Fiber-reinforced neutron shielding mortar concrete

International Nuclear Information System (INIS)

Kaji, Keisuke; Okazaki, Masaki; Ohigashi, Toshihide; Mayahara, Mitsuro.

1989-01-01

To improve the moldability, durability and economicity by adding cement curing promotors and reinforcing fibers to cement and boron compound which has been considered difficult so far, thereby enabling to add a great amount of the boron compound. The boron compound is added by from 5 to 200% by weight of powder of colemanite or borocarcite as natural ores or boric acid, borax or titanium boride, etc. as synthesis products and lithium hydroxide. calcium aluminate, etc. is added by more than 0.1% x boron compound blending ration (%) as the curing promoter. 0.3 to 5% by weight of polyvinyl alcohol type synthetic fibers, polyacrilonitrile type synthetic fibers or carbon fibers, etc. are added as the reinforcing fibers. This can prevent instantaneous coagulation, curing delay, etc. due to sulfur ions, enable easy application and molding and improve the durability and economicity. (T.M.)

Effect of Addition of A Marble Dust on Drying Shrinkage Cracks of Cement Mortar Reinforced with Various Fibers

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Basim Thabit Al-Khafaji

2017-05-01

Full Text Available This investigation is conducted to study the effect of addition of marble powder (marble dust and different fibers on drying shrinkage cracks and some properties of fibers reinforcment cement mortar. Steel molds having a trapezoidal section, and the end restrained at square shape with( 2.7 meter at length are used to study restrained drying shrinkage of cement mortar. Specimens of ( compressive .flextural. splitting strength were cast. The admixture (marble dust was used to replacie weight of cement with three levels of (4%, 8% and 16% and the fiber hemp and sisal fiber were added for all mixes with proportion by volum of cement . All specimens were cured for (14 days. Average of three results was taken for any test of compressive, tensil and flextural strength. The experimental results showed that the adding of this admixture(marble dust cause adelay in a formation of cracks predicted from a drying shrinkage ,decreases of its width , and hence increases of (compressive, splitting tensil and flextural strength at levels of (4%, and 8%. Thus there is a the positive effect when fiberes added for all mixes of cement mortar with addition of (marble dust. All The admixtures (marble dust and fibers have the obvious visible effect in the delay of the information of shrinkage cracks and the decrease of its width as Compared to the cement mortar mixes when marble dust added a alone.

Mechanical Characterization of High-Performance Steel-Fiber Reinforced Cement Composites with Self-Healing Effect

Science.gov (United States)

Kim, Dong Joo; Kang, Seok Hee; Ahn, Tae-Ho

2014-01-01

The crack self-healing behavior of high-performance steel-fiber reinforced cement composites (HPSFRCs) was investigated. High-strength deformed steel fibers were employed in a high strength mortar with very fine silica sand to decreasing the crack width by generating higher interfacial bond strength. The width of micro-cracks, strongly affected by the type of fiber and sand, clearly produced the effects on the self-healing behavior. The use of fine silica sand in HPSFRCs with high strength deformed steel fibers successfully led to rapid healing owing to very fine cracks with width less than 20 μm. The use of very fine silica sand instead of normal sand produced 17%–19% higher tensile strength and 51%–58% smaller width of micro-cracks. PMID:28788471

Pullout behavior of steel fibers from cement-based composites

DEFF Research Database (Denmark)

Shannag, M. Jamal; Brincker, Rune; Hansen, Will

1997-01-01

A comprehensive experimental program on pullout tests of steel fibers from cement based matrices is described. A specially designed single fiber pullout apparatus was used to provide a quantitative determination of interfacial properties that are relevant to toughening brittle materials through...... fiber reinforcement. The parameters investigated included a specially designed high strength cement based matrix called Densified Small Particles system (DSP), a conventional mortar matrix, fiber embeddment length, and the fiber volume fraction. The mediums from which the fiber was pulled included...... fraction in the cement matrix increase the peak pullout load and the pullout work. (3) The major bond mechanism in both systems is frictional sliding. ...

Reinforcement of cement-based matrices with graphite nanomaterials

Science.gov (United States)

Sadiq, Muhammad Maqbool

Cement-based materials offer a desirable balance of compressive strength, moisture resistance, durability, economy and energy-efficiency; their tensile strength, fracture energy and durability in aggressive environments, however, could benefit from further improvements. An option for realizing some of these improvements involves introduction of discrete fibers into concrete. When compared with today's micro-scale (steel, polypropylene, glass, etc.) fibers, graphite nanomaterials (carbon nanotube, nanofiber and graphite nanoplatelet) offer superior geometric, mechanical and physical characteristics. Graphite nanomaterials would realize their reinforcement potential as far as they are thoroughly dispersed within cement-based matrices, and effectively bond to cement hydrates. The research reported herein developed non-covalent and covalent surface modification techniques to improve the dispersion and interfacial interactions of graphite nanomaterials in cement-based matrices with a dense and well graded micro-structure. The most successful approach involved polymer wrapping of nanomaterials for increasing the density of hydrophilic groups on the nanomaterial surface without causing any damage to the their structure. The nanomaterials were characterized using various spectrometry techniques, and SEM (Scanning Electron Microscopy). The graphite nanomaterials were dispersed via selected sonication procedures in the mixing water of the cement-based matrix; conventional mixing and sample preparation techniques were then employed to prepare the cement-based nanocomposite samples, which were subjected to steam curing. Comprehensive engineering and durability characteristics of cement-based nanocomposites were determined and their chemical composition, microstructure and failure mechanisms were also assessed through various spectrometry, thermogravimetry, electron microscopy and elemental analyses. Both functionalized and non-functionalized nanomaterials as well as different

Microhardness of dual-polymerizing resin cements and foundation composite resins for luting fiber-reinforced posts.

Science.gov (United States)

Yoshida, Keiichi; Meng, Xiangfeng

2014-06-01

The optimal luting material for fiber-reinforced posts to ensure the longevity of foundation restorations remains undetermined. The purpose of this study was to evaluate the suitability of 3 dual-polymerizing resin cements and 2 dual-polymerizing foundation composite resins for luting fiber-reinforced posts by assessing their Knoop hardness number. Five specimens of dual-polymerizing resin cements (SA Cement Automix, G-Cem LincAce, and Panavia F2.0) and 5 specimens of dual-polymerizing foundation composite resins (Clearfil DC Core Plus and Unifil Core EM) were polymerized from the top by irradiation for 40 seconds. Knoop hardness numbers were measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours and 7 days after irradiation. Data were statistically analyzed by repeated measures ANOVA, 1-way ANOVA, and the Tukey compromise post hoc test (α=.05). At both times after irradiation, the 5 resins materials showed the highest Knoop hardness numbers at the 0.5-mm depth. At 7 days after irradiation, the Knoop hardness numbers of the resin materials did not differ significantly between the 8.0-mm and 10.0-mm depths (P>.05). For all materials, the Knoop hardness numbers at 7 days after irradiation were significantly higher than those at 0.5 hours after irradiation at all depths (Presin materials were found to decrease in the following order: DC Core Plus, Unifil Core EM, Panavia F2.0, SA Cement Automix, and G-Cem LincAce (Pcomposite resins were higher than those of the 3 dual-polymerizing resin cements, notable differences were seen among the 5 materials at all depths and at both times after irradiation. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Collaboration of polymer composite reinforcement and cement concrete

Science.gov (United States)

Khozin, V. G.; Gizdatullin, A. R.

2018-04-01

The results of experimental study of bond strength of cement concrete of different types with fiber reinforcing polymer (FRP) bars are reported. The reinforcing bars were manufactured of glass fibers and had a rebar with different types of the surface relief formed by winding a thin strip impregnated with a binder or by “sanding”. The pullout tests were carried out simultaneously for the steel reinforcing ribbed bars A400. The impact of friction, adhesion and mechanical bond on the strength of bonds between FRP and concrete was studied. The influence of the concrete strength and different operation factors on the bond strength of concrete was evaluated.

Assessment of Tensile Bond Strength of Fiber-Reinforced Composite Resin to Enamel Using Two Types of Resin Cements and Three Surface Treatment Methods

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Tahereh Ghaffari

2015-10-01

Full Text Available Background: Resin-bonded bridgework with a metal framework is one of the most conservative ways to replace a tooth with intact abutments. Visibility of metal substructure and debonding are the complications of these bridgeworks. Today, with the introduction of fiber-reinforced composite resins, it is possible to overcome these complications. The aim of this study was to evaluate the bond strength of fiber-reinforced composite resin materials (FRC to enamel. Methods: Seventy-two labial cross-sections were prepared from intact extracted teeth. Seventy-two rectangular samples of cured Vectris were prepared and their thickness was increased by adding Targis. The samples were divided into 3 groups for three different surface treatments: sandblasting, etching with 9% hydrofluoric acid, and roughening with a round tapered diamond bur. Each group was then divided into two subgroups for bonding to etched enamel by Enforce and Variolink II resin cements. Instron universal testing machine was used to apply a tensile force. The fracture force was recorded and the mode of failure was identified under a reflective microscope. Results: There were no significant differences in bond strength between the three surface treatment groups (P=0.53. The mean bond strength of Variolink II cement was greater than that of Enforce (P=0.04. There was no relationship between the failure modes (cohesive and adhesive and the two cement types. There was some association between surface treatment and failure mode. There were adhesive failures in sandblasted and diamond-roughened groups and the cohesive failure was dominant in the etched group. Conclusion: It is recommended that restorations made of fiber-reinforced composite resin be cemented with VariolinkII and surface-treated by hydrofluoric acid.   Keywords: Tensile bond strength; surface treatment methods; fiber-reinforced composite resin

Use of hyghly reactive rice husk ash in the production of cement matrix reinforced with Green coconut fiber

OpenAIRE

Pereira, C.L.; Savastano, H. Jr; Paya Bernabeu, Jorge Juan; Santos, S. F.; Borrachero Rosado, María Victoria; Monzó Balbuena, José Mª; Soriano Martinez, Lourdes

2013-01-01

This study evaluated the influence of partial replacement of Portland cement by rice husk ash (RHA) to enable the use of green coconut husk fiber as reinforcement for cementitious matrix. The use of highly reactive pozzolanic ash contributes for decreasing the alkaline attack on the vegetable fiber, originated from waste materials. The slurry dewatering technique was used for dispersion of the raw materials in aqueous solution, followed by vacuum drainage of water and pressing for the product...

Calcium phosphate cement scaffolds with PLGA fibers.

Science.gov (United States)

Vasconcellos, Letícia Araújo; dos Santos, Luís Alberto

2013-04-01

The use of calcium phosphate-based biomaterials has revolutionized current orthopedics and dentistry in repairing damaged parts of the skeletal system. Among those biomaterials, the cement made of hydraulic grip calcium phosphate has attracted great interest due to its biocompatibility and hardening "in situ". However, these cements have low mechanical strength compared with the bones of the human body. In the present work, we have studied the attainment of calcium phosphate cement powders and their addition to poly (co-glycolide) (PLGA) fibers to increase mechanical properties of those cements. We have used a new method that obtains fibers by dripping different reagents. PLGA fibers were frozen after lyophilized. With this new method, which was patented, it was possible to obtain fibers and reinforcing matrix which furthered the increase of mechanical properties, thus allowing the attainment of more resistant materials. The obtained materials were used in the construction of composites and scaffolds for tissue growth, keeping a higher mechanical integrity. Copyright © 2012 Elsevier B.V. All rights reserved.

Advance study of fiber-reinforced self-compacting concrete

International Nuclear Information System (INIS)

Mironova, M.; Ivanova, M.; Naidenov, V.; Georgiev, I.; Stary, J.

2015-01-01

Incorporation in concrete composition of steel macro- and micro – fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural and material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete

Advance study of fiber-reinforced self-compacting concrete

Science.gov (United States)

Mironova, M.; Ivanova, M.; Naidenov, V.; Georgiev, I.; Stary, J.

2015-10-01

Incorporation in concrete composition of steel macro- and micro - fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural and material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete.

Advance study of fiber-reinforced self-compacting concrete

Energy Technology Data Exchange (ETDEWEB)

Mironova, M., E-mail: mirona@imbm.bas.bg; Ivanova, M., E-mail: magdalena.ivanova@imbm.bas.bg; Naidenov, V., E-mail: valna53@mail.bg [Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 4, Sofia 1113 (Bulgaria); Georgiev, I., E-mail: ivan.georgiev@parallel.bas.bg [Institute of Information and Communication Technologies & Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Acad. G. Bonchev str., Sofia 1113 (Bulgaria); Stary, J., E-mail: stary@ugn.cas.cz [Institute of Geonics Czech Academy of Sciences, Studentska str., Ostrava 1768 (Czech Republic)

2015-10-28

Incorporation in concrete composition of steel macro- and micro – fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural and material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete.

Hysteretic evaluation of seismic performance of normal and fiber reinforced concrete shear walls

International Nuclear Information System (INIS)

Choun, Young Sun; Hahm, Dae Gi

2012-01-01

The use of fibers in concrete or cement composites can enhance the performance of structural elements. Fibers have been used for a cement mixture to increase the toughness and tensile strength, and to improve the cracking and deformation characteristics. The addition of fibers into concrete can improve the ductility and increase the seismic resistance of concrete structures. The application of fibers to earthquake-resistant concrete structures has a major research topic. A recent study shows that an excellent seismic performance can be obtained in shear critical members constructed with high performance fiber reinforced cement composites. To increase the seismic performance of safety related concrete structures in nuclear power plants, fibers can be used. This study investigated the effect of fibers on the hysteretic behavior of a reinforced concrete (RC) shear wall by cyclic tests

Hysteretic evaluation of seismic performance of normal and fiber reinforced concrete shear walls

Energy Technology Data Exchange (ETDEWEB)

Choun, Young Sun; Hahm, Dae Gi [KAERI, Daejeon (Korea, Republic of)

2012-10-15

The use of fibers in concrete or cement composites can enhance the performance of structural elements. Fibers have been used for a cement mixture to increase the toughness and tensile strength, and to improve the cracking and deformation characteristics. The addition of fibers into concrete can improve the ductility and increase the seismic resistance of concrete structures. The application of fibers to earthquake-resistant concrete structures has a major research topic. A recent study shows that an excellent seismic performance can be obtained in shear critical members constructed with high performance fiber reinforced cement composites. To increase the seismic performance of safety related concrete structures in nuclear power plants, fibers can be used. This study investigated the effect of fibers on the hysteretic behavior of a reinforced concrete (RC) shear wall by cyclic tests.

Influence of cellulose fibers on structure and properties of fiber reinforced foam concrete

Directory of Open Access Journals (Sweden)

Fedorov Valeriy

2018-01-01

Full Text Available One of the promising means of foamed concrete quality improvement is micro-reinforcement by adding synthetic and mineral fibers to the base mix. This research is the first to investigate peculiarities of using recycled cellulose fiber extracted from waste paper for obtaining fiber reinforced foam concrete. The paper presents results of experimental research on the influence of cellulose fibers on structure and properties of fiber reinforced foam concrete by using methods of chemical analysis and scanning electron microscopy. The research determines peculiarities of new formations appearance and densification of binder hydration products in the contact zone between fiber and cement matrix, which boost mechanical strength of fiber reinforced foam concrete. Physico-mechanical properties of fiber reinforced foam concrete were defined depending on the amount of recycled cellulose fiber added to the base mix. It was found that the use of recycled cellulose fibers allows obtaining structural thermal insulating fiber reinforced foam concretes of non-autoclaved hardening of brand D600 with regard to mean density with the following improved properties: compressive strength increased by 35% compared to basic samples, higher stability of foamed concrete mix and decreased shrinkage deformation.

Increased corrosion resistance of basalt reinforced cement compositions with nanosilica

OpenAIRE

URKHANOVA Larisa Alekseevna; LKHASARANOV Solbon Aleksandrovich; ROZINA Victoria Yevgenievna; BUYANTUEV Sergey Lubsanovich; BARDAKHANOV Sergey Prokopievich

2014-01-01

Disperse fiber reinforcement is used to improve deformation and shrinkage characteristics, flexural strength of concrete. Basalt roving and thin staple fiber are often used as mineral fibers. The paper considers the problems of using thin basalt fiber produced by centrifugal-blow method. Evaluation of the corrosion resistance of basalt fiber as part of the cement matrix was performed. Nanodispersed silica produced by electron beam accelerator was used to increase corrosion resistance of ba...

Increased corrosion resistance of basalt reinforced cement compositions with nanosilica

Directory of Open Access Journals (Sweden)

URKHANOVA Larisa Alekseevna

2014-08-01

Full Text Available Disperse fiber reinforcement is used to improve deformation and shrinkage characteristics, flexural strength of concrete. Basalt roving and thin staple fiber are often used as mineral fibers. The paper considers the problems of using thin basalt fiber produced by centrifugal-blow method. Evaluation of the corrosion resistance of basalt fiber as part of the cement matrix was performed. Nanodispersed silica produced by electron beam accelerator was used to increase corrosion resistance of basalt fiber.

Surface treatment of reinforced cement concrete mixtures of hpcm type

OpenAIRE

Vyrozhemsky, V.; Krayushkina, K.

2006-01-01

One of the most perspective ways of pavement roughness and durability improvement is the arrangement of thin cement concrete layer surface treatment reinforced with different types of fiber. The name of this material is known abroad as HPCM (High Performance Cementious Materials) durable thin layer concrete pavement in a thickness of 1 cm, dispersion-like reinforced with metal or polymer fibers. To enhance bind properties the stone material grade 3 7mm is applied on the top of concrete surfac...

Stability of reinforced cemented backfills

International Nuclear Information System (INIS)

Mitchell, R.J.; Stone, D.M.

1987-01-01

Mining with backfill has been the subject of several international meetings in recent years and a considerable research effort is being applied to improve both mining economics and ore recovery by using backfill for ground support. Classified mill tailings sands are the most commonly used backfill material but these fine sands must be stabilized before full ore pillar recovery can be achieved. Normal portland cement is generally used for stabilization but the high cost of cement prohibits high cement usage. This paper considers the use of reinforcements in cemented fill to reduce the cement usage. It is concluded that strong cemented layers at typical spacings of about 3 meters in a low cement content bulk fill can reinforce the fill and reduce the overall cement usage. Fibre reinforcements introduced into strong layers or into bulk fills are also known to be effective in reducing cement usage. Some development work is needed to produce the ideal type of anchored fibre in order to realize economic gains from fibre-reinforced fills

Microwave detection of delaminations between fiber reinforced polymer (FRP) composite and hardened cement paste

Science.gov (United States)

Hughes, D.; Kazemi, M.; Marler, K.; Zoughi, R.; Myers, J.; Nanni, A.

2002-05-01

Fiber reinforced polymer (FRP) composites are increasingly being used for the rehabilitation of concrete structures. Detection and characterization of delaminations between an FRP composite and a concrete surface are of paramount importance. Consequently, the development of a one sided, non-contact, real time and rapid nondestructive testing (NDT) technique for this purpose is of great interest. Near-field microwave NDT techniques, using open-ended rectangular waveguide probes, have shown great potential for detecting delaminations in layered composite structures such as these. The results of some theoretical and experimental investigations on a specially prepared cement paste specimen are presented here.

Interfacial fracture of dentin adhesively bonded to quartz-fiber reinforced composite

International Nuclear Information System (INIS)

Melo, Renata M.; Rahbar, Nima; Soboyejo, Wole

2011-01-01

The paper presents the results of an experimental study of interfacial failure in a multilayered structure consisting of a dentin/resin cement/quartz-fiber reinforced composite (FRC). Slices of dentin close to the pulp chamber were sandwiched by two half-circle discs made of a quartz-fiber reinforced composite, bonded with bonding agent (All-bond 2, BISCO, Schaumburg) and resin cement (Duo-link, BISCO, Schaumburg) to make Brazil-nut sandwich specimens for interfacial toughness testing. Interfacial fracture toughness (strain energy release rate, G) was measured as a function of mode mixity by changing loading angles from 0 deg. to 15 deg. The interfacial fracture surfaces were then examined using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) to determine the failure modes when loading angles changed. A computational model was also developed to calculate the driving forces, stress intensity factors and mode mixities. Interfacial toughness increased from ∼ 1.5 to 3.2 J/m 2 when the loading angle increases from ∼ 0 to 15 deg. The hybridized dentin/cement interface appeared to be tougher than the resin cement/quartz-fiber reinforced epoxy. The Brazil-nut sandwich specimen was a suitable method to investigate the mechanical integrity of dentin/cement/FRC interfaces.

Thermal performance of sisal fiber-cement roofing tiles for rural constructions

OpenAIRE

Tonoli,Gustavo Henrique Denzin; Santos,Sérgio Francisco dos; Rabi,José Antonio; Santos,Wilson Nunes dos; Savastano Junior,Holmer

2011-01-01

Roofing provides the main protection against direct solar radiation in animal housing. Appropriate thermal properties of roofing materials tend to improve the thermal comfort in the inner ambient. Nonasbestos fiber-cement roofing components reinforced with cellulose pulp from sisal (Agave sisalana) were produced by slurry and dewatering techniques, with an optional addition of polypropylene fibers. Nonasbestos tiles were evaluated and compared with commercially available asbestos-cement sheet...

Improved Sectional Image Analysis Technique for Evaluating Fiber Orientations in Fiber-Reinforced Cement-Based Materials.

Science.gov (United States)

Lee, Bang Yeon; Kang, Su-Tae; Yun, Hae-Bum; Kim, Yun Yong

2016-01-12

The distribution of fiber orientation is an important factor in determining the mechanical properties of fiber-reinforced concrete. This study proposes a new image analysis technique for improving the evaluation accuracy of fiber orientation distribution in the sectional image of fiber-reinforced concrete. A series of tests on the accuracy of fiber detection and the estimation performance of fiber orientation was performed on artificial fiber images to assess the validity of the proposed technique. The validation test results showed that the proposed technique estimates the distribution of fiber orientation more accurately than the direct measurement of fiber orientation by image analysis.

Degradation of recycled PET fibers in Portland cement-based materials

International Nuclear Information System (INIS)

Silva, D.A.; Betioli, A.M.; Gleize, P.J.P.; Roman, H.R.; Gomez, L.A.; Ribeiro, J.L.D.

2005-01-01

In order to investigate the durability of recycled PET fibers embedded in cement-based materials, fiber-reinforced mortar specimens were tested until 164 days after mixing. Compressive, tensile, and flexural strengths, elasticity modulus, and toughness of the specimens were determined. The mortars were also analyzed by SEM. The results have shown that PET fibers have no significant influence on mortars strengths and elasticity modulus. However, the toughness indexes I 5 , I 10 , and I 20 decreased with time due to the degradation of PET fibers by alkaline hydrolysis when embedded in the cement matrix. Fourier transform infrared spectroscopy (FT-IR) and SEM analysis of PET fibers immersed and kept for 150 days in alkaline solutions supported the conclusions

Analysis of the mechanical resistance and porosity of a composite cement with EVA and reinforced with piacava fibers

International Nuclear Information System (INIS)

Silva, R.M.; Dominguez, D.S.; Alvim, R.C.; Iglesias, S.M.

2013-01-01

Nowadays, a lot of solid waste material is discarded into the environment. One of these residues is the EVA (Ethyl Vinyl Acetate) which has the footwear industry, as its main consumer. Studies are focused on the reusing of these materials, particularly in the civil construction, where is used as an aggregate in the production of light mortars. Due to the specific characteristics of lightweight concrete, is necessary to reinforce these materials. The palm Attalea Funifera Martius, known as piacava, may be an excellent alternative as a reinforcement element in light cement mixes. In this work, it's verified the mechanical strength of a composite lightweight cementitious with EVA and reinforced with Piacava fibers, also, the porosity of the new material was measured. To evaluate the mechanical properties of this new material was made mechanical tests and verified the importance of vegetal fibers as the material reinforcing. For the compound porosity evaluation, samples were studied using microcomputer tomography (μTC). With images processing techniques we identify and quantify the pores. The processing digital images through μTC showed up as a non-destructive method for efficient and acceptable results. (author)

NANOFIBRILLATED CELLULOSE (NFC AS A POTENTIAL REINFORCEMENT FOR HIGH PERFORMANCE CEMENT MORTAR COMPOSITES

Directory of Open Access Journals (Sweden)

Mònica Ardanuy,

2012-07-01

Full Text Available In this work, nanofibrillated cellulose (NFC has been evaluated as a potential reinforcement for cement mortar composites. Two types of vegetable fibres with different composition and properties (cellulose content and microfibrillar angle, sisal, and cotton linters pulps, were initially characterised in order to assess their reinforcing capability. Sisal pulp was found to be most suitable as reinforcement for the brittle cementitious matrix. Nanofibrillated cellulose was produced by the application of a high intensity refining process of the sisal pulp. It was found that 6 hours of refining time was required to obtain the desired nanofibrillation of the fibers. Cement mortar composites reinforced with both the sisal fibres and the nanofibrillated cellulose were prepared, and the mechanical properties were determined under flexural tests. The cement mortar composites reinforced with the nanofibrillated cellulose exhibited enhanced flexural properties, but lower values of fracture energy, than the ones reinforced with the conventional sisal fibres.

Non-conventional cement-based composites reinforced with vegetable fibers: A review of strategies to improve durability

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Santos, S. F.

2015-03-01

Full Text Available The present review shows the state-of-art on the approachs about improving the processing, physical- mechanical performance and durability of non-conventional fiber-cement composites. The objective of this review is to show some of these strategies to mitigate the degradation of the vegetable fibers used as reinforcement in cost-effective and non-conventional fiber-cement and, consequently, to improve their mechanical and durability properties for applications in the housing construction. Beyond the introduction about vegetable fibers, the content of this review is divided in the following sections: (i surface modification of the fibers; (ii improving fiber-to-cement interface; (iii natural pozzolans; (iv accelerated carbonation; (v applications of nanoscience; and (vi principles of functionally graded materials and extrusion process were briefly discussed with focus on future research needs.La presente revisión explora la actualidad en el campo de los compuestos de fibrocemento no convencionales en relación a mejoras en el proceso productivo, el rendimiento físico-mecánico y la durabilidad. El objetivo de esta revisión es exponer algunas estrategias para mitigar la degradación de las fibras vegetales utilizadas como refuerzo en fibrocementos no convencionales y rentables, obteniendo en consecuencia una mejoría en el rendimiento de sus propiedades mecánicas y durabilidad para su aplicación en el área de la construcción de viviendas. Además de la introducción en relación a las fibras vegetales, el contenido de esta revisión se divide en las siguientes secciones: (i modificación de la superficie de las fibras; (ii mejoramiento de la interfaz fibra-cemento; (iii puzolanas naturales; (iv carbonatación acelerada; (v aplicaciones de la nanociencia; y (vi principios de los materiales funcionalmente graduados y el proceso de extrusión fueron discutidos brevemente con un enfoque a investigaciones futuras.

Durable fiber reinforced self-compacting concrete

International Nuclear Information System (INIS)

Corinaldesi, V.; Moriconi, G.

2004-01-01

In order to produce thin precast elements, a self-compacting concrete was prepared. When manufacturing these elements, homogenously dispersed steel fibers instead of ordinary steel-reinforcing mesh were added to the concrete mixture at a dosage of 10% by mass of cement. An adequate concrete strength class was achieved with a water to cement ratio of 0.40. Compression and flexure tests were carried out to assess the safety of these thin concrete elements. Moreover, serviceability aspects were taken into consideration. Firstly, drying shrinkage tests were carried out in order to evaluate the contribution of steel fibers in counteracting the high concrete strains due to a low aggregate-cement ratio. Secondly, the resistance to freezing and thawing cycles was investigated on concrete specimens in some cases superficially treated with a hydrophobic agent. Lastly, both carbonation and chloride penetration tests were carried out to assess durability behavior of this concrete mixture

Inhibition of Cracks on the Surface of Cement Mortar Using Estabragh Fibers

Directory of Open Access Journals (Sweden)

Tahereh Soleimani

2013-01-01

Full Text Available The influence of adding Estabragh fibers into the cement composites of mortar on surface cracks and mechanical properties of mortar has been studied at various fiber proportions of 0.25%, 0.5%, and 0.75%. The mortar shrinkage was evaluated by counting the number of cracks and measuring the width of cracks on the surface of mortar specimens. Although the Estabragh fibers loss their strength in an alkali environment of cement composites, the ability of Estabragh fibers to bridge on the microcracks in the mortar matrix causes a decrease in the number of cracks and in their width on the surface of the mortar samples in comparison with the plain mortar. However, considering the mechanical properties of specimens such as bending strength and compressive strength, among all fiber proportions, only the specimens with 0.25% of Estabragh fiber performed better in all respects compared to the physical and mechanical properties of reinforced cement composite of mortar. Consequently, by adding 0.25% of Estabragh fibers to the cement mortar, a remarkable inhibition in crack generation on fiber-containing cement composite of mortar is achieved.

The applicability of alkaline-resistant glass fiber in cement mortar of road pavement: Corrosion mechanism and performance analysis

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Qin Xiaochun

2017-11-01

Full Text Available The main technical requirements of road pavement concrete are high flexural strength and fatigue durability. Adding glass fiber into concrete could greatly increase flexural strength and wearing resistance of concrete. However, glass fiber has the great potential of corrosion during the cement hydration, which will directly affect the long-term performance and strength stability. In this paper, accelerated corrosion experiments have been done to find out the corrosion mechanism and property of alkali-resistant glass fiber in cement mortar. The applicability and practicability of alkaline-resistant glass fiber in road concrete have been illustrated in the analysis of flexural strength changing trend of cement mortar mixed with different proportions of activated additives to protect the corrosion of glass fiber by cement mortar. The results have shown that a 30% addition of fly ash or 10% addition of silica fume to cement matrix could effectively improve the corrosion resistance of alkali-resistant glass fiber. The optimal mixing amount of alkali-resistant glass fiber should be about 1.0 kg/m3 in consideration of ensuring the compressive strength of reinforced concrete in road pavement. The closest-packing method has been adopted in the mixture ratio design of alkali-resistant glass fiber reinforced concrete, not only to reduce the alkalinity of the cement matrix through large amount addition of activated additives but also to greatly enhance the flexural performance of concrete with the split pressure ratio improvement of 12.5–16.7%. The results suggested a prosperous application prospect for alkaline-resistant glass fiber reinforced concrete in road pavement.

Influence of polymer fibers on rheological properties of cement mortars

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Malaszkiewicz Dorota

2017-10-01

Full Text Available The reinforcing effect of fibers in cement composites often results in the improvement of the brittle nature of cementitious materials. But the decrease in the workability of fresh concrete is often the disadvantage of fibers addition. Conventional single-point workability tests cannot characterize workability of concrete in terms of fundamental rheological parameters. To this end, this paper describes an investigation of the influence of synthetic fiber additions (fiber length in the range 12–50 mm and volume fraction in the range 0–4% on the rheological properties of fiber reinforced fresh mortar (FRFM and development of these properties over time. The rheometer Viskomat XL was used in this study. Within the limitations of the instrument and testing procedure it is shown that FRFMs conform to the Bingham model. Natural postglacial sand 0/4 mm was used as a fine aggregate and cement CEMI 42.5 R was used as a binder. Three commercial synthetic fibers were selected for these examinations. Rheological properties were expressed in terms of Bingham model parameters g (yield value and h (plastic viscosity. Based on the test results it was found out that the fiber type and volume fraction affected both the yield stress and plastic viscosity.

Influence of polymer fibers on rheological properties of cement mortars

Science.gov (United States)

Malaszkiewicz, Dorota

2017-10-01

The reinforcing effect of fibers in cement composites often results in the improvement of the brittle nature of cementitious materials. But the decrease in the workability of fresh concrete is often the disadvantage of fibers addition. Conventional single-point workability tests cannot characterize workability of concrete in terms of fundamental rheological parameters. To this end, this paper describes an investigation of the influence of synthetic fiber additions (fiber length in the range 12-50 mm and volume fraction in the range 0-4%) on the rheological properties of fiber reinforced fresh mortar (FRFM) and development of these properties over time. The rheometer Viskomat XL was used in this study. Within the limitations of the instrument and testing procedure it is shown that FRFMs conform to the Bingham model. Natural postglacial sand 0/4 mm was used as a fine aggregate and cement CEMI 42.5 R was used as a binder. Three commercial synthetic fibers were selected for these examinations. Rheological properties were expressed in terms of Bingham model parameters g (yield value ) and h (plastic viscosity). Based on the test results it was found out that the fiber type and volume fraction affected both the yield stress and plastic viscosity.

Energy absorption at high strain rate of glass fiber reinforced mortars

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Fenu Luigi

2015-01-01

Full Text Available In this paper, the dynamic behaviour of cement mortars reinforced with glass fibers was studied. The influence of the addition of glass fibers on energy absorption and tensile strength at high strain-rate was investigated. Static tests in compression, in tension and in bending were first performed. Dynamic tests by means of a Modified Hopkinson Bar were then carried out in order to investigate how glass fibers affected energy absorption and tensile strength at high strain-rate of the fiber reinforced mortar. The Dynamic Increase Factor (DIF was finally evaluated.

Review of Japanese recommendations on design and construction of different classes of fiber reinforced concrete and application examples

DEFF Research Database (Denmark)

Uchida, Yuichi; Fischer, Gregor; Hishiki, Yoshihiro

2008-01-01

The development of concrete and cementitious composites with fiber reinforcement to improve the tensile load-deformation behavior has resulted in three distinct classes of materials. These include conventional Fiber Reinforced Concrete (FRC) with tension softening response, High Performance Fiber...... Reinforced Cement Composites (HPFRCC) with strain hardening and multiple cracking behavior, and Ultra High-strength Fiber Reinforced concrete (UFC) with increased tensile strength. The recommendations on the design, production, and application of these classes of fiber reinforced concrete have been...

Tensile and Flexural Properties of Cement Composites Reinforced with Flax Nonwoven Fabrics

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Josep Claramunt

2017-02-01

Full Text Available The aim of this study is to develop a process to produce high-performance cement-based composites reinforced with flax nonwoven fabrics, analyzing the influence of the fabric structure—thickness and entanglement—on mechanical behavior under flexural and tensile loadings. For this purpose, composite with flax nonwoven fabrics with different thicknesses were first prepared and their cement infiltration was evaluated with backscattered electron (BSE images. The nonwoven fabrics with the optimized thickness were then subjected to a water treatment to improve their stability to humid environments and the fiber-matrix adhesion. For a fixed thickness, the effect of the nonwoven entanglement on the mechanical behavior was evaluated under flexural and direct tension tests. The obtained results indicate that the flax nonwoven fabric reinforcement leads to cement composites with substantial enhancement of ductility.

Shear transfer in concrete reinforced with carbon fibers

Science.gov (United States)

El-Mokadem, Khaled Mounir

2001-10-01

Scope and method of study. The research started with preliminary tests and studies on the behavior and effect of carbon fibers in different water solutions and mortar/concrete mixes. The research work investigated the use of CF in the production of concrete pipes and prestressed concrete double-tee sections. The research then focused on studying the effect of using carbon fibers on the direct shear transfer of sand-lightweight reinforced concrete push-off specimens. Findings and conclusions. In general, adding carbon fibers to concrete improved its tensile characteristics but decreased its compressive strength. The decrease in compressive strength was due to the decrease in concrete density as fibers act as three-dimensional mesh that entrapped air. The decrease in compressive strength was also due to the increase in the total surface area of non-cementitious material in the concrete. Sand-lightweight reinforced concrete push-off specimens with carbon fibers had lower shear carrying capacity than those without carbon fibers for the same cement content in the concrete. Current building codes and specifications estimate the shear strength of concrete as a ratio of the compressive strength. If applying the same principals then the ratio of shear strength to compressive strength for concrete reinforced with carbon fibers is higher than that for concrete without carbon fibers.

Graphite coated PVA fibers as the reinforcement for cementitious composites

Science.gov (United States)

Zhang, Yunhua; Zhang, Zhipeng; Liu, Zhichao

2018-02-01

A new preconditioning method was developed to PVA fibers as the reinforcement in cement-based materials. Virgin PVA fibers exhibits limited adhesion to graphite powders due to the presence of oil spots on the surface. Mixing PVA fibers with a moderately concentrated KMnO4-H2SO4 solution can efficiently remove the oil spots by oxidation without creating extra precipitate (MnO2) associated with the reduction reaction. This enhances the coating of graphite powders onto fiber surface and improves the mechanical properties of PVA fiber reinforced concrete (PVA-FRC). Graphite powders yields better fiber distribution in the matrix and reduces the fiber-matrix bonding, which is beneficial in uniformly distributing the stress among embedded fibers and creating steady generation and propagation of tight microcracks. This is evidenced by the significantly enhanced strain hardening behavior and improved flexural strength and toughness.

THE INFLUENCE OF NANO-ADDITIVES ON THE PHYSICO-MECHANICAL PROPERTIES FIBER REINFORCED CONCRETE

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Евгений Петрович Матус

2018-02-01

Full Text Available The paper discusses the current state of research of the effect of nanodispersed additives on the properties of fiber reinforced portland cement composites. The results of tests on the strength and viscosity of solutions and samples of fine-grained concrete based on cement binder and cement steel and basalt fiber, carbon nanotubes, silicates, nanosized powder of CaО and degidrol. The effect of methods of introduction of the mixture of nano-additives on the clutch fibers with the matrix. Analysis of experimental data showed the absence of a systematic positive effect of increasing the mechanical strength of the composites due to the introduction of carbon nanotubes.

