Mechanical Properties Of Fiber Reinforced Concrete Research Articles

Evaluating The Impact of Pozzoloniz Additives On The Mechanical Properties of Fiber-Reinforced Concrete

Evaluating The Impact of Pozzoloniz Additives On The Mechanical Properties of Fiber-Reinforced Concrete

A Comprehensive Review: Strength Optimization of Fibre Reinforced Concrete by Using Waste Plastic Bottles

Abstract: Fibre reinforced concrete (FRC) has gained considerable attention in the construction industry due to its enhanced mechanical properties and durability. In recent years, researchers have explored innovative methods to optimize the strength and sustainability of FRC by incorporating waste materials, particularly plastic bottles. This review paper critically examines the latest advancements, methodologies, and outcomes in the utilization of waste plastic bottles to enhance the strength of fibre reinforced concrete. Various parameters such as fibre type, aspect ratio, dosage, and curing conditions are analysed to understand their impact on the mechanical properties of FRC. Additionally, the environmental implications and economic feasibility of incorporating waste plastic bottles in FRC production are discussed. The findings of this review aim to provide insights for researchers, engineers, and policymakers in promoting sustainable practices in the construction industry

Application of artificial intelligence in predicting the residual mechanical properties of fiber reinforced concrete (FRC) after high temperatures

The practical application of Artificial Intelligence (AI) approaches in estimating the mechanical properties of fiber-reinforced concrete (FRC) subjected to high temperatures was initiated by developing a dataset including concrete mixtures, geometrical and mechanical properties of fiber, and temperatures. The dataset contains compressive strength, tensile strength, and modulus of elasticity of concrete with two distinct types of fiber, i.e., steel and polypropylene with an extensive range of temperatures from 100 to 1200 ℃. The dataset determined the gaps in the literature and showed FRC with high fiber aspect ratios and higher content of fiber (>0.8%) are not studied enough. The AI-based models showed that steel fiber-reinforced concrete (SFRC) has higher residual compressive strength compared with polypropylene fiber-reinforced concrete (PFRC). An increase in steel fiber diameter and length resulted in a higher compressive strength ratio at all temperatures. Moreover, higher PP fibers content and longer PP fibers decrease the rate of tensile strength degradation. A large probabilistic analysis was performed, and it showed that the failure probability (Pf) for PFRC is independent of W/B ratios and is almost 50%;. In contrast, for SFRC, W/B ratios between 0.4 to 0.5 have lower failure probability in comparison with other W/B ratios. Moreover, Pf for both fibers at a W/B ratio of 0.5 is almost independent of fiber content. Furthermore, the critical temperature resulting in failure (defined as the residual strength ratio less than 0.5) for SFRC and PFRC is 550 ℃ and 430 ℃, respectively.

Study on Mechanical Properties of Fiber-reinforced Concrete

Study on Mechanical Properties of Fiber-reinforced Concrete

PERFORMANCE OF STEEL FIBER EXTRACTED FROM OLD WASTE TYRES ON MECHANICAL PROPERTIES OF CONCRETE FOR RIGID PAVEMENT CONSTRUCTION

The application of Waste Recycled Steel Fibers (WRSF) extracted from waste tyres in fiber-reinforced concrete production has great benefits in civil engineering. Thus, this creates a need to study the appropriate length and dosages of recycled steel fiber in fiber-reinforced concrete. In this experimental research, the effects of varying lengths (5cm and 10 cm) and dosages (1, 1.5, 2, 2.5, and 3%) of WRSF on various mechanical properties of fiber-reinforced concrete for rigid pavement construction were studied. The aggregates were taken from a stockpile, commercially available cement Dangote Ordinary Portland Cement (OPC), and potable water. Non-probable sampling techniques were adopted to collect extracted waste steel tyres. The quality test for sand (fine) and coarse aggregate satisfies the requirements specified in the ASTM. The concrete mix design was done in two categories; the first was a control mix concrete and the second was the experimental mix concrete with the addition of steel fibers with varying lengths (5cm and 10 cm) and dosages (1, 1.5, 2, 2.5, and 3%) of WRSF in concrete (percentages were determined by density for each fiber). The mix ratio of cement: sand: aggregate (1:2:3) with a constant water-to-cement ratio of 0.53 was used throughout this investigation. The outcome showed that the fiber fraction with 1.5% and 10cm of fiber had the maximum compressive strength which was 45.59 MPa, while for the fraction with 1% and 5cm of fiber, the maximum compressive strength was 43.85 MPa. The flexural strength had a maximum value of 5.88 MPa at 3% fiber content for 5cm fiber and 5.09 MPa at 3% for 10cm of fiber. The maximum tensile strength attained was 4.74 MPa and 3.50 MPa at 3% WRSF for 5cm and 10cm of fiber, respectively. The strain value had a maximum value at 3% for both 10cm and 5cm of fiber which were 0.53 and 0.6 respectively. The concrete strength which was obtained with the addition of steel fiber showed reasonable improvement in compressive, indirect tensile, and flexural strength. However, as the percentage of WRSF increased, the workability of concrete reduced.

