Fiber Concrete Research Articles

Effect of Recovered Fibers on the Behavior of Concrete in Tension

Abstract This study evaluates the performance of concrete under the effect of the addition of non-straight fibers recovered during the machining of steel parts and then studies the effect of the addition of corrugated fibers (chips) on their behavior in direct traction of the fiber concrete. In order to characterize the mechanical behavior and tearing of these fibers, three lengths of fibers were used (4 cm, 5 cm, and 6 cm); for each length we varied the percentage by volume (0.3%, 0.5%, 0.8%, 1%, and 1.2%). To make a comparative study, a second series of tests was carried out with control concrete (BT) without any fibers of the same composition. The results of the tests carried out indicate that the resistance and stiffness are significantly improved and that the fibers imparted significant ductility to the material compared to the control concrete. It was also observed that the percentage of fibers significantly influences the appearance of cracks. Moreover, with an increase in the percentage of fibers from 0.3% to 0.8%, the resistance increases, but beyond a content of 0.8%, the mechanical characteristics decrease.

ARCHITECTURAL DESIGN OF SOCIAL AND PROTECTED HOUSING FROM VOLUME BLOCKS

Purpose. Application of a systematic approach to the design of social and safe housing for the population in the form of residential buildings of rapid construction with constructive measures regarding the requirements of inclusivity. The project of a 9-story residential building using Speedstac modules with external insulation from KingSpan thermal insulation boards is proposed. Methodology. The possibility of developing design solutions for a residential building made of three-dimensional blocks with the use of insulation of facades with KingSpan slabs was considered. The advantages of block construction were analyzed and design solutions were developed for the facade, arrangement of the roof, entrances and constructive elevators in the building for people with limited physical abilities, protective premises made of steel fiber concrete. Findings. A 9-story, 54-apartment residential building is designed, which is made of three-dimensional blocks. The external walls were insulated with KingSpan plates. Originality. Application of a complex approach to the architectural design of social and safe housing. Practical value. On the example of a designed typical residential section, the following questions are considered: economical and quick-build mass housing construction in the form of buildings from volumetric blocks, energy efficiency issues are solved by the use of effective heat-insulating panels, for protection against artillery fire, the option of arranging premises made of monolithic reinforced concrete structural elements from steel fiber concrete, which has increased impact resistance characteristics, for people with physical disabilities and mobility restrictions, a solution is proposed in the form of a separate entrance to the residential section with the use of a ramp and a lift to the common corridor and elevator.

Sustainable Building Solutions: Recycled Glass Fibers in Concrete

Sustainable Building Solutions: Recycled Glass Fibers in Concrete

Fatigue Performance of Glass Reinforced Fibre Concrete in Bridge Deck Applications

Fatigue Performance of Glass Reinforced Fibre Concrete in Bridge Deck Applications

Mechanical Performance of Glass Reinforced Fibre Concrete with Different Fiber Contents

Mechanical Performance of Glass Reinforced Fibre Concrete with Different Fiber Contents

Evaluation of Crack Resistance in Glass Reinforced Fibre Concrete under Tensile Loading

Evaluation of Crack Resistance in Glass Reinforced Fibre Concrete under Tensile Loading

BEARING CAPACITY OF A BEAM DAMAGED DURING COMBAT ACTIONS STRENGTHENED WITH THE USE OF FIBER CONCRETE

The paper presents the results of a study of the load-bearing capacity of a beam damaged during hostilities, which was reinforced with steel-reinforced concrete. A beam with 20 percent damage in the compression zone is considered. Before concreting, a foam insert was installed in the area of the planned damage, the shape and dimensions of which corresponded to the planned damage. After the concrete was set to 70% grade strength, the liner was pulled out, and the resulting cavity was filled with a 2% mixture of fiber concrete. This is one of the beam strengthening options in a comprehensive damaged beam testing program, which involves the study of a series of beams with different types of damage, varying damage zone (tensile and compression) and its magnitude, geometry and method of strengthening. The authors developed a special stand for testing. The load-bearing capacity of the damaged beam reinforced with fiber concrete was 80.6 kN, or 89.5% of the load-bearing capacity of the intact beam. Cracking started at the 4th load stage, when the load value was 16.1 kN, or 20% of the bearing capacity of the damaged beam. At the same time, 10 cracks formed in the zone of pure bending, the opening width of which did not exceed half the price of the microscope division, which is 0.005 mm. At the next eight stages of loading (up to 48.4kN), no new cracks were observed, and the width of the opening of all the ones that had previously formed doubled - it reached 0.01mm. At the 12th, 13th and 19th stages of loading, 4 more cracks appeared. The maximum final crack opening width was 1.2 mm. Up to a load of 68.5kN, which is 85% of the load-bearing capacity of the damaged beam, the reinforced concrete liner works with the beam almost as a unit, and then the compressed zone of concrete squeezes out the liner. It is claimed that the strengthening of a beam with 20% damage in the compressed zone in the manner considered in the work allows to achieve its bearing capacity, which is almost 90% of the bearing capacity of an undamaged beam.

