Polyolefin Fibers Research Articles

Use of Steel and Polyolefin Fibres in the La Canda Tunnels: Applying MIVES for Assessing Sustainability Evaluation

Construction involves the use of significant quantities of raw materials and entails high-energy consumption. For the sake of choosing the most appropriate solution that considers environmental and sustainable concepts, tools such as the integrated value model for sustainable assessment (Modelo Integrado de Valor para una Evaluación Sostenible, MIVES) used in Spain, plays a key role in obtaining the best solution. MIVES is a multi-criteria decision-making method based on the value function concept and the seminars delivered by experts. Such tools, in order to show how they may work, require application to case studies. In this paper, two concrete slabs manufactured with differing reinforcements during the construction of the La Canda Tunnels are compared by means of MIVES. The two concrete slabs were reinforced with a conventional steel-mesh and with polyolefin fibres. This research was focussed on the main aspects affecting the construction. That is to say, the environmental, economic, and social factors were assessed by the method, being of special impact the issues related with maintenance of the structure. The results showed that from the point of view of sustainability, the use of polyolefin fibres provided a significant advantage, mainly due to the lower maintenance required.

A study on the efficiency of steel vs. synthetic vs. hybrid fibers on fracture behavior of concrete in flexure using acoustic emission

Synergistic effect of different fibers on the improvement of fracture behavior of concrete is a widely accepted phenomenon. However, the fracture mechanisms behind their improvement need to be clearly understood for optimizing the fiber dosage. In this work, the fracture behavior of synthetic fiber-reinforced concrete (SynFRC), steel fiber reinforced concrete (SFRC) and hybrid fiber reinforced concrete (HFRC) under flexural loading is studied using acoustic emission (AE) technique. Three different fiber dosages, by volume of concrete, of 0.50%, 0.75% and 1.0% and their hybrid combinations were considered as study parameters. Test results show that it is possible to retain sufficient workability in the fresh state and obtain good fracture resistance through a hybrid combination of hooked end steel fibers and macro- synthetic polyolefin fibers. AE parameters were investigated to acknowledge the efficiency of the fibers in improving the fracture behavior and toughness of SynFRC, SFRC, and HFRC. AE parameters such as hits, events, AE energy, and 3D-crack source locations were presented to illustrate the role of different fiber dosages on the Mode-I fracture response. The source locations of AE event above the artificial notches created at the mid-span of specimens were investigated and classified into tensile or shear cracks. AE and fracture energy increased with fiber dosage. SFRC demonstrated higher energy dissipation capacity followed by HFRC and SynFRC.

Can Polyolefin Fibre Reinforced Concrete Improve the Sustainability of a Flyover Bridge?

The use of polyolefin fibre reinforced concrete (PFRC) as an alternative for reducing the reinforcing steel bars employed in reinforced concrete has become real in the past years. This contribution analyses the improvements in sustainability that a change in the aforementioned reinforcement configuration might provide in a flyover bridge. Economic, environmental and social parameters of both possibilities were studied by means of the integrated value model for sustainable assessment. Such model, which acronym is MIVES (Modelo Integrado de Valor para una Evaluación Sostenible, MIVES), is a multi-criteria decision-making method based on the value function concept and the seminars delivered by experts. The results of the MIVES method showed that the use of PFRC in combination with reinforced concrete (RC) has a sustainability index 22% higher. An analysis of the parameters that form this evaluation shows that there are no remarkable differences in the financial costs between the two possibilities studied. Nevertheless, social and environmental aspects provide with a better qualification the option of building a bridge by using PFRC combined with RC.

Effect of Hybrid Discrete Fibers on Mechanical Properties of FRC

Combining micro and macro fibers provide high performance of fiber reinforced concrete before and after concrete matrix cracks. Concretes including different volume content of hybrid discrete fibers were evaluated regarding compressive, elastic modulus, and tensile splitting strength. Eight cases include seven types of hybrid composites that were constructed using fiber combinations of PVA and Polyolefin fibers. Test results showed that the PVA, Polyolefin, hybrid fibers reduce the compressive strength properties of concrete, especially with high volume content (2%). On the other hand, hybrid fibers improve significantly the tensile strength of concrete that leads to change the concrete behavior from brittle materials to ductile.