Experimental Study on Flexural Performance of Precast Prestressed Concrete Beams with Fiber Reinforcement

Fiber-reinforced concrete (FRC) has good toughness and a gentle stress–strain softening section, which can improve the inherent defects of concrete material such as high brittleness, easy cracking, and poor fracture toughness. In this paper, carbon fiber, aramid fiber and mixed fiber are introduced to enhance the performance of precast prestressed concrete beams (PPCB). The effects of different fiber types and adding rate on mechanical properties of FRC were studied via axial compression test and four-point bending test. Based on the flexural performance test of precast FRC beams, the failure form and the improvement degree of flexural ability of the beams were analyzed. Moreover, the load–deflection curve and the quantified ductility index obtained by the test were discussed, and the law of the improvement effect of fiber type on flexural property was revealed. The results show that the optimal addition rate of fiber is 0.6%. In addition, the addition of fiber significantly increased the cracking load and ultimate bearing capacity of the test beam, whereby the average increase in cracking load and ultimate bearing capacity was 40% and 20%, respectively. At the same time, the ductility of the beam is obviously enhanced by the action of fibers, among which the hybrid fiber has the best effect. Specifically, the ductility coefficient analysis verifies that aramid fiber plays an important role in improving the ductility of the components.

Optimisation of polypropylene and steel fibres for the enhancement of mechanical properties of fibre-reinforced concrete

Optimisation of polypropylene and steel fibres for the enhancement of mechanical properties of fibre-reinforced concrete

REVIEW OF THE MECHANICAL PROPERTIES OF FIBER CONCRETE UNDER DANIAMIC TENSION AND COMPRESSION

This article is a review of the mechanical properties of fiber-reinforced concrete at high strain rates under tensile and compressive stresses. Fibre-reinforced concrete is widely used in the construction of protective structures, in tunnels, engineering structures in seismic areas, airport runways, river and marine engineering structures and is an important substitute for classic concrete. The review covers the following aspects: advantages and disadvantages of various test methods used to determine the dynamic properties of fiber-reinforced concrete; studies of the dynamic characteristics of fiber-reinforced concrete in compression and tension, including their strength, deformation capacity and ability to absorb energy. The purpose of this review is to expand fundamental knowledge about the dynamic properties of fiber-reinforced concrete and to promote further research on its physical and mechanical characteristics and applications for increasing the strength of brittle materials. At the beginning of the review, the most commonly used test setups and methods for dynamic testing are considered. The Kolsky method is most widely used to determine properties in dynamic compression, tension, and tensile splitting at high strain rates. Further, the main part of the review considers the mechanical properties of fiber-reinforced concrete under dynamic compression and tension, including strength, impact strength, and the ability to absorb energy. Studies have shown that with an increase in the rate of deformation, the dynamic strength of fiber-reinforced concrete increases. The use of an appropriate amount of fiber leads to a significant improvement in dynamic properties. However, there is a threshold fiber content. In conclusion, by summarizing and comparing previous studies, the advantages and disadvantages of existing studies are emphasized, and suggestions for further research are made.