Enhancement of flexural behavior of hybrid flat slab by using SIFCON

Abstract Flat slab systems are widely utilized in construction due to their versatility and efficient use of space. Nevertheless, they are susceptible to flexural failure, particularly in the tension zone. To address this issue, slurry-infiltrated fiber concrete (SIFCON) has been proposed as a solution owing to its exceptional strength and durability. This research examines the effect of utilizing SIFCON in the tension zone of flat slab systems to enhance their flexural performance. The study encompasses testing eight identical slabs, two of which were cast with normal concrete, while the remaining six were hybrid slabs incorporating SIFCON. The specimens were subjected to vertical loading to compare their flexural behavior and identify the optimal dimensions for the SIFCON layer. The slabs had identical dimensions but varied in reinforcement. Group A had a reinforcement ratio of ρ = 0.5%, whereas Group B had a ratio of ρ = 0.335%. All slabs had a constant thickness of the SIFCON layer of 20 mm in the tension zone but varied in the dimensions of the SIFCON layer (100, 50, 30%) from the slab dimensions. A square plate with dimensions (140 × 140 × 20) mm supported the load for all slabs. The load was applied gradually until failure, and the load–deflection curves were recorded for each slab. The result showed that using SIFCON in the tension zone improved the flexural resistance of flat slab systems. The hybrid slabs with SIFCON demonstrated higher ultimate loads and lower deflections than the control slabs that used regular concrete. In particular, the hybrid slabs with a 100% SIFCON layer exhibited the best results, with a rise in ultimate load of 179 and 100% for Groups A and B, respectively, compared to the control slabs. In addition, there was a significant decrease in deflection of 62.35 and 52.38% for Groups A and B, respectively, relative to the control slabs. The study found that the optimal combination of the SIFCON dimension was when the 50% slab dimension was covered and the reinforcing bar area for the hybrid reinforcement system was smaller.

Experimental and Analytical Investigation of Fracture Characteristics of Steel Fiber-Reinforced Recycled Aggregate Concrete

AbstractFracture parameters of fiber concrete (FC) are currently a hot research area. Fracture mechanics is the field of solid mechanics that helps to study the type and propagation of cracks in materials. It uses methods of calculating the driving force on a crack and characterizes the material's resistance to fracture. Behavioral characteristics are determined by crack mouth opening displacement and the load–deflection method. This research identifies the fracture parameters of 33 notched simply supported beams made by recycled aggregate cement concrete with steel fiber. The recycled aggregate ratio in concrete has been altered to determine the effect on the mechanical and fracture properties. For determining fracture parameters, a 3-point bending single-edge notched fracture test was used. The results indicated that the steel fiber-reinforced concrete made with recycled aggregate showed similar performance and fracture characteristics compared to normal concrete. Thus, adding steel fibers to various concrete mixes considerably improved the fracture characteristics, while the brittleness was reduced with increased steel fiber content. Linear regression analysis also showed the accuracy of mechanical strength results as the value of R-square was close to unity. Displacement, ultimate load, brittleness (B), fracture toughness (KIC), crack mouth opening displacement (CMOD), fracture energy (GF), modulus of elasticity (E), and characteristic length (lch), were determined for both conventional and recycled aggregate specimens. The “work of fracture"—by definition the formula—is the most reliable to calculate the fracture energy as the nonlinearity is related to the performance of FC.