Influence of polyolefin fibers on the strength and deformability properties of road pavement concrete

Abstract Influence of the type and quantity of polyolefin fibers on the strength properties (compression strength, tensile strength in bending, strength in uniaxial tension), the deformation properties (elastic modulus, Poisson's coefficient) and the abrasion resistance of cement concrete with water-to-cement ratio within 0.31–0.55 were stated in the paper. The ways of fibers introduction into fresh concrete were investigated. It was shown that the fibers introduction method and procedure of mixing are the ways to improve the fibers uniform distribution in fresh concrete. The increase of the bending tensile strength and the uniaxial tensile strength of concrete with fibers reinforcement in comparison with the reference concrete was observed with the water-to-cement ratio decrease. The increase of uniaxial tensile strength at age of 28 days for concrete with macrofibers in amount of 4.5 kg/m3 was 23% and 29%; for macrofibers in quantity of 3 kg/m3 was 19% and 26% with water-cement ratio equal to 0.49 and 0.31, respectively. The maximum reduction of abrasion in the range of 7.5%–10% was observed in concrete with water-to-cement ratio within 0.44–0.55 for all investigated types of fibers. The influence of fibers on the concrete abrasion with lower W/C ratio was negligible. The results can contribute to the rational use of modified polyolefin fibers in road pavement concrete.

Mechanical and flexural performance of synthetic fibre reinforced geopolymer concrete

A comprehensive experimental program was undertaken to analyse the structural and material characteristics of synthetic fibre reinforced geopolymer concrete. This study focused on the effect of monofilament and fibrillated polypropylene fibres and monofilament structural polyolefin fibres on mechanical and flexural performance of fly ash based geopolymer concrete. Five types of synthetic fibres at a 0.5% volume fraction were added to geopolymer concretes. The specimens’ compressive strength, indirect tensile strength, modulus of elasticity, modulus of rupture, flexural toughness and fracture energy were determined. Where possible, comparative analyses where conducted to assess the performance of fibre reinforced geopolymer concrete against conventional Portland cement based systems. The flexural toughness parameters were obtained using procedure laid down in ASTM C1018, JCI-SF4 and ASTM C1609. The results indicated that the macro polyolefin fibres exhibited the largest fracture energy which is likely due to high mechanical bonding and low fibre aspect ratio. Relationships are established to predict the compressive and tensile strengths, modulus of elasticity, compressive stress–strain curve and relation between the deflection and CMOD of synthetic fibre reinforced geopolymer concrete.

Diversified Production of Recycled Aggregate Concrete Mixture with the Addition of Single and Hybrid Fibers

The low strength property of recycled concrete aggregates (RCAs) limits its widespread application in the production of high-strength recycled aggregate concrete (RAC). In this study, RCA properties were improved prior to its incorporation into an RAC mixture through surface treatment. This mixture was subsequently diversified considering the benefits of adding various fiber-reinforced systems to enhance RAC performance. Two types of short discrete synthetic fibers, namely, polyolefin and polypropylene, were added in single and hybrid forms. This study aimed to investigate the effectiveness of the diversified modification of RAC mixture production on the mechanical strength of the resulting RAC. Various properties of the modified RAC were analyzed. Although the modified RAC mixture using treated RCA significantly enhanced the mechanical strength of this RAC, the diversification of the RAC mixture with additional polyolefin and polypropylene fibers, particularly in the hybrid form, further optimized the RAC performance.

DUCTILITY RESPONSE OF HYBRID FIBRE REINFORCED CONCRETE BEAMS

Abstract: The effect of fibre content on the Strength and ductility behaviour of hybrid fibre reinforced concrete (HFRC) beams having different fibre volume fractions was investigated. The parameters of this investigation included service load, ultimate load, service load deflection, ultimate load deflection, crack width, deflection ductility and energy ductility. The fibre volume fraction (Vf) ranged from 0.0 to 2.0 percent. Steel and polyolefin fibres were combined in different proportions and their impact on the above parameters was studied. The ductile response of hybrid fibre reinforced concrete beams was compared with that of control beam. The test results show that addition of 2.0 percent by volume of hybrid fibres improve the strength and ductility appreciably. Empirical expressions for predicting the strength and ductility of hybrid fibre reinforced concrete (HFRC) are proposed based on regression analysis. A close agreement has been obtained between the predicted and experimental results.