Experimental investigation on the mechanical properties and pore structure deterioration of fiber-reinforced concrete in different freeze-thaw media

• The mechanical properties and pore structure deterioration of FRCs in five freeze-thaw media (i.e. WF, NF, SSF, SCF, HSF) were studied. • The influence of the SCF on the mechanical properties of FRCs is the greatest, followed by the HSF, SSF, WF and NF. • There is an optimal fiber dosage for the FRCs to resist freeze-thaw cycle and salt erosion. • The porosities and salt corrosion degree of the FRCs exposed on the freeze-thaw cycles significantly increased. More engineering infrastructures have been built in cold regions and even permafrost area with salt-rich media, such as seawater, saline soil or groundwater. In such environment, the concrete is not only destroyed by freeze-thaw processes, but also damaged by corrosion. Therefore, this study investigated the mechanical properties and pore structure deterioration of fiber-reinforced concrete (FRC) in five types freeze-thaw media, i.e., water (WF), natural air (NF), 5 % sodium sulfate solution (SSF), 5 % sodium chloride solution (SCF), a mixture of the 5 % sodium sulfate and 5 % sodium chloride solution (HSF). A total of 180 freeze-thaw cycles were carried out on steel fiber-reinforced concrete (SFRC), polypropylene fiber-reinforced concrete (PPFRC), and basalt fiber-reinforced concrete (BFRC). The compressive strength and elastic modulus of FRCs after freeze-thaw cycles were measured to observe the influence of different media and fibers on the mechanical properties. The deterioration of the pore structure of the FRCs was observed by SEM (scanning electron microscope), XRD (X-ray diffraction), and MIP (mercury intrusion porosimetry) tests. The results show that the influence of the SCF on the mechanical properties of concrete is the greatest, followed by HSF, SSF, WF and NF. Moreover, there is an optimal fiber dosage for the FRCs to resist freeze-thaw cycles and salt erosion, the optimal fiber dosages for the SFRC, PPFRC and BFRC were 2 %, 2 ‰ and 0.5 ‰, respectively. Additionally, compared to the concrete not exposed to freeze-thaw cycles in the NF, the porosities of the FRCs exposed to the freeze-thaw cycles significantly increased. Under the same freeze-thaw media, the porosity of the BFRC is larger than that of the PPFRC. Furthermore, for the FRCs in the SSF, the proportions of gel micro-pores (<10 nm) decreased with the number of freeze-thaw cycles, whereas the proportions of capillary pores (10–5000 nm) and macro-pores (>5000 nm) increased.

Flexural Strength Prediction of Steel Fiber-Reinforced Concrete Using Artificial Intelligence.

Research has focused on creating new methodologies such as supervised machine learning algorithms that can easily calculate the mechanical properties of fiber-reinforced concrete. This research aims to forecast the flexural strength (FS) of steel fiber-reinforced concrete (SFRC) using computational approaches essential for quick and cost-effective analysis. For this purpose, the SFRC flexural data were collected from literature reviews to create a database. Three ensembled models, i.e., Gradient Boosting (GB), Random Forest (RF), and Extreme Gradient Boosting (XGB) of machine learning techniques, were considered to predict the 28-day flexural strength of steel fiber-reinforced concrete. The efficiency of each method was assessed using the coefficient of determination (R2), statistical evaluation, and k-fold cross-validation. A sensitivity approach was also used to analyze the impact of factors on predicting results. The analysis showed that the GB and RF models performed well, and the XGB approach was in the acceptable range. Gradient Boosting showed the highest precision with an R2 of 0.96, compared to Random Forest (RF) and Extreme Gradient Boosting (XGB), which had R2 values of 0.94 and 0.86, respectively. Moreover, statistical and k-fold cross-validation studies confirmed that Gradient Boosting was the best performer, followed by Random Forest (RF), based on reduced error levels. The Extreme Gradient Boosting model performance was satisfactory. These ensemble machine learning algorithms can benefit the construction sector by providing fast and better analysis of material properties, especially for fiber-reinforced concrete.

Numerical Modeling and Diagnostic of FRC Slab under Centric and Eccentric Load

Abstract The solved area of research is the slab in interaction with the subsoil, where the goal is numerical modeling of the problem using a 3D computational model and nonlinear analysis. Specifically, the case of two experiments with a slab with centric and eccentric loading is solved. The performed experiments are used after for numerical modelling when a comprehensive set of laboratory tests of mechanical properties of fiber-reinforced concrete is also performed. Specifically, compressive strength, modulus of elasticity, splitting tensile test and bending tensile test were performed. The performed experiments are evaluated using 2D sections and 3D approximation surfaces, which are then used for load-displacement diagrams. Numerical modeling is based on nonlinear analysis and the use of the finite element method. The computational model use isoparametric finite elements. Based on the performed experiments and numerical modeling, the evaluation of the solved task is performed.