Effect of internal curing on shrinkage and cracking potential under autogenous and drying conditions

Autogenous shrinkage is a significant issue in ultra-high-performance concrete (UHPC). Internal curing has been effective in mitigating autogenous shrinkage, but its impact on drying shrinkage and crack-free concrete needs to be considered. This study investigates the controversial phenomenon of the effect of internal curing on shrinkage strains under drying conditions. A very specific steel fiber reinforced cementitious composite (Slurry infiltrated fiber concrete (SIFCON)) was examined to better understand the cumulative effects. Two additional internal curing water contents (36 kg/m3 and 60 kg/m3) and two superabsorbent polymers (SAP) with different particle sizes (D50: 215 µm and D50: 725 µm) were utilized. Shrinkage measurements were conducted on the SIFCON matrix for early (up to 7 days) and long-term (up to 90 days), under both autogenous and drying conditions. The SIFCON specimens were cured under autogenous and drying conditions for 90 days, then dried to simulate the field conditions, which was followed by crack mapping. The results indicate that SAP effectively mitigates shrinkage strains under both autogenous and drying conditions, attributed to its ability to reduce plastic shrinkage strains during the initial hours. However, crack mapping studies revealed increased cracked areas in specimens with SAP usage, higher internal curing water content, and larger SAP size. Additionally, specimens cured under autogenous conditions exhibited more cracks compared to those cured under drying conditions. This suggests that although shrinkage measurements demonstrate positive effects of internal curing in both conditions, the cumulative effect can vary.

Enhancing the dynamic splitting tensile performance of ultra-high performance concrete using waste tyre steel fibres

The application of waste fibres in ultra-high performance concrete (UHPC) would reduce the total material cost of UHPC, but it is still unclear whether industrial fibres can be replaced by waste tyre fibres in terms of the impact resistance. In the present work, a series of experiments were performed to figure out the influence of waste tyre steel fibre (WF) content (i.e., 1.0 %, 2.0 %, 3.0 % and 4.0 %) on the workability, compressive strength, elastic modulus, flexural strength and dynamic splitting performance of UHPC, in comparison with plain UHPC containing 2.0 % industrial straight steel fibre (IF). The results reveal that the slump of UHPC is reduced with the increasing WF fibre content, but the flexural and static splitting strengths of UHPC are improved by up to 31.0 % and 24.7 %, respectively, within the measured WF content. Moreover, the dynamic splitting strength and dissipation energy of UHPC are promoted when the WF content is lower than 3.0 %, while an opposite trend takes place as the content of WF reaches 4.0 %. Additionally, the dynamic increase factor of WF reinforced UHPC shows higher sensitivity to strain rate than UHPC containing 2.0 % IF throughout the strain rate range of 2.0 s−1–6.5 s−1. The optimal WF content of UHPC can be regarded as 3.0 % considering the overall static strengths, dynamic splitting behaviour, as well as economic and ecological impact.

Sustainability Enhancement through High-Dose Recycled Tire Steel Fibers in Concrete: Experimental Insights and Practical Applications

This study investigates the viability of incorporating high doses of recycled tire steel fibers (RSFs) in concrete to enhance sustainability. To address this, RSFs are incorporated at volume fractions ranging from 1% to 1.75% in the concrete mixture. The study evaluates various performance parameters, including workability, elastic modulus, compressive strength (CS), split tensile strength (SS), flexural strength (FS), linear shrinkage (LS), and water absorption (WA). Results show a 10% improvement in SS and a 4% improvement in FS compared to plain concrete (0RFRC). Additionally, RSF-reinforced concrete (RFRC) exhibits a maximum 15% reduction in LS. Water absorption slightly increases, and adverse effects on CS and workability are noted with high RSF doses. RFRC can impact the cost of rigid pavements due to reduced depth requirements. Disposing of discarded tires and their by-products has emerged as a substantial environmental challenge, obstructing progress toward achieving net-zero targets. As a sustainable solution, this study explores the potential utilization of secondary materials derived from discarded tires within the construction industry. In conclusion, this research highlights the significant potential of utilizing RSFs to enhance the sustainability of infrastructure and contribute to more eco-friendly construction practices.