DUCTILITY RESPONSE OF HYBRID FIBRE REINFORCED CONCRETE BEAMS

Abstract: The effect of fibre content on the Strength and ductility behaviour of hybrid fibre reinforced concrete (HFRC) beams having different fibre volume fractions was investigated. The parameters of this investigation included service load, ultimate load, service load deflection, ultimate load deflection, crack width, deflection ductility and energy ductility. The fibre volume fraction (Vf) ranged from 0.0 to 2.0 percent. Steel and polyolefin fibres were combined in different proportions and their impact on the above parameters was studied. The ductile response of hybrid fibre reinforced concrete beams was compared with that of control beam. The test results show that addition of 2.0 percent by volume of hybrid fibres improve the strength and ductility appreciably. Empirical expressions for predicting the strength and ductility of hybrid fibre reinforced concrete (HFRC) are proposed based on regression analysis. A close agreement has been obtained between the predicted and experimental results.

Assessment of the shear behaviour of polyolefin fibre reinforced concrete and verification by means of digital image correlation

Given that remarkable structural applications of fibre reinforced concrete have been successfully developed in the last 60 years, modern concrete codes and fib Model Code have included requirements and formulations for considering the fibre contributions in structural design. In recent times, polyolefin fibre reinforced concrete (PFRC) has been shown as an attractive alternative to steel fibres, with it being chemically stable and having a lower dosage in terms of weight to reach similar residual strengths. It is worth noting that fibre contributions are attained from flexural tensile strengths tests. However, one of the major contributions provided by fibres in rebar substitutions has involved use in replacing shear stirrups. In such a sense, while the use of steel fibres has been shown as effective there is a lack of published literature with regard to PFRC. In this study, push-off tests in specimens obtained from the remaining halves after three-point bending tests have been performed. In addition to the mechanical results obtained, digital image correlation has allowed the cracking processes of the specimens to be identified. This paper offers a significant contribution to the field, given that it relies on the assessment of the shear contributions of polyolefin fibres and comparison with the requirements of the existing codes. Moreover, it supplies notable information about residual shear strengths and the cracking processes that take place.

Performance of Fiber-Reinforced Asphalt Concretes with Various Asphalt Binders in Thailand

AbstractThis research presents a laboratory investigation into the effects of polyolefin and aramid fibers as a reinforcement material in hot-mix asphalt (HMA) mixtures, with different asphalt bind...

Behavior of Concrete under the Addition of High Volume of Polyolefin Macro Fiber and Fly Ash

This paper deals with behavior of concrete’s compressive and bending strengths with the addition of high amount of polyolefin macro fibers. Polyolefin fiber is used to increase the bending strength and compressive strength, these experiments are done to investigate the cracking behavior and found the bending strength and compressive strength of polyolefin fiber reinforced concrete. Normally, concrete is mixed with various amount of fiber, but in this experiment five different specimens were prepared, S-1 is without fiber; S-2, homogeneous mixing of fiber volume of 10 kg/m3; S-3, homogeneous mixing of fiber volume of 25 kg/m3; S-4, homogeneous mixing of fiber volume of 35 kg/m3; and S-5, which contains 25 kg/m3 fiber mixed by hand in three different layers. A small amount of fly ash (18.18% of cement mass) is also mixed in the concrete specimens for better results. Concrete specimens were tested on 7th day and 28th day of the curing process. Water absorption capacity and compressive strength tests were done in the dry state and wet state to find the strength difference. More than 50% of flexural strength was gained on the 28th day of the destructive test. Post-cracking behavior was observed on the 28th day of the test, the specimens with fiber content were found to take load after cracking and hold more load to failure.

EFFECT OF HYBRID FIBER ON THE MECHANICAL PROPERTIES OF RECYCLED AGGREGATE CONCRETE

This study investigates the effect of inclusion of polyolefin and polypropylene fibers at various volume fractions in single and hybrid forms on the mechanical properties of recycled aggregate concrete (RAC) mix that consists of treated coarse recycled concrete aggregate (RCA). Testing parameters, such as compressive strength, flexural strength, static modulus of elasticity, and impact load resistance, are utilized to evaluate the mechanical strength of specimens. The various properties of the modified RAC are also analyzed and compared with those of normal concrete and unmodified RAC specimens. Findings indicate that the mechanical strength properties of RAC mixture using treated RCA were significantly enhanced by adding fibers. The overall optimized mechanical strength results could be obtained in RAC mixtures with fiber in hybrid form, where their compressive strength at long-term curing age, can be significantly improved by 7% upto 11% higher than normal concrete. In addition, RAC mix with hybrid fibers produced the highest flexural strength and impact load resistance by an increase of 5% and 175%, respectively as compared with the control concrete.