Flexural Cracking Behavior Of Steel Fiber Reinforced Concrete Beams

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Ashraf Abdalkader

2017-08-01

Full Text Available Steel fibers are added to concrete due to its ability to improve the tensile strength and control propagation of cracks in reinforced concrete members. Steel fiber reinforced concrete is made of cement fine water and coarse aggregate in addition to steel fibers. In this experimental work flexural cracking behavior of reinforced concrete beams contains different percentage of hooked-end steel fibers with length of 50 mm and equivalent diameter of 0.5 mm was studied. The beams were tested under third-point loading test at 28 days. First cracking load maximum crack width cracks number and load-deflection relations were investigated to evaluate the flexural cracking behavior of concrete beams with 34 MPa target mean strength. Workability wet density compressive and splitting tensile strength were also investigated. The results showed that the flexural crack width is significantly reduced with the addition of steel fibers. Fiber contents of 1.0 resulted in 81 reduction in maximum crack width compared to control concrete without fiber. The results also showed that the first cracking load and maximum load are increased with the addition of steel fibers.

Reinforcement of Recycled Foamed Asphalt Using Short Polypropylene Fibers

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Yongjoo Kim

2013-01-01

Full Text Available This paper presents the reinforcing effects of the inclusion of short polypropylene fibers on recycled foamed asphalt (RFA mixture. Short polypropylene fibers of 10 mm length with a 0.15% by weight mixing ratio of the fiber to the asphalt binder were used. The Marshall stability test, the indirect tensile strength test, the resilient modulus test, and wheel tracking test of the RFA mixtures were conducted. The test results were compared to find out the reinforcing effects of the inclusion of the fiber and the other mixtures, which included the conventional recycled foamed asphalt (RFA mixtures; the cement reinforced recycled foamed asphalt (CRFA mixtures; the semihot recycled foamed asphalt (SRFA mixtures; and recycled hot-mix asphalt (RHMA mixtures. It is found that the FRFA mixture shows higher Marshall stability than the RFA and SRFA mixtures, higher indirect tensile strength than the RFA mixture, and higher rut resistance than the RFA, SRFA, and RHMA mixtures as seen from the wheel tracking test.

Self-Shrinkage Behaviors of Waste Paper Fiber Reinforced Cement Paste considering Its Self-Curing Effect at Early-Ages

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Zhengwu Jiang

2016-01-01

Full Text Available The aim of this paper was to study how the early-age self-shrinkage behavior of cement paste is affected by the addition of the waste paper fibers under sealed conditions. Although the primary focus was to determine whether the waste paper fibers are suitable to mitigate self-shrinkage as an internal curing agent under different adding ways, evaluating their strength, pore structure, and hydration properties provided further insight into the self-cured behavior of cement paste. Under the wet mixing condition, the waste paper fibers could mitigate the self-shrinkage of cement paste and, at additions of 0.2% by mass of cement, the waste paper fibers were found to show significant self-shrinkage cracking control while providing some internal curing. In addition, the self-curing efficiency results were analyzed based on the strength and the self-shrinkage behaviors of cement paste. Results indicated that, under a low water cement ratio, an optimal dosage and adding ways of the waste paper fibers could enhance the self-curing efficiency of cement paste.

Stabilized fiber-reinforced pavement base course with recycled aggregate

Science.gov (United States)

Sobhan, Khaled

This study evaluates the benefits to be gained by using a composite highway base course material consisting of recycled crushed concrete aggregate, portland cement, fly ash, and a modest amount of reinforcing fibers. The primary objectives of this research were to (a) quantify the improvement that is obtained by adding fibers to a lean concrete composite (made from recycled aggregate and low quantities of Portland cement and/or fly ash), (b) evaluate the mechanical behavior of such a composite base course material under both static and repeated loads, and (c) utilize the laboratory-determined properties with a mechanistic design method to assess the potential advantages. The split tensile strength of a stabilized recycled aggregate base course material was found to be exponentially related to the compacted dry density of the mix. A lean mix containing 4% cement and 4% fly ash (by weight) develops sufficient unconfined compressive, split tensile, and flexural strengths to be used as a high quality stabilized base course. The addition of 4% (by weight) of hooked-end steel fibers significantly enhances the post-peak load-deformation response of the composite in both indirect tension and static flexure. The flexural fatigue behavior of the 4% cement-4% fly ash mix is comparable to all commonly used stabilized materials, including regular concrete; the inclusion of 4% hooked-end fibers to this mix significantly improves its resistance to fatigue failure. The resilient moduli of stabilized recycled aggregate in flexure are comparable to the values obtained for traditional soil-cement mixes. In general, the fibers are effective in retarding the rate of fatigue damage accumulation, which is quantified in terms of a damage index defined by an energy-based approach. The thickness design curves for a stabilized recycled aggregate base course, as developed by using an elastic layer approach, is shown to be in close agreement with a theoretical model (based on Westergaard

A micromorphic model for steel fiber reinforced concrete.

Science.gov (United States)

Oliver, J; Mora, D F; Huespe, A E; Weyler, R

2012-10-15

A new formulation to model the mechanical behavior of high performance fiber reinforced cement composites with arbitrarily oriented short fibers is presented. The formulation can be considered as a two scale approach, in which the macroscopic model, at the structural level, takes into account the mesostructural phenomenon associated with the fiber-matrix interface bond/slip process. This phenomenon is contemplated by including, in the macroscopic description, a micromorphic field representing the relative fiber-cement displacement. Then, the theoretical framework, from which the governing equations of the problem are derived, can be assimilated to a specific case of the material multifield theory. The balance equation derived for this model, connecting the micro stresses with the micromorphic forces, has a physical meaning related with the fiber-matrix bond slip mechanism. Differently to previous procedures in the literature, addressed to model fiber reinforced composites, where this equation has been added as an additional independent ingredient of the methodology, in the present approach it arises as a natural result derived from the multifield theory. Every component of the composite is defined with a specific free energy and constitutive relation. The mixture theory is adopted to define the overall free energy of the composite, which is assumed to be homogeneously constituted, in the sense that every infinitesimal volume is occupied by all the components in a proportion given by the corresponding volume fraction. The numerical model is assessed by means of a selected set of experiments that prove the viability of the present approach.

Optimization of fly ash as sand replacement materials (SRM) in cement composites containing coconut fiber

Science.gov (United States)

Nadzri, N. I. M.; Jamaludin, S. B.; Mazlee, M. N.; Jamal, Z. A. Z.

2016-07-01

The need of utilizing industrial and agricultural wastes is very important to maintain sustainability. These wastes are often incorporated with cement composites to improve performances in term of physical and mechanical properties. This study presents the results of the investigation of the response of cement composites containing coconut fiber as reinforcement and fly ash use as substitution of sand at different hardening days. Hardening periods of time (7, 14 and 28 days) were selected to study the properties of cement composites. Optimization result showed that 20 wt. % of fly ash (FA) is a suitable material for sand replacement (SRM). Meanwhile 14 days of hardening period gave highest compressive strength (70.12 MPa) from the cement composite containing 9 wt. % of coconut fiber and fly ash. This strength was comparable with the cement without coconut fiber (74.19 MPa) after 28 days of curing.

Seating load parameters impact on dental ceramic reinforcement conferred by cementation with resin-cements.

LENUS (Irish Health Repository)

Addison, Owen

2010-09-01

Cementation of all-ceramic restorations with resin-cements has been demonstrated to reduce the incidence of fracture in service. The aim was to investigate the influence of loading force and loading duration applied during cementation on the reinforcement conferred by a resin-cement on a leucite reinforced glass-ceramic.

A multi-scale investigation of the mechanical behavior of durable sisal fiber cement composites

OpenAIRE

Silva, Flávio de Andrade; Toledo Filho, Romildo D.; Mobasher, Barzin; Chawla, Nikhilesh

2010-01-01

Durable sisal fiber cement composites reinforced with long unidirectional aligned fibers were developed and their mechanical behavior was characterized in a multi-scale level. Tensile tests were performed in individual sisal fibers. Weibull statistics were used to quantify the degree of variability in fiber strength at different gage lengths. The fiber-matrix pull-out behavior was evaluated at several curing ages and embedded lengths. The composite's mechanical response was measured under dir...

Effect of reinforcement fibers on the collapse potential of clayey sands

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Adjabi Souhila

2018-01-01

Full Text Available The collapse of soils under wetting is a major problem in Geotechnical engineering. The erection of structures on these types of soils, located in arid and semi-arid zones, needs careful treatment of these soils. Soil reinforcement techniques have been rapidly increased during these two decades because of their effectiveness in geotechnical engineering. The aim of this experimental work is to investigate the collapsible soil behaviour in order to improve its characteristics. To achieve this goal, Polyethylene fibers, and Sisal fibers were used as Polyethylene fibers content in mass are varied from 0% (unreinforced samples to 15%; and Sisal fibers content from 0.5% to 1%. The fiber reinforcement is combined with other processing procedures such as compaction and the addition of CPA cement to decrease the collapse potential.

Evaluation of Shear Resisting Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

International Nuclear Information System (INIS)

Choun, Youngsun; Park, Junhee

2014-01-01

Conventional reinforced concrete (RC) members generally show a rapid deterioration in shear resisting mechanisms under a reversed cyclic load. However, the use of high-performance fiber-reinforced cement composites provides excellent damage tolerance under large displacement reversals compared with regular concrete. Previous experimental studies have indicated that the use of fibers in conventional RC can enhance the structural and functional performance of prestressed concrete containment buildings (PCCBs) in nuclear power plants. This study evaluates the shear resisting capacity for a PCCB constructed using steel fiber reinforced concrete (SFRC) or polyamide fiber reinforced concrete (PFRC). The effects of steel and polyamide fibers on the shear performance of a PCCB were investigated. It was revealed that steel fibers are more effective to enhance the shear resisting capacity of a PCCB than polyamide fibers. The ductility and energy dissipation increase significantly in fiber reinforced PCCBs

Evaluation of Shear Resisting Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

Energy Technology Data Exchange (ETDEWEB)

Choun, Youngsun; Park, Junhee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Conventional reinforced concrete (RC) members generally show a rapid deterioration in shear resisting mechanisms under a reversed cyclic load. However, the use of high-performance fiber-reinforced cement composites provides excellent damage tolerance under large displacement reversals compared with regular concrete. Previous experimental studies have indicated that the use of fibers in conventional RC can enhance the structural and functional performance of prestressed concrete containment buildings (PCCBs) in nuclear power plants. This study evaluates the shear resisting capacity for a PCCB constructed using steel fiber reinforced concrete (SFRC) or polyamide fiber reinforced concrete (PFRC). The effects of steel and polyamide fibers on the shear performance of a PCCB were investigated. It was revealed that steel fibers are more effective to enhance the shear resisting capacity of a PCCB than polyamide fibers. The ductility and energy dissipation increase significantly in fiber reinforced PCCBs.

Evaluation of seismic shear capacity of prestressed concrete containment vessels with fiber reinforcement

Energy Technology Data Exchange (ETDEWEB)

Choun, Young Sun; Park, Jun Hee [Integrated Safety Assessment Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

Fibers have been used in cement mixture to improve its toughness, ductility, and tensile strength, and to enhance the cracking and deformation characteristics of concrete structural members. The addition of fibers into conventional reinforced concrete can enhance the structural and functional performances of safety-related concrete structures in nuclear power plants. The effects of steel and polyamide fibers on the shear resisting capacity of a prestressed concrete containment vessel (PCCV) were investigated in this study. For a comparative evaluation between the shear performances of structural walls constructed with conventional concrete, steel fiber reinforced concrete, and polyamide fiber reinforced concrete, cyclic tests for wall specimens were conducted and hysteretic models were derived. The shear resisting capacity of a PCCV constructed with fiber reinforced concrete can be improved considerably. When steel fiber reinforced concrete contains hooked steel fibers in a volume fraction of 1.0%, the maximum lateral displacement of a PCCV can be improved by > 50%, in comparison with that of a conventional PCCV. When polyamide fiber reinforced concrete contains polyamide fibers in a volume fraction of 1.5%, the maximum lateral displacement of a PCCV can be enhanced by ∼40%. In particular, the energy dissipation capacity in a fiber reinforced PCCV can be enhanced by > 200%. The addition of fibers into conventional concrete increases the ductility and energy dissipation of wall structures significantly. Fibers can be effectively used to improve the structural performance of a PCCV subjected to strong ground motions. Steel fibers are more effective in enhancing the shear performance of a PCCV than polyamide fibers.

Evaluation of seismic shear capacity of prestressed concrete containment vessels with fiber reinforcement

International Nuclear Information System (INIS)

Choun, Young Sun; Park, Jun Hee

2015-01-01

Fibers have been used in cement mixture to improve its toughness, ductility, and tensile strength, and to enhance the cracking and deformation characteristics of concrete structural members. The addition of fibers into conventional reinforced concrete can enhance the structural and functional performances of safety-related concrete structures in nuclear power plants. The effects of steel and polyamide fibers on the shear resisting capacity of a prestressed concrete containment vessel (PCCV) were investigated in this study. For a comparative evaluation between the shear performances of structural walls constructed with conventional concrete, steel fiber reinforced concrete, and polyamide fiber reinforced concrete, cyclic tests for wall specimens were conducted and hysteretic models were derived. The shear resisting capacity of a PCCV constructed with fiber reinforced concrete can be improved considerably. When steel fiber reinforced concrete contains hooked steel fibers in a volume fraction of 1.0%, the maximum lateral displacement of a PCCV can be improved by > 50%, in comparison with that of a conventional PCCV. When polyamide fiber reinforced concrete contains polyamide fibers in a volume fraction of 1.5%, the maximum lateral displacement of a PCCV can be enhanced by ∼40%. In particular, the energy dissipation capacity in a fiber reinforced PCCV can be enhanced by > 200%. The addition of fibers into conventional concrete increases the ductility and energy dissipation of wall structures significantly. Fibers can be effectively used to improve the structural performance of a PCCV subjected to strong ground motions. Steel fibers are more effective in enhancing the shear performance of a PCCV than polyamide fibers

Bonding Characteristics of Macrosynthetic Fiber in Latex-Modified Fiber-Reinforced Cement Composites as a Function of Carbon Nanotube Content

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Ji-Hong Jean

2016-01-01

Full Text Available The effect of carbon nanotube content (0, 0.5, 1.0, 1.5, and 2.0% of the cement weight on the bonding properties of macrosynthetic fiber in latex-modified hybrid fiber cement-based composites (LMHFRCCs was evaluated. The slump value, compressive strength, and bonding strength were measured for each LMHFRCC. As the carbon nanotube content increased to 1.5%, the bonding properties of the macrosynthetic fiber improved. However, the bonding performance deteriorated at a carbon nanotube content of 2.0%. A decrease in the fluidity of the mix negatively affected the dispersion of the nanotubes in the LMHFRCCs. The addition of carbon nanotubes also affected the relative bonding strength independently of the improvement in compressive strength. Microscopic analysis of the macrosynthetic fiber surfaces was used to understand changes in the bonding behavior.

Characterization and treatment of sisal fiber residues for cement-based composite application

OpenAIRE

Lima,Paulo R. L.; Santos,Rogério J.; Ferreira,Saulo R.; Toledo Filho,Romildo D.

2014-01-01

Sisal fiber is an important agricultural product used in the manufacture of ropes, rugs and also as a reinforcement of polymeric or cement-based composites. However, during the fiber production process a large amount of residues is generated which currently have a low potential for commercial use. The aim of this study is to characterize the agricultural residues by the production and improvement of sisal fiber, called field bush and refugo and verify the potentiality of their use in the rein...

Properties of Fiber-Reinforced Mortars Incorporating Nano-Silica

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Ahmed Ghazy

2016-02-01

Full Text Available Repair and rehabilitation of deteriorating concrete elements are of significant concern in many infrastructural facilities and remain a challenging task. Concerted research efforts are needed to develop repair materials that are sustainable, durable, and cost-effective. Research data show that fiber-reinforced mortars/concretes have superior performance in terms of volume stability and toughness. In addition, it has been recently reported that nano-silica particles can generally improve the mechanical and durability properties of cement-based systems. Thus, there has been a growing interest in the use of nano-modified fiber-reinforced cementitious composites/mortars (NFRM in repair and rehabilitation applications of concrete structures. The current study investigates various mechanical and durability properties of nano-modified mortar containing different types of fibers (steel, basalt, and hybrid (basalt and polypropylene, in terms of compressive and flexural strengths, toughness, drying shrinkage, penetrability, and resistance to salt-frost scaling. The results highlight the overall effectiveness of the NFRM owing to the synergistic effects of nano-silica and fibers.

Performance of Lightweight Natural-Fiber Reinforced Concrete

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Hardjasaputra Harianto

2017-01-01

Full Text Available Concrete, the most common construction material, has negligible tension capacity. However, a reinforcement material such as natural fibers, can be used to improve the tensile properties of concrete. This paper presents experiments conducted on Super Lightweight Concrete mixed with coconut fibers (SLNFRC. Coconut fibers are regarded as one of the toughest natural fibers to strengthen concrete. Coconut fiber reinforced composites have been considered as a sustainable construction material because the fibers are derived from waste. These wastes, which are available in large quantities in Asia, have to be extracted from the husk of coconut fruits and must pass a mechanical process before being added to a concrete mixture. The Super Lightweight Concrete was made by mixing concrete paste with foam agent that can reduce the overall weight of concrete up to 60% with compressive strength up to 6 MPa. The Super Lightweight Concrete is intended to be used for non-structural walls, as alternative conventional construction materials such as brick walls. The influence of coconut fibers content in increasing the flexural tensile strength of Super Lightweight Concrete was studied in this research. The fiber content studied include 0%, 0.1%, 0.175%, and 0.25% by weight of cement content. Sixteen specimens of SLNFRC mini beams of 60 mm x 60 mm x 300 mm were tested to failure to investigate their flexural strengths. The optimum percent fibers yielding higher tensile strength was found to be 0.175%

Experimental and numerical analysis of short sisal fiber-cement composites produced with recycled matrix

OpenAIRE

Lima, Paulo Roberto Lopes; Barros, Joaquim A. O.; Santos, Daniele Justo; Fontes, Cintia Maria; Lima, José Mário F.; Toledo Filho, Romildo

2016-01-01

"Published online: 02 Jan 2017" The proper use of renewable or recycled source materials can contribute significantly to reducing the environmental impact of construction industry. In this work, cement based composites reinforced with natural fibers were developed and their mechanical behavior was characterized. To ensure the composite sustainability and durability, the ordinary Portland cement matrix was modified by adding metakaolin and the natural aggregate was substitute...

Steel fiber reinforced concrete

International Nuclear Information System (INIS)

Baloch, S.U.

2005-01-01

Steel-Fiber Reinforced Concrete is constructed by adding short fibers of small cross-sectional size .to the fresh concrete. These fibers reinforce the concrete in all directions, as they are randomly oriented. The improved mechanical properties of concrete include ductility, impact-resistance, compressive, tensile and flexural strength and abrasion-resistance. These uniqlte properties of the fiber- reinforcement can be exploited to great advantage in concrete structural members containing both conventional bar-reinforcement and steel fibers. The improvements in mechanical properties of cementitious materials resulting from steel-fiber reinforcement depend on the type, geometry, volume fraction and material-properties of fibers, the matrix mix proportions and the fiber-matrix interfacial bond characteristics. Effects of steel fibers on the mechanical properties of concrete have been investigated in this paper through a comprehensive testing-programme, by varying the fiber volume fraction and the aspect-ratio (Lid) of fibers. Significant improvements are observed in compressive, tensile, flexural strength and impact-resistance of concrete, accompanied by marked improvement in ductility. optimum fiber-volume fraction and aspect-ratio of steel fibers is identified. Test results are analyzed in details and relevant conclusions drawn. The research is finally concluded with future research needs. (author)

Post-cracking behavior of blocks, prisms, and small concrete walls reinforced with plant fiber

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I. I. Soto

Full Text Available Structural masonry using concrete blocks promotes the rationalization of construction projects, lowering the final cost of a building through the elimination of forms and the reduction of the consumption of reinforcement bars. Moreover, production of a block containing a combination of concrete and vegetable fiber sisal results in a unit with properties such as mechanical strength, stiffness, flexibility, ability to absorb energy, and post-cracking behavior that are comparable to those of a block produced with plain concrete. Herein are reported the results of a study on the post-cracking behavior of blocks, prisms, and small walls reinforced with sisal fibers (lengths of 20 mm and 40 mm added at volume fractions of 0.5% and 1%. Tests were performed to characterize the fibers and blocks and to determine the compressive strength of the units, prisms, and small walls. The deformation modulus of the elements was calculated and the stress-strain curves were plotted to gain a better understanding of the values obtained. The compression test results for the small walls reinforced with fibers were similar to those of the reference walls and better than the blocks and prisms with added fibers, which had resistances lower than those of the corresponding conventional materials. All elements prepared with the addition of sisal exhibited an increase in the deformation capacity (conferred by the fibers, which was observed in the stress-strain curves. The failure mode of the reference elements was characterized by an abrupt fracture, whereas the reinforced elements underwent ductile breakage. This result was because of the presence of the fibers, which remained attached to the faces of the cracks via adhesion to the cement matrix, thus preventing loss of continuity in the material. Therefore, the cement/plant fiber composites are advantageous in terms of their ductility and ability to resist further damage after cracking.

Mechanical Properties of Fiber Reinforced Lightweight Concrete Containing Surfactant

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Yoo-Jae Kim

2010-01-01

Full Text Available Fiber reinforced aerated lightweight concrete (FALC was developed to reduce concrete's density and to improve its fire resistance, thermal conductivity, and energy absorption. Compression tests were performed to determine basic properties of FALC. The primary independent variables were the types and volume fraction of fibers, and the amount of air in the concrete. Polypropylene and carbon fibers were investigated at 0, 1, 2, 3, and 4% volume ratios. The lightweight aggregate used was made of expanded clay. A self-compaction agent was used to reduce the water-cement ratio and keep good workability. A surfactant was also added to introduce air into the concrete. This study provides basic information regarding the mechanical properties of FALC and compares FALC with fiber reinforced lightweight concrete. The properties investigated include the unit weight, uniaxial compressive strength, modulus of elasticity, and toughness index. Based on the properties, a stress-strain prediction model was proposed. It was demonstrated that the proposed model accurately predicts the stress-strain behavior of FALC.

Flexural Behavior of High-Volume Steel Fiber Cementitious Composite Externally Reinforced with Basalt FRP Sheet

OpenAIRE

Seungwon Kim; Cheolwoo Park

2016-01-01

High-performance fiber-reinforced cementitious composites (HPFRCCs) are characterized by unique tensile strain hardening and multiple microcracking behaviors. The HPFRCC, which demonstrates remarkable properties such as strength, ductility, toughness, durability, stiffness, and thermal resistance, is a class of fiber cement composite with fine aggregates. It can withstand tensile stresses by forming distributed microcracks owing to the embedded fibers in the concrete, which improve the energy...

An innovative approach to achieve re-centering and ductility of cement mortar beams through randomly distributed pseudo-elastic shape memory alloy fibers

Science.gov (United States)

Shajil, N.; Srinivasan, S. M.; Santhanam, M.

2012-04-01

Fibers can play a major role in post cracking behavior of concrete members, because of their ability to bridge cracks and distribute the stress across the crack. Addition of steel fibers in mortar and concrete can improve toughness of the structural member and impart significant energy dissipation through slow pull out. However, steel fibers undergo plastic deformation at low strain levels, and cannot regain their shape upon unloading. This is a major disadvantage in strong cyclic loading conditions, such as those caused by earthquakes, where self-centering ability of the fibers is a desired characteristic in addition to ductility of the reinforced cement concrete. Fibers made from an alternative material such as shape memory alloy (SMA) could offer a scope for re-centering, thus improving performance especially after a severe loading has occurred. In this study, the load-deformation characteristics of SMA fiber reinforced cement mortar beams under cyclic loading conditions were investigated to assess the re-centering performance. This study involved experiments on prismatic members, and related analysis for the assessment and prediction of re-centering. The performances of NiTi fiber reinforced mortars are compared with mortars with same volume fraction of steel fibers. Since re-entrant corners and beam columns joints are prone to failure during a strong ground motion, a study was conducted to determine the behavior of these reinforced with NiTi fiber. Comparison is made with the results of steel fiber reinforced cases. NiTi fibers showed significantly improved re-centering and energy dissipation characteristics compared to the steel fibers.

Flexural Behavior of High-Volume Steel Fiber Cementitious Composite Externally Reinforced with Basalt FRP Sheet

Directory of Open Access Journals (Sweden)

Seungwon Kim

2016-01-01

Full Text Available High-performance fiber-reinforced cementitious composites (HPFRCCs are characterized by unique tensile strain hardening and multiple microcracking behaviors. The HPFRCC, which demonstrates remarkable properties such as strength, ductility, toughness, durability, stiffness, and thermal resistance, is a class of fiber cement composite with fine aggregates. It can withstand tensile stresses by forming distributed microcracks owing to the embedded fibers in the concrete, which improve the energy absorption capacity and apparent ductility. This high energy absorbing capacity can be enhanced further by an external stiff fiber-reinforced polymer (FRP. Basalt fabric is externally bonded as a sheet on concrete materials to enhance the durability and resistance to fire and other environmental attacks. This study investigates the flexural performance of an HPFRCC that is externally reinforced with multiple layers of basalt FRP. The HPFRCC considered in the study contains steel fibers at a volume fraction of 8%.

Reinforcing of Cement Composites by Estabragh Fibres

Science.gov (United States)

Merati, A. A.

2014-04-01

The influence of Estabragh fibres has been studied to improve the performance characteristics of the reinforced cement composites. The concrete shrinkage was evaluated by counting the number of cracks and measuring the width of cracks on the surface of concrete specimens. Although, the Estabragh fibres lose their strength in an alkali environment of cement composites, but, the ability of Estabragh fibres to bridge on the micro cracks in the concrete matrix causes to decrease the width of the cracks on the surface of the concrete samples in comparison with the plain concrete. However, considering the mechanical properties of specimens such as bending strength and impact resistance, the specimens with 0.25 % of Estabragh fibre performed better in all respects compared to the physical and mechanical properties of reinforced cement composite of concrete. Consequently, by adding 0.25 % of Estabragh fibres to the cement composite of concrete, a remarkable improvement in physical and mechanical properties of fibre-containing cement composite is achieved.

Development of Composite for Thermal Barriers Reinforced by Ceramic Fibers

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Ondřej Holčapek

2018-01-01

Full Text Available The paper introduces the development process of fiber-reinforced composite with increased resistance to elevated temperatures, which could be additionally increased by the hydrothermal curing. However, production of these composites is extremely energy intensive, and that is why the process of the design reflects environmental aspects by incorporation of waste material—fine ceramic powder applied as cement replacement. Studied composite materials consisted of the basalt aggregate, ceramic fibers applied up to 8% by volume, calcium-aluminous cement (CAC, ceramic powder up to 25% by mass (by 5% as cement replacement, plasticizer, and water. All studied mixtures were subjected to thermal loading on three thermal levels: 105°C, 600°C, and 1000°C. Experimental assessment was performed in terms of both initial and residual material properties; flow test of fresh mixtures, bulk density, compressive strength, flexural strength, fracture energy, and dynamic modulus of elasticity were investigated to find out an optimal dosage of ceramic fibers. Resulting set of composites containing 4% of ceramic fibers with various modifications by ceramic powder was cured under specific hydrothermal condition and again subjected to elevated temperatures. One of the most valuable benefits of additional hydrothermal curing of the composites lies in the higher residual mechanical properties, what allows successful utilization of cured composite as a thermal barrier in civil engineering. Mixtures containing ceramic powder as cement substitute exhibited after hydrothermal curing increase of residual flexural strength about 35%; on the other hand, pure mixture exhibited increase up to 10% even higher absolute values.

Impact of Aggregates Size and Fibers on basic Mechanical Properties of Asphalt Emulsion—Cement Concrete

Science.gov (United States)

Fu, Jun; Liu, Zhihong; Liu, Jie

2018-01-01

Asphalt Emulsion—Cement Concrete (AECC) is currently considered as a typical semi-flexibility material. One of the disadvantages of this material is brittle fracture and lacking ductility. This study aims at accelerating the basic mechanical properties of AECC using fibers and different aggregates size. The mix of AECC was introduced and the different content of fibers and aggregates size were studied. The results showed that the smaller aggregates size could improve the young’s modulus and compressive strength as well as fiber. The modulus-compressive strength ratio of fiber reinforced AECC is always below 500.

Mechanical characterization and structural analysis of recycled fiber-reinforced-polymer resin-transfer-molded beams

Science.gov (United States)

Tan, Eugene Wie Loon

1999-09-01

The present investigation was focussed on the mechanical characterization and structural analysis of resin-transfer-molded beams containing recycled fiber-reinforced polymers. The beams were structurally reinforced with continuous unidirectional glass fibers. The reinforcing filler materials consisted entirely of recycled fiber-reinforced polymer wastes (trim and overspray). The principal resin was a 100-percent dicyclo-pentadiene unsaturated polyester specially formulated with very low viscosity for resin transfer molding. Variations of the resin transfer molding technique were employed to produce specimens for material characterization. The basic materials that constituted the structural beams, continuous-glass-fiber-reinforced, recycled-trim-filled and recycled-overspray-filled unsaturated polyesters, were fully characterized in axial and transverse compression and tension, and inplane and interlaminar shear, to ascertain their strengths, ultimate strains, elastic moduli and Poisson's ratios. Experimentally determined mechanical properties of the recycled-trim-filled and recycled-overspray-filled materials from the present investigation were superior to those of unsaturated polyester polymer concretes and Portland cement concretes. Mechanical testing and finite element analyses of flexure (1 x 1 x 20 in) and beam (2 x 4 x 40 in) specimens were conducted. These structurally-reinforced specimens were tested and analyzed in four-point, third-point flexure to determine their ultimate loads, maximum fiber stresses and mid-span deflections. The experimentally determined load capacities of these specimens were compared to those of equivalent steel-reinforced Portland cement concrete beams computed using reinforced concrete theory. Mechanics of materials beam theory was utilized to predict the ultimate loads and mid-span deflections of the flexure and beam specimens. However, these predictions proved to be severely inadequate. Finite element (fracture propagation

Air-Cured Fiber-Cement Composite Mixtures with Different Types of Cellulose Fibers

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Ali Murat Soydan

2018-01-01

Full Text Available This present study was carried out to check the feasibility of different cellulose fibers obtained from cropped virgin cellulose, blenched eucalyptus, and araucaria pulps through different new environmentally friendly curing processes for fiber-cement production. The aim is to introduce the different sources of cellulose fibers with lower cost to produce the “fiber-cement without autoclave” (FCWA. The slurries used in the experiments contain approximately 8% wt. of cellulose. The influence of the waste marble powder addition to the cement mixture was also studied. The physical and mechanical properties of the products which were prepared with this method under different curing conditions were investigated. The mechanical properties of eucalyptus cellulose appear to offer the best combination, especially after longer air-cure cycles. The results showed that the production of FCWA is very economical by using waste marble powders. And moreover, two new types of cellulose fibers (eucalyptus and araucaria celluloses; EuC and ArC, resp., which provide a better density and packing in the fiber-cement leading to better modulus of rupture (MOR and modulus of elasticity (MOE values as virgin cellulose (ViC, are very usable for production of the fiber-cement in industrial scale.

A comparative evaluation of compressive strength of Portland cement with zinc oxide eugenol and Polymer-reinforced cement: an in vitro analysis.

Science.gov (United States)

Prakasam, S; Bharadwaj, Prakasam; Loganathan, S C; Prasanth, B Krishna

2014-01-01

The purpose of this study is to evaluate the ultimate compressive strength of 50% and 25% Portland cement mixed with Polymer-reinforced zinc oxide eugenol and zinc oxide eugenol cement after 1 hour, 24 hours, and 7 days. One hundred and eighty samples were selected. The samples were made cylindrical of size 6 × 8 mm and were divided into six groups as follows with each group consisting of 10 samples. Group 1: Polymer-reinforced zinc oxide eugenol with 50% Portland cement (PMZNPC 50%) Group 2: Polymer-reinforced zinc oxide eugenol with 25% Portland cement (PMZNPC 25%) Group 3: Polymer-reinforced zinc oxide eugenol with 0% Portland cement (PMZNPC 0%) Group 4: Zinc oxide eugenol with 50% Portland cement (ZNPC 50%) Group 5: Zinc oxide eugenol with 25% Portland cement (ZNPC 25%) Group 6: Zinc oxide eugenol with 0% Portland cement (ZNPC 0%) These samples were further subdivided based on time interval and were tested at 1 hour, 24 hours and at 7 th day. After each period of time all the specimens were tested by vertical CVR loaded frame with capacity of 5 tones/0473-10kan National Physical laboratory, New Delhi and the results were statistically analyzed using ANOVA and Scheffe test. Polymer-reinforced cement with 50% Portland cement, Zinc oxide with 50% Portland cement, Polymer-reinforced cement with 25% Portland cement and Zinc oxide with 25% Portland cement exhibited higher compressive strength when compared to Zinc oxide with 0% Portland cement and Polymer-reinforced cement with 0% Portland cement, at different periods of time. The difference between these two groups were statistically significant (P Portland cement in Zinc oxide eugenol and Polymer-modified zinc oxide cement can be used as core build up material and permanent filling material. It is concluded that 50% and 25% Portland cement in zinc oxide eugenol and polymer-modified zinc oxide eugenol results in higher compressive strength and hence can be used as permanent filling material and core built

The usage of carbon fiber reinforcement polymer and glass fiber reinforcement polymer for retrofit technology building

Science.gov (United States)

Tarigan, Johannes; Meka, Randi; Nursyamsi

2018-03-01

Fiber Reinforcement Polymer has been used as a material technology since the 1970s in Europe. Fiber Reinforcement Polymer can reinforce the structure externally, and used in many types of buildings like beams, columns, and slabs. It has high tensile strength. Fiber Reinforcement Polymer also has high rigidity and strength. The profile of Fiber Reinforcement Polymer is thin and light, installation is simple to conduct. One of Fiber Reinforcement Polymer material is Carbon Fiber Reinforcement Polymer and Glass Fiber Reinforcement Polymer. These materials is tested when it is installed on concrete cylinders, to obtain the comparison of compressive strength CFRP and GFRP. The dimension of concrete is diameter of 15 cm and height of 30 cm. It is amounted to 15 and divided into three groups. The test is performed until it collapsed to obtain maximum load. The results of research using CFRP and GFRP have shown the significant enhancement in compressive strength. CFRP can increase the compressive strength of 26.89%, and GFRP of 14.89%. For the comparison of two materials, CFRP is more strengthening than GFRP regarding increasing compressive strength. The usage of CFRP and GFRP can increase the loading capacity.

Continuous Natural Fiber Reinforced Thermoplastic Composites by Fiber Surface Modification

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Patcharat Wongsriraksa

2013-01-01

Full Text Available Continuous natural fiber reinforced thermoplastic materials are expected to replace inorganic fiber reinforced thermosetting materials. However, in the process of fabricating the composite, it is difficult to impregnate the thermoplastic resin into reinforcement fiber because of the high melt viscosity. Therefore, intermediate material, which allows high impregnation during molding, has been investigated for fabricating continuous fiber reinforced thermoplastic composite by aligning resin fiber alongside reinforcing fiber with braiding technique. This intermediate material has been called “microbraid yarn (MBY.” Moreover, it is well known that the interfacial properties between natural fiber and resin are low; therefore, surface treatment on continuous natural fiber was performed by using polyurethane (PU and flexible epoxy (FLEX to improve the interfacial properties. The effect of surface treatment on the mechanical properties of continuous natural fiber reinforced thermoplastic composites was examined. From these results, it was suggested that surface treatment by PU with low content could produce composites with better mechanical properties.

Method of adhering bone to a rigid substrate using a graphite fiber reinforced bone cement

Science.gov (United States)

Knoell, A. C.; Maxwell, H. G. (Inventor)

1977-01-01

A method is described for adhering bone to the surface of a rigid substrate such as a metal or resin prosthesis using an improved surgical bone cement. The bone cement has mechanical properties more nearly matched to those of animal bone and thermal curing characteristics which result in less traumatization of body tissues and comprises a dispersion of short high modulus graphite fibers within a bonder composition including polymer dissolved in reactive monomer such as polymethylmethacrylate dissolved in methylmethacrylate monomer.

Effect of hybrid fiber reinforcement on the cracking process in fiber reinforced cementitious composites

DEFF Research Database (Denmark)

Pereira, Eduardo B.; Fischer, Gregor; Barros, Joaquim A.O.

2012-01-01

The simultaneous use of different types of fibers as reinforcement in cementitious matrix composites is typically motivated by the underlying principle of a multi-scale nature of the cracking processes in fiber reinforced cementitious composites. It has been hypothesized that while undergoing...... tensile deformations in the composite, the fibers with different geometrical and mechanical properties restrain the propagation and further development of cracking at different scales from the micro- to the macro-scale. The optimized design of the fiber reinforcing systems requires the objective...... materials is carried out by assessing directly their tensile stress-crack opening behavior. The efficiency of hybrid fiber reinforcements and the multi-scale nature of cracking processes are discussed based on the experimental results obtained, as well as the micro-mechanisms underlying the contribution...

Shrinkage deformation of cement foam concrete

Science.gov (United States)

Kudyakov, A. I.; Steshenko, A. B.