Mechanical Performance of Polymeric ARGF-Based Fly Ash-Concrete Composites: A Study for Eco-Friendly Circular Economy Application.

At present, low tensile mechanical properties and a high carbon footprint are considered the chief drawbacks of plain cement concrete (PCC). At the same time, the combination of supplementary cementitious material (SCM) and reinforcement of fiber filaments is an innovative and eco-friendly approach to overcome the tensile and environmental drawbacks of plain cement concrete (PCC). The combined and individual effect of fly ash (FA) and Alkali resistance glass fiber (ARGF) with several contents on the mechanical characteristics of M20 grade plain cement concrete was investigated in this study. A total of 20 concrete mix proportions were prepared with numerous contents of FA (i.e., 0, 10, 20, 30 and 40%) and ARGF (i.e., 0, 0.5, 1 and 1.5%). The curing of these concrete specimens was carried out for 7 and 28 days. For the analysis of concrete mechanical characteristics, the following flexural, split tensile, and compressive strength tests were applied to these casted specimens. The outcomes reveal that the mechanical properties increase with the addition of fibers and decrease at 30 and 40% replacement of cement with fly ash. Replacement of cement at higher percentages (i.e., 30 and 40) negatively affects the mechanical properties of concrete. On the other hand, the addition of fibers positively enhanced the flexural and tensile strength of concrete mixes with and without FA in contrast to compressive strength. In the end, it was concluded that the combined addition of these two materials enhances the strength and toughness of plain cement concrete, supportive of the application of an eco-friendly circular economy. The relationship among the mechanical properties of fiber-reinforced concrete was successfully generated at each percentage of fly ash. The R-square for general relationships varied from (0.48–0.90) to (0.68–0.96) for each percentage of FA fiber reinforced concrete. Additionally, the accumulation of fibers effectively boosts the mechanical properties of all concrete mixes.

Effects of Low Temperatures on Flexural Strength of Macro-Synthetic Fiber Reinforced Concrete: Experimental and Numerical Investigation

Fiber-reinforced concrete (FRC) is an attractive alternative to traditional steel bar-reinforced concrete structures, as evidenced by the constantly increasing market consumption of structural fibers for this purpose. In spite of significant research dedicated to FRC, less attention has been given to the effects of low temperatures on the mechanical properties of FRC, which can be critical for a variety of structural typologies and regions. With this in mind, an experimental program was carried out to assess the flexural behavior of macro-synthetic fiber-reinforced concrete (MSFRC) at different temperatures (from 20 °C to −30 °C) by means of three-point bending notched beam tests. The tested MSFRCs were produced by varying the content of polypropylene fibers (4 and 8 kg/m3). The results proved that the flexural strength capacity of all MSFRCs improved with decreasing temperature. Finite element analyses were then used to calibrate constitutive models following fib Model Code 2010 guidelines and to formulate empirical adjustments for taking into account the effects of low temperatures. The outcomes of this research are the basis for future experimental and numerical efforts meant to improve the design of MSFRCs subjected to low temperatures during service conditions.

РАСЧЕТ ФИБРОБЕТОННЫХ КОНСТРУКЦИЙ С УЧЕТОМ ФИЗЧЕСКОЙ НЕЛИНЕЙНОСТИ

The availability of information about the physical and mechanical properties of fiber-reinforced concrete allows to calculate structures based on it with a proper approximation to reality. The experimental data on the elastic modulus of the first and second kind, the Poisson's ratio, the tensile and compressive strength limits for characteristic fiber lengths and the percentage of reinforcement by weight are a condition for creating an algorithm for calculating such structures. This is facilitated by the transition from a linear elastic formulation of the problem to the consideration of physical nonlinearity. In the framework of software systems based on a finite element model of a deformable body, an iterative process is acceptable, due to the convergence of the solution. The proposed method of additional loads in the finite element interpretation leaves the accumulated experience of computer-aided design. The iterative calculation procedure contains cycles with a gradual approximation of the physical modules to their true value as a result of the convergence of the solution of the problem. The convergence criterion has an energy nature. The calculation of the modules is based on the dependencies of the mechanics of a deformable solid. This gives a fundamental character to the formulation of the problem. The effect of the proposed method is demonstrated by the example of calculating a buried cylindrical tank made of glass-fiber concrete for liquid. The addition of glass fibers to concrete leads to an improvement in the resistance to cracking and a decrease in the amount of crack opening.

