance of high zirconium alkali-resistant glass fiber reinforced concrete compared with other fiber is not outstanding, but the comprehensive analysis shows that it has advantages in the use of the corrosion environment.

A Study on Elastic Deformation Behavior of Steel Fiber-Reinforced Concrete for Pavements

The present study discusses the experimental investigation of steel fiber-reinforced concrete slabs on ground under wheel load with the objective of understanding the stress behavior when subjected to central and edge wheel loading. The steel fiber-reinforced fly ash concrete slabs of 900 mm × 900 mm, 150 mm thickness were investigated in this study. Strain gauges and data acquisition system were used to measure the strains at the center and the edge of the slab under the action of the load. The load versus strain relationship under central and edge loading for reference concrete and steel fiber fly ash concrete showed a linear variation even up to the pressure of 2.5 MPa, which is much beyond the conventional tyre inflation pressure of 0.8 MPa. The load versus strain graphs clearly signify the higher modulus of elasticity of fly ash steel fiber-reinforced concrete. The stresses were calculated using IITRIGID software and ANSYS software and were found matching significantly. The value of modulus of elasticity of fly ash steel fiber-reinforced concrete (FS) using ANSYS model for experimental values of load and strains measured was approximated to 34,000 N/mm2 and was found to closely match with the experimentally obtained modulus of elasticity. No significant effect of Poisson’s ratio of concrete on load–strain characteristics was observed within the range 0.15–0.2 of concrete.

Flexural behavior of basalt fiber-reinforced concrete slab strips reinforced with BFRP and GFRP bars

This research investigates experimentally and analytically a novel one-way slab system reinforced with either basalt fiber-reinforced polymer (BFRP) or glass fiber-reinforced polymer (GFRP) longitudinal bars embedded in fiber-reinforced concrete (FRC) incorporating basalt macro-fibers (BMF). Twelve one-way concrete slab strips were prepared and tested to failure under four-point loading configuration. The investigated parameters included the type of fiber-reinforced polymer bars (BFRP and GFRP), the longitudinal reinforcement ratio ρf (1.4 and 2.8ρbf, where ρbf is the balanced reinforcement ratio), and the volume fraction of the fibers added (0, 0.5, 1, and 2% per volume). The test results demonstrated the promise of BMF to enhance the flexural performance of the tested slab strips in terms of ductility and load-carrying capacities. The formulations of different available codes and design guidelines were used to predict the test results. Comparison between the experimental and predicted results showed the adequacy of the models to predict the flexural performance of the tested slab strips. The findings of this study demonstrated the potential of using the BMF as alternatives to conventional fibers in flexural concrete members.