2015-01-01

The article presents the results of research of dispersion-reinforced cement foam concrete with chrysotile asbestos fibers. The goal was to study the patterns of influence of chrysotile asbestos fibers on drying shrinkage deformation of cement foam concrete of natural hardening. The chrysotile asbestos fiber contains cylindrical fiber shaped particles with a diameter of 0.55 micron to 8 microns, which are composed of nanostructures of the same form with diameters up to 55 nm and length up to 22 microns. Taking into account the wall thickness, effective reinforcement can be achieved only by microtube foam materials, the so- called carbon nanotubes, the dimensions of which are of power less that the wall pore diameter. The presence of not reinforced foam concrete pores with perforated walls causes a decrease in its strength, decreases the mechanical properties of the investigated material and increases its shrinkage. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % by weight of cement provides the finely porous foam concrete structure with more uniform size closed pores, which are uniformly distributed over the volume. This reduces the shrinkage deformation of foam concrete by 50%.

Nanostructural Characteristics and Interfacial Properties of Polymer Fibers in Cement Matrix.

Science.gov (United States)

Shalchy, Faezeh; Rahbar, Nima

2015-08-12

Concrete is the most used material in the world. It is also one of the most versatile yet complex materials that humans have used for construction. However, an important weakness of concrete (cement-based composites) is its low tensile properties. Therefore, over the past 30 years many studies were focused on improving its tensile properties using a variety of physical and chemical methods. One of the most successful attempts is to use polymer fibers in the structure of concrete to obtain a composite with high tensile strength and ductility. The advantages of polymer fiber as reinforcing material in concrete, both with regard to reducing environmental pollution and the positive effects on a country's economy, are beyond dispute. However, a thorough understanding of the mechanical behavior of fiber-reinforced concrete requires a knowledge of fiber/matrix interfaces at the nanoscale. In this study, a combination of atomistic simulations and experimental techniques has been used to study the nanostructure of fiber/matrix interfaces. A new model for calcium-silicate-hydrate (C-S-H)/fiber interfaces is also proposed on the basis of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. Finally, the adhesion energy between the C-S-H gel and three different polymeric fibers (poly(vinyl alcohol), nylon-6, and polypropylene) were numerically studied at the atomistic level because adhesion plays a key role in the design of ductile fiber-reinforced composites. The mechanisms of adhesion as a function of the nanostructure of fiber/matrix interfaces are further studied and discussed. It is observed that the functional group in the structure of polymer macromolecule affects the adhesion energy primarily by changing the C/S ratio of the C-S-H at the interface and by absorbing additional positive ions in the C-S-H structure.

Physical and Mechanical Properties of Composites Made with Aluminous Cement and Basalt Fibers Developed for High Temperature Application

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Pavel Reiterman

2015-01-01

Full Text Available Present paper deals with the experimental study of the composition of refractory fiber-reinforced aluminous cement based composites and its response to gradual thermal loading. Basalt fibers were applied in doses of 0.25, 0.5, 1.0, 2.0, and 4.0% in volume. Simultaneously, binder system based on the aluminous cement was modified by fine ground ceramic powder originated from the accurate ceramic blocks production. Ceramic powder was dosed as partial replacement of used cement of 5, 10, 15, 20, and 25%. Influence of composition changes was evaluated by the results of physical and mechanical testing; compressive strength, flexural strength, bulk density, and fracture energy were determined on the different levels of temperature loading. Increased dose of basalt fibers allows reaching expected higher values of fracture energy, but with respect to results of compressive and flexural strength determination as an optimal rate of basalt fibers dose was considered 0.25% in volume. Fine ground ceramic powder application led to extensive increase of residual mechanical parameters just up to replacement of 10%. Higher replacement of aluminous cement reduced final values of bulk density but kept mechanical properties on the level of mixtures without aluminous cement replacement.

Influence of reinforcement and cemented parts on quality of radiological shields

International Nuclear Information System (INIS)

Ablewicz, Z.

1974-01-01

Results of studies of the influence of reinforcement density and shape of cemented parts on quality of radiological shields are presented. The studies were carried out on built shields and on experimental blocks. The experimental studies were aimed at determination of filling degree under cemented parts of different shapes using two kinds of cement normal and heavy one and at determination of filling degree of space with dense reinforcement as well as space near boarding. The influence of reinforcement density was studied using different spacing between bars and rows of bars. In the case of difficulties with good filling under the cemented parts so called ''beard'' and more liquid mixtures were used with success. (Z.M.)

THE USE OF SISAL FIBRE AS REINFORCEMENT IN CEMENT BASED COMPOSITES

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Romildo Dias Tolêdo Filho

1999-08-01

Full Text Available ABSTRACT The inclusion of fibre reinforcement in concrete, mortar and cement paste can enhance many of the engineering properties of the basic materials, such as fracture toughness, flexural strength and resistance to fatigue, impact, thermal shock and spalling. In recent years, a great deal of interest has been created worldwide on the potential applications of natural fibre reinforced, cement based composites. Investigations have been carried out in many countries on various mechanical properties, physical performance and durability of cement based matrices reinforced with naturally occurring fibres including sisal, coconut, jute, bamboo and wood fibres. These fibres have always been considered promising as reinforcement of cement based matrices because of their availability, low cost and low consumption of energy. In this review, the general properties of the composites are described in relation to fibre content, length, strength and stiffness. A chronological development of sisal fibre reinforced, cement based matrices is reported and experimental data are provided to illustrate the performance of sisal fibre reinforced cement composites. A brief description on the use of these composite materials as building products has been included. The influence of sisal fibres on the development of plastic shrinkage in the pre-hardened state, on tensile, compressive and bending strength in the hardened state of mortar mixes is discussed. Creep and drying shrinkage of the composites and the durability of natural fibres in cement based matrices are of particular interest and are also highlighted. The results show that the composites reinforced with sisal fibres are reliable materials to be used in practice for the production of structural elements to be used in rural and civil construction. This material could be a substitute asbestos-cement composite, which is a serious hazard to human and animal health and is prohibited in industrialized countries. The

Constitutive modeling of fiber-reinforced cement composites

Science.gov (United States)

Boulfiza, Mohamed

The role of fibers in the enhancement of the inherently low tensile stress and strain capacities of fiber reinforced cementitious composites (FRC) has been addressed through both the phenomenological, using concepts of continuum damage mechanics, and micro-mechanical approaches leading to the development of a closing pressure that could be used in a cohesive crack analysis. The observed enhancements in the matrix behavior is assumed to be related to the ability of the material to transfer stress across cracks. In the micromechanics approach, this is modeled by the introduction of a nonlinear closing pressure at the crack lips. Due to the different nature of cracking in the pre-peak and post peak regimes, two different micro-mechanical models of the cohesive pressure have been proposed, one for the strain hardening stage and another for the strain softening regime. This cohesive pressure is subsequently incorporated into a finite element code so that a nonlinear fracture analysis can be carried out. On top of the fact that a direct fracture analysis has been performed to predict the response of some FRC structural elements, a numerical procedure for the homogenization of FRC materials has been proposed. In this latter approach, a link is established between the cracking taking place at the meso-scale and its mechanical characteristics as represented by the Young's modulus. A parametric study has been carried out to investigate the effect of crack patterning and fiber volume fractions on the overall Young's modulus and the thermodynamic force associated with the tensorial damage variable. After showing the usefulness and power of phenomenological continuum damage mechanics (PCDM) in the prediction of ERC materials' response to a stimuli (loading), a combined PCDM-NLFMsp1 approach is proposed to model (predict, forecast) the complete response of the composite up to failure. Based on experimental observations, this approach assumes that damage mechanics which predicts

Adaptive Crack Modeling with Interface Solid Elements for Plain and Fiber Reinforced Concrete Structures.

Science.gov (United States)

Zhan, Yijian; Meschke, Günther

2017-07-08

The effective analysis of the nonlinear behavior of cement-based engineering structures not only demands physically-reliable models, but also computationally-efficient algorithms. Based on a continuum interface element formulation that is suitable to capture complex cracking phenomena in concrete materials and structures, an adaptive mesh processing technique is proposed for computational simulations of plain and fiber-reinforced concrete structures to progressively disintegrate the initial finite element mesh and to add degenerated solid elements into the interfacial gaps. In comparison with the implementation where the entire mesh is processed prior to the computation, the proposed adaptive cracking model allows simulating the failure behavior of plain and fiber-reinforced concrete structures with remarkably reduced computational expense.

Some Properties of Carbon Fiber Reinforced Magnetic Reactive Powder Concrete Containing Nano Silica

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Zain El-Abdin Raouf

2016-08-01

Full Text Available This study involves the design of 24 mixtures of fiber reinforced magnetic reactive powder concrete containing nano silica. Tap water was used for 12 of these mixtures, while magnetic water was used for the others. The nano silica (NS with ratios (1, 1.5, 2, 2.5 and 3 % by weight of cement, were used for all the mixtures. The results have shown that the mixture containing 2.5% NS gives the highest compressive strength at age 7 days. Many different other tests were carried out, the results have shown that the carbon fiber reinforced magnetic reactive powder concrete containing 2.5% NS (CFRMRPCCNS had higher compressive strength, modulus of rupture, splitting tension, stress in compression and strain in compression than the corresponding values for the carbon fiber reinforced nonmagnetic reactive powder concrete containing the same ratio of NS (CFRNRPCCNS. The percentage increase in these values for CFRMRPCCNS were (22.37, 17.96, 19.44, 6.44 and 25.8 % at 28 days respectively, as compared with the corresponding CFRNRPCCNS mixtures.

Extraction and characterization of Retama monosperma fibers

African Journals Online (AJOL)

XPERT

monosperma leaves and their mechanical, physical and chemical characteristics. The fibers .... The hook was removed gently, and the behavior of the fiber was observed ..... fibers reinforced cement mortar slabs: a comparative study. Cement.

Sisal organosolv pulp as reinforcement for cement based composites

OpenAIRE

Joaquim, Ana Paula; Tonoli, Gustavo Henrique Denzin; Santos, Sérgio Francisco Dos; Savastano Junior, Holmer

2009-01-01

The present work describes non-conventional sisal (Agave sisalana) chemical (organosolv) pulp from residues of cordage as reinforcement to cement based materials. Sisal organosolv pulp was produced in a 1:1 ethanol/water mixture and post chemically and physically characterized in order to compare its properties with sisal kraft pulp. Cement based composites reinforced with organosolv or kraft pulps and combined with polypropylene (PP) fibres were produced by the slurry de-watering and pressin...

Releasability of asbestos fibers from weathered roof cement.

Science.gov (United States)

Oberta, Andrew F; Poye, Lee; Compton, Steven P

2018-03-26

Chrysotile asbestos fibers were added to roofing products, including roof cement, for several decades. The fibers were described as "encapsulated" and therefore incapable of being released, an assertion that is disproved by the study reported herein. Three test panels of roof cement from the original container were exposed to ambient weathering in 2015 and 2016. Two panels were then sampled using the ASTM D5755 microvacuum method. Sampling revealed a light brown sub-layer under the dark brown surface layer, both of which crumbled and became friable during sampling. Analysis of the microvacuum samples with transmission electron microscopy showed that the material on the two panels contained 4,432,000 and 3,320,000 asbestos structures per cm² with nearly all of the structures consisting of fibers less than 5 µm long. Energy dispersive spectrometry determined that none of the fibers reported were coated with asphalt. The presence of free fibers were confirmed by direct examination of the surfaces of the panels and of dust released from handling the panels via scanning electron microscopy. This study confirmed the releasability of uncoated asbestos fibers from dried roof cement that was indicated in two previous studies published in 2007 and 2010. These results suggest that the finding of the 5th Circuit Court in 1997 that uncoated airborne asbestos fibers cannot be released from roof cement, and therefore do not present a potential exposure by inhalation, was erroneous in retrospect. Theexemption of roof cement from regulation under the Occupational Safety and Health Administration Construction Industry Standard for asbestos by the Court should not be relied on by employers of workers who remove weathered asbestos-containing roof cement, and precautions should be taken against exposure to airborne asbestos fibers during this work.

Chairside fabricated fiber-reinforced composite fixed partial denture

Directory of Open Access Journals (Sweden)

Sufyan Garoushi

2007-01-01

Full Text Available The advances in the materials and techniques for adhesive dentistry have allowed the development of non-invasive or minimally invasive approaches for replacing a missing tooth in those clinical situations when conservation of adjacent teeth is needed. Good mechanical and cosmetic/aesthetic properties of fiber-reinforced composite (FRC, with good bonding properties with composite resin cement and veneering composite are needed in FRC devices. Some recent studies have shown that adhesives of composite resins and luting cements allow diffusion of the adhesives to the FRC framework of the bridges. By this so-called interdiffusion bonding is formed [1]. FRC bridges can be made in dental laboratories or chairside. This article describes a clinical case of chairside (directly made FRC Bridge, which was used according to the principles of minimal invasive approach. Treatment was performed by Professor Vallittu from the University of Turku, Finland.

Evaluation of Ultimate Pressure Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

Energy Technology Data Exchange (ETDEWEB)

Choun, Youngsun; Hahm, Daegi [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Fiber reinforced concrete (FRC) includes thousands of small fibers that are distributed randomly in the concrete. Fibers resist the growth of cracks in concrete through their bridging at the cracks. Therefore, FRC fails in tension only when the fibers break or are pulled out of the cement matrix. For this reason, the addition of fibers in concrete mixing increases the tensile toughness of concrete and enhances the post-cracking behavior. A prevention of through-wall cracks and an increase of the post-cracking ductility will improve the ultimate internal pressure capacity of a prestressed concrete containment building (PCCB). In this study, the effects of steel or polyamide fiber reinforcement on the ultimate pressure capacity of a PCCB are evaluated. When R-SFRC contains hooked steel fibers in a volume fraction of 1.0%, the ultimate pressure capacity of a PCCB can be improved by 17%. When R-PFRC contains polyamide fibers in a volume fraction of 1.5%, the ultimate pressure capacity of a PCCB can be enhanced by 10%. Further studies are needed to determine the strain limits acceptable for PCCBs reinforced with fibers.

Evaluation of Ultimate Pressure Capacity of a Prestressed Concrete Containment Building with Steel or Polyamide Fiber Reinforcement

International Nuclear Information System (INIS)

Choun, Youngsun; Hahm, Daegi

2014-01-01

Fiber reinforced concrete (FRC) includes thousands of small fibers that are distributed randomly in the concrete. Fibers resist the growth of cracks in concrete through their bridging at the cracks. Therefore, FRC fails in tension only when the fibers break or are pulled out of the cement matrix. For this reason, the addition of fibers in concrete mixing increases the tensile toughness of concrete and enhances the post-cracking behavior. A prevention of through-wall cracks and an increase of the post-cracking ductility will improve the ultimate internal pressure capacity of a prestressed concrete containment building (PCCB). In this study, the effects of steel or polyamide fiber reinforcement on the ultimate pressure capacity of a PCCB are evaluated. When R-SFRC contains hooked steel fibers in a volume fraction of 1.0%, the ultimate pressure capacity of a PCCB can be improved by 17%. When R-PFRC contains polyamide fibers in a volume fraction of 1.5%, the ultimate pressure capacity of a PCCB can be enhanced by 10%. Further studies are needed to determine the strain limits acceptable for PCCBs reinforced with fibers

A State-of-the-Art Review on Soil Reinforcement Technology Using Natural Plant Fiber Materials: Past Findings, Present Trends and Future Directions.

Science.gov (United States)

Gowthaman, Sivakumar; Nakashima, Kazunori; Kawasaki, Satoru

2018-04-04

Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS) and randomly distributed fiber-reinforced soil (RDFS) are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line.

A State-of-the-Art Review on Soil Reinforcement Technology Using Natural Plant Fiber Materials: Past Findings, Present Trends and Future Directions

Directory of Open Access Journals (Sweden)

Sivakumar Gowthaman

2018-04-01

Full Text Available Incorporating sustainable materials into geotechnical applications increases day by day due to the consideration of impacts on healthy geo-environment and future generations. The environmental issues associated with conventional synthetic materials such as cement, plastic-composites, steel and ashes necessitate alternative approaches in geotechnical engineering. Recently, natural fiber materials in place of synthetic material have gained momentum as an emulating soil-reinforcement technique in sustainable geotechnics. However, the natural fibers are innately different from such synthetic material whereas behavior of fiber-reinforced soil is influenced not only by physical-mechanical properties but also by biochemical properties. In the present review, the applicability of natural plant fibers as oriented distributed fiber-reinforced soil (ODFS and randomly distributed fiber-reinforced soil (RDFS are extensively discussed and emphasized the inspiration of RDFS based on the emerging trend. Review also attempts to explore the importance of biochemical composition of natural-fibers on the performance in subsoil reinforced conditions. The treatment methods which enhances the behavior and lifetime of fibers, are also presented. While outlining the current potential of fiber reinforcement technology, some key research gaps have been highlighted at their importance. Finally, the review briefly documents the future direction of the fiber reinforcement technology by associating bio-mediated technological line.

Use of wet concrete spraying in building technology of reinforced-concrete fiber slabs according to «Monofant» system

OpenAIRE

BUGAYEVSKIY S.

2016-01-01

Technology of cementation of reinforced-concrete slabs with non-extractable-liners for the «Monofant» system, using wet concrete spraying is implemented. A compression test for obtained columns made of fiber concrete is carried out.

Hybrid Fiber Layup and Fiber-Reinforced Polymeric Composites Produced Therefrom

Science.gov (United States)

Barnell, Thomas J. (Inventor); Garrigan, Sean P. (Inventor); Rauscher, Michael D. (Inventor); Dietsch, Benjamin A. (Inventor); Cupp, Gary N. (Inventor)

2018-01-01

Embodiments of a hybrid fiber layup used to form a fiber-reinforced polymeric composite, and a fiber-reinforced polymeric composite produced therefrom are disclosed. The hybrid fiber layup comprises one or more dry fiber strips and one or more prepreg fiber strips arranged side by side within each layer, wherein the prepreg fiber strips comprise fiber material impregnated with polymer resin and the dry fiber strips comprise fiber material without impregnated polymer resin.

Polymer reinforcement of cement systems

International Nuclear Information System (INIS)

Swamy, R.N.

1979-01-01

In the last couple of decades several cement- and concrete-based composites have come into prominence. Of these, cement-polymer composites, like cement-fibre composites, have been recognised as very promising, and considerable research and development on their properties, fabrication methods and application are in progress. Of the three types of concrete materials which incorporate polymers to form composites, polymer impregnated concrete forms a major development in which hardened concrete is impregnated with a liquid monomer which is subsequently polymerized to form a rigid polymer network in the pores of the parent material. In this first part of the extensive review of the polymer reinforcement of cement systems, the process technology of the various monomer impregnation techniques and the properties of the impregnated composite are assessed critically. It is shown that the high durability and superior performance of polymer impregnated concrete can provide an economic and competitive alternative in in situ strengthening, and in other areas where conventional concrete can only at best provide adequate performance. The review includes a section on radiation-induced polymerization. (author)

Effect of Chopped Basalt Fibers on the Mechanical Properties and Microstructure of High Performance Fiber Reinforced Concrete

Directory of Open Access Journals (Sweden)

Tehmina Ayub

2014-01-01

Full Text Available This paper presents the mechanical properties and the microstructure of the high performance fiber reinforced concrete (HPFRC containing up to 3% volume fraction of chopped Basalt fibers. Three types of the concrete were prepared, out of which, the first type was prepared by utilizing 100% cement content. The other two types of the concrete were prepared by replacing 10% cement content with silica fume and the locally produced metakaolin. Using each concrete type, four mixes were prepared in which Basalt fibers were added in the range of 0–3%; that is, total twelve mixes of the HPFRC concrete were prepared. From each of the twelve concrete mixes, total twelve specimens were cast to determine the mechanical properties of the HPFRC including compressive strength (cube and cylinder, splitting tensile strength, and the flexural strength. In this way, a total of 108 specimens were cast and tested in this study. Test results showed that the addition of the Basalt fibers significantly increased the tensile splitting strength and the flexural strength of the HPFRC, while there was slight improvement in the compressive strength with the addition of Basalt fibers. The microstructure of HPFRC was examined to determine the interfacial transition zone (ITZ between the aggregates and the paste by using field emission scanning electron microscope (FESEM, which showed the improvement of the ITZ due to the addition of the Basalt fibers.

Carbon fiber reinforced asphalt concrete

International Nuclear Information System (INIS)

Jahromi, Saeed G.

2008-01-01

Fibers are often used in the manufacture of other materials. For many years, they have been utilized extensively in numerous applications in civil engineering. Fiber-reinforcement refers to incorporating materials with desired properties within some other materials lacking those properties. Use of fibers is not a new phenomenon, as the technique of fiber-reinforced bitumen began early as 1950. In all industrialized countries today, nearly all concretes used in construction are reinforced. A multitude of fibers and fiber materials are being introduced in the market regularly. The present paper presents characteristics and properties of carbon fiber-reinforced asphalt mixtures, which improve the performance of pavements. To evaluate the effect of fiber contents on bituminous mixtures, laboratory investigations were carried out on the samples with and without fibers. During the course of this study, various tests were undertaken, applying Marshall Test indirect tensile test, creep test and resistance to fatigue cracking by using repeated load indirect tensile test. Carbon fiber exhibited consistency in results and as such it was observed that the addition of fiber does affect the properties of bituminous mixtures, i.e. an increase in its stability and decrease in the flow value as well as an increase in voids in the mix. Results indicate that fibers have the potential to resist structural distress in pavement, in the wake of growing traffic loads and thus improve fatigue by increasing resistance to cracks or permanent deformation. On the whole, the results show that the addition of carbon fiber will improve some of the mechanical properties like fatigue and deformation in the flexible pavement. (author)

Sisal organosolv pulp as reinforcement for cement based composites

Directory of Open Access Journals (Sweden)

Ana Paula Joaquim

2009-09-01

Full Text Available The present work describes non-conventional sisal (Agave sisalana chemical (organosolv pulp from residues of cordage as reinforcement to cement based materials. Sisal organosolv pulp was produced in a 1:1 ethanol/water mixture and post chemically and physically characterized in order to compare its properties with sisal kraft pulp. Cement based composites reinforced with organosolv or kraft pulps and combined with polypropylene (PP fibres were produced by the slurry de-watering and pressing method as a crude simulation of the Hatschek process. Composites were evaluated at 28 days of age, after exposition to accelerated carbonation and after 100 soak/dry cycles. Composites containing organosolv pulp presented lower mechanical strength, water absorption and apparent porosity than composites reinforced with kraft pulp. The best mechanical performance after ageing was also achieved by samples reinforced with kraft pulp. The addition of PP fibres favoured the maintenance of toughness after ageing. Accelerated carbonation promoted the densification of the composites reinforced with sisal organosolv + PP fibres.

Potential of Carbon Nanotube Reinforced Cement Composites as Concrete Repair Material

Directory of Open Access Journals (Sweden)

Tanvir Manzur

2016-01-01

Full Text Available Carbon nanotubes (CNTs are a virtually ideal reinforcing agent due to extremely high aspect ratios and ultra high strengths. It is evident from contemporary research that utilization of CNT in producing new cement-based composite materials has a great potential. Consequently, possible practical application of CNT reinforced cementitious composites has immense prospect in the field of applied nanotechnology within construction industry. Several repair, retrofit, and strengthening techniques are currently available to enhance the integrity and durability of concrete structures with cracks and spalling, but applicability and/or reliability is/are often limited. Therefore, there is always a need for innovative high performing concrete repair materials with good mechanical, rheological, and durability properties. Considering the mechanical properties of carbon nanotubes (CNTs and the test results of CNT reinforced cement composites, it is apparent that such composites could be used conveniently as concrete repair material. With this end in view, the applicability of multiwalled carbon nanotube (MWNT reinforced cement composites as concrete repair material has been evaluated in this study in terms of setting time, bleeding, and bonding strength (slant shear tests. It has been found that MWNT reinforced cement mortar has good prospective as concrete repair material since such composites exhibited desirable behavior in setting time, bleeding, and slant shear.

Microstructural changes and residual properties of fiber reinforced cement composites exposed to elevated temperatures

Czech Academy of Sciences Publication Activity Database

Keppert, M.; Vejmelková, E.; Švarcová, Silvie; Bezdička, Petr; Černý, R.

2012-01-01

Roč. 17, č. 2 (2012), s. 77-89 ISSN 1425-8129 Institutional research plan: CEZ:AV0Z40320502 Keywords : fiber reinforced cementcomposites * high temperatures * mineralodical composition * microstructure * residual strength * apparent moisture diffusivity Subject RIV: JI - Composite Materials Impact factor: 0.385, year: 2012

Flexural strength using Steel Plate, Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) on reinforced concrete beam in building technology

Science.gov (United States)

Tarigan, Johannes; Patra, Fadel Muhammad; Sitorus, Torang

2018-03-01

Reinforced concrete structures are very commonly used in buildings because they are cheaper than the steel structures. But in reality, many concrete structures are damaged, so there are several ways to overcome this problem, by providing reinforcement with Fiber Reinforced Polymer (FRP) and reinforcement with steel plates. Each type of reinforcements has its advantages and disadvantages. In this study, researchers discuss the comparison between flexural strength of reinforced concrete beam using steel plates and Fiber Reinforced Polymer (FRP). In this case, the researchers use Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) as external reinforcements. The dimension of the beams is 15 x 25 cm with the length of 320 cm. Based on the analytical results, the strength of the beam with CFRP is 1.991 times its initial, GFRP is 1.877 times while with the steel plate is 1.646 times. Based on test results, the strength of the beam with CFRP is 1.444 times its initial, GFRP is 1.333 times while the steel plate is 1.167 times. Based on these test results, the authors conclude that beam with CFRP is the best choice for external reinforcement in building technology than the others.

Natural fiber-reinforced polymer composites

International Nuclear Information System (INIS)

Taj, S.; Khan, S.; Munawar, M.A.

2007-01-01

Natural fibers have been used to reinforce materials for over 3,000 years. More recently they have been employed in combination with plastics. Many types of natural fi fibers have been investigated for use in plastics including Flax, hemp, jute, straw, wood fiber, rice husks, wheat, barley, oats, rye, cane (sugar and bamboo), grass reeds, kenaf, ramie, oil palm empty fruit bunch, sisal, coir, water hyacinth, pennywort, kapok, paper-mulberry, raphia, banana fiber, pineapple leaf fiber and papyrus. Natural fibers have the advantage that they are renewable resources and have marketing appeal. The Asian markets have been using natural fibers for many years e.g., jute is a common reinforcement in India. Natural fibers are increasingly used in automotive and packaging materials. Pakistan is an agricultural country and it is the main stay of Pakistan's economy. Thousands of tons of different crops are produced but most of their wastes do not have any useful utilization. Agricultural wastes include wheat husk, rice husk, and their straw, hemp fiber and shells of various dry fruits. These agricultural wastes can be used to prepare fiber reinforced polymer composites for commercial use. This report examines the different types of fibers available and the current status of research. Many references to the latest work on properties, processing and application have been cited in this review. (author)

Superconducting properties and uniaxial strain characteristics of Nb3Sn fiber-reinforced superconductors with tantalum reinforcement fibers

International Nuclear Information System (INIS)

Arai, Kazuaki; Umeda, Masaichi; Agatsuma, Koh; Tateishi, Hiroshi

1998-01-01

We have been developing fiber-reinforced superconductors (FRS) for high-field and large-scale magnets. Tungsten fibers have been selected as the reinforcement fiber for FRS so far because tungsten has the highest elastic modulus of approximately 400 GPa which can minimize the strain from electromagnetic force. The preparation process of FRS consists of sputtering deposition and heat treatment because it may be difficult to apply drawing methods to materials of high-elastic modulus such as tungsten. Tantalum has high elastic modulus of 178 GPa and its thermal expansion coefficient that is closer to that of Nb 3 Sn than tungsten's, which means prestrain in Nb 3 Sn in FRS is reduced by adopting tantalum fibers. Tantalum has been used as barriers between bronze and copper in conventional Nb 3 Sn superconductors which are usually prepared with drawing process despite of the tantalum's high elastic modulus. That implies drawing process may be applied to prepare FRS with tantalum reinforcement fibers. In this paper, FRS using tantalum fibers prepared with sputtering process are described with making comparison with FRS of tungsten to clarify the basic properties of FRS using tantalum fibers. Depth profiles in Nb 3 Sn layer in FRS were measured to examine reaction between superconducting layers and reinforcement fibers. Superconducting properties including strain and stress characteristics were shown. Those data will contribute to design of FRS using tantalum reinforcement fibers with adopts the drawing processes. (author)

Effect of resin cement, aging process and root level on the bond strength of the resin-fiber posts

Science.gov (United States)

Almuhim, Khalid Salman

Background. Little is known about the long-term clinical bonding effectiveness of the Fiber-reinforced composite (FRC) posts cemented with self-etch adhesive systems. Bond stability and longevity of the cemented post are adversely affected by physical and chemical factors over time, such as expansion and contraction stresses caused by thermal changes and occlusal load. This clinical condition can be simulated in vitro by thermocyclic loading; and bonding effectiveness can be evaluated by applying the micropush out test. Therefore, more in vitro studies are needed to evaluate the bond strength of the fiber posts cemented with different resin cement systems after simulating the artificial aging induced by thermocycling. The aim of this study was to compare the microtensile bond strength of two different resin cement systems (total etch, and self-etch resin cement system) used for cementation of fiber reinforced composite posts in three different aging periods using thermocycling. Methods. Following IRB approval, sixty freshly extracted bicuspid single rooted natural teeth were endodontically treated, and the post-spaces were prepared to receive a fiber-post cemented with either a total etch resin cement (Rely-X Ultimate) or with a self-etch resin cement (Rely-X Unicem). No thermocycling, 20,000 and 40,000 cycles was used to age the specimens. Teeth were randomly allocated into six different groups: G1 - Control: Rely-X Ultimate cement with no thermocycling. G2: Rely-X Ultimate cement with 20,000 thermocycling. G3: Rely-X Ultimate cement with 40,000 thermocycling. G4: Rely-X Unicem cement. G5: Rely-X Unicem cement. G6: Rely-X Unicem cement. Microtensile bond strength determined using a micropush out test on a universal testing machine (MTS). Additionally, the failure mode of each specimen was observed under a stereomicroscope (Olympus) at 40x magnification. Finally, one representative sample was randomly selected from each of the five failure modes for scanning

Performance polymeric concrete with synthetic fiber reinforcement against reflective cracking in rigid pavement overlay

International Nuclear Information System (INIS)

Khan, N.U.; Khan, B.

2012-01-01

Cement concrete pavements are used for heavy traffic loads throughout the world owing to its better and economical performance. Placing of a concrete overlay on the existing pavement is the most prevalent rehabilitating method for such pavements, however, the problem associated with the newly placed overlay is the occurrence of reflective cracking. This paper presents an assessment of the performance of polymeric concrete with synthetic fiber reinforcement against reflective cracking in an overlay system. The performance of polymeric concrete with synthetic fibers as an overlay material is measured in terms of the load-deflection, strain-deflection and load-strain behavior of beams of the polymeric concrete. For this purpose, five types of beams having different number of fiber wires and position are tested for flexure strength. Deflection/strains for each increment of load are recorded. In addition, cubes of plain concrete and of concrete with synthetic fiber needles were tested after 7 and 28 days for compressive strengths. Finite element models in ANSYS software for the beams have also been developed. Beams with greater number of longitudinal fiber wires displayed relatively better performance against deflection whilst beams with synthetic fiber needles showed better performance against strains. Thus, polymeric concrete overlay with fiber reinforcement will serve relatively better against occurrence of reflective cracking. (author)

Effect of kenaf fiber in reinforced concrete slab

Science.gov (United States)

Syed Mohsin, S. M.; Baarimah, A. O.; Jokhio, G. A.

2018-04-01

The effect of kenaf fibers in reinforced concrete slab with different thickness is discusses and presented in this paper. Kenaf fiber is a type of natural fiber and is added in the reinforced concrete slab to improve the structure strength and ductility. For this study, three types of mixtures were prepared with fiber volume fraction of 0%, 1% and 2%, respectively. The design compressive strength considered was 20 MPa. Six cubes were prepared to be tested at 7th and 28th day. A total of six reinforced concrete slab with two variances of thickness were also prepared and tested under four-point bending test. The differences in the thickness is to study the potential of kenaf fiber to serve as part of shear reinforcement in reinforced concrete slab that was design to fail in shear. It was observed that, addition of kenaf fiber in reinforced concrete slab improves the flexural strength and ductility of the reinforced concrete slab. In the slab with reduction in thickness, the mode of failure change from brittle to ductile with the inclusion of kenaf fiber.

Fatigue Performance of Fiber Reinforced Concrete

DEFF Research Database (Denmark)

Jun, Zhang; Stang, Henrik

1996-01-01

The objective of the present study is to obtain basic data of fibre reinforced concrete under fatigue load and to set up a theoretical model based on micromechanics. In this study, the bridging stress in fiber reinforced concrete under cyclic tensile load was investigted in details. The damage...... mechanism of the interface between fiber and matrix was proposed and a rational model given. Finally, the response of a steel fiber reinforced concrete beam under fatigue loading was predicted based on this model and compared with experimental results....

Effect of nylon fiber on mechanical properties of cement based mortar

Science.gov (United States)

Hanif, I. M.; Syuhaili, M. R. Noor; Hasmori, M. F.; Shahmi, S. M.

2017-11-01

An investigation has been carried out to study the effect of nylon fiber on the mechanical properties of cement based mortar after receiving large quantities of nylon waste. Subsequently, this research was conducted to compare the compressive, tensile and flexural strength of normal cement based mortar with nylon fiber cement based mortar. All samples using constant water-cement ratio of 0.63 and three different percentages of nylon fiber were added in the mixture during the samples preparation period which consists of 0.5%, 1.5% and 2.5% by total weight of cement based mortar. The results obtained with different nylon percentage marked an increases in compressive strength (up to 17%), tensile strength (up to 21%) and flexural strength (up to 13%) when compared with control cement based mortar samples. Therefore, the results obtained from this study shows that by using nylon fiber as additive material can improve the mechanical properties of the cement based mortar and at the same time produce a good sustainable product that can protects and conserve the marine environment.

Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

Science.gov (United States)

Aslani, Farhad; Nejadi, Shami

2012-09-01

Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths ( τ ( app)) and slip coefficient ( β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle ( ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers

THE USE OF SISAL FIBRE AS REINFORCEMENT IN CEMENT BASED COMPOSITES

OpenAIRE

Tolêdo Filho,Romildo Dias; Joseph,Kuruvilla; Ghavami,Khosrow; England,George Leslie

1999-01-01

ABSTRACT The inclusion of fibre reinforcement in concrete, mortar and cement paste can enhance many of the engineering properties of the basic materials, such as fracture toughness, flexural strength and resistance to fatigue, impact, thermal shock and spalling. In recent years, a great deal of interest has been created worldwide on the potential applications of natural fibre reinforced, cement based composites. Investigations have been carried out in many countries on various mechanical prop...

Enhanced impact properties of cementitious composites reinforced with pultruded flax/polymeric matrix fabric

Directory of Open Access Journals (Sweden)

Magdi El-Messiry

2017-09-01

Full Text Available Fiber reinforced concrete (FRC has become increasingly applied in civil engineering in the last decades. Natural fiber fabric reinforced cement composites are considered to prevent damage resulting from an impact loading on the cementite plate. Flax woven fabric that has a high energy absorption capability was chosen. To increase the interfacial shear properties, the fabric was pultruded with different matrix properties that affect the strength and toughness of the pultruded fabric. In this study, three fabric structures are used to increase the anchoring of the cement in the fabric. The compressive strength and the impact energy were measured. The results revealed that pultruded fabric reinforced cement composite (PFRC absorbs much more impact energy. PFRC under impact loading has more micro cracks, while plain cement specimen shows brittle failure. The compressive test results of PFRC indicate that flax fiber fabric polymer enhanced compressive strength remarkably. Fiber reinforcement is a very effective in improving the impact resistance of PFRC. The study defines the influence factors that control the energy dissipation of the composite, which are the hardness of the polymer and the fabric cover factor. Significant correlation between impact energy and compressive strength was proved.

Mechanical Properties of High Volume Fly Ash Concrete Reinforced with Hybrid Fibers

Directory of Open Access Journals (Sweden)

Rooban Chakravarthy

2016-01-01

Full Text Available Fly ash substitution to cement is a well-recognized approach to reduce CO2 emissions. Although fly ash concrete is prone to brittle behavior, researchers have shown that addition of fibers could reduce brittle behavior. Previous research efforts seem to have utlised a single type of fiber or two types of fibers. In this research, three types of fibers, steel, polypropylene, and basalt as 0%, 0.50%, 0.75%, and 1% by volume of concrete, were mixed in varying proportions with concrete specimens substituted with 50% fly ash (class F. All specimens were tested for compressive strength, indirect tensile strength, and flexural strength over a period of 3 to 56 days of curing. Test results showed that significant improvement in mechanical properties could be obtained by a particular hybrid fiber reinforcement combination (1% steel fiber, 0.75% polypropylene fiber, and 0.75% basalt fiber. The strength values were observed to exceed previous research results. Workability of concrete was affected when the fiber combination exceeded 3%. Thus a limiting value for adding fibers and the combination to achieve maximum strengths have been identified in this research.

Effect of sepiolite on the flocculation of suspensions of fibre-reinforced cement

International Nuclear Information System (INIS)

Jarabo, Rocio; Fuente, Elena; Moral, Ana; Blanco, Angeles; Izquierdo, Laura; Negro, Carlos

2010-01-01

Sepiolite is used to increase thixotropy of cement slurries for easier processing, to prevent sagging and to provide a better final quality in the manufacture of fibre-reinforced cement products. However, the effect of sepiolite on flocculation and its interactions with the components of fibre cement are yet unknown. The aim of this research is to study the effects of sepiolite on the flocculation of different fibre-reinforced cement slurries induced by anionic polyacrylamides (A-PAMs). Flocculation and floc properties were studied by monitoring the chord size distribution in real time employing a focused beam reflectance measurement (FBRM) probe. The results show that sepiolite increases floc size and floc stability in fibre-cement suspensions. Sepiolite competes with fibres and clay for A-PAMs adsorption and its interaction with A-PAM improves flocculation of mineral particles.