Efficiency of steel and macro-synthetic structural fibers on the flexure-shear behaviour of prestressed concrete beams

The efficiency of steel and structural synthetic fibers on the performance improvement of prestressed concrete (PSC) beams under combined flexure-shear is studied. Results of eleven PSC beams tested at a shear span (a) to depth (d) ratio of five are presented. Discrete steel and macro synthetic structural polyolefin fibers of varying dosages of 0.35%, 0.7% and 1.0% by volume of concrete were used. The effect of fiber addition on overall load – displacement, load- strain, and strain energy absorption capacity of PSC beams is analysed. Other parameters such as shear span to depth ratio (a/d), compressive strength of concrete, prestressing reinforcement ratio were kept constant. The test results portray that the addition of steel fibers stiffens the post cracking response, increases the strain energy absorption capacity more efficiently when compared to macro synthetic fibers (Polyolefin). The failure mode changed from less ductile flexure-shear to more ductile flexure dominant mode at 0.35% and 0.70% volumetric dosage of steel and synthetic fibers, respectively. The strain energy absorption capacity increased by more than 100% at 1.0% fiber addition for both steel and macro-synthetic fibers.

The mechanical and durability properties of concrete containing hybrid synthetic fibers

In this study, the fresh and hardened properties of concrete including hybridization of polyolefin (PO) and polypropylene (PP) fibers were investigated. The twelve mixtures consisting of different dosages of PO and PP fibers were considered. Mixtures consisted of PO fibers at the volume fractions of 0.5, 1 and 1.5% that some part of those replaced with PP fibers at volume fractions of 0.1% and 0.2%. The properties of mixtures were evaluated using slump and Inverted slump cone tests in fresh state, and using compressive, splitting, and flexural tests in hardened state. In addition, the durability properties were investigated using water absorption, electrical resistivity and chloride penetration tests. The reinforced concrete beams including fibers were made and tested under accelerated corrosion. The influence of fibers on structural performance of sound and corroded beams were assessed by four-point loading test.The results indicated that hybridization of PO with PP fibers can improve the compressive and splitting tensile strength of mixtures up to 7.5% and 23% compared to those of control mixture, respectively. However, the hybridization of these fibers did not show a positive effect on post-cracking behavior at the flexural test. From durability viewpoint, replacement of some part of PO fibers with PP fibers can control the negative effect of using PO macro fibers. However, at the high volume fraction of fibers, the hybridization of PO with PP fibers showed the negative effect. Based on an overall view of results, hybridization of PO and PP fibers at the volume fraction of 0.9% and 0.1%, respectively, can be recommended for practical usage. This combination of fibers decreased the corrosion of steel in RC beams and improved the key parameters of structural behavior such as yield and ultimate loading, and stiffness of beams.

Comparative flexural performance of compacted cement-fiber-sand

This research investigates the influence of seven different fiber types on the flexural performance of compacted cement-fiber-sand (CCFS) with four fiber fractions (0.5, 1, 1.5 and 2% by volume). The seven types of fibers are 12 mm polypropylene, 19 mm polypropylene, 40 mm polypropylene, 55 mm polypropylene, 33 mm steel, 50 mm steel and 58 mm polyolefin fibers. The overall CCFS performance was divided into seven sub design performance indicators: (1) peak strength; (2) peak strength ratio; (3) residual strength ratio; (4) ductility index; (5) toughness; (6) equivalent flexural strength ratio; and (7) maximum crack width. The interaction mechanism of the fiber/cement-sand interface was investigated by scanning electron microscopy. Finally, the effectiveness of each fiber type was compared and rated in terms of the overall performance. The results show that the 50 mm steel fiber provided the best overall sub performance, resulting in an excellent overall flexural performance; in comparison, the 12 mm polypropylene fiber exhibited very poor performance. However, the 19 mm polypropylene and 33 mm steel fiber specimens provided very good and good overall performances, respectively. The nature of the fiber surface and the fiber length affects the overall performance of CCFS. The surface of the steel fibers, compared to the other synthetic fiber types, is more hydrophilic and is more compacted in a cemented-sand matrix without separation of the interfacial zone, providing the best overall flexural performance.