Effect of steel fiber on the permeability of freeze-thaw damaged concrete under splitting tensile and compressive loads

This study investigated the effect of steel fibers on the permeability and mechanical properties of freeze-thaw damaged concrete under splitting tensile and compressive loads. A specially designed permeability apparatus is used to investigate the continuous permeability performance of steel fiber reinforced concrete (SFRC) subjected to loads. Results demonstrated that for the concrete without load, the addition of steel fibers exhibits a negative effect on the impermeability performance of the concrete matrix without freeze-thaw damage. The initial permeability of SFRC specimens is between 81.7 % and 180 % higher than that of NC specimens. The addition of steel fibers shows a positive effect on the impermeability of concrete subjected to freeze-thaw cycles. The permeability of SFRC under loads can be categorized into two stages. In the first stage, the concrete matrix is the main water channel. The addition of steel fiber can effectively increase the maximum radial deformation of the first stage and maintain low permeability of concrete in a large radial deformation range. In the second stage, concrete cracks are the main water channels. Both the addition of steel fibers and freeze-thaw cycles can reduce the permeability of the concrete in the second stage. Furthermore, under compressive load, with the increasing of stress level, the permeability of SFRC exhibits a slowly decreasing trend, this is followed by a significant increasing trend. The addition of steel fibers can maintain low permeability performance in a large stress level range, and as the steel fiber content increases, the permeability at peak load gradually decreases. The strain–permeability curves of SFRC under splitting tensile and compressive loads subjected to freeze-thaw cycles are investigated. The permeability of SFRC gradually increases with the increasing of the number of freeze-thaw cycles when the compressive strain exceeds 0.002. However, the opposite trend is observed under splitting tensile load. Notably, the reduction in concrete permeability due to the steel fibers is more significant under splitting tensile load than that under compressive load. Future work might integrate this research with stress-strain constitutive equations and finite element analysis. This will offer a foundational framework for engineering applications aimed at enhancing the permeability of steel fiber concrete under freeze-thaw conditions.

Comparative Study of Various Fibers in Concrete Subjected to Elevated Temperatures

In this paper fiber reinforced concrete is a two-phase material consisting of a matrix which is reinforced with randomly oriented small diameter fibers to improve the mechanical properties of the matrix. It increases the tensile strength of the concrete. Two types of fibers have been used in this paper i.e steel fiber and glass fiber. Steel fiber reinforced concrete is a homogeneous distribution of randomly oriented discontinuous and discrete steel fibers. It is available in the forms of Carbon steel or stainless steel. It has a high tensile and compressive strength. The Glass fibers are formed by drawing the molten material rapidly from a melted batch in a crucible or furnace. Glass fibers do not have a negative effect on the well-known high compressive strength of concrete. Thus, it shows that the fiber reinforced concrete is in good workable condition rather than without super plasticizer. The addition of 2% steel fiber and 0.5% -1% of glass fiber in concrete is found to be optimum as well as effective and economical as it gives good compression, tensile, and flexural strength for the concrete. Carbon fiber is composed of carbon atoms bonded together to form a long chain. The fibers are extremely stiff, strong, and light, and are used in many processes to create excellent building materials. Carbon fiber material comes in a variety of "raw" building-blocks, including yarns, uni-directional, weaves, braids, and several others, which are in turn used to create composite parts. The properties of a carbon fiber part are close to that of steel and the weight is close to that of plastic. Thus, the strength to weight of a carbon fiber part is much higher than either steel or plastic (Polyvinyl alcohol) (PVA) is well known as a synthetic biodegradable polymer and possesses excellent mechanical properties. PVA “displays strong interaction with carbon nanotubes” (CNTs), resulting in exceptional properties that are not found in another polymer

Long-term performance of concrete reinforced with scrap tire steel fibers in hybrid and non-hybrid forms: Experimental behavior and practical applications