Single fiber pullout from hybrid fiber reinforced concrete

NARCIS (Netherlands)

Markovich, I.; Van Mier, J.G.M.; Walraven, J.C.

2001-01-01

Hybrid fiber reinforcement can be very efficient for improving the tensile response of the composite. In such materials, fibers of different geometries can act as bridging mechanisms over cracks of different widths. The fiber bridging efficiency depends on the interface properties, which makes

Study on the effects of white rice husk ash and fibrous materials additions on some properties of fiber-cement composites.

Science.gov (United States)

Hamzeh, Yahya; Ziabari, Kamran Pourhooshyar; Torkaman, Javad; Ashori, Alireza; Jafari, Mohammad

2013-03-15

This work assesses the effects of white rice husk ash (WRHA) as pozzolanic material, virgin kraft pulp (VKP), old corrugated container (OCC) and fibers derived from fiberboard (FFB) as reinforcing agents on some properties of blended cement composites. In the sample preparation, composites were manufactured using fiber-to-cement ratio of 25:75 by weight and 5% CaCl(2) as accelerator. Type II Portland cement was replaced by WRHA at 0%, 25% and 50% by weight of binder. A water-to-binder ratio of 0.55 was used for all blended cement paste mixes. For parametric study, compressive strength, water absorption and density of the composite samples were evaluated. Results showed that WRHA can be applied as a pozzolanic material to cement and also improved resistance to water absorption. However, increasing the replacement level of WRHA tends to reduce the compressive strength due to the low binding ability. The optimum replacement level of WRHA in mortar was 25% by weight of binder; this replacement percentage resulted in better compressive strengths and water absorption. OCC fiber is shown to be superior to VKF and FFB fibers in increasing the compressive strength, due to its superior strength properties. As expected, the increase of the WRHA content induced the reduction of bulk density of the cement composites. Statistical analysis showed that the interaction of above-mentioned variable parameters was significant on the mechanical and physical properties at 1% confidence level. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Influence of Portland Cement Class on the Corrosion Rate of Steel Reinforcement in Cement Mortar Caused by Penetrating Chloride and Sulfate from the Environment

Directory of Open Access Journals (Sweden)

Bikić, F.

2013-01-01

Full Text Available The influence of portland cement class on the corrosion rate of steel reinforcement in cement mortar caused by penetrating chloride or sulfate from the environment in already hardened cement mortar is investigated in this paper. Three classes of portland cement have been used for the tests, PC 35, PC 45 and PC 55. Cylindrical samples of cement mortar with steel reinfor- cement in the middle were treated 6 months at room temperature in the following solutions: w(SO42- = 2.1 % and w(Cl- = 5 %. Two techniques have been used for testing corrosion rate of steel reinforcement in cement mortar: Tafel extrapolation technique and potentiodynamic polarization technique. Investigations were conducted by potentiostat/galvanostat Princeton Applied Research 263A-2 with the software PowerCORR®. The results of both techniques indi-cate the most active corrosion of steel reinforcement in the samples prepared from cement PC 35 in both treated solutions, while the lowest corrosion of the steel reinforcement was observed in cement samples prepared from cement PC 55. This conclusion was drawn by analyzing the results shown in Figs. 1–4. Comparing corrosion current density of samples, working electrodes, Figs. 1 and 2, Table 2, the results show the most stable corrosion of steel reinforcement in samples prepared from cement PC 55, and the most active corrosion in samples prepared from ce- ment PC 35. The most active corrosion in samples prepared from cement PC 35 is evident from the positions of the open circuit potentials whose values are less for samples prepared from cement PC 35 in both the treated solution, Figs. 1 and 2, Table 2. Comparison of the anodic polarization curves of the working electrodes in both the treated solutions, Figs. 3 and 4, also shows that the intensity of corrosion is the largest for the working electrodes prepared from cement PC 35 and the smallest for the working electrodes prepared from cement PC 55. Investigation results should be

Hybrid Effect Evaluation of Steel Fiber and Carbon Fiber on the Performance of the Fiber Reinforced Concrete.

Science.gov (United States)

Song, Weimin; Yin, Jian

2016-08-18

Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF) and carbon fiber (CF) was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC), carbon fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC) were explored at steel fiber volume fraction 0.5%, 1%, 1.5% and carbon fiber 0.1%, 0.2%, 0.3%. Results showed that the addition of steel fiber and carbon fiber can increase the compressive strength. SF, CF and the hybridization between them could increase the compressive toughness significantly. The impact test results showed that as the volume of fiber increased, the impact number of the first visible crack and the ultimate failure also increased. The improvement of toughness mainly lay in improving the crack resistance after the first crack. Based on the test results, the positive hybrid effect of steel fiber and carbon fiber existed in hybrid fiber reinforced concrete. The relationship between the compressive toughness and impact toughness was also explored.

Behavior of Low Grade Steel Fiber Reinforced Concrete Made with Fresh and Recycled Brick Aggregates

Directory of Open Access Journals (Sweden)

Md. Shariful Islam

2017-01-01

Full Text Available In recent years, recycled aggregates from construction and demolition waste (CDW have been widely accepted in construction sectors as the replacement of coarse aggregate in order to minimize the excessive use of natural resources. In this paper, an experimental investigation is carried out to observe the influence of low grade steel fiber reinforcements on the stress-strain behavior of concrete made with recycled and fresh brick aggregates. In addition, compressive strength by destructive and nondestructive tests, splitting tensile strength, and Young’s modulus are determined. Hooked end steel wires with 50 mm of length and an aspect ratio of 55.6 are used as fiber reinforcements in a volume fraction of 0% (control case, 0.50%, and 1.00% in concrete mixes. The same gradation of aggregates and water-cement ratio (w/c=0.44 were used to assess the effect of steel fiber in all these concrete mixes. All tests were conducted at 7, 14, and 28 days to perceive the effect of age on different mechanical properties. The experimental results show that around 10%～15% and 40%～60% increase in 28 days compressive strength and tensile strength of steel fiber reinforced concrete, respectively, compared to those of the control case. It is observed that the effect of addition of 1% fiber on the concrete compressive strength is little compared to that of 0.5% steel fiber addition. On the other hand, strain of concrete at failure of steel fiber reinforced concrete has increased almost twice compared to the control case. A simple analytical model is also proposed to generate the ascending portions of the stress-strain curve of concrete. There exists a good correlation between the experimental results and the analytical model. A relatively ductile failure is observed for the concrete made with low grade steel fibers.

Performance of Lightweight Natural-Fiber Reinforced Concrete

OpenAIRE

Hardjasaputra Harianto; Ng Gino; Urgessa Girum; Lesmana Gabriella; Sidharta Steven

2017-01-01

Concrete, the most common construction material, has negligible tension capacity. However, a reinforcement material such as natural fibers, can be used to improve the tensile properties of concrete. This paper presents experiments conducted on Super Lightweight Concrete mixed with coconut fibers (SLNFRC). Coconut fibers are regarded as one of the toughest natural fibers to strengthen concrete. Coconut fiber reinforced composites have been considered as a sustainable construction material beca...

Enhancing corrosion resistance of reinforced concrete structures with hybrid fiber reinforced concrete

International Nuclear Information System (INIS)

Blunt, J.; Jen, G.; Ostertag, C.P.

2015-01-01

Highlights: • Reinforced concrete beams were subjected to cyclic flexural loading. • Hybrid fiber reinforced composites were effective in reducing corrosion rates. • Crack resistance due to fibers increased corrosion resistance of steel rebar. • Galvanic corrosion measurements underestimated corrosion rates. • Polarization resistance measurements predicted mass loss more accurately. - Abstract: Service loads well below the yield strength of steel reinforcing bars lead to cracking of reinforced concrete. This paper investigates whether the crack resistance of Hybrid Fiber Reinforced Concrete (HyFRC) reduces the corrosion rate of steel reinforcing bars in concrete after cyclic flexural loading. The reinforcing bars were extracted to examine their surface for corrosion and compare microcell and macrocell corrosion mass loss estimates against direct gravimetric measurements. A delay in corrosion initiation and lower active corrosion rates were observed in the HyFRC beam specimens when compared to reinforced specimens containing plain concrete matrices cycled at the same flexural load

Homogenization of long fiber reinforced composites including fiber bending effects

DEFF Research Database (Denmark)

Poulios, Konstantinos; Niordson, Christian Frithiof

2016-01-01

This paper presents a homogenization method, which accounts for intrinsic size effects related to the fiber diameter in long fiber reinforced composite materials with two independent constitutive models for the matrix and fiber materials. A new choice of internal kinematic variables allows...... of the reinforcing fibers is captured by higher order strain terms, resulting in an accurate representation of the micro-mechanical behavior of the composite. Numerical examples show that the accuracy of the proposed model is very close to a non-homogenized finite-element model with an explicit discretization...

Flexural strength of self compacting fiber reinforced concrete beams using polypropylene fiber: An experimental study

Science.gov (United States)

Lisantono, Ade; Praja, Baskoro Abdi; Hermawan, Billy Nouwen

2017-11-01

One of the methods to increase the tensile strength of concrete is adding a fiber material into the concrete. While to reduce a noise in a construction project, a self compacting concrete was a good choices in the project. This paper presents an experimental study of flexural behavior and strength of self compacting fiber reinforced concrete (RC) beams using polypropylene fiber. The micro monofilament polypropylene fibers with the proportion 0.9 kg/m3 of concrete weight were used in this study. Four beam specimens were cast and tested in this study. Two beams were cast of self compacting reinforced concrete without fiber, and two beams were cast of self compacting fiber reinforced concrete using polypropylene. The beams specimen had the section of (180×260) mm and the length was 2000 mm. The beams had simple supported with the span of 1800 mm. The longitudinal reinforcements were using diameter of 10 mm. Two reinforcements of Ø10 mm were put for compressive reinforcement and three reinforcements of Ø10 mm were put for tensile reinforcement. The shear reinforcement was using diameter of 8 mm. The shear reinforcements with spacing of 100 mm were put in the one fourth near to the support and the spacing of 150 mm were put in the middle span. Two points loading were used in the testing. The result shows that the load-carrying capacity of the self compacting reinforced concrete beam using polypropylene was a little bit higher than the self compacting reinforced concrete beam without polypropylene. The increment of load-carrying capacity of self compacting polypropylene fiber reinforced concrete was not so significant because the increment was only 2.80 % compare to self compacting non fiber reinforced concrete. And from the load-carrying capacity-deflection relationship curves show that both the self compacting polypropylene fiber reinforced concrete beam and the self compacting non fiber reinforced concrete beam were ductile beams.

Quantitative radiographic analysis of fiber reinforced polymer composites.

Science.gov (United States)

Baidya, K P; Ramakrishna, S; Rahman, M; Ritchie, A

2001-01-01

X-ray radiographic examination of the bone fracture healing process is a widely used method in the treatment and management of patients. Medical devices made of metallic alloys reportedly produce considerable artifacts that make the interpretation of radiographs difficult. Fiber reinforced polymer composite materials have been proposed to replace metallic alloys in certain medical devices because of their radiolucency, light weight, and tailorable mechanical properties. The primary objective of this paper is to provide a comparable radiographic analysis of different fiber reinforced polymer composites that are considered suitable for biomedical applications. Composite materials investigated consist of glass, aramid (Kevlar-29), and carbon reinforcement fibers, and epoxy and polyether-ether-ketone (PEEK) matrices. The total mass attenuation coefficient of each material was measured using clinical X-rays (50 kev). The carbon fiber reinforced composites were found to be more radiolucent than the glass and kevlar fiber reinforced composites.

Fracture toughness of titanium–cement interfaces: effects of fibers and loading angles

Directory of Open Access Journals (Sweden)

Khandaker M

2014-04-01

Full Text Available Morshed Khandaker,1 Khatri Chhetri Utsaha,1 Tracy Morris21Department of Engineering and Physics, 2Department of Mathematics and Statistics, University of Central Oklahoma, Edmond, OK, USAAbstract: Ideal implant–cement or implant–bone interfaces are required for implant fixation and the filling of tissue defects created by disease. Micron- to nanosize osseointegrated features, such as surface roughness, fibers, porosity, and particles, have been fused with implants for improving the osseointegration of an implant with the host tissue in orthopedics and dentistry. The effects of fibers and loading angles on the interface fracture toughness of implant–cement specimens with and without fibers at the interface are not yet known. Such studies are important for the design of a long-lasting implant for orthopedic applications. The goal of this study was to improve the fracture toughness of an implant–cement interface by deposition of micron- to nanosize fibers on an implant surface. There were two objectives in the study: 1 to evaluate the influence of fibers on the fracture toughness of implant–cement interfaces with and without fibers at the interfaces, and 2 to evaluate the influence of loading angles on implant–cement interfaces with and without fibers at the interfaces. This study used titanium as the implant, poly(methyl methacrylate (PMMA as cement, and polycaprolactone (PCL as fiber materials. An electrospinning unit was fabricated for the deposition of PCL unidirectional fibers on titanium (Ti plates. The Evex tensile test stage was used to determine the interface fracture toughness (KC of Ti–PMMA with and without PCL fibers at 0°, 45°, and 90° loading angles, referred to in this article as tension, mixed, and shear tests. The study did not find any significant interaction between fiber and loading angles (P>0.05, although there was a significant difference in the KC means of Ti–PMMA samples for the loading angles (P<0

Effects of fibers on expansive shotcrete mixtures consisting of calcium sulfoaluminate cement, ordinary Portland cement, and calcium sulfate

Directory of Open Access Journals (Sweden)

H. Yu

2018-04-01

Full Text Available The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction method is using expansive shotcrete mixture consisting of calcium sulfoaluminate cement (CSA, ordinary Portland cement (OPC, and calcium sulfate (CS to reduce shrinkage. Furthermore, fibers can be added to the mixture to restrain expansion and impede cracking. The objective of this paper is to study the effects of nylon fiber, glass fiber, and steel fiber on an expansive shotcrete mixture that can better resist cracking. In this study, parameters such as density, water absorption, volume of permeable voids, unconfined compressive strength (UCS, splitting tensile strength (STS, and volume change of fiber-added expansive mixtures were determined at different time periods (i.e. the strengths on the 28th day, and the volume changes on the 1st, 7th, 14th, 21st, and 28th days. The results show that addition of fibers can improve mixture durability, in the form of decreased water absorption and reduced permeable pore space content. Moreover, the expansion of the CSA-OPC-CS mixture was restrained up to 50% by glass fiber, up to 43% by nylon fiber, and up to 28% by steel fiber. The results show that the STS was improved by 57% with glass fiber addition, 43% with steel fiber addition, and 38% with nylon fiber addition. The UCS was also increased by 31% after steel fiber addition, 26% after nylon fiber addition, and 16% after glass fiber addition. These results suggest that fiber additions to the expansive shotcrete mixtures can improve durability and strengths while controlling expansion. Keywords: Shotcrete, Restrained expansion, Fibers, Calcium sulfoaluminate cement (CSA, Ordinary Portland cement (OPC, Calcium sulfate (CS

Cohesive fracture model for functionally graded fiber reinforced concrete

International Nuclear Information System (INIS)

Park, Kyoungsoo; Paulino, Glaucio H.; Roesler, Jeffery

2010-01-01

A simple, effective, and practical constitutive model for cohesive fracture of fiber reinforced concrete is proposed by differentiating the aggregate bridging zone and the fiber bridging zone. The aggregate bridging zone is related to the total fracture energy of plain concrete, while the fiber bridging zone is associated with the difference between the total fracture energy of fiber reinforced concrete and the total fracture energy of plain concrete. The cohesive fracture model is defined by experimental fracture parameters, which are obtained through three-point bending and split tensile tests. As expected, the model describes fracture behavior of plain concrete beams. In addition, it predicts the fracture behavior of either fiber reinforced concrete beams or a combination of plain and fiber reinforced concrete functionally layered in a single beam specimen. The validated model is also applied to investigate continuously, functionally graded fiber reinforced concrete composites.

Reinforcing graphene oxide/cement composite with NH2 ...

Indian Academy of Sciences (India)

Reinforcing graphene oxide/cement composite with NH2 functionalizing group. M EBRAHIMIZADEH ABRISHAMI1,∗ and V ZAHABI2. 1Materials and Electroceramics Laboratory, Department of Physics, Ferdowsi University of Mashhad, Mashhad. 9177948974, Iran. 2Department of Civil Engineering, Islamic Azad University, ...

Influence of fiber upon the radiation degradation of fiber-reinforced plastics

International Nuclear Information System (INIS)

Udagawa, Akira

1992-01-01

Influences of fiber upon the radiation degradation of fiber-reinforced plastics were investigated by using 2 MeV electrons. Radiation resistances were evaluated from the three-point bending strength of the fiber laminates which used bisphenol A-type epoxy resin as a matrix. Carbon fiber laminates had higher radiation resistance values than the laminates made of glass fiber. Model laminates using polyethylene as a matrix were prepared in order to examine the differences between carbon fiber and glass fiber filler, the relation between gel fraction and absorbed dose was established. When the polyethylene was filled in the carbon fiber, forming the gel was strikingly delayed. This result suggests that radiation protective action existing in carbon fiber to matrix resin is the main cause of the higher radiation resistance of carbon fiber reinforced plastics. (author)

Structural Behavior of Concrete Beams Reinforced with Basalt Fiber Reinforced Polymer (BFRP) Bars

Science.gov (United States)

Ovitigala, Thilan

The main challenge for civil engineers is to provide sustainable, environmentally friendly and financially feasible structures to the society. Finding new materials such as fiber reinforced polymer (FRP) material that can fulfill the above requirements is a must. FRP material was expensive and it was limited to niche markets such as space shuttles and air industry in the 1960s. Over the time, it became cheaper and spread to other industries such as sporting goods in the 1980-1990, and then towards the infrastructure industry. Design and construction guidelines are available for carbon fiber reinforced polymer (CFRP), aramid fiber reinforced polymer (AFRP) and glass fiber reinforced polymer (GFRP) and they are currently used in structural applications. Since FRP is linear elastic brittle material, design guidelines for the steel reinforcement are not valid for FRP materials. Corrosion of steel reinforcement affects the durability of the concrete structures. FRP reinforcement is identified as an alternative to steel reinforcement in corrosive environments. Although basalt fiber reinforced polymer (BFRP) has many advantages over other FRP materials, but limited studies have been done. These studies didn't include larger BFRP bar diameters that are mostly used in practice. Therefore, larger beam sizes with larger BFRP reinforcement bar diameters are needed to investigate the flexural and shear behavior of BFRP reinforced concrete beams. Also, shear behavior of BFRP reinforced concrete beams was not yet studied. Experimental testing of mechanical properties and bond strength of BFRP bars and flexural and shear behavior of BFRP reinforced concrete beams are needed to include BFRP reinforcement bars in the design codes. This study mainly focuses on the use of BFRP bars as internal reinforcement. The test results of the mechanical properties of BFRP reinforcement bars, the bond strength of BFRP reinforcement bars, and the flexural and shear behavior of concrete beams

Electrically conductive Portland cement concrete.

Science.gov (United States)

1986-01-01

There is a need for an effective, simple-to-install secondary anode system for use in the cathodic protection of reinforced concrete bridge decks. In pursuit of such a system, carbon fibers and carbon black were incorporated in portland cement concre...

Experimental analysis of reinforced concrete beams strengthened in bending with carbon fiber reinforced polymer

Directory of Open Access Journals (Sweden)

M. M. VIEIRA

Full Text Available The use of carbon fiber reinforced polymer (CFRP has been widely used for the reinforcement of concrete structures due to its practicality and versatility in application, low weight, high tensile strength and corrosion resistance. Some construction companies use CFRP in flexural strengthening of reinforced concrete beams, but without anchor systems. Therefore, the aim of this study is analyze, through an experimental program, the structural behavior of reinforced concrete beams flexural strengthened by CFRP without anchor fibers, varying steel reinforcement and the amount of carbon fibers reinforcement layers. Thus, two groups of reinforced concrete beams were produced with the same geometric feature but with different steel reinforcement. Each group had five beams: one that is not reinforced with CFRP (reference and other reinforced with two, three, four and five layers of carbon fibers. Beams were designed using a computational routine developed in MAPLE software and subsequently tested in 4-point points flexural test up to collapse. Experimental tests have confirmed the effectiveness of the reinforcement, ratifying that beams collapse at higher loads and lower deformation as the amount of fibers in the reinforcing layers increased. However, the increase in the number of layers did not provide a significant increase in the performance of strengthened beams, indicating that it was not possible to take full advantage of strengthening applied due to the occurrence of premature failure mode in the strengthened beams for pullout of the cover that could have been avoided through the use of a suitable anchoring system for CFRP.

Assessment of Physical and Mechanical Properties of Cement Panel Influenced by Treated and Untreated Coconut Fiber Addition

Science.gov (United States)

Abdullah, Alida; Jamaludin, Shamsul Baharin; Anwar, Mohamed Iylia; Noor, Mazlee Mohd; Hussin, Kamarudin

This project was conducted to produce a cement panel with the addition of treated and untreated coconut fiber in cement panel. Coconut fiber was added to replace coarse aggregate (sand) in this cement panel. In this project, the ratios used to design the mixture were 1:1:0, 1:0.97:0.03, 1:0.94:0.06, 1:0.91:0.09 (cement: sand: coconut fiber). The water cement ratio was constant at 0.55. The sizes of sample tested were, 160 mm x 40 mm x 40 mm for compression test, and 100 mm x 100 mm x 40 mm for density, moisture content and water absorption tests. After curing samples for 28 days, it was found that the addition of coconut fiber, further increase in compressive strength of cement panel with untreated coconut fiber. Moisture content of cement panel with treated coconut fiber increased with increasing content of coconut fiber whereas water absorption of cement panel with untreated coconut fiber increased with increasing content of coconut fiber. The density of cement panel decreased with the addition of untreated and treated coconut fiber.

Deflection hardening of sustainable fiber–cement composites

OpenAIRE

Lima, P. R. L.; Santos, D. O. J.; Fontes, C. M. A.; Barros, Joaquim A. O.; Toledo Filho, R. D.

2016-01-01

In the present study sisal fiber–cement composites reinforced with 4% and 6% of short fibers were developed and their physical–mechanical behavior was characterized. To ensure the composite sustainability and durability, the ordinary Portland cement matrix was modified by adding fly ash and metakaolin, and the natural aggregate was substituted by 10% and 20% of recycled concrete aggregate. Flat sheets were cast in a self-compacted cement matrix and bending tests were performed ...

Fracture strengths of chair-side-generated veneers cemented with glass fibers.

Science.gov (United States)

Turkaslan, S; Bagis, B; Akan, E; Mutluay, M M; Vallittu, P K

2015-01-01

CAD/CAM (computer-aided design and computer-aided manufacturing) systems have refreshed the idea of chair-side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of CAD/CAM-generated ceramic veneers. Therefore, this study compared the fracture strengths of ceramic veneers produced at chair side and cemented with or without glass fibers with those of composite veneers. Thirty intact mandibular incisors were randomly divided into three groups ( n = 10) and treated with CAD/CAM-fabricated veneers cemented with dual-cure composite resin luting cement (CRLC; Group 1), CAD/CAM-fabricated veneers cemented with a glass fiber network (GFN) and dual-cure CRLC (Group 2), and a direct particulate filler composite veneer constructed utilizing fiber and a restorative composite resin (Group 3). The specimens were tested with a universal testing machine after thermal cycling treatment. The loads at the start of fracture were the lowest for traditionally fabricated composite veneers and higher for CAD/CAM-generated. Veneers cemented either without or with the GFN. The failure initiation loads (N) for the veneers were 798.92 for Group 1, 836.27 for Group 2, and 585.93 for Group 3. The predominant failure mode is adhesive failure between the laminates and teeth for Group 1, cohesive failure in the luting layer for Group 2, and cohesive laminate failure for Group 3, which showed chipping and small fractures. Ceramic material is a reliable alternative for veneer construction at chair side. Fibers at the cementation interface may improve the clinical longevity and provide higher fracture strength values.

Push-out bond strengths of different dental cements used to cement glass fiber posts.

Science.gov (United States)

Pereira, Jefferson Ricardo; Lins do Valle, Accácio; Ghizoni, Janaina Salomon; Lorenzoni, Fábio César; Ramos, Marcelo Barbosa; Barbosa, Marcelo Ramos; Dos Reis Só, Marcus Vinícius

2013-08-01

Since the introduction of glass fiber posts, irreversible vertical root fractures have become a rare occurrence; however, adhesive failure has become the primary failure mode. The purpose of this study was to evaluate the push-out bond strength of glass fiber posts cemented with different luting agents on 3 segments of the root. Eighty human maxillary canines with similar root lengths were randomly divided into 8 groups (n=10) according to the cement assessed (Rely X luting, Luting and Lining, Ketac Cem, Rely X ARC, Biscem, Duo-link, Rely X U100, and Variolink II). After standardized post space preparation, the root dentin was pretreated for dual-polymerizing resin cements and untreated for the other cements. The mixed luting cement paste was inserted into post spaces with a spiral file and applied to the post surface that was seated into the canal. After 7 days, the teeth were sectioned perpendicular to their long axis into 1-mm-thick sections. The push-out test was performed at a speed of 0.5 mm/min until extrusion of the post occurred. The results were evaluated by 2-way ANOVA and the all pairwise multiple comparison procedures (Tukey test) (α=.05). ANOVA showed that the type of interaction between cement and root location significantly influenced the push-out strength (Pcements and glass ionomer cements showed significantly higher values compared to dual-polymerizing resin cements. In all root segments, dual-polymerizing resin cements provided significantly lower bond strength. Significant differences among root segments were found only for Duo-link cement. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Application of Fiber Reinforcement Concrete Technique in Civil ...

African Journals Online (AJOL)

modulus of elasticity, high tensile strength, improved fatigue and impact resistance. Reinforcing the concrete structures with fibers such as polyester is one of the possible ways to provide all the criteria of the durable repair material. This type of reinforcement is called Fiber Reinforcement of Concrete Structures. There is an ...

Analysis of the mechanical resistance and porosity of a composite cement with EVA and reinforced with piacava fibers; Analise da resistencia mecanica e porosidade de um composito cimenticio leve com EVA e reforcado com fibras de piacava

Energy Technology Data Exchange (ETDEWEB)

Silva, R.M.; Dominguez, D.S.; Alvim, R.C.; Iglesias, S.M., E-mail: regilan@hotmail.com [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil)

2013-07-01

Nowadays, a lot of solid waste material is discarded into the environment. One of these residues is the EVA (Ethyl Vinyl Acetate) which has the footwear industry, as its main consumer. Studies are focused on the reusing of these materials, particularly in the civil construction, where is used as an aggregate in the production of light mortars. Due to the specific characteristics of lightweight concrete, is necessary to reinforce these materials. The palm Attalea Funifera Martius, known as piacava, may be an excellent alternative as a reinforcement element in light cement mixes. In this work, it's verified the mechanical strength of a composite lightweight cementitious with EVA and reinforced with Piacava fibers, also, the porosity of the new material was measured. To evaluate the mechanical properties of this new material was made mechanical tests and verified the importance of vegetal fibers as the material reinforcing. For the compound porosity evaluation, samples were studied using microcomputer tomography (μTC). With images processing techniques we identify and quantify the pores. The processing digital images through μTC showed up as a non-destructive method for efficient and acceptable results. (author)

Comparison between three glass fiber post cementation techniques.

Science.gov (United States)

Migliau, Guido; Piccoli, Luca; Di Carlo, Stefano; Pompa, Giorgio; Besharat, Laith Konstantinos; Dolci, Marco

2017-01-01

The aim of this experimental study was to compare the traditional cement systems with those of the latest generation, to assess if indeed these could represent of viable substitutes in the cementation of indirect restorations, and in the specific case of endodontic posts. The assessment of the validity of the cementing methods was performed according to the test of the push-out, conducted on sections obtained from the roots of treated teeth. The samples were divided into three groups. Group A (10 samples): etching for 30 seconds with 37% orthophosphoric acid (Superlux-Thixo-etch-DMG) combined with a dual-curing adhesive system (LuxaBond-Total Etch-DMG), dual-cured resin-composite cement (LuxaCore-DMG) and glass fiber posts (LuxaPost-DMG). Group B (10 samples): self-adhesive resin cement (Breeze-Pentron Clinical) and glass fiber posts (LuxaPost-DMG). Group C (10 samples): 3 steps light-curing, self-etching, self-conditioning bonding agent (Contax-Total-etch-DMG), dual-cured resin-composite cement (LuxaCore-DMG) and glass fiber posts (LuxaPost-DMG). The survey was conducted by examining the breaking resistance of the post-cement-tooth complex, subjected to a mechanical force. Statistical analysis was performed using SPSS Inc. ver. 13.0, Chicago, IL, USA. Group A values of bond strenth ranged from a minimum of 10.14 Mpa to a maximum value of 14.73 Mpa with a mean value of 12.58 Mpa. In Group B the highest value of bond strength was 6.54 Mpa and the minimum 5.55 Mpa. The mean value of the bond strength for the entire group was 6.58 Mpa. In Group C the highest bond strength was 6.59 Mpa whereas the lowest bond strength was 4.84 Mpa. Mean value of the bond strength of Group C was calculated at 5.7 Mpa. Etching with orthophosphoric acid combined with a dual-curing adhesive system and a dual-cured resin-composite cement was the technique that guaranteed the highest bond strength. Lowest bond strength values were obtained when dual self-adhesive cement was used.

[Carbon fiber-reinforced plastics as implant materials].

Science.gov (United States)

Bader, R; Steinhauser, E; Rechl, H; Siebels, W; Mittelmeier, W; Gradinger, R

2003-01-01

Carbon fiber-reinforced plastics have been used clinically as an implant material for different applications for over 20 years.A review of technical basics of the composite materials (carbon fibers and matrix systems), fields of application,advantages (e.g., postoperative visualization without distortion in computed and magnetic resonance tomography), and disadvantages with use as an implant material is given. The question of the biocompatibility of carbon fiber-reinforced plastics is discussed on the basis of experimental and clinical studies. Selected implant systems made of carbon composite materials for treatments in orthopedic surgery such as joint replacement, tumor surgery, and spinal operations are presented and assessed. Present applications for carbon fiber reinforced plastics are seen in the field of spinal surgery, both as cages for interbody fusion and vertebral body replacement.

Radiographic control of mineral fibre-reinforced cement plates

International Nuclear Information System (INIS)

Domanus, J.C.; Moeller Jensen, L.

1980-03-01

The usefulnes of the radiographic technique in the examination of Spinrock fibres reinforced cement plates was investigated with soft X-rays. A preliminary investigation has shown that soft X-rays are most suitable for radiography of cement plates, and therefore a 50 kV X-ray machine with a 0.5 mm focus and beryllium window X-ray tube was used througout the investigation. X-ray films of different speed and graininess were used, and it was proved that a relatively fast Kodak Industrex D film can produce radiographs of adequate quality. An Agfa-Gevaert Structurix IC paper can also be used. (author)

Finite element analysis and experimental verification of Polymer reinforced CRC improved for close-in detonation

DEFF Research Database (Denmark)

Riisgaard, Benjamin; Georgakis, Christos; Stang, Henrik

2007-01-01

Compact Reinforced Composite, CRC, is a high-strength cement-based composite that holds an enormous flexural and energy-absorbing capacity due to the close-spaced high strength steel reinforcement and a high-strength cement-based fiber DSP matrix. The material has been used in various constructions...

Microstructure and mechanical properties of carbon fiber reinforced ...

Indian Academy of Sciences (India)

68

Alumina; composites; carbon fiber reinforcement; sol; mechanical properties. 1. Introduction ... The reinforcement was 3D carbon fiber (T300 3k, ex-PAN carbon fiber ... where f(a/H) = 2.9(a/H)1/2 – 4.6(a/H)3/2 + 21.8(a/H)5/2. – 37.6(a/H)7/2 + ...

Experimental research on continuous basalt fiber and basalt-fibers-reinforced polymers

Science.gov (United States)

Zhang, Xueyi; Zou, Guangping; Shen, Zhiqiang

2008-11-01

The interest for continuous basalt fibers and reinforced polymers has recently grown because of its low price and rich natural resource. Basalt fiber was one type of high performance inorganic fibers which were made from natural basalt by the method of melt extraction. This paper discusses basic mechanical properties of basalt fiber. The other work in this paper was to conduct tensile testing of continuous basalt fiber-reinforced polymer rod. Tensile strength and stress-strain curve were obtained in this testing. The strength of rod was fairly equal to rod of E-glass fibers and weaker than rod of carbon fibers. Surface of crack of rod was studied. An investigation of fracture mechanism between matrix and fiber was analyzed by SEM (Scanning electron microscopy) method. A poor adhesion between the matrix and fibers was also shown for composites analyzing SEM photos. The promising tensile properties of the presented basalt fibers composites have shown their great potential as alternative classical composites.

Fracture strengths of chair‑side‑generated veneers cemented with ...

African Journals Online (AJOL)

2014-06-09

Jun 9, 2014 ... Group 1), CAD/CAM‑fabricated veneers cemented with a glass fiber ... specimens were tested with a universal testing machine after thermal cycling treatment. ... The purpose of the current in vitro study is to determine the ..... fracture resistance of fiber reinforced cups‑replacing composite restorations.

Containment performance evaluation of prestressed concrete containment vessels with fiber reinforcement

Energy Technology Data Exchange (ETDEWEB)

Choun, Young Sun; Park, Hyung Kui [Integrated Safety Assessment Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-12-15

Fibers in concrete resist the growth of cracks and enhance the postcracking behavior of structures. The addition of fibers into a conventional reinforced concrete can improve the structural and functional performance of safety-related concrete structures in nuclear power plants. The influence of fibers on the ultimate internal pressure capacity of a prestressed concrete containment vessel (PCCV) was investigated through a comparison of the ultimate pressure capacities between conventional and fiber-reinforced PCCVs. Steel and polyamide fibers were used. The tension behaviors of conventional concrete and fiber-reinforced concrete specimens were investigated through uniaxial tension tests and their tension-stiffening models were obtained. For a PCCV reinforced with 1% volume hooked-end steel fiber, the ultimate pressure capacity increased by approximately 12% in comparison with that for a conventional PCCV. For a PCCV reinforced with 1.5% volume polyamide fiber, an increase of approximately 3% was estimated for the ultimate pressure capacity. The ultimate pressure capacity can be greatly improved by introducing steel and polyamide fibers in a conventional reinforced concrete. Steel fibers are more effective at enhancing the containment performance of a PCCV than polyamide fibers. The fiber reinforcement was shown to be more effective at a high pressure loading and a low prestress level.

Containment performance evaluation of prestressed concrete containment vessels with fiber reinforcement

International Nuclear Information System (INIS)

Choun, Young Sun; Park, Hyung Kui

2015-01-01

Fibers in concrete resist the growth of cracks and enhance the postcracking behavior of structures. The addition of fibers into a conventional reinforced concrete can improve the structural and functional performance of safety-related concrete structures in nuclear power plants. The influence of fibers on the ultimate internal pressure capacity of a prestressed concrete containment vessel (PCCV) was investigated through a comparison of the ultimate pressure capacities between conventional and fiber-reinforced PCCVs. Steel and polyamide fibers were used. The tension behaviors of conventional concrete and fiber-reinforced concrete specimens were investigated through uniaxial tension tests and their tension-stiffening models were obtained. For a PCCV reinforced with 1% volume hooked-end steel fiber, the ultimate pressure capacity increased by approximately 12% in comparison with that for a conventional PCCV. For a PCCV reinforced with 1.5% volume polyamide fiber, an increase of approximately 3% was estimated for the ultimate pressure capacity. The ultimate pressure capacity can be greatly improved by introducing steel and polyamide fibers in a conventional reinforced concrete. Steel fibers are more effective at enhancing the containment performance of a PCCV than polyamide fibers. The fiber reinforcement was shown to be more effective at a high pressure loading and a low prestress level

New Polylactic Acid Composites Reinforced with Artichoke Fibers

OpenAIRE

Botta, Luigi; Fiore, Vincenzo; Scalici, Tommaso; Valenza, Antonino;  , Roberto

2015-01-01

In this work, artichoke fibers were used for the first time to prepare poly(lactic acid) (PLA)-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w) were prepared by the film-stacking method: the first one (UNID) reinforced with unidirectional long artichoke fibers, the second one (RANDOM) reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanica...

Improving degradation resistance of sisal fiber in concrete through fiber surface treatment

Science.gov (United States)

Wei, Jianqiang; Meyer, Christian

2014-01-01

As part of an ongoing effort to improve the sustainability of reinforced concrete, recycled concrete aggregate is being considered together with natural fibers such as sisal fiber as replacement of synthetic reinforcement. Since natural fibers are known to undergo potential deterioration in the alkaline cement matrix especially in outdoor erosive environment, they need to be treated to improve their durability. This paper describes two such methods (thermal and Na2CO3 treatment) and evaluates their effects on the degradation resistance of sisal fiber and durability of sisal fiber-reinforced concrete with recycled concrete aggregate. Concrete specimens were subjected to cycles of wetting and drying to accelerate aging. The microstructure, tensile strength and Young's modulus of sisal fiber as well as the weight loss of the composite were evaluated. Of primary interest were the effects on compressive and splitting tensile strength of sisal fiber-reinforced concrete. Thermal treatment and Na2CO3 surface treatment were shown to improve the durability of the composite as measured by splitting tensile strength by 36.5% and 46.2% and the compressive strength by 31.1% and 45.4%, respectively. The mechanisms of these two treatment methods were also analyzed. The thermal treatment achieved improvement of cellulose's crystallization, which ensured the initial strength and improved durability of sisal fiber. A layer consisting of calcium carbonate sediments, which protects the internals of a fiber from the strong alkali solution formed in the cement hydration process, was formed and filled in pits and cavities on the Na2CO3 treated sisal fiber's surface to improve their corrosion resistance and durability and reduced the detrimental effects of Na+ ions on concrete.