EVALUACIÓN DE LA RESISTENCIA A CORTANTE DE HORMIGONES REFORZADOS CON FIBRAS DE POLIOLEFINA Y ACERO

Recent research and applications have shown that fibre reinforced concrete (FRC) is an attractive solution also for structural elements [1]. The addition of fibres improves the material response when subjected to bending and tensile stresses [2]. The objective of this study was to assess the shear behaviour of steel and polyolefin fibre reinforced concrete. The experimental campaign was conducted using push-off specimens obtained from the remaining halves of specimens previously tested in flexural tensile tests. Moreover, the tests were performed with a digital image correlation system (DIC) in order to associate the cracking processes with residual shear strengths during the test. The results showed that the higher fibre dosage the higher maximum shear strengths as well as residual shear load bearing capacity. Keywords: Fibre reinforced concrete, shear strength, push-off test, digital image correlation

Restrained Shrinkage Cracking of Fiber-Reinforced High-Strength Concrete

Concrete shrinkage and volume reduction happens due to the loss of moisture, which eventually results in cracks and more concrete deformation. In this study, the effect of polypropylene (PP), steel, glass, basalt, and polyolefin fibers on compressive and flexural strength, drying shrinkage, and cracking potential, using the ring test at early ages of high-strength concrete mixtures, was investigated. The restrained shrinkage test was performed on concrete ring specimens according to the ASTM C1581 standard. The crack width and age of restrained shrinkage cracking were the main parameters studied in this research. The results indicated that the addition of fiber increases the compressive strength by 16%, 20%, and 3% at the age of 3, 7, and 28 days, respectively, and increases the flexural toughness index up to 7.7 times. Steel and glass fibers had a better performance in flexural strength, but relatively poor action in the velocity reduction and cracking time of the restrained shrinkage. Additionally, cracks in all concrete ring specimens except for the polypropylene-containing mixture, was developed to a full depth crack. The mixture with polypropylene fiber indicated a reduction in crack width up to 62% and an increasing age cracking up to 84%.

Behaviour of hybrid fibre reinforced concrete beams strengthened with GFRP laminates

This study aims to investigate the flexural behaviour of glass fibre reinforced polymer (GFRP) laminated hybrid fibre reinforced concrete (HFRC) beams. The flexural and ductility performance of GFRP laminated HFRC beams having different proportions of polyolefin and steel fibres with 1.0% of total volume fraction were investigated. The parameters of this investigation included: load and deflection at first crack, yield, and ultimate stages, ductility and crack width. A total of seven beams of 150x250 mm in cross-section were tested in the laboratory over an effective span of 2800 mm. One reinforced concrete (RC) beam without any internal or external GFRP was taken as the reference beam. Of the remaining six beams, one beam was strengthened with GFRP, one beam with 100% steel fibres was strengthened with GFRP and four beams, each with different volume proportions of polyolefin and steel fibres (20:80, 30:70, 40:60, 50:50) were strengthened with GFRP. All the above beams were tested until failure. The experimental results show that a fibre volume proportion of 40:60 (polyolefin-steel) has significantly improved the overall performance of the tested beams.

Mechanical Properties of Polyolefin Fiber-Reinforced Light Weight Concrete

The utilization of polyolefin fibers in reinforced concrete can potentially enhance the properties of the concrete by changing the interfacial properties of the fiber-matrix interface. The objective of this research was to determine the mechanical properties of polyolefin fiber reinforced lightweight concrete (LWC). Compressive, flexural, and splitting tensile strengths of the sample were measured. Polyolefin fibers were added to the reinforced composite in variable amounts (0-2%). The lightweight concrete was designed to achieve compressive strength target of at least 30 MPa with a density value of 1800 kg/m 3 after 28 days of storage. The results showed that the highest compressive strength was obtained in LWC containing 1% fiber led to an increase of about 8%. However, a reduction in compressive strength was observed when the amount of fiber was increased. Moreover, increasing the amount of fiber presented a growth in rupture modulus as well as splitting tensile strength.