Analysis of Fiber-Reinforced Concrete Slabs under Centric and Eccentric Load.

Research on the interaction between slabs and subsoil involves the field of materials engineering, concrete structures, and geotechnics. In the vast majority of cases, research focuses on only one of these areas, whereas for advanced study and computer simulations, detailed knowledge of the whole task is required. Among the new knowledge and information upon which this article focuses is the evaluation of subsoil stress using specialized pressure cells, along with detailed measurements of the deformation of a fiber-reinforced concrete slab. From a design point of view, this research is focused on the issue of the center of the cross section and the influence of eccentricity. Knowledge in this area is not yet comprehensively available for fiber-reinforced concrete slabs, where 2D deformation sections of the slab and 3D deformation surfaces of the slab are used in experiments. The experimental program includes a centrically and eccentrically loaded slab. These are structural elements that were tested on a specialized device. Both slabs had the same concrete recipe, with a dispersed reinforcement content of 25 kg/m3. The dimensions of the slab were 2000 × 2000 × 150 mm. Laboratory tests assessed compressive strength, the modulus of elasticity, splitting tensile strength, and bending tensile strength. Based on approximate data from the 3D deformation surfaces, an evaluation of the load-displacement diagrams for the center of the slab and for the center of eccentricity was performed. In conclusion, an overall evaluation and discussion of the results relies on experiments and the mechanical properties of fiber-reinforced concrete.

Reliability-based assessment of the partial factor for shear design of fibre reinforced concrete members without shear reinforcement

Fibre reinforced concrete (FRC) is increasingly used for structural purposes owing to its many benefits, especially in terms of improved overall sustainability of FRC structures relative to traditional reinforced concrete (RC). Such increased structural use of FRC requires safe and reliable models for its design in ultimate limit states (ULS). Particularly important are models for shear strength of FRC members without shear resistance due to the potential of brittle failure. The fib Model Code 2010 contains a model for the shear strength of FRC members without shear reinforcement and the same partial factor accepted for RC structures is accepted for FRC elements. This approach, however, is potentially on the unsafe side since the uncertainties of some design-determining mechanical properties of FRC (i.e., residual flexural strength) are larger than those for RC. Therefore, in this study, a comprehensive reliability-based calibration of the partial factor γc for the shear design of FRC members without shear reinforcement according to the fib Model Code 2010 model is performed. As a first step, the model error δ is assessed on 332 experimental results. Then, a parametric analysis of 700 cases is performed and a relationship between the target failure probability βR and γc is established. The results demonstrate that the current model together with the prescribed value of γc = 1.50 does not comply with the failure probabilities accepted for the different consequences of failure of FRC members over a 50-year service life. Therefore, changes to the shear resistance model are proposed in order to achieve the target failure probabilities.

Mechanical properties of fiber-reinforced concrete containing waste porcelain aggregates under elevated temperatures

Concrete has recently found increasing applications in structures exposed to high temperatures. It is, therefore, necessary from an engineering viewpoint to improve the mechanical properties of the concrete used in such structures. Concrete structures exposed to high temperatures are prone to serious damages due to the heat-induced physical and chemical changes in concrete that reduce its compressive, tensile, and flexural strengths as well as its modulus of elasticity. A remedy is to use refractory materials to increase the heat resistance of concrete. In this study, waste porcelain ceramic was used as aggregate material to achieve enhancements in concrete mechanical properties under high temperatures with the simultaneously additional advantage of abating environmental pollution. Additionally, polypropylene and steel fibers, as well as ordinary Portland and refractory cement, were used to cast 120 cylindrical specimens 100 mm × 200 mm in size to be exposed to temperatures of 400 and 800 °C in a laboratory furnace. The compressive and tensile strengths of the specimens were measured upon cooling, their weight losses were determined, and finally, crack assessment was performed using fractal dimension. All the specimens exhibited reduced compressive and tensile strengths with increasing temperature albeit at different rates depending on their ingredient materials such that higher strengths were recorded at 400 °C for specimens containing Portland cement and at 800 °C for those containing refractory cement. Application of steel fibers increased heat resistance and decreased strength drop by up to 20% and 30% at 400 and 800 °C, respectively. This is while the application of polypropylene (PP) fiber had no significant effects on such mechanical properties as compressive or tensile strength but it prevented concrete spalling.