UV irradiation improves the bond strength of resin cement to fiber posts.

Science.gov (United States)

Zhong, Bo; Zhang, Yong; Zhou, Jianfeng; Chen, Li; Li, Deli; Tan, Jianguo

2011-01-01

The purpose is to evaluate the effect of UV irradiation on the bond strength between epoxy-based glass fiber posts and resin cement. Twelve epoxy-based glass fiber posts were randomly divided into three groups. Group 1 (Cont.): No surface treatment. Group 2 (Low-UV): UV irradiation was conducted from a distance of 10 cm for 10 min. Group 3 (High-UV): UV irradiation was conducted from a distance of 1 cm for 3 min. A resin cement (CLEARFIL SA LUTING) was used for the post cementation to form resin slabs which contained fiber posts in the center. Microtensile bond strengths were tested and the mean bond strengths (MPa) were 18.81 for Cont. group, 23.65 for Low-UV group, 34.75 for High-UV group. UV irradiation had a significant effect on the bond strength (pUV irradiation demonstrates its capability to improve the bond strength between epoxy-based glass fiber posts and resin cement.

SYNTHESIS AND CHARACTERIZATION OF CANNABIS INDICA FIBER REINFORCED COMPOSITES

Directory of Open Access Journals (Sweden)

Amar Singh Singha

2011-04-01

Full Text Available This paper reports on the synthesis of Cannabis indica fiber-reinforced composites using Urea-Resorcinol-Formaldehyde (URF as a novel matrix through compression molding technique. The polycondensation between urea, resorcinol, and formaldehyde in different molar ratios was applied to the synthesis of the URF polymer matrix. A thermosetting matrix based composite, reinforced with lignocellulose from Cannabis indica with different fiber loadings 10, 20, 30, 40, and 50% by weight, was obtained. The mechanical properties of randomly oriented intimately mixed fiber particle reinforced composites were determined. Effects of fiber loadings on mechanical properties such as tensile, compressive, flexural strength, and wear resistance were evaluated. Results showed that mechanical properties of URF resin matrix increased considerably when reinforced with particles of Cannabis indica fiber. Thermal (TGA/DTA/DTG and morphological studies (SEM of the resin, fiber and polymer composite thus synthesized were carried out.

Self-healing in single and multiple fiber(s reinforced polymer composites

Directory of Open Access Journals (Sweden)

Woldesenbet E.

2010-06-01

Full Text Available You Polymer composites have been attractive medium to introduce the autonomic healing concept into modern day engineering materials. To date, there has been significant research in self-healing polymeric materials including several studies specifically in fiber reinforced polymers. Even though several methods have been suggested in autonomic healing materials, the concept of repair by bleeding of enclosed functional agents has garnered wide attention by the scientific community. A self-healing fiber reinforced polymer composite has been developed. Tensile tests are carried out on specimens that are fabricated by using the following components: hollow and solid glass fibers, healing agent, catalysts, multi-walled carbon nanotubes, and a polymer resin matrix. The test results have demonstrated that single fiber polymer composites and multiple fiber reinforced polymer matrix composites with healing agents and catalysts have provided 90.7% and 76.55% restoration of the original tensile strength, respectively. Incorporation of functionalized multi-walled carbon nanotubes in the healing medium of the single fiber polymer composite has provided additional efficiency. Healing is found to be localized, allowing multiple healing in the presence of several cracks.

Mechanical Behavior of Granular/Particulate Media Reinforced with Fibers

National Research Council Canada - National Science Library

Michalowski, Radoslw

1999-01-01

Fiber-reinforced ganular composites (for instance, fiber-reinforced sand) are considered as construction materials for such applications as subgrades of airfields and roads, aircraft parking facilities, etc...

Investigation of Waste Paper Cellulosic Fibers Utilization into Cement Based Building Materials

Directory of Open Access Journals (Sweden)

Viola Hospodarova

2018-03-01

Full Text Available Recently, the utilization of renewable natural cellulosic materials, such as wood, plants, and waste paper in the preparation of building materials has attracted significant interest. This is due to their advantageous properties, low environmental impact and low cost. The objective of this paper is to investigate the influence of recycled cellulosic fibers (in the amount 0.5 wt % of the filler and binder weight and superplasticizer (in the amount 0.5 wt % of the cement weight on the resulting properties of cement composites (consistency of fresh mixture, density, thermal conductivity, and compressive and flexural strength for hardening times of 1, 3, 7, 28, and 90 days. Plasticizer use improved the workability of fresh cement mixture. In comparison to the reference sample, the results revealed a decrease in density of 6.8% and in the thermal conductivity of composites with cellulosic fibers of 34%. The highest values of compressive (48.4 MPa and flexural (up to 7 MPa strength were achieved for hardened fiber cement specimens with plasticizer due to their significantly better dispersion of cement particles and improved bond strength between fibers and matrix.

Effect of Fiber Layers on the Fracture Resistance of Fiber Reinforced Composite Bridges

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A Fazel

2011-08-01

Full Text Available Introduction: The purpose of this in vitro study was to introduce the fiber reinforced composite bridges and evaluate the most suitable site and position for placement of fibers in order to get maximum strength. Methods: The study included 20 second premolars and 20 second molars selected for fabricating twenty fiber reinforced composite bridges. Twenty specimens were selected for one fiber layer and the remaining teeth for two fiber layers. In the first group, fibers were placed in the inferior third and in the second group, fibers were placed in both the middle and inferior third region. After tooth preparation, the restorations were fabricated, thermocycled and then loaded with universal testing machine in the middle of the pontics with crosshead speed of 1mm/min. Data was analyzed by Kolmogorov-Smirnov test, Independent sample t test and Kaplan-Meier test. Mode of failure was evaluated using stereomicroscope. Results: Mean fracture resistance for the first and second groups was 1416±467N and 1349±397N, respectively. No significant differences were observed between the groups (P>0.05.In the first group, 5 specimens had delamintation and 5 specimens had detachment between fibers and resin composite. In the second group, there were 4 and 6 delaminations and detachments, respectively. There was no fracture within the fiber. Conclusion: In the fiber reinforced fixed partial dentures, fibers reinforce the tensile side of the connectors but placement of additional fibers at other sites does not increase the fracture resistance of the restoration.

Thermomechanical analyses of phenolic foam reinforced with glass fiber mat

International Nuclear Information System (INIS)

Zhou, Jintang; Yao, Zhengjun; Chen, Yongxin; Wei, Dongbo; Wu, Yibing

2013-01-01

Highlights: • Over 10% glass fiber was used to reinforce phenolic foam in the shape of glass fiber mat. • Nucleating agents were used together with glass fiber mat and improved tensile strength of phenolic foam by 215.6%. • Nucleating agents lead to a smaller bubble size of phenolic foam. • The glass transition temperature of phenolic foam remained unchanged during the reinforcement. - Abstract: In this paper, thermomechanical analysis (TMA) and dynamic mechanical analysis were employed to study the properties of phenolic foam reinforced with glass fiber mat. Unreinforced phenolic foam was taken as the control sample. Mechanical tests and scanning electron microscopy were performed to confirm the results of TMA. The results show that glass fiber mat reinforcement improves the mechanical performance of phenolic foam, and nucleating agents improve it further. Phenolic foam reinforced with glass fiber mat has a smaller thermal expansion coefficient compared with unreinforced foam. The storage modulus of the reinforced phenolic foam is also higher than that in unreinforced foam, whereas the loss modulus of the former is lower than that of the latter. The glass transition temperature of the phenolic foam matrix remains unchanged during the reinforcement

A comparative evaluation of compressive strength of Portland cement with zinc oxide eugenol and Polymer-reinforced cement: An in vitro analysis

OpenAIRE

S Prakasam; Prakasam Bharadwaj; S C Loganathan; B Krishna Prasanth

2014-01-01

Objective: The purpose of this study is to evaluate the ultimate compressive strength of 50% and 25% Portland cement mixed with Polymer-reinforced zinc oxide eugenol and zinc oxide eugenol cement after 1 hour, 24 hours, and 7 days. Materials and Methods: One hundred and eighty samples were selected. The samples were made cylindrical of size 6 × 8 mm and were divided into six groups as follows with each group consisting of 10 samples. Group 1: Polymer-reinforced zinc oxide eugenol with...

Fracture detection in concrete by glass fiber cloth reinforced plastics

Science.gov (United States)

Shin, Soon-Gi; Lee, Sung-Riong

2006-04-01

Two types of carbon (carbon fiber and carbon powder) and a glass cloth were used as conductive phases and a reinforcing fiber, respectively, in polymer rods. The carbon powder was used for fabricating electrically conductive carbon powder-glass fiber reinforced plastic (CP-GFRP) rods. The carbon fiber tows and the CP-GFRP rods were adhered to mortar specimens using epoxy resin and glass fiber cloth. On bending, the electrical resistance of the carbon fiber tow attached to the mortar specimen increased greatly after crack generation, and that of the CP-GFRP rod increased after the early stages of deflection in the mortar. Therefore, the CP-GFRP rod is superior to the carbon fiber tow in detecting fractures. Also, by reinforcing with a glass fiber cloth reinforced plastic, the strength of the mortar specimens became more than twice as strong as that of the unreinforced mortar.

Accounting for Fiber Bending Effects in Homogenization of Long Fiber Reinforced Composites

DEFF Research Database (Denmark)

Poulios, Konstantinos; Niordson, Christian Frithiof

2015-01-01

The present work deals with homogenized finite-element models of long fiber reinforced composite materials in the context of studying compressive failure modes such as the formation of kink bands and fiber micro-buckling. Compared to finite-element models with an explicit discretization of the ma......The present work deals with homogenized finite-element models of long fiber reinforced composite materials in the context of studying compressive failure modes such as the formation of kink bands and fiber micro-buckling. Compared to finite-element models with an explicit discretization...... of the material micro-structure including individual fibers, homogenized models are computationally more efficient and hence more suitable for modeling of larger and complex structure. Nevertheless, the formulation of homogenized models is more complicated, especially if the bending stiffness of the reinforcing...... fibers is to be taken into account. In that case, so-called higher order strain terms need to be considered. In this paper, important relevant works from the literature are discussed and numerical results from a new homogenization model are presented. The new model accounts for two independent...

Stainless and Galvanized Steel, Hydrophobic Admixture and Flexible Polymer-Cement Coating Compared in Increasing Durability of Reinforced Concrete Structures

Science.gov (United States)

Tittarelli, Francesca; Giosuè, Chiara; Mobili, Alessandra

2017-08-01

The use of stainless or galvanized steel reinforcements, a hydrophobic admixture or a flexible polymer-cement coating were compared as methods to improve the corrosion resistance of sound or cracked reinforced concrete specimens exposed to chloride rich solutions. The results show that in full immersion condition, negligible corrosion rates were detected in all cracked specimens, except those treated with the flexible polymer-cement mortar as preventive method against corrosion and the hydrophobic concrete specimens. High corrosion rates were measured in all cracked specimens exposed to wet-dry cycles, except for those reinforced with stainless steel, those treated with the flexible polymer-cement coating as restorative method against reinforcement corrosion and for hydrophobic concrete specimens reinforced with galvanized steel reinforcements.

In vitro study of transverse strength of fiber reinforced composites.

Science.gov (United States)

Mosharraf, R; Hashemi, Z; Torkan, S

2011-01-01

Reinforcement with fiber is an effective method for considerable improvement in flexural properties of indirect composite resin restorations. The aim of this in-vitro study was to compare the transverse strength of composite resin bars reinforced with pre-impregnated and non-impregnated fibers. Thirty six bar type composite resin specimens (3×2×25 mm) were constructed in three groups. The first group was the control group (C) without any fiber reinforcement. The specimens in the second group (P) were reinforced with pre-impregnated fibers and the third group (N) with non-impregnated fibers. These specimens were tested by the three-point bending method to measure primary transverse strength. Data were statistically analyzed with one way ANOVA and Tukey's tests. There was a significant difference among the mean primary transverse strength in the three groups (Ptransverse strength (Pstudy, it was concluded that reinforcement with fiber considerably increased the transverse strength of composite resin specimens, but impregnation of the fiber used implemented no significant difference in the transverse strength of composite resin samples.

Strength behaviour of kerosene coated coir fiber-reinforced expansive soil

OpenAIRE

Ramasubbarao Godavarthi Venkata

2014-01-01

Coir fibers are extracted from the husks surrounding the coconut. Coir fibers can be effectively used as reinforcing material but it has less durability and hence coir fiber coated with kerosene is used as reinforcement in the present study. The objective of the present investigation is to study the strength behavior of expansive soil reinforced with 5mm long randomly distributed kerosene coated coir fibers in 0% (unreinforced), 0.5%, 1% and 1.5% by dry wei...

Fiber-Reinforced Polymer Nets for Strengthening Lava Stone Masonries in Historical Buildings

Directory of Open Access Journals (Sweden)

Santi Maria Cascone

2016-04-01

Full Text Available The strengthening of masonries is a crucial step in building restoration works because of its relevance, mostly with regard to the improvement of building seismic behavior. Current building technologies are based on the use of steel nets which are incorporated into cement plasters. The use of steel has a number of contraindications that can be solved by using composite materials such as glass fiber nets, which have high mechanical characteristics and lightness, elasticity, corrosion resistance, and compatibility with lime plaster. Building interventions, that take into account the application of glass fiber nets, are very sustainable from several points of view, e.g., material production, in situ works, economic cost and durability. In Italy, several experiments have been carried out in situ with the aim of testing the mechanical characteristics of masonries which have been treated with fiber-reinforced polymer (FRP nets. This paper deals with a series of in situ tests carried out during the restoration works of an important historical building located in Catania (Sicily, Italy. The results achieved are largely positive.

Ceramic fiber reinforced filter

Science.gov (United States)

Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

1991-01-01

A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

Strain monitoring of cement-based materials with embedded polyvinyl alcohol - carbon nanotube (PVA-CNT fibers

Directory of Open Access Journals (Sweden)

Zoi S. Metaxa

2017-04-01

Full Text Available This article investigates the possibility of exploiting innovative polyvinyl alcohol fibers reinforced with carbon nanotubes (PVA-CNT fiber as a strain sensor in cement mortars used in the restoration of Cultural Heritage Monuments. Two types of PVA-CNT fibers were embedded in the matrix at a short distance from the bottom of the beam and their readings were correlated with traditional sensors, e.g. strain gauges and Fiber Optic Bragg Gratings. The Electrical Resistance Change (ERC of the embedded PVA-CNT fiber was in-situ monitored during four-point bending mechanical tests. For the case of coated PVA-CNT fiber, a linear correlation of the applied strain at the bottom surface of the specimen along with ERC values of the fiber was noticed for the low strain regime. For the case of incremental increasing loading – unloading loops, the coated and annealed PVA-CNT fiber gave the best results either as embedded or as ‘surface attached’ sensor that exhibited linear correlation of ERC with applied strain for the low applied strain regime as well as hysteresis loops during unloading. The article discusses their high potential to be exploited as strain/damage sensor in applications of civil engineering as well as in restoration of Monuments of Cultural Heritage.

Growth, structure, and optical properties of carbon-reinforced silica fibers

International Nuclear Information System (INIS)

Zhang, Z. J.; Ajayan, P. M.; Ramanath, G.; Vacik, J.; Xu, Y. H.

2001-01-01

We report the synthesis of carbon-reinforced silica fibers by methane exposure of metallocene-treated oxidized-Si(001) substrates at 1100 degree C. The SiO 2 cap layer transforms into silica fibers reinforced by glassy carbon in the core during methane exposure. High-resolution electron microscopy and spatially resolved spectroscopy measurements of the fibers reveal an amorphous structure without a hollow, and domains of glassy carbon embedded at the fiber core. The carbon-reinforced fibers are optically transparent and have an optical band gap of ≅3.1 eV. These fibers are organized in radial patterns that vary for different metallocene species. On nickelocene-treated substrates, the fibers originate from the circumference of the circular templates and grow outwards, forming radial patterns. On ferrocene-treated substrates, randomly oriented fibers grow within as well as slightly outside the perimeter of the templates, forming wreath-like patterns. Aligned growth of such fibers could be useful for fabricating optoelectronics devices and reinforced composites. [copyright] 2001 American Institute of Physics

Abrasion Properties of Steel Fiber Reinforced Silica Fume Concrete According to Los Angeles and Water Abrasion Tests

Directory of Open Access Journals (Sweden)

Tsan-Ching CHENG

2014-12-01

Full Text Available The current study mainly investigated the influence of different tests on the abrasion resistance of concrete mixed with steel fibers and silica fume. The abrasion resistance was assessed at 28, 56 and 91 days on concretes with water-binder ratios of 0.35 and 0.55 where in some mixes silica fume was substituted by 5 % of cement by weight. Steel fibers of 0.5 % and 1.0 % of concrete volume were also added into the test concrete by replacement of coarse and fine aggregates. The results showed that concrete with higher compressive strength in Los Angeles abrasion tests also had better abrasion resistance. The inclusion of steel fibers into test concrete with a water-binder ratio of 0.35 resulted in a significant increase in compressive strength. This concrete also displayed better abrasion resistance and splitting tensile strength than reference concrete; in the test sample with a water-binder ratio of 0.55, the added steel fibers was unable to effectively produce cementation with the concrete. The inclusion of silica fume improved the abrasion resistance of concretes. In water abrasion testing, the abrasion resistance of concrete containing steel fiber was worse than that of concrete without steel fibers. In the water abrasion testing, the surface of steel fiber reinforced concrete was eroded by water and steel balls, and the impact caused the steel fibers to separate from the concrete and led to higher wear loss. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6460

Thermal and mechanical properties of NaOH treated hemp fabric and calcined nanoclay-reinforced cement nanocomposites

International Nuclear Information System (INIS)

Hakamy, A.; Shaikh, F.U.A.; Low, I.M.

2015-01-01

Highlights: • Fabrication of nanoclay and hemp fabric-reinforced cement composites. • The optimum nanoclay and hemp fabric content is 1.0 and 6.9 wt.% respectively. • Surface-treated hemp fabric-reinforced cement composites demonstrated better mechanical properties. • Surface modification of hemp fabric was effective in improving the hemp fabric-cement matrix adhesion. - Abstract: Cement nanocomposites reinforced with hemp fabrics and calcined nanoclay (CNC) have been fabricated and investigated. CNC is prepared by heating nanoclay (Cloisite 30B) at 900 °C for 2 h. The influences of CNC dispersion on the mechanical properties and thermal properties of these composites have been characterized in terms of porosity, density, water absorption, flexural strength, fracture toughness, impact strength and thermal stability. The microstructure is investigated using Quantitative X-ray Diffraction Analysis (QXDA) and High Resolution Transmission Electron Microscopy (HRTEM). The effects of alkali (NaOH) treatment of hemp fabric on the mechanical properties of hemp fabric-reinforced cement composites with different fabric contents of 4.5, 5.7, 6.9 and 8.1 wt% are also investigated. Results show that the optimum hemp fabric content is 6.9 wt% (i.e. 6 fabric layers). Results also indicated that physical, mechanical and thermal properties were enhanced due to the addition of CNC into the cement matrix and the optimum content of CNC was 1 wt%. The treated hemp fabric-reinforced nanocomposites containing 1 wt% CNC exhibited the highest flexural strength, fracture toughness, impact strength and thermal stability by virtue of good fibre–matrix interface. This environmentally friendly nanocomposite can be used for various construction applications such as ceilings and roofs

Analytical, Numerical and Experimental Examination of Reinforced Composites Beams Covered with Carbon Fiber Reinforced Plastic

Science.gov (United States)

Kasimzade, A. A.; Tuhta, S.

2012-03-01

In the article, analytical, numerical (Finite Element Method) and experimental investigation results of beam that was strengthened with fiber reinforced plastic-FRP composite has been given as comparative, the effect of FRP wrapping number to the maximum load and moment capacity has been evaluated depending on this results. Carbon FRP qualitative dependences have been occurred between wrapping number and beam load and moment capacity for repair-strengthen the reinforced concrete beams with carbon fiber. Shown possibilities of application traditional known analysis programs, for the analysis of Carbon Fiber Reinforced Plastic (CFRP) strengthened structures.

PULLOUT BEHAVIOR OF OXYGEN PLASMA TREATED POLYMER FIBERS FROM CEMENT MATRIX

Directory of Open Access Journals (Sweden)

Jan Trejbal

2017-11-01

Full Text Available The aim of this work is to describe bonding properties between surface treated polymer fibers and a cement matrix. In order to increase an interaction between the matrix and fiber surfaces, two fiber types having approx. 0.5 mm in diameter were modified by mean of oxygen plasma treatment. Surface physical changes of treated fibers were examined using SEM morphology observation and interfacial adhesion mechanical tests. The principle of mechanical tests rested on a single fiber pulling out from the matrix (cement paste, CEM I 42.5 R, w/c 0.4. The embedded length was equal to 50 % of original fiber length (50 mm, where the fiber free-end displacement and force resisting to the displacement were monitored. It was pointed out that interfacial shear stress needed to break the bond between the modified fibers and the matrix increased almost by 15–65 % if compared to reference fibers. When the fiber free-end displacement reached to 3.5 mm, the shear strength increased almost twice.

Bond of reinforcing bars in self-compacting steel fiber reinforced concrete

NARCIS (Netherlands)

Schumacher, P.; Bigaj-van Vliet, A.J.; Braam, C.R.; Uijl, J.A. den; Walraven, J.C.

2002-01-01

Pull-out tests were performed on 10 mm diameter ribbed bars embedded along three times the bar diameter in 200 mm cubes made of plain and steel fiber reinforced concrete (SFRC) of normal strength (B45). The fiber content was 60 and 120 kg/m3, respectively, the aspect ratio of the fibers was 45 and

Compressive Behavior of Fiber-Reinforced Concrete with End-Hooked Steel Fibers

Directory of Open Access Journals (Sweden)

Seong-Cheol Lee

2015-03-01

Full Text Available In this paper, the compressive behavior of fiber-reinforced concrete with end-hooked steel fibers has been investigated through a uniaxial compression test in which the variables were concrete compressive strength, fiber volumetric ratio, and fiber aspect ratio (length to diameter. In order to minimize the effect of specimen size on fiber distribution, 48 cylinder specimens 150 mm in diameter and 300 mm in height were prepared and then subjected to uniaxial compression. From the test results, it was shown that steel fiber-reinforced concrete (SFRC specimens exhibited ductile behavior after reaching their compressive strength. It was also shown that the strain at the compressive strength generally increased along with an increase in the fiber volumetric ratio and fiber aspect ratio, while the elastic modulus decreased. With consideration for the effect of steel fibers, a model for the stress–strain relationship of SFRC under compression is proposed here. Simple formulae to predict the strain at the compressive strength and the elastic modulus of SFRC were developed as well. The proposed model and formulae will be useful for realistic predictions of the structural behavior of SFRC members or structures.

Compressive Behavior of Fiber-Reinforced Concrete with End-Hooked Steel Fibers.

Science.gov (United States)

Lee, Seong-Cheol; Oh, Joung-Hwan; Cho, Jae-Yeol

2015-03-27

In this paper, the compressive behavior of fiber-reinforced concrete with end-hooked steel fibers has been investigated through a uniaxial compression test in which the variables were concrete compressive strength, fiber volumetric ratio, and fiber aspect ratio (length to diameter). In order to minimize the effect of specimen size on fiber distribution, 48 cylinder specimens 150 mm in diameter and 300 mm in height were prepared and then subjected to uniaxial compression. From the test results, it was shown that steel fiber-reinforced concrete (SFRC) specimens exhibited ductile behavior after reaching their compressive strength. It was also shown that the strain at the compressive strength generally increased along with an increase in the fiber volumetric ratio and fiber aspect ratio, while the elastic modulus decreased. With consideration for the effect of steel fibers, a model for the stress-strain relationship of SFRC under compression is proposed here. Simple formulae to predict the strain at the compressive strength and the elastic modulus of SFRC were developed as well. The proposed model and formulae will be useful for realistic predictions of the structural behavior of SFRC members or structures.

On the simulation of kink bands in fiber reinforced composites

DEFF Research Database (Denmark)

Sørensen, K.D.; Mikkelsen, Lars Pilgaard; Jensen, H.M.

2007-01-01

Simulations of kink band formation in fiber reinforced composites are carried out using the commercial finite element program ABAQUS. A smeared-out, plane constitutive model for fiber reinforced materials is implemented as a user subroutine, and effects of fiber misalignment on elastic and plastic...

Numerical modeling of hybrid fiber-reinforced concrete (hyfrc)

International Nuclear Information System (INIS)

Hameed, R.; Turatsinze, A.

2015-01-01

A model for numerical simulation of mechanical response of concrete reinforced with slipping and non slipping metallic fibers in hybrid form is presented in this paper. Constitutive law used to model plain concrete behaviour is based on plasticity and damage theories, and is capable to determine localized crack opening in three dimensional (3-D) systems. Behaviour law used for slipping metallic fibers is formulated based on effective stress carried by these fibers after when concrete matrix is cracked. A continuous approach is proposed to model the effect of addition of non-slipping metallic fibers in plain concrete. This approach considers the constitutive law of concrete matrix with increased fracture energy in tension obtained experimentally in direct tension tests on Fiber Reinforced Concrete (FRC). To simulate the mechanical behaviour of hybrid fiber-reinforced concrete (HyFRC), proposed approaches to model non-slipping metallic fibers and constitutive law of plain concrete and slipping fibers are used simultaneously without any additive equation. All the parameters used by the proposed model have physical meanings and are determined through experiments or drawn from literature. The model was implemented in Finite Element (FE) Code CASTEM and tested on FRC prismatic notched specimens in flexure. Model prediction showed good agreement with experimental results. (author)

Addition of Wollastonite Fibers to Calcium Phosphate Cement Increases Cell Viability and Stimulates Differentiation of Osteoblast-Like Cells

Directory of Open Access Journals (Sweden)

Juliana Almeida Domingues

2017-01-01

Full Text Available Calcium phosphate cement (CPC that is based on α-tricalcium phosphate (α-TCP is considered desirable for bone tissue engineering because of its relatively rapid degradation properties. However, such cement is relatively weak, restricting its use to areas of low mechanical stress. Wollastonite fibers (WF have been used to improve the mechanical strength of biomaterials. However, the biological properties of WF remain poorly understood. Here, we tested the response of osteoblast-like cells to being cultured on CPC reinforced with 5% of WF (CPC-WF. We found that both types of cement studied achieved an ion balance for calcium and phosphate after 3 days of immersion in culture medium and this allowed subsequent long-term cell culture. CPC-WF increased cell viability and stimulated cell differentiation, compared to nonreinforced CPC. We hypothesize that late silicon release by CPC-WF induces increased cell proliferation and differentiation. Based on our findings, we propose that CPC-WF is a promising material for bone tissue engineering applications.

Electromechanical behavior of fiber-reinforced dielectric elastomer membrane

Directory of Open Access Journals (Sweden)

Chi Li

2015-04-01

Full Text Available Based on its large deformation, light weight, and high energy density, dielectric elastomer (DE has been used as driven muscle in many areas. We design the fiber-reinforced DE membrane by adding fibers in the membrane. The deformation and driven force direction of the membrane can be tuned by changing the fiber arrangements. The actuation in the perpendicular direction of the DE membrane with long fibers first increases and then decreases by the increasing of the fiber spacing in the perpendicular direction. The horizontal actuation of the membrane decreases by decreasing the spacing of short fibers. In the membrane-inflating structure, the radially arranged fibers will break the axisymmetric behavior of the structure. The top area of the inflated balloon without fiber will buckle up when the voltage reaches a certain level. Finite element simulations based on nonlinear field theory are conducted to investigate the effects of fiber arrangement and verify the experimental results. This work can guide the design of fiber-reinforced DE.

Strength and thermal stability of fiber reinforced plastic composites ...

African Journals Online (AJOL)

Therefore, the strength properties and thermal stability of plastic composites reinforced with rattan fibers were investigated in this work. Particles of rattan species (Eremospatha macrocarpa (EM) and Laccosperma secundiflorum (LS)) were blended with High-Density Polyethylene (HDPE) to produce fiber reinforced plastic ...

Mechanical interaction between concrete and structural reinforcement in the tension stiffening process

DEFF Research Database (Denmark)

Lárusson, Lárus Helgi; Fischer, Gregor; Jönsson, Jeppe

2011-01-01

as Engineered Cementitious Composite (ECC), have been combined with steel and glass fiber reinforced polymer (GFRP) reinforcement to contrast the effects of brittle and ductile cement matrices as well as elastic/plastic and elastic reinforcement on the tension stiffening process. Particular focus...... investigated using an image-based deformation measurement and analysis system. This allowed for detailed view of surface deformations and the implications on the resulting response of the member in tension. In this study, conventional concrete and a ductile, strain hardening cement composite, known...

FEM performance of concrete beams reinforced by carbon fiber bars

Directory of Open Access Journals (Sweden)

Hasan Hashim

2018-01-01

Full Text Available Concrete structures may be vulnerable to harsh environment, reinforcement with Fiber Reinforced Polymer (FRP bars have an increasing acceptance than normal steel. The nature of (FRP bar is (non-corrosive which is very beneficial for increased durability as well as the reinforcement of FRP bar has higher strength than steel bar. FRP usage are being specified more and more by public structural engineers and individual companies as main reinforcement and as strengthening of structures. Steel reinforcement as compared to (FRP reinforcement are decreasingly acceptable for structural concrete reinforcement including precast concrete, cast in place concrete, columns, beams and other components. Carbon Fiber Reinforcement Polymer (CFRP have a very high modulus of elasticity “high modulus” and very high tensile strength. In aerospace industry, CFRP with high modulus are popular among all FRPs because it has a high strength to weight ratio. In this research, a finite element models will be used to represent beams with Carbon Fiber Reinforcement and beams with steel reinforcement. The primary objective of the research is the evaluation of the effect of (CFR on beam reinforcement.

Fiber glass reinforced structural materials for aerospace application

Science.gov (United States)

Bartlett, D. H.

1968-01-01

Evaluation of fiber glass reinforced plastic materials concludes that fiber glass construction is lighter than aluminum alloy construction. Low thermal conductivity and strength makes the fiber glass material useful in cryogenic tank supports.

Compatibility of vegetable fibers with Portland cement and its relationship with the physical properties

Directory of Open Access Journals (Sweden)

Maria L. Marques

2016-05-01

Full Text Available ABSTRACT The use of vegetable fiber residue in cementitious matrices can be a sustainable technological alternative; however, it still has problems related to the chemical compatibility between the cement and the fibers. The present study evaluated the compatibility of vegetable fibers with cement using three methods of calculation and determined certain physical properties of the fibers and the curve of the temporal evolution of temperature for each composite. The surfaces of the composites were evaluated through atomic force microscope images and the results showed that the pretreatment of fiber washing significantly favors the compatibility with cement for fibers of eucalyptus, coconut and cocoa, with no influence for water hyacinth fiber. Bivariate correlation analyses showed that the compatibility of the composites is favored by the reduction in the degree of swelling, packing density and specific mass. The results showed that there is a potential use of plant fiber in civil construction and that the physical properties of each type of fiber can offer elements for its selection and pretreatment.

Radiation processing for carbon fiber-reinforced polytetrafluoroethylene composite materials

International Nuclear Information System (INIS)

Oshima, Akihiro; Udagawa, Akira; Morita, Yousuke

2001-01-01

The present work is an attempt to evaluate the performance of the fiber composites with crosslinked polytetrafluoroethylene (PTFE) as a polymer matrix by radiation. The uni-directional carbon fiber-reinforced composites were fabricated with PTFE fine powder impregnation method and then crosslinked by electron beams irradiation under selective conditions. The carbon fiber-reinforced crosslinked PTFE composites show good mechanical properties compared with crosslinked PTFE. The radiation resistance of crosslinked PTFE composites is improved more than that of crosslinked resin without fiber. (author)

MECHANICAL CHARACTERIZATION AND ANALYSIS OF RANDOMLY DISTRIBUTED SHORT BANANA FIBER REINFORCED EPOXY COMPOSITES

Directory of Open Access Journals (Sweden)

R. K. Misra

2014-03-01

Full Text Available Short banana fiber reinforced composites have been prepared in laboratory to determine mechanical properties. It has been observed that as soon as the percentage of the banana fiber increases slightly there is a tremendous increase in ultimate tensile strength, % of strain and young modulus of elasticity. Reinforcement of banana fibers in epoxy resin increases stiffness and decreases damping properties of the composites. Therefore, 2.468% banana fiber reinforced composite plate stabilizes early as compared to 7.7135 % banana fiber reinforced composite plate but less stiff as compared to 7.7135 % banana fiber reinforced composite plate

Shear strength of reinforced concrete beams strengthened by P.B.O. fiber mesh under loading

Directory of Open Access Journals (Sweden)

Blikharskyy Zinoviy

2017-01-01

Full Text Available This article presents experimental study of sheer strength of reinforced concrete beams without transverse steel reinforcement, which strengthened by composite materials. The feature of tests is that the beams’ strengthening is made under simultaneous action of loading. The research program involves a series of test beams with size 2100 × 200 × 100 mm and which contains control sample and three reinforced samples by reinforcing FRCM system. FRCM system consisting of two components: mineral mortar based on modified cement Ruredil X Mesh M750 and reinforcing P.B.O. fiber mesh Ruredil X Mesh Gold (Italy. The strength research of test samples was carried out with the shear distance to effective depth ratio a/d = 2. The strengthening loading levels were selected at 0.0, 0.3, 0.5 from shear strength of non strengthened control sample. As a result of experimental studies we found that during strengthening design the inclined cross section of beams we should take into account the existing level of loading. Using the strengthening system Ruredil X Mesh Gold the strengthening effect is reduced at 2.8 to 2.9 times while the existing level of loading increase from 0 to 50%.

Determination of tensile forces to enhance the supply stability of reinforced fiber

Energy Technology Data Exchange (ETDEWEB)

Kim, Kun Woo; Lee, Jae Wook; Jang, Jin Seok; Jeong, Myeong Sik; Oh, Joo Young; Kang, Hoon; Kang, Ji Heon [Daegyeong Regional Division, Korea Institute of Industrial Technology, Daegu (Korea, Republic of); Kim, Hyung Ryul [Agency for Defense Development, Changwon (Korea, Republic of); Yoo, Wan Suk [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)

2016-12-15

The manufacturing process of long fiber thermoplastic is initiated by supplying reinforced fiber wound in a spool dispenser. If problems such as tangling or kinking occur in the apparatus used for supplying the reinforced fiber in the long-fiber thermoplastic direct process, the productivity of the long-fiber thermoplastic decreases. Therefore, it is important to enhance the supply stability of reinforced fiber. In general, the increase in supply stability can be achieved by maintaining a steady balloon shape that is controlled by the unwinding velocity or tensile force of the reinforced fiber. In this research, the range of suitable tensile force was determined under the assumption that the unwinding velocity remained constant. The reinforced fiber was assumed to be inextensible, homogeneous, and isotropic and to have uniform density. The transient-state unwinding equation of motion to analyze the unwinding motion of reinforced fiber can be derived by using Hamilton’s principle for an open system in which mass can change within a control volume. In the process of solving the transient-state unwinding equation of motion, the exact two-point boundary conditions are adopted for each time step.

Rheology of Carbon Fibre Reinforced Cement-Based Mortar

International Nuclear Information System (INIS)

Banfill, Phillip F. G.; Starrs, Gerry; McCarter, W. John

2008-01-01

Carbon fibre reinforced cement based materials (CFRCs) offer the possibility of fabricating 'smart' electrically conductive materials. Rheology of the fresh mix is crucial to satisfactory moulding and fresh CFRC conforms to the Bingham model with slight structural breakdown. Both yield stress and plastic viscosity increase with increasing fibre length and volume concentration. Using a modified Viskomat NT, the concentration dependence of CFRC rheology up to 1.5% fibre volume is reported

Rheology of Carbon Fibre Reinforced Cement-Based Mortar

Science.gov (United States)

Banfill, Phillip F. G.; Starrs, Gerry; McCarter, W. John

2008-07-01

Carbon fibre reinforced cement based materials (CFRCs) offer the possibility of fabricating "smart" electrically conductive materials. Rheology of the fresh mix is crucial to satisfactory moulding and fresh CFRC conforms to the Bingham model with slight structural breakdown. Both yield stress and plastic viscosity increase with increasing fibre length and volume concentration. Using a modified Viskomat NT, the concentration dependence of CFRC rheology up to 1.5% fibre volume is reported.

Effect of the Type of Surface Treatment and Cement on the Chloride Induced Corrosion of Galvanized Reinforcements

Science.gov (United States)

Tittarelli, Francesca; Mobili, Alessandra; Vicerè, Anna Maria; Roventi, Gabriella; Bellezze, Tiziano

2017-10-01

The effect of a new passivation treatment, obtained by immersion of the galvanized reinforcements in a trivalent chromium salts based solution, on the chlorides induced corrosion has been investigated. To investigate also the effect of cement alkalinity on corrosion behaviour of reinforcements, concretes manufactured with three different European cements were compared. The obtained results show that the alternative treatment based on hexavalent chromium-free baths forms effective protection layers on the galvanized rebar surfaces. The higher corrosion rates of zinc coating in concrete manufactured with Portland cement compared to those recorded for bars in concrete manufactured with pozzolanic cement depends strongly on the higher chloride content at the steel concrete interface.