This study examines the potential impact of scrap tire steel fibers (SSFs) on concrete properties, focusing on long-term performance. The reuse of discarded tires in construction addresses the environmental challenge of tire disposal. While previous research has explored SSFs in concrete, long-term properties and practical implementation pathways of SSF-reinforced concrete are lacking. To address these gaps, this study assesses the influence of locally available SSFs from Bratislava, Slovakia, on concrete properties, specifically targeting the 120-day hardened properties. Locally sourced C20/25 concrete is used, incorporating SSFs in non-hybrid (single type of fibers) and hybrid forms (30% industrial hook end steel fibers “ISF”). SSF dosages range from 0.3% to 1.75% for non-hybrid fibers and 0.50% to 0.70% for hybrid fibers. Experimental properties, including elastic modulus (EM), compressive strength (CS), tensile splitting strength (SS), flexure strength (FS), residual flexure strength (RFS), linear shrinkage (LS), and water absorption (WA), are evaluated. The toughness and energy absorption capacity are demonstrated for SS and FS. The results indicate that the inclusion of SSFs enhances the EM and SS of SSF-reinforced concrete (SSFRC). Additionally, SSFRC exhibits reduced linear shrinkage compared to concrete without SSFs. Notably, the hybrid fiber concrete (HSFRC) shows superior performance, outperforming both ISF concrete and SSFRC in enhancing the considered properties. HSFRC exhibits promising potential for replacing ISF concrete in various civil engineering applications. However, further investigation is needed to evaluate the performance of HSFRC under extreme environmental conditions.

Sustainable one-part alkali activated slag/fly ash Geo-SIFCOM containing recycled sands: Mechanical, flexural, durability and microstructural properties

Slurry Infiltrated Fiber Concrete or Composite (SIFCOM) is a unique form of steel-fiber-reinforced cement composite that possesses exceptional toughness and superior mechanical properties like compressive, shear, tensile, and flexural strengths. New supplies of fine aggregate are required since the construction industry is experiencing natural sand shortage. By thoroughly evaluating workability, mechanical properties, flexural toughness, durability and microstructure, this study demonstrates the potential of various recycled sands from different sources in the manufacture of sustainable slag/fly ash one-part alkali activated SIFCOM (Geo-SIFCOM). Recycled concrete, brick and ceramic sands were used as a substitute of 10, 25 and 50% by volume of silica sand. Steel fiber ratios of 5%, 10%, and 15% were used and exposed to heat curing for 6, 24 and 48 h at 80 °C. Taguchi method was used to investigate the optimum mixture. The results showed that 24 h heat-cured mixture containing 25% recycled concrete sand and 15% fiber (C25F15) had the largest compressive strengths of 68.49 MPa, 74.53 MPa and 80 MPa at 7, 28, and 91 days, respectively. All 6 h – cured mixtures containing 100% slag exhibited the best resistance to freeze-thaw and the mixtures heat cured for 6 h demonstrated the best compressive strength resistance to elevated temperature and F-T cycles regardless of FA content. The largest flexural toughness was also assessed for the mixture with 50% brick sand and 15% fiber (B50F15) heat-cured for 6 h. The mixture with 50% FA and 50%slag (50% ceramic sand and 15% fiber) exhibited the best high temperature resistance.

Durability and Accelerated Ageing of Natural Fibers in Concrete as a Sustainable Construction Material.

This paper presents an experimental study on the influence of alkaline environments on natural fibers of plant and mineral origin in concretes. The durability of concrete-based composite materials is influenced by the properties of the reinforcing fiber, and the serviceability of concrete is dependent on its durability. The aim of the present study is to investigate the strength, weight loss %, and surface degradation of jute, sugarcane, coconut, sisal, as well as basalt fibers through an accelerated aging method when used as reinforcements in concrete. The samples were immersed in an alkaline environment of sodium and calcium hydroxide at two different levels of pH for one week. Further, the fibers were immersed in NaOH and Ca(OH)2 solutions of 1 M, 2 M, 4 M, and 6 M concentrations for 48 h in order to investigate the gradual effect of an alkaline environment on the mechanical properties of the fiber. It was concluded that the weight loss % was greatest for jute fibers when used in concrete composite, while there was no significant effect on the basalt fiber samples. The strength of jute fiber in the concrete sample was also most severely affected by the aging process, compared to other fibers. The strength of basalt fibers in a concrete composite was least affected by the aging process. In some cases, the sisal fiber sample showed an increase in fiber tenacity after the aging process due to fibrillation, which might have increased the interfacial area. The fiber microstructure before and after the aging was evaluated through the use of scanning electron microscopy (SEM). SEM analyses of different fibers were carried out to investigate surface degradation. The fiber pull-out strength was found to be the greatest for basalt fiber, followed by jute and sisal. This is indicative of the excellent adhesion of such fibers with cement in a concrete composite. In these cases, the use of sisal fiber results in defibrillation and increased specific surface area. Sugarcane and coconut fibers ruptured due to their inherent weakness and provided only a small increment in the mechanical performance of the concrete. Basalt fiber-reinforced concrete offered the greatest compressive strength, followed by jute and sisal. These observations provide crucial information regarding the durability and aging of natural fiber-reinforced concrete.