Effects of Coarse Aggregate Maximum Size on Synthetic/Steel Fiber Reinforced Concrete Performance with Different Fiber Parameters

Recently, fiber has been incorporated into concrete mixtures, where its distribution in the concrete matrix helps to improve and enhance the mechanical properties of fiber-reinforced concrete (FRC). The aim of this study is to investigate the influence of steel and synthetic fiber parameters, along with different coarse aggregate maximum sizes (CAMZs) on FRC performance. Additionally, in past research, the empirical relationships among the compressive, tensile, and flexural strengths of plain concrete and FRC were assessed, and correlations between these mechanical properties of FRC were examined. For each CAMZ, four fiber dosages for each fiber type were considered. The results demonstrate the mechanical properties of FRC enhanced as the fiber length increased from 13 mm to 60 mm, the CAMZ increased from 9.5 mm to 37.5 mm, and the ratio of the fiber length to the CAMZ was in the range of 0.35–5.68. All mixtures have been intended to exhibit similar compressive strengths; however, the synthetic/steel fiber advanced the brittleness ratio of specimens with G10, G19, and G38 to approximately 36.8%, 40.7%, and 47.4% greater than the contral specimens, respectively. In addition, from the regression analysis investigation, there are strong correlations from the regression analysis of the mechanical property results of FRC.

Mechanical properties of fiber-reinforced concrete with adapted rheology

This paper aims to assess and enhance the prediction of mechanical properties of fiber-reinforced self-consolidating concrete (FR-SCC) and fiber-reinforced superworkable concrete (FR-SWC) that can be used for infrastructure construction and rehabilitation. The mechanical properties included compressive strength (f'cf), splitting tensile strength (f'spf), flexural strength (frf), and elastic modulus (Ecf) and their increase with curing time. A total of 69 FR-SCC and FR-SWC mixtures were used in this investigation that involved the consideration of test results of 1467 cylindrical and 106 prismatic specimens tested at 3–365 days of age. The mixture parameters included fiber type (five types), fiber volume (0.25%–0.75%), material characteristics, mixture proportioning, admixture type and combination, as well as consolidation energy in the case of FR-SWC, and curing. The measured mechanical properties were compared to values estimated from 35 different models that take into consideration the fiber characteristics.Test results indicate that the mean experimental-to-theoretical ratio (mean exp/theo) and corresponding coefficients of variation (COV) obtained with the original models that yielded the best prediction (one model for each mechanical property) were 0.98–1.06 and 11%–18%, respectively. The best original models were then modified and new proposed models were developed, leading to mean exp/theo values of 1.00–1.02 and COV values of 8%–11%.

Strength characteristics of fibre-reinforced concrete containing nano-silica

In this investigation, nanotechnology is employed as a way of improving the fresh and mechanical properties of fiber-reinforced concrete containing Poly Propylene (PP) and Nano-Silica (NS). Nano-silica was used as partial substitute of cement (0%, 2.5%, 5.0%, 7.5% and 10% by weight of cement) and polypropylene (PP) fibers as reinforcement from 0% to 0.75% in steps of 0.25. The fresh and hardened properties of concrete such as workability, density, compressive strength and tensile strength were tested. The investigation was done on plain concrete as control, fibre reinforced concrete (without nano-silica) and fibre-reinforced concrete containing nano-silica. Results showed that utilizing 5% nano-silica (by the weight of cementitious materials) improved the compressive strength by as much as 36%, but workability is significantly reduced. Test results also showed that fusing polypropylene strands in concrete improved the splitting tensile strength of the concrete considerably. In conclusion, nanotechnology and fibre reinforcement improves concrete performance in that the mechanical properties are significantly enhanced.