Material equations for the calculations of steel fiber reinforced concrete members

International Nuclear Information System (INIS)

Jonas, W.

1993-01-01

Steel fiber reinforced concrete (SFRC) is made by the addition of steel fibers to fresh concrete. Usually the fibers are about 0.4-0.8mm in diameter and 25-80mm long. The addition of about 50-120 kg/m 3 is a practical and useful amount. That is about 0.6-1.5% by volume. The fibers are uniformly dispersed with a suitable concrete mix, so that clusters and uneven concentrations are prevented. The tensile strength of steel fiber reinforced concrete is scarcely better compared to that of plain concrete, but the fibers are very effective at preventing the propagation of tensile cracks. Thereby the tensile strength of fiber reinforced concrete is a reliable value. The addition of steel fibers also leads to a considerable increase of plastic deformations in the post cracking region, in comparison to plain concrete members. For nuclear power plant construction the use of steel fiber concrete with additional reinforcement of normal or prestressing steel is of special interest. The finished members exhibit good crack behaviour, increased shear strength and a considerable ability to absorb mechanical energy. These are valuable properties for members providing protection against extreme load cases (e.g. aircraft crash, earthquake, blast caused by explosion, debris due to hurricane, internal pressure loads or debris due to bursting of vessels or pipes). The behaviour of a reinforced concrete beam with steel fiber reinforced concrete against that of a reinforced beam without is shown. Until now the use of steel fiber reinforced concrete in civil engineering has been restricted because of the lack of design rules. For the preparation of fundamental principles and for the development of design rules HOCHTIEF has undertaken a series of tests on steel fiber reinforced concrete members with and without additional bar reinforcement. For this purpose HOCHTIEF has carried out several series of tests using either static, impact or cyclic loadings. In section 2 of this paper the elements

Reinforcement of tire tread and radiator hose rubbers with short aramid fibers

OpenAIRE

Shirazi, Morteza; Noordermeer, Jacobus W.M.

2010-01-01

Short fiber reinforced rubber composites have gained great importance due to their advantages in processing and low cost, coupled with high strength. Reinforcement with short fibers offers attractive features such as design flexibility, high modulus, tear strength, etc. The degree of reinforcement depends upon many parameters, such as: the nature of the rubber matrix, the type of fiber, the concentration and orientation of the fibers, fiber to rubber adhesion to generate a strong interface, f...

Nanofibrillated cellulose (NFC) as a potential reinforcement for high performance cement mortar composites

OpenAIRE

Ardanuy Raso, Mònica; Claramunt Blanes, Josep; Arévalo Peces, Raquel; Parés Sabatés, Ferran; Aracri, Elisabetta; Vidal Lluciá, Teresa

2012-01-01

In this work, nanofibrillated cellulose (NFC) has been evaluated as a potential reinforcement for cement mortar composites. Two types of vegetable fibres with different composition and properties (cellulose content and microfibrillar angle), sisal, and cotton linters pulps, were initially characterized in order to assess their reinforcement capability. Sisal pulp was found to be most suitable as reinforcement for their brittle cementitious matrix. Nanofibrillated cellulose was produced by th...

Normal Strength Steel Fiber Reinforced Concrete Subjected to Explosive Loading

OpenAIRE

Mohammed Alias Yusof; Norazman Norazman; Ariffin Ariffin; Fauzi Mohd Zain; Risby Risby; CP Ng

2011-01-01

This paper presents the results of an experimental investigation on the behavior of plain reinforced concrete and Normal strength steel fiber reinforced concrete panels (SFRC) subjected to explosive loading. The experiment were performed by the Blast Research Unit Faculty of Engineering, University Pertahanan Nasional Malaysia A total of 8 reinforced concrete panels of 600mm x 600mm x 100mm were tested. The steel fiber reinforced concrete panels incorporated three different volume fraction, 0...

Carbon Fiber Reinforced Polymer Grids for Shear and End Zone Reinforcement in Bridge Beams

Science.gov (United States)

2018-01-01

Corrosion of reinforcing steel reduces life spans of bridges throughout the United States; therefore, using non-corroding carbon fiber reinforced polymer (CFRP) reinforcement is seen as a way to increase service life. The use of CFRP as the flexural ...

Agricultural residues based composites part II: Hydration characteristics of cement- cellulosic fibers composites

International Nuclear Information System (INIS)

Hekal, E.E.; Kishar, E.A.; Abd-El-Khader, A.H.; Ibrahim, A.A.; Mobarak, F.M.

2005-01-01

The aim of this study is the utilization of the local agricultural wastes, such as ice straw bagasse, cotton stalks and linen fibers, which cause a big environmental problem. Different cement-fiber composites were prepared using 1.5, 3, 4.5 and 6% fibers by weight of cement. The lengths of the fibers used were 0.5, 0.8, and 1.25 mm. Hydration of the different, composites was carried out at room temperature for various lime intervals namely, 1.3,7 .28 and 90 days. Combined water contents, compressive strength and phase composition of the different prepared composites were examined

Fiber reinforced silicon-containing arylacetylene resin composites

Directory of Open Access Journals (Sweden)

2007-12-01

Full Text Available A silicon-containing arylacetylene resin (SAR, a poly(dimethylsilyleneethynylene phenyleneethynylene (PMSEPE, was synthesized. The PMSEPE is a solid resin at ambient temperature with a softening temperature about 60°C and soluble in some solvents like tetrahydrofuran. The melt viscosity of the PMSEPE resin is less than 1 Pa•s. The resin could cure at the temperature of lower than 200°C. Fiber reinforced PMSEPE composites were prepared from prepregs which were made by the impregnation of fibers in PMSEPE resin solution. The composites exhibit good mechanical properties at room temperature and 250°C. The observation on fracture surfaces of the composites reinforced by glass fibers and carbon fibers demonstrates that the adhesion between the fibers and resin is good. The results from an oxyacetylene flame test show that the composites have good ablation performance and XRD analyses indicate that SiC forms in the residues during the ablation of the composites.

Design aid for shear strengthening of reinforced concrete T-joints using carbon fiber reinforced plastic composites

Science.gov (United States)

Gergely, Ioan

The research presented in the present work focuses on the shear strengthening of beam column joints using carbon fiber composites, a material considered in seismic retrofit in recent years more than any other new material. These composites, or fiber reinforced polymers, offer huge advantages over structural steel reinforced concrete or timber. A few of these advantages are the superior resistance to corrosion, high stiffness to weight and strength to weight ratios, and the ability to control the material's behavior by selecting the orientation of the fibers. The design and field application research on reinforced concrete cap beam-column joints includes analytical investigations using pushover analysis; design of carbon fiber layout, experimental tests and field applications. Several beam column joints have been tested recently with design variables as the type of composite system, fiber orientation and the width of carbon fiber sheets. The surface preparation has been found to be critical for the bond between concrete and composite material, which is the most important factor in joint shear strengthening. The final goal of this thesis is to develop design aids for retrofitting reinforced concrete beam column joints. Two bridge bents were tested on the Interstate-15 corridor. One bent was tested in the as-is condition. Carbon fiber reinforced plastic composite sheets were used to externally reinforce the second bridge bent. By applying the composite, the displacement ductility has been doubled, and the bent overall lateral load capacity has been increased as well. The finite element model (using DRAIN-2DX) was calibrated to model the actual stiffness of the supports. The results were similar to the experimental findings.

Fiber reinforced concrete as a material for nuclear reactor containment buildings

International Nuclear Information System (INIS)

Mallikarjuna; Banthia, N.; Mindess, S.

1991-01-01

The fiber reinforced concrete as a constructional material for nuclear reactor containment buildings calls for an examination of its individual characteristics and potentialities due to its inherent superiority over normal plain and reinforced concrete. In the present investigation, first, to study the static behavior of straight, hooked-end and crimped fibers, recently developed nonlinear three-dimensional interface (contact) element has been used in conjunction with the eight nodded hexahedron and two nodded bar elements for concrete and steel fiber respectively. Then impact tests were carried out on fiber reinforced concrete beams with an instrumented drop weight impact machine. Two different concrete mixes were tested: normal strength and high strength concrete specimens. Fibers in the concrete mix found to significantly increase the ductility and the impact resistance of the composite. Deformed fibers increase peak pull-out load and pull-out distance, and perform better in the steel fiber reinforced concrete (SFRC) structures. (author)

Preliminary Study on Impact Resistances of Fiber Reinforced Concrete Applied Nuclear Power Plants

International Nuclear Information System (INIS)

Jin, Byeong Moo; Kim, Young Jin; Jeon, Se Jin

2013-01-01

Studies to improve the impact resistance depending upon design parameters for fiber reinforced concrete, such as type of fibers and application ratio, are in progress. Authors assessed first the impact resistance of concrete walls depending upon fiber types and missile impact velocities. The safety assessment of nuclear power plants against large civil aircraft crashes have been accomplished for normal concrete and fiber reinforced concretes in this study. Studies on the safety assessments on the nuclear power plants against large civil aircraft crashes are ongoing actively. As a step of evaluating the applicability of fiber reinforced concrete in means of ensuring more structural safety of the nuclear power plants against impact, the impact resistance for the 1% steel and 2% polyamide fiber reinforced concretes have been evaluated. For reactor containment building structures, it seem there is no impact resistance enhancement of fiber reinforced concrete applied to reactor containment building in the cases of impact velocity 150 m/sec considered in this study. However this results from the pre-stressing forces which introduce compressive stresses in concrete wall and dome section of reactor containment building. Nonetheless there may be benefits to apply fiber reinforced concrete to nuclear power plants. For double containment type reactor containment building, the outer structure is a reinforced concrete structure. The impact resistances for non pre-stressed cylindrical reactor containment buildings are enhanced by 23 to 47 % for 2 % polyamide fiber reinforced concretes and 1 % steel fiber reinforced concretes respectively. For other buildings such as auxiliary building, compound building and fuel storage building surrounding the reactor containment building, there are so many reinforced concrete walls which are anticipated some enhancements of impact resistance by using fiber reinforced concretes. And heavier or faster large civil aircraft impacts produce higher

Preliminary Study on Impact Resistances of Fiber Reinforced Concrete Applied Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Jin, Byeong Moo; Kim, Young Jin; Jeon, Se Jin [Daewoo E and C Co. Ltd., Suwon (Korea, Republic of)

2013-10-15

Studies to improve the impact resistance depending upon design parameters for fiber reinforced concrete, such as type of fibers and application ratio, are in progress. Authors assessed first the impact resistance of concrete walls depending upon fiber types and missile impact velocities. The safety assessment of nuclear power plants against large civil aircraft crashes have been accomplished for normal concrete and fiber reinforced concretes in this study. Studies on the safety assessments on the nuclear power plants against large civil aircraft crashes are ongoing actively. As a step of evaluating the applicability of fiber reinforced concrete in means of ensuring more structural safety of the nuclear power plants against impact, the impact resistance for the 1% steel and 2% polyamide fiber reinforced concretes have been evaluated. For reactor containment building structures, it seem there is no impact resistance enhancement of fiber reinforced concrete applied to reactor containment building in the cases of impact velocity 150 m/sec considered in this study. However this results from the pre-stressing forces which introduce compressive stresses in concrete wall and dome section of reactor containment building. Nonetheless there may be benefits to apply fiber reinforced concrete to nuclear power plants. For double containment type reactor containment building, the outer structure is a reinforced concrete structure. The impact resistances for non pre-stressed cylindrical reactor containment buildings are enhanced by 23 to 47 % for 2 % polyamide fiber reinforced concretes and 1 % steel fiber reinforced concretes respectively. For other buildings such as auxiliary building, compound building and fuel storage building surrounding the reactor containment building, there are so many reinforced concrete walls which are anticipated some enhancements of impact resistance by using fiber reinforced concretes. And heavier or faster large civil aircraft impacts produce higher

Stress-Strain Relationship of Synthetic Fiber Reinforced Concrete Columns

Directory of Open Access Journals (Sweden)

Rosidawani

2017-01-01

Full Text Available Many empirical confinement models for normal and high strength concrete have been developed. Nevertheless, reported studies in the term of confinement of fiber reinforced concrete are limited. Whereas, the use of fiber reinforced concrete in structural elements has become the subject of the research and has indicated positive experiences. Since the stress-strain relationship of concrete in compression is required for analysis of structural members, the study of the stress-strain relationship for synthetic fiber reinforced concrete is substantial. The aim of the study is to examine the capabilities of the various models available in the literature to predict the actual experimental behavior of synthetic fiber reinforced high-strength concrete columns. The experimental data used are the results of the circular column specimens with the spiral spacing and the volume fraction of synthetic fiber as the test variables. The axial stress-strain curves from the tests are then compared with the various models of confinement from the literature. The performance index of each model is measured by using the coefficient of variation (COV concept of stress and strain behavior parameter. Among the confinement models, Cusson model shows the closest valid value of the coefficient of variation.

Modelling of the glass fiber length and the glass fiber length distribution in the compounding of short glass fiber-reinforced thermoplastics

Science.gov (United States)

Kloke, P.; Herken, T.; Schöppner, V.; Rudloff, J.; Kretschmer, K.; Heidemeyer, P.; Bastian, M.; Walther, Dridger, A.

2014-05-01

The use of short glass fiber-reinforced thermoplastics for the production of highly stressed parts in the plastics processing industry has experienced an enormous boom in the last few years. The reasons for this are primarily the improvements to the stiffness and strength properties brought about by fiber reinforcement. These positive characteristics of glass fiber-reinforced polymers are governed predominantly by the mean glass fiber length and the glass fiber length distribution. It is not enough to describe the properties of a plastics component solely as a function of the mean glass fiber length [1]. For this reason, a mathematical-physical model has been developed for describing the glass fiber length distribution in compounding. With this model, it is possible on the one hand to optimize processes for the production of short glass fiber-reinforced thermoplastics, and, on the other, to obtain information on the final distribution, on the basis of which much more detailed statements can be made about the subsequent properties of the molded part. Based on experimental tests, it was shown that this model is able to accurately describe the change in glass fiber length distribution in compounding.

Physico-Chemical studies on irradiated polymer-reinforcement cement mortar composites

International Nuclear Information System (INIS)

Younes, M.M.

2001-01-01

The reinforced concrete suffers from corrosion by several salts, acids or alkalies and physico-mechanical properties are greatly affected. This leads to reduce the life of reinforced concrete structure. The present investigation deals with a comparison of corrosion presentation efficiency and passivity retention of reinforcement steel coated with methylethyl and propyl inhibitors which are prepared by using γ radiation and non-coated steel embedded in γ -induced polyester cement mortar composites. From the results of these studies several conclusions could be derived and these are summarized as follows: 1- The time required to reach passivation for coated steel embedded in the mortar after soaking in tap water for 28 days lies within the range 5-15 minutes; whereas, the time required to reach passivation for steel embedded in the polyester cement mortar composites is very short (1 minute). This result is related to the presence of copolymerized polyester in the pore system of the specimens. 2- The time required to reach passivation for steel coated by inhibitors in the mortar specimens after curing in tap water for 6 months is lower than that of non -coated steel embedded in the mortar specimens cured at the same conditions. 3- A relatively high degree of corrosion inhibition was obtained for the steel embedded in polyester-cement mortar composites after curing in sea water for 28 days, the time required to reach passivation is considered as moderate in the case of methyl and ethyl inhibitors the time to passivation (T.T.P.) = 9 minutes and the degree of inhibition of steel coated with the propyl inhibitor is comparatively low (T.T.P.=21 minutes)

Fracture strength of fiber-reinforced surface-retained anterior cantilever restorations

NARCIS (Netherlands)

Oezcan, Mutlu; Kumbuloglu, Ovul; User, Atilla

2008-01-01

Purpose: This study compared the fracture strength of direct anterior cantilever fiber-reinforced composite (FRC) fixed partial dentures (FPD) reinforced with 3 types of E-glass fibers preimpregnated with either urethane tetramethacrylate, bisphenol glycidylmethacrylate/polymethyl methacrylate, or

Evaluation of the thermal properties of polypropylene reinforced with palm fibers composites

International Nuclear Information System (INIS)

Capri, M.R.; Santana, L.C.; Mulinari, D.R.

2016-01-01

The aim of this study was to characterize polypropylene reinforced with palm composites. Of this form, it was studied physical and chemical modifications of the in nature fibers, washed with hot water and mercerized. The composites of polypropylene reinforced with 5%, 10% and 20% (wt /wt) in nature fibers and mercerized were evaluated thermally. The fibers were characterized by SEM XRD and TGA / DSC techniques. Results revealed that the mercerized fibers presented higher crystallinity when compared to others, as well as increased roughness, facilitating interlacing with the reinforcement matrix. Thermal studies of the fibers showed that the mercerization caused displacement curves paragraph higher temperatures. The composites reinforced with treated fibers presented largest temperatures and enthalpies of degradation. The content of fiber influenced in enthalpy degradation and reduction in fusion temperature. (author)

Characterization and modeling of fiber reinforced concrete for structural applications in beams and plates

DEFF Research Database (Denmark)

Paegle, Ieva

(i.e., stirrups) is investigated in detail using digital image correlation (DIC) measurement technique. The use of steel fibers to replace traditional shear reinforcement is not without precedent in current reinforced concrete design codes. However, more detailed information is provided......Fiber reinforced concrete (FRC) with discrete, short and randomly distributed fibers can be specified and designed for structural applications in flexural members. In certain cases, fibers are used as the only reinforcement, while in other cases fibers are used in combination with a reduced amount...... are considered in structural design, the work presented in this thesis analyzes in detail many commonly used test methods on three types of FRC, including Polypropylene Fiber Reinforced Concrete (PP-FRC), Polyvinyl Alcohol Fiber Reinforced Concrete called Engineered Cementitious Composite (ECC) and Steel Fiber...

Utilization of power plant bottom ash as aggregates in fiber-reinforced cellular concrete.

Science.gov (United States)

Lee, H K; Kim, H K; Hwang, E A

2010-02-01

Recently, millions tons of bottom ash wastes from thermoelectric power plants have been disposed of in landfills and coastal areas, regardless of its recycling possibility in construction fields. Fiber-reinforced cellular concrete (FRCC) of low density and of high strength may be attainable through the addition of bottom ash due to its relatively high strength. This paper focuses on evaluating the feasibility of utilizing bottom ash of thermoelectric power plant wastes as aggregates in FRCC. The flow characteristics of cement mortar with bottom ash aggregates and the effect of aggregate type and size on concrete density and compressive strength were investigated. In addition, the effects of adding steel and polypropylene fibers for improving the strength of concrete were also investigated. The results from this study suggest that bottom ash can be applied as a construction material which may not only improve the compressive strength of FRCC significantly but also reduce problems related to bottom ash waste.

Micromechanical Modeling of Fiber-Reinforced Composites with Statistically Equivalent Random Fiber Distribution

Directory of Open Access Journals (Sweden)

Wenzhi Wang

2016-07-01

Full Text Available Modeling the random fiber distribution of a fiber-reinforced composite is of great importance for studying the progressive failure behavior of the material on the micro scale. In this paper, we develop a new algorithm for generating random representative volume elements (RVEs with statistical equivalent fiber distribution against the actual material microstructure. The realistic statistical data is utilized as inputs of the new method, which is archived through implementation of the probability equations. Extensive statistical analysis is conducted to examine the capability of the proposed method and to compare it with existing methods. It is found that the proposed method presents a good match with experimental results in all aspects including the nearest neighbor distance, nearest neighbor orientation, Ripley’s K function, and the radial distribution function. Finite element analysis is presented to predict the effective elastic properties of a carbon/epoxy composite, to validate the generated random representative volume elements, and to provide insights of the effect of fiber distribution on the elastic properties. The present algorithm is shown to be highly accurate and can be used to generate statistically equivalent RVEs for not only fiber-reinforced composites but also other materials such as foam materials and particle-reinforced composites.

Hybrid fiber reinforcement and crack formation in Cementitious Composite Materials

DEFF Research Database (Denmark)

Pereira, E.B.; Fischer, Gregor; Barros, J.A.O.

2011-01-01

reinforcement systems. The research described in this paper shows that the multi-scale conception of cracking and the use of hybrid fiber reinforcements do not necessarily result in an improved tensile behavior of the composite. Particular material design requirements may nevertheless justify the use of hybrid......- to the macroscale. In this study, the performance of different fiber reinforced cementitious composites is assessed in terms of their tensile stress-crack opening behavior. The results obtained from this investigation allow a direct quantitative comparison of the behavior obtained from the different fiber...

Strain Sharing Assessment in Woven Fiber Reinforced Concrete Beams Using Fiber Bragg Grating Sensors.

Science.gov (United States)

Montanini, Roberto; Recupero, Antonino; De Domenico, Fabrizio; Freni, Fabrizio

2016-09-22

Embedded fiber Bragg grating sensors have been extensively used worldwide for health monitoring of smart structures. In civil engineering, they provide a powerful method for monitoring the performance of composite reinforcements used for concrete structure rehabilitation and retrofitting. This paper discusses the problem of investigating the strain transfer mechanism in composite strengthened concrete beams subjected to three-point bending tests. Fiber Bragg grating sensors were embedded both in the concrete tensioned surface and in the woven fiber reinforcement. It has been shown that, if interface decoupling occurs, strain in the concrete can be up to 3.8 times higher than that developed in the reinforcement. A zero friction slipping model was developed which fitted very well the experimental data.

Single Fibre Pullout from Hybrid Fiber Reinforced Concrete

NARCIS (Netherlands)

Markovich, I.; Van Mier, J.G.M.; Walraven, J.C.

2001-01-01

Hybrid fiber reinforcement can be very efficient for improving the tensile response of the composite. In such materials, fibers of different geometries can act as bridging mechanisms over cracks of different widths. The fiber bridging efficiency depends on the interface properties, which makes

Mechanical characterization of glass fiber (woven roving/chopped strand mat E-glass fiber) reinforced polyester composites

Science.gov (United States)

Bhaskar, V. Vijaya; Srinivas, Kolla

2017-07-01

Polymer reinforced composites have been replacing most of the engineering material and their applications become more and more day by day. Polymer composites have been analyzing from past thirty five years for their betterment for adapting more applications. This paper aims at the mechanical properties of polyester reinforced with glass fiber composites. The glass fiber is reinforced with polyester in two forms viz Woven Rovings (WRG) and Chopped Strand Mat (CSMG) E-glass fibers. The composites are fabricated by hand lay-up technique and the composites are cut as per ASTM Standard sizes for corresponding tests like flexural, compression and impact tests, so that flexural strength, compression strength, impact strength and inter laminar shear stress(ILSS) of polymer matrix composites are analyzed. From the tests and further calculations, the polyester composites reinforced with Chopped Strand Mat glass fiber have shown better performance against flexural load, compression load and impact load than that of Woven Roving glass fiber.

Strain measurement in a concrete beam by use of the Brillouin-scattering-based distributed fiber sensor with single-mode fibers embedded in glass fiber reinforced polymer rods and bonded to steel reinforcing bars.

Science.gov (United States)

Zeng, Xiaodong; Bao, Xiaoyi; Chhoa, Chia Yee; Bremner, Theodore W; Brown, Anthony W; DeMerchant, Michael D; Ferrier, Graham; Kalamkarov, Alexander L; Georgiades, Anastasis V

2002-08-20

The strain measurement of a 1.65-m reinforced concrete beam by use of a distributed fiber strain sensor with a 50-cm spatial resolution and 5-cm readout resolution is reported. The strain-measurement accuracy is +/-15 microepsilon (microm/m) according to the system calibration in the laboratory environment with non-uniform-distributed strain and +/-5 microepsilon with uniform strain distribution. The strain distribution has been measured for one-point and two-point loading patterns for optical fibers embedded in pultruded glass fiber reinforced polymer (GFRP) rods and those bonded to steel reinforcing bars. In the one-point loading case, the strain deviations are +/-7 and +/-15 microepsilon for fibers embedded in the GFRP rods and fibers bonded to steel reinforcing bars, respectively, whereas the strain deviation is +/-20 microepsilon for the two-point loading case.

Direct Shear Behavior of Fiber Reinforced Concrete Elements

Directory of Open Access Journals (Sweden)

Hussein Al-Quraishi

2018-01-01

Full Text Available Improving the accuracy of load-deformation behavior, failure mode, and ultimate load capacity for reinforced concrete members subjected to in-plane loadings such as corbels, wall to foundation connections and panels need shear strength behavior to be included. Shear design in reinforced concrete structures depends on crack width, crack slippage and roughness of the surface of cracks. This paper illustrates results of an experimental investigation conducted to investigate the direct shear strength of fiber normal strength concrete (NSC and reactive powder concrete (RPC. The tests were performed along a pre-selected shear plane in concrete members named push-off specimens. The effectiveness of concrete compressive strength, volume fraction of steel fiber, and shear reinforcement ratio on shear transfer capacity were considered in this study. Furthermore, failure modes, shear stress-slip behavior, and shear stress-crack width behavior were also presented in this study. Tests’ results showed that volume fraction of steel fiber and compressive strength of concrete in NSC and RPC play a major role in improving the shear strength of concrete. As expectedly, due to dowel action, the shear reinforcement is the predominant factor in resisting the shear stress. The shear failure of NSC and RPC has the sudden mode of failure (brittle failure with the approximately linear behavior of shear stress-slip relationship till failure. Using RPC instead of NSC with the same amount of steel fibers in constructing the push-off specimen result in high shear strength. In NSC, shear strength influenced by the three major factors; crack surface friction, aggregate interlock and steel fiber content if present. Whereas, RPC has only steel fiber and cracks surface friction influencing the shear strength. Due to cementitious nature of RPC in comparisons with NSC, the RPC specimen shows greater cracks width. It is observed that the Mattock model gives very satisfactory

Fiber breakage phenomena in long fiber reinforced plastic preparation

International Nuclear Information System (INIS)

Huang, Chao-Tsai; Tseng, Huan-Chang; Chang, Rong-Yeu; Vlcek, Jiri

2015-01-01

Due to the high demand of smart green, the lightweight technologies have become the driving force for the development of automotives and other industries in recent years. Among those technologies, using short and long fiber-reinforced plastics (FRP) to replace some metal components can reduce the weight of an automotive significantly. However, the microstructures of fibers inside plastic matrix are too complicated to manage and control during the injection molding through the screw, the runner, the gate, and then into the cavity. This study focuses on the fiber breakage phenomena during the screw plastification. Results show that fiber breakage is strongly dependent on screw design and operation. When the screw geometry changes, the fiber breakage could be larger even with lower compression ratio. (paper)

Engineering Properties of Treated Natural Hemp Fiber-Reinforced Concrete

Directory of Open Access Journals (Sweden)

Xiangming Zhou

2017-06-01

Full Text Available In recent years, the construction industry has seen a significant rise in the use of natural fibers, for producing building materials. Research has shown that treated hemp fiber-reinforced concrete (THFRC can provide a low-cost building material for residential and low-rise buildings, while achieving sustainable construction and meeting future environmental targets. This study involved enhancing the mechanical properties of hemp fiber-reinforced concrete through the Ca(OH2 solution pretreatment of fibers. Both untreated (UHFRC and treated (THFRC hemp fiber-reinforced concrete were tested containing 15-mm length fiber, at a volume fraction of 1%. From the mechanical strength tests, it was observed that the 28-day tensile and compressive strength of THFRC was 16.9 and 10% higher, respectively, than UHFRC. Based on the critical stress intensity factor (KICs and critical strain energy release rate (GICs, the fracture toughness of THFRC at 28 days was also found to be 7–13% higher than UHFRC. Additionally, based on the determined brittleness number (Q and modulus of elasticity, the THFRC was found to be 11% less brittle and 10.8% more ductile. Furthermore, qualitative analysis supported many of the mechanical strength findings through favorable surface roughness observed on treated fibers and resistance to fiber pull-out.

Isolation of aramid nanofibers for high strength multiscale fiber reinforced composites

Science.gov (United States)

Lin, Jiajun; Patterson, Brendan A.; Malakooti, Mohammad H.; Sodano, Henry A.

2018-03-01

Aramid fibers are famous for their high specific strength and energy absorption properties and have been intensively used for soft body armor and ballistic protection. However, the use of aramid fiber reinforced composites is barely observed in structural applications. Aramid fibers have smooth and inert surfaces that are unable to form robust adhesion to polymeric matrices due to their high crystallinity. Here, a novel method to effectively integrate aramid fibers into composites is developed through utilization of aramid nanofibers. Aramid nanofibers are prepared from macroscale aramid fibers (such as Kevlar®) and isolated through a simple and scalable dissolution method. Prepared aramid nanofibers are dispersible in many polymers due to their improved surface reactivity, meanwhile preserve the conjugated structure and likely the strength of their macroscale counterparts. Simultaneously improved elastic modulus, strength and fracture toughness are observed in aramid nanofiber reinforced epoxy nanocomposites. When integrated in continuous fiber reinforced composites, aramid nanofibers can also enhance interfacial properties by forming hydrogen bonds and π-π coordination to bridge matrix and macroscale fibers. Such multiscale reinforcement by aramid nanofibers and continuous fibers results in strong polymeric composites with robust mechanical properties that are necessary and long desired for structural applications.

FLEXURAL TOUGHNESS OF STEEL FIBER REINFORCED CONCRETE

Directory of Open Access Journals (Sweden)

Fehmi ÇİVİCİ

2006-02-01

Full Text Available Fiber concrete is a composite material which has mechanical and physical characteristics unlike plain concrete. One of the important mechanical characteristics of fiber concrete is its energy absorbing capability. This characteristics which is also called toughness, is defined as the total area under the load-deflection curve. A number of composite characteristics such as crack resistance, ductility and impact resistance are related to the energy absorbtion capacity. According to ASTM C 1018 and JSCE SF-4 the calculation of toughness is determined by uniaxial flexural testing. Fiber concrete is often used in plates such as bridge decks, airport pavements, parking areas, subjected to cavitation and erosion. In this paper, toughness has been determined according to ASTM C 1018 and JSCE SF-4 methods by testing beam specimens. Energy absorbing capacities of plain and steel fiber reinforced concrete has been compared by evaluating the results of two methods. Also plain and steel fiber reinforced plate specimens behaviors subjected to biaxial flexure are compared by the loaddeflection curves of each specimen.

Health monitoring of precast bridge deck panels reinforced with glass fiber reinforced polymer (GFRP) bars.

Science.gov (United States)

2012-03-01

The present research project investigates monitoring concrete precast panels for bridge decks that are reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Due to the lack of long term research on concrete members reinforced with GFRP bars, lo...

Jordanian silica sand and cement as a reinforcement material for polystyrene matrix composites

International Nuclear Information System (INIS)

Jalham, S. I.

1999-01-01

The behaviour of polystyrene matrix composites with different percentages of Jordaanian Silica Sand as a Reinforcement Materials (0, 5, 25, 50, and 75 wt%) and different mean grain sizes of sand particles (60, 75, 85, and 300μ m) and with cement as a boning materials in the amount fo 1/6 wt% of the wt% of silica sand were manufactured and tested under compression loading in the Industrial Engineering Department as the Uninersity of Jordan as a part of large study on local materials. The main conclusions of this investigation are: a long-term, durable structure of the polystyrene composite reinforced by silica sand and cement was achieved by mixing the constituents with water; the higher the volume fraction of the reinforcement, the higher the volume fraction of reinforcement, the higher the strength while for 75% of reinforcement, the strength dropped to an amount less than that of the matrix; the higher the grain size, the higher the strength; longitudinal brittle fracture was observed for the composites, and a homogeneous distribution of the sand particles helped in increasing the strength of the composite by playing an important role in distributing the applied load. (author). 11 refs., 6 tabs, 2 figs

The Integration of EIS parameters and bulk matrix characterization in studying reinforced cement-based materials

NARCIS (Netherlands)

Koleva, D.A.; Van Breugel, K.

2012-01-01

Corrosion in reinforced concrete is a major and costly concern, arising from the higher complexity of involved phenomena on different levels of material science (e.g. electrochemistry, concrete material science) and material properties (macro/micro/ nano). Reinforced cement-based systems (e.g.

The integration of eis parameters and bulk matrix characteristics in studying reinforced cement-based materials

NARCIS (Netherlands)

Koleva, D.A.; Van Breugel, K.

2011-01-01

Corrosion in reinforced concrete is a major and costly concern, arising from the higher complexity of involved phenomena on different levels of material science (e.g. electrochemistry, concrete material science) and material properties (macro/micro/ nano). Reinforced cement-based systems (e.g.

Micro-Mechanical Modeling of Fiber Reinforced Concrete

DEFF Research Database (Denmark)

Stang, Henrik

1999-01-01

of Fiber Reinforced Concrete (FRC) on the micro- the meso- as well as the macro-level, i.e. modeling aspects of fiber-matrix interaction, overall constitutive modeling and structural modeling. Emphasis is placed on the micro- and meso-aspects, however, some basic results on the macro-level are also...

Reinforcement of tire tread and radiator hose rubbers with short aramid fibers

NARCIS (Netherlands)

Shirazi, Morteza; Noordermeer, Jacobus W.M.

2010-01-01

Short fiber reinforced rubber composites have gained great importance due to their advantages in processing and low cost, coupled with high strength. Reinforcement with short fibers offers attractive features such as design flexibility, high modulus, tear strength, etc. The degree of reinforcement

Effects of endodontic post surface treatment, dentin conditioning, and artificial aging on the retention of glass fiber-reinforced composite resin posts.

Science.gov (United States)

Albashaireh, Zakereyya S; Ghazal, Muhamad; Kern, Matthias

2010-01-01

Several post surface treatments with or without the application of a bonding agent have been recommended to improve the bond strength of resin cements to posts. A regimen that produces the maximum bond strength of glass fiber-reinforced composite resin posts has not been verified. The purpose of this study was to evaluate the influence of post surface conditioning methods and artificial aging on the retention and microleakage of adhesively luted glass fiber-reinforced composite resin posts. Seventy-two endodontically treated single-rooted teeth were prepared for glass fiber-reinforced composite resin posts. The posts were submitted to 3 different surface treatments (n=24), including no treatment, etching with phosphoric acid, and airborne-particle abrasion. Subgroups of the posts (n=8) were then allocated for 3 different experimental conditions: no artificial aging, no bonding agent; no artificial aging, bonding agent; or artificial aging, bonding agent. The posts were luted with resin cement (Calibra). Post retention was measured in tension at a crosshead speed of 2 mm/min. The posts assigned for microleakage investigation were placed in fuchsin dye for 72 hours. The dislodged posts and the post spaces were examined microscopically to evaluate the mode of failure and explore the microleakage. Data were analyzed by 2-way ANOVA followed by Tukey HSD test (alpha=.05). The mean (SD) retention values for test groups ranged from 269 (63.8) to 349 (52.2) N. The retention values of the airborne-particle-abrasion group were significantly higher than those of the acidic-treatment and no-treatment groups. The application of bonding agent on the post surface produced no significant influence on retention. The mean retention values after artificial aging were significantly higher than without artificial aging. Microscopic evaluation demonstrated that the failure mode was primarily mixed. Treating the surface of the posts with phosphoric acid for 15 seconds before cementation

Effect of ultraviolet light irradiation on bond strength of fiber post: Evaluation of surface characteristic and bonded area of fiber post with resin cement

OpenAIRE

Reza, Fazal; Ibrahim, Nur Sukainah

2015-01-01

Objective: Fiber post is cemented to a root canal to restore coronal tooth structure. This research aims to evaluate the effect of ultraviolet (UV) irradiation on bond strength of fiber post with resin cement. Materials and Methods: A total of 40 of the two types of fiber posts, namely, FRC Prostec (FRC) and Fiber KOR (KOR), were used for the experiment. UV irradiation was applied on top of the fiber post surface for 0, 15, 20, and 30 min. The irradiated surface of the fiber posts (n = 5) wer...

Effect of PVA fiber content on creep property of fiber reinforced high-strength concrete columns

Science.gov (United States)

Xu, Zongnan; Wang, Tao; Wang, Weilun

2018-04-01

The effect of PVA (polyvinyl alcohol) fiber content on the creep property of fiber reinforced high-strength concrete columns was investigated. The correction factor of PVA fiber content was proposed and the creep prediction model of ACI209 was modified. Controlling the concrete strength as C80, changing the content of PVA fiber (volume fraction 0%, 0.25%, 0.5%, 1% respectively), the creep experiment of PVA fiber reinforced concrete columns was carried out, the creep coefficient of each specimen was calculated to characterize the creep property. The influence of PVA fiber content on the creep property was analyzed based on the creep coefficient and the calculation results of several frequently used creep prediction models. The correction factor of PVA fiber content was proposed to modify the ACI209 creep prediction model.

Properties of discontinuous S2-glass fiber-particulate-reinforced resin composites with two different fiber length distributions.

Science.gov (United States)

Huang, Qiting; Garoushi, Sufyan; Lin, Zhengmei; He, Jingwei; Qin, Wei; Liu, Fang; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

2017-10-01

To investigate the reinforcing efficiency and light curing properties of discontinuous S2-glass fiber-particulate reinforced resin composite and to examine length distribution of discontinuous S2-glass fibers after a mixing process into resin composite. Experimental S2-glass fiber-particulate reinforced resin composites were prepared by mixing 10wt% of discontinuous S2-glass fibers, which had been manually cut into two different lengths (1.5 and 3.0mm), with various weight ratios of dimethacrylate based resin matrix and silaned BaAlSiO 2 filler particulates. The resin composite made with 25wt% of UDMA/SR833s resin system and 75wt% of silaned BaAlSiO 2 filler particulates was used as control composite which had similar composition as the commonly used resin composites. Flexural strength (FS), flexural modulus (FM) and work of fracture (WOF) were measured. Fractured specimens were observed by scanning electron microscopy. Double bond conversion (DC) and fiber length distribution were also studied. Reinforcement of resin composites with discontinuous S2-glass fibers can significantly increase the FS, FM and WOF of resin composites over the control. The fibers from the mixed resin composites showed great variation in final fiber length. The mean aspect ratio of experimental composites containing 62.5wt% of particulate fillers and 10wt% of 1.5 or 3.0mm cutting S2-glass fibers was 70 and 132, respectively. No difference was found in DC between resin composites containing S2-glass fibers with two different cutting lengths. Discontinuous S2-glass fibers can effectively reinforce the particulate-filled resin composite and thus may be potential to manufacture resin composites for high-stress bearing application. Copyright © 2017. Published by Elsevier Ltd.