Pore morphology based on graphene oxide modified steel fibre concrete for freeze–thaw resistance

The effect on frost resistance of the pore morphology and pore space distribution of graphene oxide-steel fiber reinforced concrete (GO-SFRC) has been researched systematically by X-ray computed tomography (X-CT) technology. As graphene oxide is added to steel fiber concrete, the pore morphology and spatial distribution will be altered. Combined with the strength loss and dynamic elastic modulus loss of GO-SFRC specimens after freeze–thaw cycles, the effect that graphene oxide shows significant effect on the frost resistance of steel fiber concrete through analyzed. The results demonstrate that GO-SFRC concrete has significantly better frost resistance than ordinary SFRC concrete based on the analysis of compressive strength loss and dynamic elastic modulus loss of the specimens. Experiments show that the porosity and pore distribution was different for the five GO-SFRCs and the pore sphericity was closely related to the content and dispersion of graphene oxide. Overall, the GO coordination regulates the relationship between porosity, sphericity, and pore size. In addition, the compressive strength of graphene oxide-steel fiber-reinforced concrete was also analyzed in terms of pore parameters, such as pore sphericity, flatness, and porosity.

Effect of recycled lime sludge, calcined clay and silica fume blended binder-based fibrous concrete with superior impact strength and fracture toughness

This study investigated the impact strength of fibrous concrete and its mode I, mode III, and mixed-mode I/III fracture toughness. Three binders were produced with varying compositions. The first binder was created by combining 95% clinker and 5% gypsum. The second binder consisted of 50% clinker, 30% calcined clay, 15% recycled lime sludge (RLS), and 5% gypsum. The third binder was composed of 50% clinker, 15% RLS, 30% silica fume, and 5% gypsum. There were three groups of binders used to classify the twelve different mixes. Each group comprises four different concrete mixtures: non-fibrous concrete, conventional fibrous concrete and two functionally graded fibrous concrete (FGFC) with three layers. Short-crimped steel fibres were utilized at an average dosage of 1.5% by volume. The fibre dosage of 2 and 2.25% was used in the top and bottom layers of FGFC and 0 and 0.5% were used in the middle. Besides, a microstructure study was performed to evaluate the strength development phases, utilizing X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis techniques. Findings reveal that the mixture comprising an RLS and calcined clay binder combination exhibited the best compressive and impact strength performance. Introducing a three-layered concrete specimen with higher fibre content at the outer layer exhibits exceptional impact resistance compared to traditional fibrous concrete. Besides, fracture toughness under mode III is more critical than mode I and I/III and an increase in the load angle results in a reduced rate of improvement in fracture toughness.

Implementation of two-stage mixing approach to improve the performance of fiber reinforced concrete for sustainable construction

Concrete has a significant impact on the environment, and the use of fibers in concrete is a way to mitigate its environmental impact. In this study, two-stage mixing approach (TSMA), typically utilized to enhance the quality of the interfacial transition zone (ITZ) of recycled aggregate concrete mixtures, was employed to enhance the performance fiber reinforced concrete (FRC) mixtures by improving the fiber–matrix ITZ. To investigate the effectiveness, FRC mixtures were prepared using standard (ordinary) and modified (TSMA) mixing approaches. Subsequently, their mechanical properties were measured, and microstructural analyses were conducted to examine fiber–matrix ITZ. In the end, a case study for a concrete pavement was carried out to examine the effect of improved performance on the cost and environmental impact of FRC. Based on the results, up to a 30.6% increase in FRC residual flexural strength ratio was obtained for modified mixing method, without considerable change in strength and stiffness. Microstructural analyses were found to support the ITZ improvement provided by the employed mixing methodology. Furthermore, material-related cost and environmental impact values were found to decrease up to 6% based on the case study conducted. As a result, the implementation of TSMA for FRC was found to be a promising technique to enhance FRC performance and suggestions were provided for the future studies to further improve the obtained benefits.