Hybrid fiber and nanopowder reinforced composites for wind turbine blades

Directory of Open Access Journals (Sweden)

Nikoloz M. Chikhradze

2015-01-01

Full Text Available The results of an investigation into the production of wind turbine blades manufactured using polymer composites reinforced by hybrid (carbon, basalt, glass fibers and strengthened by various nanopowders (oxides, carbides, borides are presented. The hybrid fiber-reinforced composites (HFRC were manufactured with prepreg technology by molding pre-saturated epoxy-strengthened matrix-reinforced fabric. Performance of the manufactured composites was estimated with values of the coefficient of operating condition (COC at a moderate and elevated temperature.

Performance of steel wool fiber reinforced geopolymer concrete

Science.gov (United States)

Faris, Meor Ahmad; Abdullah, Mohd Mustafa Al Bakri; Ismail, Khairul Nizar; Muniandy, Ratnasamy; Ariffin, Nurliayana

2017-09-01

In this paper, performance of geopolymer concrete was studied by mixing of Class F fly ash from Manjung power station, Lumut, Perak, Malaysia with alkaline activator which are combination of sodium hydroxide and sodium silicate. Steel wool fiber were added into the geopolymer concrete as reinforcement with different weight percentage vary from 0 % - 5 %. Chemical compositions of Malaysian fly ash was first analyzed by using X-ray fluorescence. All geopolymer concrete reinforced with steel wool fiber with different weight percentage were tested in terms of density, workability, and compression. Result shows Malaysian fly ash identified by using XRF was class F. Density of geopolymer concrete close to density of OPC which is approximately 2400 kg/m3 and the density was increase gradually with the additions of steel fiber. However, the inclusions of steel fibers also shows some reduction to the workability of geopolymer concrete. Besides, the compressive strength was increased with the increasing of fibers addition until maximum of 18.6 % improvement at 3 % of steel fibers.

Effect of fiber content on flexural properties of glass fiber-reinforced polyamide-6 prepared by injection molding.

Science.gov (United States)

Nagakura, Manamu; Tanimoto, Yasuhiro; Nishiyama, Norihiro

2017-07-26

The use of non-metal clasp denture (NMCD) materials may seriously affect the remaining tissues because of the low rigidity of NMCD materials such as polyamides. The purpose of this study was to develop a high-rigidity glass fiber-reinforced thermoplastic (GFRTP) composed of E-glass fiber and polyamide-6 for NMCDs using an injection molding. The reinforcing effects of fiber on the flexural properties of GFRTPs were investigated using glass fiber content ranging from 0 to 50 mass%. Three-point bending tests indicated that the flexural strength and elastic modulus of a GFRTP with a fiber content of 50 mass% were 5.4 and 4.7 times higher than those of unreinforced polyamide-6, respectively. The result showed that the physical characteristics of GFRTPs were greatly improved by increasing the fiber content, and the beneficial effects of fiber reinforcement were evident. The findings suggest that the injection-molded GFRTPs are adaptable to NMCDs because of their excellent mechanical properties.

Tensile Capacity of U-bar Loop Connections with Precast Fiber Reinforced Dowels

DEFF Research Database (Denmark)

Sørensen, Jesper Harrild; Hoang, Linh Cao; Olesen, John Forbes

2016-01-01

This paper describes an investigation of the tensile capacity of in-situ cast U-bar loop connections between precast concrete elements. The basic idea is to introduce a small precast cylindrical dowel of fiber reinforced mortar that fits into the bend diameter of the overlapping U...... that use of a precast fiber reinforced dowel performs at a slightly lower load level, as compared to a connection grouted solely with regular mortar and reinforced with the same amount of transverse reinforcement. However, the load-displacement response of specimens with a fiber reinforced dowel is closer......-bars. The remaining part of the connection is cast in-situ with a regular mortar, which then encapsulates the precast dowel. Different dowel configurations have been investigated, including the use of steel or synthetic fibers with or without lacer bars placed within the precast dowel. The experimental results show...

RESIDUAL PROPERTIES OF FIBER-REINFORCED REFRACTORY COMPOSITES WITH A FIRECLAY FILLER

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Marcel Jogl

2016-02-01

Full Text Available The aim of our study was to develop a composite material for industrial use that is resistant to the effect of high temperatures. The binder system based on aluminous cement was modified by adding finely-ground ceramic powder and metakaolin to reduce costs and also to reduce adverse effects on the environment due to high energy consumption for cement production. Additives were applied as a partial aluminous cement replacement in doses of 10, 20 and 30% by weight. The composites were evaluated on the basis of their mechanical properties and their bulk density after gradual temperature loading. The influence of basalt fibers and modifications to the binder system were studied at the same time. Basalt fibers were applied in doses of 0.5% and 2.0% by volume. The results confirmed the potential of the mineral additives studied here for practical applications, taking into account the residual mechanical parameters after thermal loading. The addition of ceramic powder reduced the bulk density by 5% for each 10% of cement substitution, but the residual values were very similar. The bulk density and the compressive strength were reduced when basalt fibers were applied, and the flexural strength was significantly increased in proportion to the fiber dosages. Metakaolin seems to be a more suitable additive than the ceramic powder that was applied here, because there was a significant increase in the mechanical parameters and also in the residual values of all properties that were studied.

Primary Manufacturing Processes for Fiber Reinforced Composites: History, Development & Future Research Trends

Science.gov (United States)

Tapan Bhatt, Alpa; Gohil, Piyush P.; Chaudhary, Vijaykumar

2018-03-01

Composite Materials are becoming more popular gradually replacing traditional material with extra strength, lighter weight and superior property. The world is exploring use of fiber reinforced composites in all application which includes air, land and water transport, construction industry, toys, instrumentation, medicine and the list is endless. Based on application and reinforcement used, there are many ways to manufactures parts with fiber reinforced composites. In this paper various manufacturing processes have been discussed at length, to make fiber reinforced composites components. The authors have endeavored to include all the processes available recently in composite industry. Paper first highlights history of fiber reinforced composites manufacturing, and then the comparison of different manufacturing process to build composites have been discussed, to give clear understanding on, which process should be selected, based on reinforcement, matrix and application. All though, there are several advantages to use such fiber reinforcement composites, still industries have not grown at par and there is a lot of scope to improve these industries. At last, where India stands today, what are the challenges in market has been highlighted and future market and research trend of exploring such composite industries have been discussed. This work is carried out as a part of research project sanctioned by GUJCOST, Gandhinagar.

Electrochemical corrosion of carbon-fiber-reinforced plastic-metal electrode couples in corrosion media

International Nuclear Information System (INIS)

Chukalovskaya, T.V.; Shcherbakov, A.I.; Chigirinskaya, L.A.; Bandurkin, V.V.; Medova, I.L.; Chukalovskij, P.A.

1995-01-01

Polarization diagrams, obtained for carbon-fiber-reinforced plastic(cathode)-metallic material(anode) contact couples are analyzed to predict the corrosion behaviour of some technical metals and alloys (carbon steel, stainless steels, brass, aluminium, titanium) in contact with carbon-fiber-reinforced plastic in differen agressive media (H 2 SO 4 , HCl, H 3 PO 4 , NaOH solutions in wide temperature and concentration range, synthetic seawater at 30 and 50 deg C). The predicted behaviour was supported by direct investigation into carbon-fiber-reinforced plastic-titanium and carbon-fiber-reinforced plastic-aluminium contact couples at different square ratios. 6 refs.; 4 figs

Evaluating the mechanical properties of E-Glass fiber/carbon fiber reinforced interpenetrating polymer networks

Directory of Open Access Journals (Sweden)

G. Suresh

2015-02-01

Full Text Available A series of vinyl ester and polyurethane interpenetrating polymer networks were prepared by changing the component ratios of VER (Vinyl ester and PU (Polyurethane and the polymerization process was confirmed with Fourier Transform infrared spectroscopy. IPN (Inter Penetrating Polymer Network - VER/PU reinforced Glass and carbon fiber composite laminates were made using the Hand lay up technique. The Mechanical properties of the E-glass and carbon fiber specimens were compared from tests including Tensile, Compressive, Flexural, ILSS (Inter Laminar Shear Strength, Impact & Head Deflection Test (HDT. The IPN Reinforced Carbon fiber specimen showed better results in all the tests than E-Glass fibre reinforced IPN laminate with same thickness of the specimen, according to ASTM standards. It was found that the combination of 60%VER and 40%PU IPN exhibits better impact strength and maximum elongation at break, but at the slight expense of mechanical properties such as tensile, compressive, flexural, ILSS properties. The morphology of the unreinforced and reinforced composites was analyzed with help of scanning electron microscopy.

Biodegradable green composites reinforced by the fiber recycling from disposable chopsticks

International Nuclear Information System (INIS)

Shih, Yeng-Fong; Huang, Chien-Chung; Chen, Po-Wei

2010-01-01

The use of disposable chopsticks is very popular in chopsticks-using countries, such as Taiwan, China and Japan, and is one of the major sources of waste in these countries. In this study, the fiber recycling from disposable chopsticks was chemically modified by coupling agents. Furthermore, the modified fiber was added to the biodegradable polymer (polylactic acid, PLA), to form novel fiber-reinforced green composites. These composites prepared by melt-mixing method, were examined by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and mechanical tests. The results indicated that the T g of PLA was increased by the addition of fiber, which may improve the heat resistance of PLA. The thermogravimetric analysis of the composites showed that the degradation process of fiber-filled systems started earlier than that of plain PLA, but possessed a higher char yield. Mechanical tests showed that the tensile strength of the composites markedly increased with the fiber content, reaching 115 MPa in the case of being reinforced with 40 phr fiber, which is about 3 times higher as compared to the pristine PLA. Furthermore, this type of reinforced PLA would be more environmental friendly than the artificial additive-reinforced one, and could effectively reduce and reuse the waste of disposable chopsticks.

Axial compression behaviour of reinforced wallettes fabricated using wood-wool cement panel

Science.gov (United States)

Noh, M. S. Md; Kamarudin, A. F.; Mokhatar, S. N.; Jaudin, A. R.; Ahmad, Z.; Ibrahim, A.; Muhamad, A. A.

2018-04-01

Wood-wool cement composite panel (WWCP) is one of wood based composite material that produced in a stable panel form and suitable to be used as building wall system to replace non-ecofriendly material such as brick and other masonry element. Heavy construction material such as brick requires more manpower and consume a lot of time to build the wall panel. WWCP is a lightweight material with a density range from 300 kg/m3 to 500 kg/m3 and also capable to support an imposed load from the building. This study reported on the axial compression behaviour of prefabricated reinforced wallettes constructed with wood-wool cement panel. A total of six specimens were fabricated using two layers of cross laminated WWCP bonded with normal mortar paste (Portland cement) at a mix ratio of 1:3 (cement : sand). As part of lifting mechanism, the wallettes were equipped with three steel reinforcement (T12) that embedded inside the core of wallettes. Three replicates of wallettes specimens with dimension 600 mm width and 600 mm length were fabricated without surface plaster and with 16 mm thickness of surface plaster. The wallettes were tested under axial compression load after 28 days of fabrication until failure. The result indicated that, the application of surface plaster significantly increases the loading capacity about 35 % and different orientation of the panels improve the bonding strength of the wall.

Fiber-reinforced composites materials, manufacturing, and design

CERN Document Server

Mallick, P K

2007-01-01

The newly expanded and revised edition of Fiber-Reinforced Composites: Materials, Manufacturing, and Design presents the most up-to-date resource available on state-of-the-art composite materials. This book is unique in that it not only offers a current analysis of mechanics and properties, but also examines the latest advances in test methods, applications, manufacturing processes, and design aspects involving composites. This third edition presents thorough coverage of newly developed materials including nanocomposites. It also adds more emphasis on underlying theories, practical methods, and problem-solving skills employed in real-world applications of composite materials. Each chapter contains new examples drawn from diverse applications and additional problems to reinforce the practical relevance of key concepts. New in The Third Edition: Contains new sections on material substitution, cost analysis, nano- and natural fibers, fiber architecture, and carbon-carbon composites Provides a new chapter on poly...

Continuous Modeling Technique of Fiber Pullout from a Cement Matrix with Different Interface Mechanical Properties Using Finite Element Program

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Leandro Ferreira Friedrich

Full Text Available Abstract Fiber-matrix interface performance has a great influence on the mechanical properties of fiber reinforced composite. This influence is mainly presented during fiber pullout from the matrix. As fiber pullout process consists of fiber debonding stage and pullout stage which involve complex contact problem, numerical modeling is a best way to investigate the interface influence. Although many numerical research works have been conducted, practical and effective technique suitable for continuous modeling of fiber pullout process is still scarce. The reason is in that numerical divergence frequently happens, leading to the modeling interruption. By interacting the popular finite element program ANSYS with the MATLAB, we proposed continuous modeling technique and realized modeling of fiber pullout from cement matrix with desired interface mechanical performance. For debonding process, we used interface elements with cohesive surface traction and exponential failure behavior. For pullout process, we switched interface elements to spring elements with variable stiffness, which is related to the interface shear stress as a function of the interface slip displacement. For both processes, the results obtained are very good in comparison with other numerical or analytical models and experimental tests. We suggest using the present technique to model toughening achieved by randomly distributed fibers.

Assessment of the mechanical properties of sisal fiber-reinforced silty clay using triaxial shear tests.

Science.gov (United States)

Wu, Yankai; Li, Yanbin; Niu, Bin

2014-01-01

Fiber reinforcement is widely used in construction engineering to improve the mechanical properties of soil because it increases the soil's strength and improves the soil's mechanical properties. However, the mechanical properties of fiber-reinforced soils remain controversial. The present study investigated the mechanical properties of silty clay reinforced with discrete, randomly distributed sisal fibers using triaxial shear tests. The sisal fibers were cut to different lengths, randomly mixed with silty clay in varying percentages, and compacted to the maximum dry density at the optimum moisture content. The results indicate that with a fiber length of 10 mm and content of 1.0%, sisal fiber-reinforced silty clay is 20% stronger than nonreinforced silty clay. The fiber-reinforced silty clay exhibited crack fracture and surface shear fracture failure modes, implying that sisal fiber is a good earth reinforcement material with potential applications in civil engineering, dam foundation, roadbed engineering, and ground treatment.

Assessment of the Mechanical Properties of Sisal Fiber-Reinforced Silty Clay Using Triaxial Shear Tests

Directory of Open Access Journals (Sweden)

Yankai Wu

2014-01-01

Full Text Available Fiber reinforcement is widely used in construction engineering to improve the mechanical properties of soil because it increases the soil’s strength and improves the soil’s mechanical properties. However, the mechanical properties of fiber-reinforced soils remain controversial. The present study investigated the mechanical properties of silty clay reinforced with discrete, randomly distributed sisal fibers using triaxial shear tests. The sisal fibers were cut to different lengths, randomly mixed with silty clay in varying percentages, and compacted to the maximum dry density at the optimum moisture content. The results indicate that with a fiber length of 10 mm and content of 1.0%, sisal fiber-reinforced silty clay is 20% stronger than nonreinforced silty clay. The fiber-reinforced silty clay exhibited crack fracture and surface shear fracture failure modes, implying that sisal fiber is a good earth reinforcement material with potential applications in civil engineering, dam foundation, roadbed engineering, and ground treatment.

Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

Directory of Open Access Journals (Sweden)

Lei Gao

2015-01-01

Full Text Available In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%. When the effect of length is researched, different lengths of basalt fibers with 4 mm, 8 mm, 12 mm, and 15 mm are put into soil at the same content of 0.05%. Experimental results show that basalt fiber can effectively improve the UCS of clay soil. And the best content and length are 0.25% and 12 mm, respectively. The results also show that the basalt fiber reinforced clay soil has the “poststrong” characteristic. About the reinforcement mechanism, the fiber and soil column-net model is proposed in this paper. Based on this model and SEM images, the effect of fiber content and length is related to the change of fiber-soil column and formation of effective fiber-soil net.

Effect of hot-dry environment on fiber-reinforced self-compacting concrete

Science.gov (United States)

Tioua, Tahar; Kriker, Abdelouahed; Salhi, Aimad; Barluenga, Gonzalo

2016-07-01

Drying shrinkage can be a major reason for the deterioration of concrete structures. Variation in ambient temperature and relative humidity cause changes in the properties of hardened concrete which can affect their mechanical and drying shrinkage characteristics. The present study investigated mechanical strength and particularly drying shrinkage properties of self-compacting concretes (SCC) reinforced with date palm fiber exposed to hot and dry environment. In this study a total of nine different fibers reinforced self compacting concrete (FRSCC) mixtures and one mixture without fiber were prepared. The volume fraction and the length of fibers reinforcement were 0.1-0.2-0.3% and 10-20-30 mm. It was observed that drying shrinkage lessened with adding low volumetric fraction and short length of fibers in curing condition (T = 20 °C and RH = 50 ± 5 %), but increased in hot and dry environment.

Orientation factor and number of fibers at failure plane in ring-type steel fiber reinforced concrete

International Nuclear Information System (INIS)

Lee, C.; Kim, H.

2010-01-01

Considering the probabilistic distributions of fibers in ring-type steel fiber reinforced concrete, the orientation factor and the number of ring-type steel fibers crossing the failure plane were theoretically derived as a function of fiber geometry, specimen dimensions, and fiber volume fraction. A total number of 24 specimens were tested incorporating different fiber types, specimen geometry, and fiber volume fractions of 0.2% and 0.4%: 5 beams and 5 panels containing straight steel fibers; and 6 beams and 8 panels containing ring-type steel fibers. Measurements were made to assess the number of fibers at fractured surfaces of steel fiber reinforced concrete. The developed theoretical expressions reasonably predicted the orientation factor and the number of ring-type steel fibers at failure plane: the average and the standard deviation for the ratios of the test to theory were 1.03 and 0.26, respectively. Theoretical investigations and comparisons were made for the values of orientation factor and the number of fibers at failure plane for straight steel fibers and ring-type steel fibers.

Elastic behavior and onset of cracking in cement composite plates reinforced by perforated thin steel sheets

Science.gov (United States)

Aronchik, V.

1996-03-01

Thin cement mortar plates reinforced by perforated thin steel sheets have been tested in four-point flexure loading. Six kinds of sheet reinforcement and to additional ones (for control) were used. Perforated sheets of the Daugavpils Factory of Machinery Chains differed by their thickness (0.6-1.8 mm), shape (round, rectangular, oval, "dumbbell"), and mark of steel (St. 08, 50, 70). Dimensions of plantes were 100×20×2 cm. Cements-sand mortar with a 1∶2 ratio of cement PZ35 and river sand of 3 mm grains was used as a matrix. Control specimens of similar dimensions and matrix were reinforced by wire cages and meshes (ferrocement). The testing was performed using an UMM-5 testing machine. Maximum deflection (at the midspan), tension, and shear strains were recorded. The expeimental data are presented in tables and graphs. The testing results showed that the elasticity modulus of material was in good agreement with the "admixture rule;" an onset of cracking for all types (excluding one) practically did not differ from reference samples; the mode of fracture in typical cases included an adhesion failure and significant shear strains. In one case the limit of the tension strength of the reinforcement was achieved.

Study of the Microstructure Evolution of Low-pH Cements Based on Ordinary Portland Cement (OPC by Mid- and Near-Infrared Spectroscopy, and Their Influence on Corrosion of Steel Reinforcement

Directory of Open Access Journals (Sweden)

Juan García Olmo

2013-06-01

Full Text Available Low-pH cements are designed to be used in underground repositories for high level waste. When they are based on Ordinary Portland Cements (OPC, high mineral admixture contents must be used which significantly modify their microstructure properties and performance. This paper evaluates the microstructure evolution of low-pH cement pastes based on OPC plus silica fume and/or fly ashes, using Mid-Infrared and Near-Infrared spectroscopy to detect cement pastes mainly composed of high polymerized C-A-S-H gels with low C/S ratios. In addition, the lower pore solution pH of these special cementitious materials have been monitored with embedded metallic sensors. Besides, as the use of reinforced concrete can be required in underground repositories, the influence of low-pH cementitious materials on steel reinforcement corrosion was analysed. Due to their lower pore solution pH and their different pore solution chemical composition a clear influence on steel reinforcement corrosion was detected.

Numerical Investigation of Delamination in Drilling of Carbon Fiber Reinforced Polymer Composites

Science.gov (United States)

Tang, Wenliang; Chen, Yan; Yang, Haojun; Wang, Hua; Yao, Qiwei

2018-03-01

Drilling of carbon fiber reinforced polymer (CFRP) is a challenging task in modern manufacturing sector and machining induced delamination is one of the major problems affecting assembly precision. In this work, a new three-dimensional (3D) finite element model is developed to study the chip formation and entrance delamination in drilling of CFRP composites on the microscopic level. Fiber phase, matrix phase and equivalent homogeneous phase in the multi-phase model have different constitutive behaviors, respectively. A comparative drilling test, in which the cement carbide drill and unidirectional CFRP laminate are employed, is conducted to validate the proposedmodel in terms of the delamination and the similar changing trend is obtained. Microscopic mechanism of entrance delamination together with the chip formation process at four special fiber cutting angles (0°, 45°, 90° and 135°) is investigated. Moreover, the peeling force is also predicted. The results show that the delamination occurrence and the chip formation are both strongly dependent on the fiber cutting angle. The length of entrance delamination rises with increasing fiber cutting angles. Negligible delamination at 0° is attributed to the compression by the minor flank face. For 45° and 90°, the delamination resulted from the mode III fracture. At 135°, serious delamination which is driven by the mode I and III fractures is more inclined to occur and the peeling force reaches its maximum. Such numerical models can help understand the mechanism of hole entrance delamination further and provide guidance for the damage-free drilling of CFRP.

STUDY THE CREEP OF TUBULAR SHAPED FIBER REINFORCED COMPOSITES

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Najat J. Saleh

2013-05-01

Full Text Available Inpresent work tubular –shaped fiber reinforced composites were manufactured byusing two types of resins ( Epoxy and unsaturated polyester and separatelyreinforced with glass, carbon and kevlar-49 fibers (filament and woven roving,hybrid reinforcement composites of these fibers were also prepared. The fiberswere wet wound on a mandrel using a purposely designed winding machine,developed by modifying an ordinary lathe, in winding angle of 55° for filament. A creep test was made of either the fulltube or specimens taken from it. Creep was found to increase upon reinforcementin accordance to the rule of mixture and mainly decided by the type of singleor hybridized fibers. The creep behavior, showed that the observed strain tendsto appear much faster at higher temperature as compared with that exhibited atroom temperate. The creep rate also found to be depending on fiber type, matrixtype, and the fiber /matrix bonding. The creep energy calculated fromexperimental observations was found to exhibit highest value for hybridizedreinforcement.

A method for calculating equivalent diameter of fiber in self-compacting fiber reinforced concrete

NARCIS (Netherlands)

Yu, R.; Spiesz, P.R.; Brouwers, H.J.H.; Fischer, H.-B.; Bode, K.-A.; Beuthan, C.

2012-01-01

This paper presents a method for calculating the equivalent diameter of fiber in self-compacting fiber reinforced concrete (SCFRC). The key idea is to utilize a small amount of particles with a narrow particle size distribution to replace the fibers by the same volume, without causing any obvious

Radiation processing for PTFE composite reinforced with carbon fiber

International Nuclear Information System (INIS)

Akihiro Oshima; Akira Udagawa; Yousuke Morita

1999-01-01

The present work is an attempt to evaluate the performance of crosslinked PTFE as a polymer matrix for carbon fiber-reinforced composite materials. The carbon fiber-reinforced PTFE pre-composite, which is laminated with PTFE fine powder, is crosslinked by electron beam irradiation. Mechanical and frictional properties of the crosslinked PTFE composite obtained are higher than those of PTFE resin. The crosslinked PTFE composite with high mechanical and radiation resistant performance is obtained by radiation crosslinking process

State-of-Practice on the Dynamic Response of Structures Strengthened with Fiber Reinforced Polymers (FRPs)

Science.gov (United States)

2015-07-01

entitled “Design guidelines for blast strengthening of concrete and masonry structures using Fiber - Reinforced Polymer (FRP).” Seismic provision...2 Reinforced Concrete Fiber Reinforced Polymers are frequently used to retrofit and repair reinforced concrete structures. Most of the work...tested 72 laboratory-size beams (3-in. by 3-in. cross-section and 30–in. long) of unreinforced and nylon fiber reinforced light-weight concrete that

Crack widths in concrete with fibers and main reinforcement

DEFF Research Database (Denmark)

Christensen, Frede; Ulfkjær, Jens Peder; Brincker, Rune

2015-01-01

The main object of the research work presented in this paper is to establish design tools for concrete structures where main reinforcement is combined with addition of short discrete steel fibers. The work is concerned with calculating and measuring crack widths in structural elements subjected...... to bending load. Thus, the aim of the work is to enable engineers to calculate crack widths for flexural concrete members and analyze how different combinations of amounts of fibers and amounts of main reinforcement can meet a given maximum crack width requirement. A mathematical model including...... the ductility of the fiber reinforced concrete (FRC) is set up and experimental work is conducted in order to verify the crack width model. The ductility of the FRC is taken into account by using the stress crack width relation. The constitutive model for the FRC is based on the idea that the initial part...

Performance of carbon fiber reinforced rubber composite armour against shaped charge jet penetration

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Yue Lian-yong

2016-01-01

Full Text Available Natural rubber is reinforced with carbon fiber; the protective performances of the carbonfiber reinforced rubber composite armour to shaped charge jet have been studied based on the depth of penetration experiments. The craters on the witness blocks, the nature rubber based composite plates’ deformation and the Scanning Electron Microscopy for the hybrid fiber reinforced rubber plate also is analyzed. The results showed that the composite armour can affect the stability of the jet and made part of the jet fracture. The carbon fiber reinforced rubber composite armour has good defence ablity especially when the nature rubber plate hybrid 15% volume percentage carbonfiber and the obliquity angle is 68°. The hybrid fiber reinforced rubber composite armour can be used as a new kind of light protective armour.

The effect of pressure changes during simulated diving on the pull out strength of glass fiber posts

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Meenal Nitin Gulve

2013-01-01

Conclusion: Dentist should consider using resin reinforced glass ionomer or resin cement, for the cementation of glass fiber post, for the patients such as divers, who are likely to be exposed to pressure cycling.

Basalt fiber reinforced polymer composites: Processing and properties

Science.gov (United States)

Liu, Qiang

A high efficiency rig was designed and built for in-plane permeability measurement of fabric materials. A new data derivation procedure to acquire the flow fluid pattern in the experiment was developed. The measurement results of the in-plane permeability for basalt twill 31 fabric material showed that a high correlation exists between the two principal permeability values for this fabric at 35% fiber volume fraction. This may be the most important scientific contribution made in this thesis. The results from radial measurements corresponded quite well with those from Unidirectional (UD) measurements, which is a well-established technique. No significant differences in mechanical properties were found between basalt fabric reinforced polymer composites and glass composites reinforced by a fabric of similar weave pattern. Aging results indicate that the interfacial region in basalt composites may be more vulnerable to environmental damage than that in glass composites. However, the basalt/epoxy interface may have been more durable than the glass/epoxy interface in tension-tension fatigue because the basalt composites have significantly longer fatigue life. In this thesis, chapter I reviews the literature on fiber reinforced polymer composites, with concentration on permeability measurement, mechanical properties and durability. Chapter II discusses the design of the new rig for in-plane permeability measurement, the new derivation procedure for monitoring of the fluid flow pattern, and the permeability measurement results. Chapter III compares the mechanical properties and durability between basalt fiber and glass fiber reinforced polymer composites. Lastly, chapter IV gives some suggestions and recommendations for future work.

Mechanical Behavior of Stainless Steel Fiber-Reinforced Composites Exposed to Accelerated Corrosion

Science.gov (United States)

O’Brien, Caitlin; McBride, Amanda; E. Zaghi, Arash; Burke, Kelly A.; Hill, Alex

2017-01-01

Recent advancements in metal fibers have introduced a promising new type of stainless steel fiber with high stiffness, high failure strain, and a thickness corrosion. The main goal of this study is to compare the impact of corrosion on the mechanical properties of steel fiber-reinforced composites with those of conventional types of stainless steel. By providing experimental evidences, this study may promote the application of steel fiber-reinforced composite as a viable alternative to conventional metals. Samples of steel fiber-reinforced polymer and four different types of stainless steel were subjected to 144 and 288 h of corrosion in ferric chloride solution to simulate accelerated corrosion conditions. The weight losses due to corrosion were recorded. The corroded and control samples were tested under monotonic tensile loading to measure the ultimate stresses and strains. The effect of corrosion on the mechanical properties of the different materials was evaluated. The digital image correlation (DIC) technique was used to investigate the failure mechanism of the corrosion-damaged specimens. Overall, steel fiber-reinforced composites had the greatest corrosion resistance. PMID:28773132

Reinforcement of RC structure by carbon fibers

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Kissi B.

2016-01-01

Full Text Available In recent years, rehabilitation has been the subject of extensive research due to the increased spending on building maintenance work and restoration of built works. In all cases, it is essential to carry out methods of reinforcement or maintenance of structural elements, following an inspection analysis and methodology of a correct diagnosis. This research focuses on the calculation of the necessary reinforcement sections of carbon fiber for structural elements with reinforced concrete in order to improve their load bearing capacity and rigidity. The different results obtained reveal a considerable gain in resistance and deformation capacity of reinforced sections without significant increase in the weight of the rehabilitated elements.

Bending test in epoxy composites reinforced with continuous and aligned PALF fibers

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Gabriel Oliveira Glória

2017-10-01

Full Text Available Sustainable actions aiming to prevent increasing worldwide pollution are motivating the substitution of environmentally friendly materials for conventional synthetic ones. A typical example is the use of natural lignocellulosic fiber (LCF as reinforcement of polymer composites that have traditionally been reinforced with glass fiber. Both scientific research and engineering applications support the use of numerous LCFs composites. The pineapple fiber (PALF, extracted from the leaves of Ananas comosus, is considered a LCF with potential for composite reinforcement. However, specific mechanical properties and microstructural characterization are still necessary for this purpose. Therefore, the objective of this short work is to evaluate the flexural properties, by means of three points, bend tests, of epoxy composites incorporated with up to 30 vol% of PALF. Results reveal that continuous and aligned fibers significantly increase the flexural strength. Scanning electron microscopy disclosed the fracture mechanism responsible for this reinforcement. Keywords: Pineapple fibers, PALF, Flexural properties, Bending test, Epoxy composites, Fracture mechanism

Natural Kenaf Fiber Reinforced Composites as Engineered Structural Materials

Science.gov (United States)

Dittenber, David B.

The objective of this work was to provide a comprehensive evaluation of natural fiber reinforced polymer (NFRP)'s ability to act as a structural material. As a chemical treatment, aligned kenaf fibers were treated with sodium hydroxide (alkalization) in different concentrations and durations and then manufactured into kenaf fiber / vinyl ester composite plates. Single fiber tensile properties and composite flexural properties, both in dry and saturated environments, were assessed. Based on ASTM standard testing, a comparison of flexural, tensile, compressive, and shear mechanical properties was also made between an untreated kenaf fiber reinforced composite, a chemically treated kenaf fiber reinforced composite, a glass fiber reinforced composite, and oriented strand board (OSB). The mechanical properties were evaluated for dry samples, samples immersed in water for 50 hours, and samples immersed in water until saturation (~2700 hours). Since NFRPs are more vulnerable to environmental effects than synthetic fiber composites, a series of weathering and environmental tests were conducted on the kenaf fiber composites. The environmental conditions studied include real-time outdoor weathering, elevated temperatures, immersion in different pH solutions, and UV exposure. In all of these tests, degradation was found to be more pronounced in the NFRPs than in the glass FRPs; however, in nearly every case the degradation was less than 50% of the flexural strength or stiffness. Using a method of overlapping and meshing discontinuous fiber ends, large mats of fiber bundles were manufactured into composite facesheets for structural insulated panels (SIPs). The polyisocyanurate foam cores proved to be poorly matched to the strength and stiffness of the NFRP facesheets, leading to premature core shear or delamination failures in both flexure and compressive testing. The NFRPs were found to match well with the theoretical stiffness prediction methods of classical lamination

Finite element modelling of concrete beams reinforced with hybrid fiber reinforced bars

Science.gov (United States)

Smring, Santa binti; Salleh, Norhafizah; Hamid, NoorAzlina Abdul; Majid, Masni A.

2017-11-01

Concrete is a heterogeneous composite material made up of cement, sand, coarse aggregate and water mixed in a desired proportion to obtain the required strength. Plain concrete does not with stand tension as compared to compression. In order to compensate this drawback steel reinforcement are provided in concrete. Now a day, for improving the properties of concrete and also to take up tension combination of steel and glass fibre-reinforced polymer (GFRP) bars promises favourable strength, serviceability, and durability. To verify its promise and support design concrete structures with hybrid type of reinforcement, this study have investigated the load-deflection behaviour of concrete beams reinforced with hybrid GFRP and steel bars by using ATENA software. Fourteen beams, including six control beams reinforced with only steel or only GFRP bars, were analysed. The ratio and the ordinate of GFRP to steel were the main parameters investigated. The behaviour of these beams was investigated via the load-deflection characteristics, cracking behaviour and mode of failure. Hybrid GFRP-Steel reinforced concrete beam showed the improvement in both ultimate capacity and deflection concomitant to the steel reinforced concrete beam. On the other hand, finite element (FE) modelling which is ATENA were validated with previous experiment and promising the good result to be used for further analyses and development in the field of present study.

Elastic properties of uniaxial-fiber reinforced composites - General features

Science.gov (United States)

Datta, Subhendu; Ledbetter, Hassel; Lei, Ming

The salient features of the elastic properties of uniaxial-fiber-reinforced composites are examined by considering the complete set of elastic constants of composites comprising isotropic uniaxial fibers in an isotropic matrix. Such materials exhibit transverse-isotropic symmetry and five independent elastic constants in Voigt notation: C(11), C(33), C(44), C(66), and C(13). These C(ij) constants are calculated over the entire fiber-volume-fraction range 0.0-1.0, using a scattered-plane-wave ensemple-average model. Some practical elastic constants such as the principal Young moduli and the principal Poisson ratios are considered, and the behavior of these constants is discussed. Also presented are the results for the four principal sound velocities used to study uniaxial-fiber-reinforced composites: v(11), v(33), v(12), and v(13).

Steel fiber reinforced concrete subjected to elevated cyclic temperatures

International Nuclear Information System (INIS)

Yousif, R. A.; Rasheed, H. M.; Muhammad, H. A.

1997-01-01

The results from a series of tests on steel fiber reinforced concrete at elevated cyclic temperature are presented. The residual compressive strength and ultimate splitting tensile strength were nadir's on specimen ts with no fibers and with 0.5% and 1% plain steel fibers over a temperature range of 300-700 C. concrete was subjected to one, two or three cycles of heating and cooling. In general the exposure to temperature decreased the strength of concrete, although the number of heating cycles seems only to have a secondary effect. The results also show that the steel fiber reinforced concrete performs better than plain concrete. Two equations were suggested to predict the strength of concrete and the results show good agreement with the experimental values. . (authors). 10 refs., 1 tabs. 3 figs

Rotation capacity of self-compacting steel fiber reinforced concrete

NARCIS (Netherlands)

Schumacher, P.

2006-01-01

Steel fiber reinforced concrete (SFRC) has been used in segmental tunnel linings in the past years. In order to investigate the effect of steel fibers on the rotation capacity of plastic hinges in self-compacting concrete (SCC) the effect of the addition of fibers to SCC in compression, tension and

Energy Absorption Capacity in Natural Fiber Reinforcement Composites Structures

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Elías López-Alba

2018-03-01

Full Text Available The study of natural fiber reinforcement composite structures has focused the attention of the automobile industry due to the new regulation in relation to the recyclability and the reusability of the materials preserving and/or improving the mechanical characteristics. The influence of different parameters on the material behavior of natural fiber reinforced plastic structures has been investigated, showing the potential for transport application in energy absorbing structures. Two different woven fabrics (twill and hopsack made of flax fibers as well as a non-woven mat made of a mixture of hemp and kenaf fibers were employed as reinforcing materials. These reinforcing textiles were impregnated with both HD-PE (high-density polyethylen and PLA (polylactic acid matrix, using a continuous compression molding press. The impregnated semi-finished laminates (so-called organic sheets were thermoformed in a second step to half-tubes that were assembled through vibration-welding process to cylindric crash absorbers. The specimens were loaded by compression to determine the specific energy absorption capacity. Quasi-static test results were compared to dynamic test data obtained on a catapult arrangement. The differences on the specific energies absorption (SEA as a function of different parameters, such as the wall thickness, the weave material type, the reinforced textiles, and the matrix used, depending on the velocity rate application were quantified. In the case of quasi-static analysis it is observed a 20% increment in the SEA value when wove Hopsack fabric reinforcement is employed. No velocity rate influence from the material was observed on the SEA evaluation at higher speeds used to perform the experiments. The influence of the weave configuration (Hopsack seems to be more stable against buckling effects at low loading rates with 10% higher SEA values. An increase of SEA level of up to 72% for PLA matrix was observed when compared with HD

Research of movement process of fiber suspension in accelerating unit of wet grinding disintegrator

Science.gov (United States)

Mykhaylichenko, S. A.; Dubinin, N. N.; Kachaev, A. E.; Goncharov, S. I.; Farafonov, A. A.

2018-03-01

At the present stage of development of building material science, products reinforced with fibers of various origin (mineral, organic, metal and others) are commonly used. Determination of the optimal structure and the chemical composition of the fiber depends on a number of requirements for filler, binder, and other miscellaneous additives, etc. The rational combination of physical and chemical composition of the primary matrix of the product (e.g., binders, cement) with dispersion of anisotropic fiber of filler not only contributes to the strength of products, but also stabilizes their internal structure: prevents the occurrence of internal stress of the cement stone, increases the adhesive interaction of particles of cement at the contact boundary with fibers, etc.

Mechanical properties of fiber reinforced restorative composite with two distinguished fiber length distribution.

Science.gov (United States)

Lassila, Lippo; Garoushi, Sufyan; Vallittu, Pekka K; Säilynoja, Eija

2016-07-01

The purpose of this study was to investigate the reinforcing effect of discontinuous glass fiber fillers with different length scales on fracture toughness and flexural properties of dental composite. Experimental fiber reinforced composite (Exp-FRC) was prepared by mixing 27wt% of discontinuous E-glass fibers having two different length scales (micrometer and millimeter) with various weight ratios (1:1, 2:1, 1:0 respectively) to the 23wt% of dimethacrylate based resin matrix and then 50wt% of silane treated silica filler were added gradually using high speed mixing machine. As control, commercial FRC and conventional posterior composites were used (everX Posterior, Alert, and Filtek Superme). Fracture toughness, work of fracture, flexural strength, and flexural modulus were determined for each composite material following ISO standards. The specimens (n=6) were dry stored (37°C for 2 days) before they were tested. Scanning electron microscopy was used to evaluate the microstructure of the experimental FRC composites. The results were statistically analyzed using ANOVA followed by post-hoc Tukey׳s test. Level of significance was set at 0.05. ANOVA revealed that experimental composites reinforced with different fiber length scales (hybrid Exp-FRC) had statistically significantly higher mechanical performance of fracture toughness (4.7MPam(1/2)) and flexural strength (155MPa) (plength scales of discontinues fiber fillers (hybrid) with polymer matrix yielded improved mechanical performance compared to commercial FRC and conventional posterior composites. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characteristics and applications of high-performance fiber reinforced asphalt concrete

Science.gov (United States)

Park, Philip

Steel fiber reinforced asphalt concrete (SFRAC) is suggested in this research as a multifunctional high performance material that can potentially lead to a breakthrough in developing a sustainable transportation system. The innovative use of steel fibers in asphalt concrete is expected to improve mechanical performance and electrical conductivity of asphalt concrete that is used for paving 94% of U. S. roadways. In an effort to understand the fiber reinforcing mechanisms in SFRAC, the interaction between a single straight steel fiber and the surrounding asphalt matrix is investigated through single fiber pull-out tests and detailed numerical simulations. It is shown that pull-out failure modes can be classified into three types: matrix, interface, and mixed failure modes and that there is a critical shear stress, independent of temperature and loading rate, beyond which interfacial debonding will occur. The reinforcing effects of SFRAC with various fiber sizes and shapes are investigated through indirect tension tests at low temperature. Compared to unreinforced specimens, fiber reinforced specimens exhibit up to 62.5% increase in indirect tensile strength and 895% improvements in toughness. The documented improvements are the highest attributed to fiber reinforcement in asphalt concrete to date. The use of steel fibers and other conductive additives provides an opportunity to make asphalt pavement electrically conductive, which opens up the possibility for multifunctional applications. Various asphalt mixtures and mastics are tested and the results indicate that the electrical resistivity of asphaltic materials can be manipulated over a wide range by replacing a part of traditional fillers with a specific type of graphite powder. Another important achievement of this study is development and validation of a three dimensional nonlinear viscoelastic constitutive model that is capable of simulating both linear and nonlinear viscoelasticity of asphaltic materials. The

Interface stresses in fiber-reinforced materials with regular fiber arrangements

Science.gov (United States)

Mueller, W. H.; Schmauder, S.

The theory of linear elasticity is used here to analyze the stresses inside and at the surface of fiber-reinforced composites. Plane strain, plane stress, and generalized plane strain are analyzed using the shell model and the BHE model and are numerically studied using finite element analysis. Interface stresses are shown to depend weakly on Poisson's ratio. For equal values of the ratio, generalized plane strain and plane strain results are identical. For small volume fractions up to 40 vol pct of fibers, the shell and the BHE models predict the interface stresses very well over a wide range of elastic mismatches and for different fiber arrangements. At higher volume fractions the stresses are influenced by interactions with neighboring fibers. Introducing an external pressure into the shell model allows the prediction of interface stresses in real composite with isolated or regularly arranged fibers.

Bending strength and fracture surface topography of natural fiber-reinforced shell for investment casting process

Directory of Open Access Journals (Sweden)

Kai Lu

2016-05-01

Full Text Available In order to improve the properties of silica sol shell for investment casting process, various contents of cattail fibers were added into the slurry to prepare a fiber-reinforced shell in the present study. The bending strength of fiber-reinforced shell was investigated and the fracture surfaces of shell specimens were observed using SEM. It is found that the bending strength increases with the increase of fiber content, and the bending strength of a green shell with 1.0 wt.% fiber addition increases by 44% compared to the fiber-free shell. The failure of specimens of the fiber-reinforced green shell results from fiber rupture and debonding between the interface of fibers and adhesive under the bending load. The micro-crack propagation in the matrix is inhibited by the micro-holes for ablation of fibers in specimens of the fiber-reinforced shell during the stage of being fired. As a result, the bending strength of specimens of the fired shell had no significant drop. Particularly, the bending strength of specimens of the fired shell reinforced with 0.6wt.% fiber reached the maximum value of 4.6 MPa.

Flexural properties of polyethylene, glass and carbon fiber-reinforced resin composites for prosthetic frameworks.

Science.gov (United States)

Maruo, Yukinori; Nishigawa, Goro; Irie, Masao; Yoshihara, Kumiko; Minagi, Shogo

2015-01-01

High flexural properties are needed for fixed partial denture or implant prosthesis to resist susceptibility to failures caused by occlusal overload. The aim of this investigation was to clarify the effects of four different kinds of fibers on the flexural properties of fiber-reinforced composites. Polyethylene fiber, glass fiber and two types of carbon fibers were used for reinforcement. Seven groups of specimens, 2 × 2 × 25 mm, were prepared (n = 10 per group). Four groups of resin composite specimens were reinforced with polyethylene, glass or one type of carbon fiber. The remaining three groups served as controls, with each group comprising one brand of resin composite without any fiber. After 24-h water storage in 37°C distilled water, the flexural properties of each specimen were examined with static three-point flexural test at a crosshead speed of 0.5 mm/min. Compared to the control without any fiber, glass and carbon fibers significantly increased the flexural strength (p glass fiber (p glass fibers (p > 0.05). Fibers could, therefore, improve the flexural properties of resin composite and carbon fibers in longitudinal form yielded the better effects for reinforcement.

Analysis of the strength and stiffness of timber beams reinforced with carbon fiber and glass fiber

Directory of Open Access Journals (Sweden)

Juliano Fiorelli

2003-06-01

Full Text Available An experimental analysis of pinewood beams (Pinus caribea var hondurensis reinforced with glass and/or carbon fibers is discussed. The theoretical model employed to calculate the beam's bending strength takes into account the timber's ultimate limit states of tensile strength and failure by compression, considering a model of fragile elastic tension and plastic elastic compression. The validity of the theoretical model is confirmed by a comparison of the theoretical and experimental results, while the efficiency of the fiber reinforcement is corroborated by the increased strength and stiffness of the reinforced timber beams.

Fatigue resistance and stiffness of glass fiber-reinforced urethane dimethacrylate composite.

Science.gov (United States)

Narva, Katja K; Lassila, Lippo V J; Vallittu, Pekka K

2004-02-01

Retentive properties of cast metal clasps decrease over time because of metal fatigue. Novel fiber-reinforced composite materials are purported to have increased fatigue resistance compared with metals and may offer a solution to the problem of metal fatigue. The aim of this study was to investigate the fatigue resistance and stiffness of E-glass fiber-reinforced composite. Twelve cylindrical fiber-reinforced composite test cylinders (2 mm in diameter and 60 mm in length) were made from light-polymerized urethane dimethacrylate monomer with unidirectional, single-stranded, polymer preimpregnated E-glass fiber reinforcement. Six cylinders were stored in dry conditions and 6 in distilled water for 30 days before testing. Fatigue resistance was measured by a constant-deflection fatigue test with 1 mm of deflection across a specimen span of 11 mm for a maximum of 150,000 loading cycles. The resistance of the cylinder against deflection was measured (N) and the mean values of the force were compared by 1-way analysis of variance (alpha = .05). The flexural modulus (GPa) was calculated for the dry and water-stored cylinders for the first loading cycle. Scanning electron microscopy was used to assess the distribution of the fibers, and the volume percent of fibers and polymer were assessed by combustion analysis. The test cylinders did not fracture due to fatigue following 150,000 loading cycles. Flexural modulus at the first loading cycle was 18.9 (+/- 2.9) GPa and 17.5 (+/- 1.7) GPa for the dry and water-stored cylinders, respectively. The mean force required to cause the first 1-mm deflection was 33.5 (+/- 5.2) N and 37.7 (+/- 3.6) N for the dry and water stored cylinders, respectively; however, the differences were not significant. After 150,000 cycles the mean force to cause 1-mm deflection was significantly reduced to 23.4 (+/- 8.5) N and 13.1 (+/- 3.5) N, respectively (P fiber- and polymer-rich areas within the specimens and indicated that individual fibers were

Mallow Fiber-Reinforced Epoxy Composites in Multilayered Armor for Personal Ballistic Protection

Science.gov (United States)

Nascimento, Lucio Fábio Cassiano; Louro, Luis Henrique Leme; Monteiro, Sergio Neves; Lima, Édio Pereira; da Luz, Fernanda Santos

2017-10-01

Lighter and less expensive polymer composites reinforced with natural fibers have been investigated as possible components of a multilayered armor system (MAS) for personal protection against high-velocity ammunition. Their ballistic performance was consistently found comparable with that of conventional Kevlar® synthetic aramid fiber. Among the numerous existing natural fibers with the potential for reinforcing polymer composites to replace Kevlar® in MAS, mallow fiber has not been fully investigated. Thus, the objective of this work is to evaluate the ballistic performance of epoxy composites reinforced with 30 vol.% of aligned mallow fibers as a second MAS layer backing a front ceramic plate. The results using high-velocity 7.62 ammunition show a similar indentation to a Kevlar® layer with the same thickness. An impedance matching calculation supports the similar ballistic performance of mallow fiber composite and Kevlar®. Reduced MAS costs associated with the mallow fiber composite are practical advantages over Kevlar®.

Predicting the drying shrinkage behavior of high strength portland cement mortar under the combined influence of fine aggregate and steel micro fiber

International Nuclear Information System (INIS)

Li, Zhengqi

2017-01-01

The workability, 28-day compressive strength and free drying shrinkage of a very high strength (121-142 MPa) steel micro fiber reinforced portland cement mortar were studied under a combined influence of fine aggregate content and fiber content. The test results showed that an increase in the fine aggregate content resulted in decreases in the workability, 28-day compressive strength and drying shrinkage of mortar at a fixed fiber content. An increase in the fiber content resulted in decreases in the workability and drying shrinkage of mortar, but an increase in the 28-day compressive strength of mortar at a fixed fine aggregate content. The modified Gardner model most accurately predicted the drying shrinkage development of the high strength mortars, followed by the Ross model and the ACI 209R-92 model. The Gardner model gave the least accurate prediction for it was developed based on a database of normal strength concrete. [es

Predicting the drying shrinkage behavior of high strength portland cement mortar under the combined influence of fine aggregate and steel micro fiber

Directory of Open Access Journals (Sweden)

Zhengqi Li

2017-03-01

Full Text Available The workability, 28-day compressive strength and free drying shrinkage of a very high strength (121-142 MPa steel micro fiber reinforced portland cement mortar were studied under a combined influence of fine aggregate content and fiber content. The test results showed that an increase in the fine aggregate content resulted in decreases in the workability, 28-day compressive strength and drying shrinkage of mortar at a fixed fiber content. An increase in the fiber content resulted in decreases in the workability and drying shrinkage of mortar, but an increase in the 28-day compressive strength of mortar at a fixed fine aggregate content. The modified Gardner model most accurately predicted the drying shrinkage development of the high strength mortars, followed by the Ross model and the ACI 209R-92 model. The Gardner model gave the least accurate prediction for it was developed based on a database of normal strength concrete.

Simulation of crack propagation in fiber-reinforced concrete by fracture mechanics

International Nuclear Information System (INIS)

Zhang Jun; Li, Victor C.

2004-01-01

Mode I crack propagation in fiber-reinforced concrete (FRC) is simulated by a fracture mechanics approach. A superposition method is applied to calculate the crack tip stress intensity factor. The model relies on the fracture toughness of hardened cement paste (K IC ) and the crack bridging law, so-called stress-crack width (σ-δ) relationship of the material, as the fundamental material parameters for model input. As two examples, experimental data from steel FRC beams under three-point bending load are analyzed with the present fracture mechanics model. A good agreement has been found between model predictions and experimental results in terms of flexural stress-crack mouth opening displacement (CMOD) diagrams. These analyses and comparisons confirm that the structural performance of concrete and FRC elements, such as beams in bending, can be predicted by the simple fracture mechanics model as long as the related material properties, K IC and (σ-δ) relationship, are known

Preparation and characterization of carbon nanotube-hybridized carbon fiber to reinforce epoxy composite

International Nuclear Information System (INIS)

An, Feng; Lu, Chunxiang; Li, Yonghong; Guo, Jinhai; Lu, Xiaoxuan; Lu, Huibin; He, Shuqing; Yang, Yu

2012-01-01

Highlights: → CNTs were uniformly grown onto the carbon fibers. → No obvious mechanical properties of carbon fiber were observed after CNT growth. → The IFSS of multiscale epoxy composite was measured by single fiber pull-out tests. → Observing fractography of composite, the fracture modes of CNTs were discussed. -- Abstract: The multiscale carbon nanotube-hybridized carbon fiber was prepared by a newly developed aerosol-assisted chemical vapour deposition. Scanning electron microscopy and transmission electron microscope were carried out to characterize this multiscale material. Compared with the original carbon fibers, the fabrication of this hybrid fiber resulted in an almost threefold increase of BET surface area to reach 2.22 m 2 /g. Meanwhile, there was a slight degradation of fiber tensile strength within 10%, while the fiber modulus was not significantly affected. The interfacial shearing strength of a carbon fiber-reinforced polymer composite with carbon nanotube-hybridized carbon fiber and an epoxy matrix was determined from the single fiber pull-out tests of microdroplet composite. Due to an efficient increase of load transfer at the fiber/matrix interfaces, the interracial shear strength of composite reinforced by carbon nanotube-hybridized carbon fiber is almost 94% higher than that of one reinforced by the original carbon fiber. Based on the fractured morphologies of the composites, the interfacial reinforcing mechanisms were discussed through proposing different types of carbon nanotube fracture modes along with fiber pulling out from epoxy composites.

Nano-Fiber Reinforced Enhancements in Composite Polymer Matrices

Science.gov (United States)

Chamis, Christos C.

2009-01-01

Nano-fibers are used to reinforce polymer matrices to enhance the matrix dependent properties that are subsequently used in conventional structural composites. A quasi isotropic configuration is used in arranging like nano-fibers through the thickness to ascertain equiaxial enhanced matrix behavior. The nano-fiber volume ratios are used to obtain the enhanced matrix strength properties for 0.01,0.03, and 0.05 nano-fiber volume rates. These enhanced nano-fiber matrices are used with conventional fiber volume ratios of 0.3 and 0.5 to obtain the composite properties. Results show that nano-fiber enhanced matrices of higher than 0.3 nano-fiber volume ratio are degrading the composite properties.

Optimising of Steel Fiber Reinforced Concrete Mix Design | Beddar ...

African Journals Online (AJOL)

Optimising of Steel Fiber Reinforced Concrete Mix Design. ... as a result of the loss of mixture workability that will be translated into a difficult concrete casting in site. ... An experimental study of an optimisation method of fibres in reinforced ...

Electromagnetic configurable architectures for assessment of Carbon Fiber Reinforced Plastics

Directory of Open Access Journals (Sweden)

Steigmann Rozina

2017-01-01

Full Text Available Carbon Fiber Reinforced Plastics are used in most wide domains due their low density, lack of mechanical fatigue phenomena and high strength–to weight ratio. From electromagnetic point of view, Carbon Fiber Reinforced Plastics structure represents an inhomogeneous structure of electric conductive fibers embedded into a dielectric material, thus an electromagnetic configurable architecture can be used to evaluate above mentioned defects. The paper proposes a special sensor, send receiver type and the obtaining of electromagnetic image by post-processing each coil signals in each point of scanning, using a sub-encoding image reconstruction algorithm and super-resolution procedures. The layout of fibers can be detected interrogating only diagonal reception coils.

Fiber-reinforced Composite Resin Prosthesis to Restore Missing ...

African Journals Online (AJOL)

A fiber-reinforced composite inlay-onlay FPD was used for a single posterior tooth replacement in a patient refusing implant for psychological reasons. The FRC-FPD was made of pre-impregnated E-glass fibers (everStick, StickTeck, Turku, Finland) embedded in a resin matrix (Stick Resin, StickTeck, Turku, Finland).

Behaviour of reinforced columns with E_Glass fiber and carbon fiber

OpenAIRE

BOUCHELAGHEM Hafida; BEZAZI Abederrezak; Benzanache Naziha; SCARPA Fabrizio

2018-01-01

Externally bonded reinforcement using Fiber Reinforced Polymer (FRP) is a good response to the concern represented by the need for rehabilitation of concrete structures. These techniques are more and more attractive because of their fast and low labour costs, very good strength to weight ratio, good fatigue properties, and non-corrosive characteristics of FRP. The present work is an experimental study investigating the mechanical behaviour under a uni-axial loading of short concrete columns r...

Effects of Interface Modification on Mechanical Behavior of Hi-Nicalon Fiber-Reinforced Celsian Matrix Composites

Science.gov (United States)

Bansal, Narottam P.; Eldridge, Jeffrey I.

1997-01-01

Unidirectional celsian matrix composites having approx. 42 volume percent of uncoated or BN/SiC-coated Hi-Nicalon fibers were tested in three-point bend at room temperature. The uncoated fiber-reinforced composites showed catastrophic failure with strength of 210 +/- 35 MPa and a flat fracture surface. In contrast, composites reinforced with BN/SiC-coated fibers exhibited graceful failure with extensive fiber pullout. Values of first matrix cracking stress and strain were 435 +/- 35 MPa and 0.27 +/- 0.01 %, respectively, with ultimate strength as high as 960 MPa. The elastic Young's modulus of the uncoated and BN/SiC-coated fiber-reinforced composites were measured as 184 q 4 GPa and 165 +/- 5 GPa, respectively. Fiber push-through tests and microscopic examination indicated no chemical reaction at the uncoated or coated fiber-matrix interface. The low strength of the uncoated fiber-reinforced composite is probably due to degradation of the fibers from mechanical surface damage during processing. Because both the coated and uncoated fiber reinforced composites exhibited weak interfaces, the beneficial effect of the BN-SiC dual layer is primarily the protection of fibers from mechanical damage during processing.

MICROWAVE INDUCED DEGRADATION OF GLASS FIBER REINFORCED POLYESTER FOR FIBER AND RESIN RECOVERY

DEFF Research Database (Denmark)

Ucar, Hülya; Nielsen, Rudi Pankratz; Søgaard, Erik Gydesen

A solvolysis process to depolymerize the resin in glass fiber reinforced composites and recover the glass fibers has been investigated using microwave induced irradiation. The depolymerization was carried out in HNO3 with concentrations in the range of 1M-7M and in KOH with concentrations ranging...

Thin fiber and textile reinforced cementitious systems

National Research Council Canada - National Science Library

Aldea, Corina-Maria

2007-01-01

This Special Publication (SP) contains ten papers which provide insight on the topics of state of the art of thin fiber and textile-reinforced cementitious systems both in academia and the industry...

Thermal stress control using waste steel fibers in massive concretes

Science.gov (United States)

Sarabi, Sahar; Bakhshi, Hossein; Sarkardeh, Hamed; Nikoo, Hamed Safaye

2017-11-01

One of the important subjects in massive concrete structures is the control of the generated heat of hydration and consequently the potential of cracking due to the thermal stress expansion. In the present study, using the waste turnery steel fibers in the massive concretes, the amount of used cement was reduced without changing the compressive strength. By substituting a part of the cement with waste steel fibers, the costs and the generated hydration heat were reduced and the tensile strength was increased. The results showed that by using 0.5% turnery waste steel fibers and consequently, reducing to 32% the cement content, the hydration heat reduced to 23.4% without changing the compressive strength. Moreover, the maximum heat gradient reduced from 18.5% in the plain concrete sample to 12% in the fiber-reinforced concrete sample.

MECHANICAL AND THERMO–MECHANICAL PROPERTIES OF BI-DIRECTIONAL AND SHORT CARBON FIBER REINFORCED EPOXY COMPOSITES

Directory of Open Access Journals (Sweden)

G. AGARWAL

2014-10-01

Full Text Available This paper based on bidirectional and short carbon fiber reinforced epoxy composites reports the effect of fiber loading on physical, mechanical and thermo-mechanical properties respectively. The five different fiber loading, i.e., 10wt. %, 20wt. %, 30wt. %, 40wt. % and 50wt. % were taken for evaluating the above said properties. The physical and mechanical properties, i.e., hardness, tensile strength, flexural strength, inter-laminar shear strength and impact strength are determined to represent the behaviour of composite structures with that of fiber loading. Thermo-mechanical properties of the material are measured with the help of Dynamic Mechanical Analyser to measure the damping capacity of the material that is used to reduce the vibrations. The effect of storage modulus, loss modulus and tan delta with temperature are determined. Finally, Cole–Cole analysis is performed on both bidirectional and short carbon fiber reinforced epoxy composites to distinguish the material properties of either homogeneous or heterogeneous materials. The results show that with the increase in fiber loading the mechanical properties of bidirectional carbon fiber reinforced epoxy composites increases as compared to short carbon fiber reinforced epoxy composites except in case of hardness, short carbon fiber reinforced composites shows better results. Similarly, as far as Loss modulus, storage modulus is concerned bidirectional carbon fiber shows better damping behaviour than short carbon fiber reinforced composites.

Strain Measurement Using Embedded Fiber Bragg Grating Sensors Inside an Anchored Carbon Fiber Polymer Reinforcement Prestressing Rod for Structural Monitoring

DEFF Research Database (Denmark)

Kerrouche, Abdelfateh; Boyle, William J.O.; Sun, Tong

2009-01-01

Results are reported from a study carried out using a series of Bragg grating based optical fiber sensors written into a very short length (60mm) optical fiber net work and integrated into carbon fiber polymer reinforcement (CFPR) rod. Such rods are used as reinforcements in concrete structures...

Carbon Fiber Reinforced Carbon Composite Valve for an Internal Combustion Engine

Science.gov (United States)

Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

1999-01-01

A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers throughout the valve's stem and head is disclosed. The valve includes braided carbon fiber material over axially aligned unidirectional carbon fibers forming a valve stem; the braided and unidirectional carbon fibers being broomed out at one end of the valve stem forming the shape of the valve head; the valve-shaped structure being densified and rigidized with a matrix of carbon containing discontinuous carbon fibers: and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.

Comparison of Mechanical Properties of Lightweight and Normal Weight Concretes Reinforced with Steel Fibers

Directory of Open Access Journals (Sweden)

A. Ali

2018-04-01

Full Text Available Compared to conventional concrete, lightweight concrete is more brittle in nature however, in many situations its application is advantageous due to its lower weight. The associated brittleness issue can be, to some extent, addressed by incorporation of discrete fibers. It is now established that fibers modify some fresh and hardened concrete properties. However, evaluation of those properties for lightweight fiber-reinforced concrete (LWFC against conventional/normal weight concrete of similar strength class has not been done before. Current study not only discusses the change in these properties for lightweight concrete after the addition of steel fibers, but also presents a comparison of these properties with conventional concrete with and without fibers. Both the lightweight and conventional concrete were reinforced with similar types and quantity of fibers. Hooked end steel fibers were added in the quantities of 0, 20, 40 and 60kg/m3. For similar compressive strength class, results indicate that compared to normal weight fiber-reinforced concrete (NWFC, lightweight fiber-reinforced concrete (LWFC has better fresh concrete properties, but performs poorly when tested for hardened concrete properties.

A study on the crushing behavior of basalt fiber reinforced composite structures

Science.gov (United States)

Pandian, A.; Veerasimman, A. P.; Vairavan, M.; Francisco, C.; Sultan, M. T. H.

2016-10-01

The crushing behavior and energy absorption capacity of basalt fiber reinforced hollow square structure composites are studied under axial compression. Using the hand layup technique, basalt fiber reinforced composites were fabricated using general purpose (GP) polyester resin with the help of wooden square shaped mould of varying height (100 mm, 150 mm and 200 mm). For comparison, similar specimens of glass fiber reinforced polymer composites were also fabricated and tested. Axial compression load is applied over the top end of the specimen with cross head speed as 2 mm/min using Universal Testing Machine (UTM). From the experimental results, the load-deformation characteristics of both glass fiber and basalt fiber composites were investigated. Crashworthiness and mode of collapse for the composites were determined from load-deformation curve, and they were then compared to each other in terms of their crushing behaviors.

Ceramic fiber reinforced glass-ceramic matrix composite

Science.gov (United States)

Bansal, Narottam P. (Inventor)

1993-01-01

A slurry of BSAS glass powders is cast into tapes which are cut to predetermined sizes. Mats of continuous chemical vapor deposition (CVD)-SiC fibers are alternately stacked with these matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite which is heated to burn out organic constituents. The remaining interim material is then hot-pressed to form a BSAS glass-ceramic fiber-reinforced composite.

Nano-Aramid Fiber Reinforced Polyurethane Foam

Science.gov (United States)

Semmes, Edmund B.; Frances, Arnold

2008-01-01

Closed cell polyurethane and, particularly, polyisocyanurate foams are a large family of flexible and rigid products the result of a reactive two part process wherein a urethane based polyol is combined with a foaming or "blowing" agent to create a cellular solid at room temperature. The ratio of reactive components, the constituency of the base materials, temperature, humidity, molding, pouring, spraying and many other processing techniques vary greatly. However, there is no known process for incorporating reinforcing fibers small enough to be integrally dispersed within the cell walls resulting in superior final products. The key differentiating aspect from the current state of art resides in the many processing technologies to be fully developed from the novel concept of milled nano pulp aramid fibers and their enabling entanglement capability fully enclosed within the cell walls of these closed cell urethane foams. The authors present the results of research and development of reinforced foam processing, equipment development, strength characteristics and the evolution of its many applications.

Fabrication of fiber-reinforced composites by chemical vapor infiltration

Energy Technology Data Exchange (ETDEWEB)

Besmann, T.M.; McLaughlin, J.C. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Probst, K.J.; Anderson, T.J. [Univ. of Florida, Gainesville, FL (United States). Dept. of Chemical Engineering; Starr, T.L. [Georgia Inst. of Tech., Atlanta, GA (United States). Dept. of Materials Science and Engineering

1997-12-01

Silicon carbide-based heat exchanger tubes are of interest to energy production and conversion systems due to their excellent high temperature properties. Fiber-reinforced SiC is of particular importance for these applications since it is substantially tougher than monolithic SiC, and therefore more damage and thermal shock tolerant. This paper reviews a program to develop a scaled-up system for the chemical vapor infiltration of tubular shapes of fiber-reinforced SiC. The efforts include producing a unique furnace design, extensive process and system modeling, and experimental efforts to demonstrate tube fabrication.

Influence of Hybridizing Flax and Hemp-Agave Fibers with Glass Fiber as Reinforcement in a Polyurethane Composite

Directory of Open Access Journals (Sweden)

Pankaj Pandey

2016-05-01

Full Text Available In this study, six combinations of flax, hemp, and glass fiber were investigated for a hybrid reinforcement system in a polyurethane (PU composite. The natural fibers were combined with glass fibers in a PU composite in order to achieve a better mechanical reinforcement in the composite material. The effect of fiber hybridization in PU composites was evaluated through physical and mechanical properties such as water absorption (WA, specific gravity (SG, coefficient of linear thermal expansion (CLTE, flexural and compression properties, and hardness. The mechanical properties of hybridized samples showed mixed trends compared to the unhybridized samples, but hybridization with glass fiber reduced water absorption by 37% and 43% for flax and hemp-agave PU composites respectively.

Numerical investigation of friction joint between Basalt Fiber Reinforced Composites and aluminum

DEFF Research Database (Denmark)

Costache, Andrei; Berggreen, Christian; Sivebæk, Ion Marius

2016-01-01

and stiffer flexible risers, which would be well suited for ultra deep water applications. This paper develops a new finite element model used for evaluating the efficiency of anchoring flat unidirectional fiber reinforced tendons in a mechanical grip. It consists two flat grips with the fiber reinforced...

New Polylactic Acid Composites Reinforced with Artichoke Fibers

Directory of Open Access Journals (Sweden)

Luigi Botta

2015-11-01

Full Text Available In this work, artichoke fibers were used for the first time to prepare poly(lactic acid (PLA-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w were prepared by the film-stacking method: the first one (UNID reinforced with unidirectional long artichoke fibers, the second one (RANDOM reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanical tests. The morphology of the fracture surfaces was analyzed through scanning electron microscopy (SEM. Moreover, a theoretical model, i.e., Hill’s method, was used to fit the experimental Young’s modulus of the biocomposites. The quasi-static tensile tests revealed that the modulus of UNID composites is significantly higher than that of the neat PLA (i.e., ~40%. Moreover, the tensile strength is slightly higher than that of the neat matrix. The other way around, the stiffness of RANDOM composites is not significantly improved, and the tensile strength decreases in comparison to the neat PLA.

Basalt woven fiber reinforced vinylester composites: Flexural and electrical properties

International Nuclear Information System (INIS)

Carmisciano, Salvatore; Rosa, Igor Maria De; Sarasini, Fabrizio; Tamburrano, Alessio; Valente, Marco

2011-01-01

A preliminary comparative study of basalt and E-glass woven fabric reinforced composites was performed. The fabrics were characterized by the same weave pattern and the laminates tested by the same fiber volume fraction. Results of the flexural and interlaminar characterization are reported. Basalt fiber composites showed higher flexural modulus and apparent interlaminar shear strength (ILSS) in comparison with E-glass ones but also a lower flexural strength and similar electrical properties. With this fiber volume fraction, scanning electron microscopy (SEM) analysis of the fractured surfaces enabled a better understanding both of the failure modes involved and of points of concern. Nevertheless, the results of this study seem promising in view of a full exploitation of basalt fibers as reinforcement in polymer matrix composites (PMCs).

Fiber orientation interpolation for the multiscale analysis of short fiber reinforced composite parts

Science.gov (United States)

Köbler, Jonathan; Schneider, Matti; Ospald, Felix; Andrä, Heiko; Müller, Ralf

2018-06-01

For short fiber reinforced plastic parts the local fiber orientation has a strong influence on the mechanical properties. To enable multiscale computations using surrogate models we advocate a two-step identification strategy. Firstly, for a number of sample orientations an effective model is derived by numerical methods available in the literature. Secondly, to cover a general orientation state, these effective models are interpolated. In this article we develop a novel and effective strategy to carry out this interpolation. Firstly, taking into account symmetry arguments, we reduce the fiber orientation phase space to a triangle in R^2 . For an associated triangulation of this triangle we furnish each node with an surrogate model. Then, we use linear interpolation on the fiber orientation triangle to equip each fiber orientation state with an effective stress. The proposed approach is quite general, and works for any physically nonlinear constitutive law on the micro-scale, as long as surrogate models for single fiber orientation states can be extracted. To demonstrate the capabilities of our scheme we study the viscoelastic creep behavior of short glass fiber reinforced PA66, and use Schapery's collocation method together with FFT-based computational homogenization to derive single orientation state effective models. We discuss the efficient implementation of our method, and present results of a component scale computation on a benchmark component by using ABAQUS ®.

Fiber orientation interpolation for the multiscale analysis of short fiber reinforced composite parts

Science.gov (United States)

Köbler, Jonathan; Schneider, Matti; Ospald, Felix; Andrä, Heiko; Müller, Ralf

2018-04-01

For short fiber reinforced plastic parts the local fiber orientation has a strong influence on the mechanical properties. To enable multiscale computations using surrogate models we advocate a two-step identification strategy. Firstly, for a number of sample orientations an effective model is derived by numerical methods available in the literature. Secondly, to cover a general orientation state, these effective models are interpolated. In this article we develop a novel and effective strategy to carry out this interpolation. Firstly, taking into account symmetry arguments, we reduce the fiber orientation phase space to a triangle in R^2 . For an associated triangulation of this triangle we furnish each node with an surrogate model. Then, we use linear interpolation on the fiber orientation triangle to equip each fiber orientation state with an effective stress. The proposed approach is quite general, and works for any physically nonlinear constitutive law on the micro-scale, as long as surrogate models for single fiber orientation states can be extracted. To demonstrate the capabilities of our scheme we study the viscoelastic creep behavior of short glass fiber reinforced PA66, and use Schapery's collocation method together with FFT-based computational homogenization to derive single orientation state effective models. We discuss the efficient implementation of our method, and present results of a component scale computation on a benchmark component by using ABAQUS ®.

Seawater infiltration effect on thermal degradation of fiber reinforced epoxy composites

Science.gov (United States)

Ibrahim, Mohd Haziq Izzuddin bin; Hassan, Mohamad Zaki bin; Ibrahim, Ikhwan; Rashidi, Ahmad Hadi Mohamed; Nor, Siti Fadzilah M.; Daud, Mohd Yusof Md

2018-05-01

Seawater salinity has been associated with the reduction of polymer structure durability. The aim of this study is to investigate the change in thermal degradation of fiber reinforced epoxy composite due to the presence of seawater. Carbon fiber, carbon/kevlar, fiberglass, and jute that reinforced with epoxy resin was laminated through hand-layup technique. Initially, these specimen was sectioned to 5×5 mm dimension, then immersed in seawater and distilled water at room temperature until it has thoroughly saturated. Following, the thermal degradation analysis using Differential Scanning Calorimetry (DSC), the thermic changes due to seawater infiltration was defined. The finding shows that moisture absorption reduces the glass transition temperature (Tg) of fiber reinforced epoxy composite. However, the glass transition temperature (Tg) of seawater infiltrated laminate composite is compareable with distilled water infiltrated laminate composite. The carbon fiber reinfored epoxy has the highest glass transition temperature out of all specimen.

CO2-laser-assisted processing of glass fiber-reinforced thermoplastic composites

Science.gov (United States)

Brecher, Christian; Emonts, Michael; Schares, Richard Ludwig; Stimpfl, Joffrey

2013-02-01

To fully exploit the potential of fiber-reinforced thermoplastic composites (FRTC) and to achieve a broad industrial application, automated manufacturing systems are crucial. Investigations at Fraunhofer IPT have proven that the use of laser system technology in processing FRTC allows to achieve high throughput, quality, flexibility, reproducibility and out-of-autoclave processing simultaneously. As 90% of the FRP in Europe1 are glass fiber-reinforced a high impact can be achieved by introducing laser-assisted processing with all its benefits to glass fiber-reinforced thermoplastics (GFRTC). Fraunhofer IPT has developed the diode laser-assisted tape placement (laying and winding) to process carbon fiber-reinforced thermoplastic composites (CFRTC) for years. However, this technology cannot be transferred unchanged to process milky transparent GFRTC prepregs (preimpregnated fibers). Due to the short wavelength (approx. 980 nm) and therefore high transmission less than 20% of the diode laser energy is absorbed as heat into non-colored GFRTC prepregs. Hence, the use of a different wave length, e.g. CO2-laser (10.6 μm) with more than 90% laser absorption, is required to allow the full potential of laser-assisted processing of GFRTC. Also the absorption of CO2-laser radiation at the surface compared to volume absorption of diode laser radiation is beneficial for the interlaminar joining of GFRTC. Fraunhofer IPT is currently developing and investigating the CO2-laser-assisted tape placement including new system, beam guiding, process and monitoring technology to enable a resource and energy efficient mass production of GFRP composites, e.g. pipes, tanks, masts. The successful processing of non-colored glass fiber-reinforced Polypropylene (PP) and Polyphenylene Sulfide (PPS) has already been proven.

Studies on fabrication of glass fiber reinforced composites using polymer blends

Science.gov (United States)

Patel, R. H.; Kachhia, P. H.; Patel, S. N.; Rathod, S. T.; Valand, J. K.

2018-05-01

Glass fiber reinforced PVC/NBR composites have been fabricated via hot compression moulding process. PVC is brittle in nature and thus lower thermal stability. Therefore, to improve the toughness of PVC, NBR was incorporated in certain proportions. As both are polar and thus they are compatible. To improve the strength property further, these blends were used to fabricate glass fiber reinforced composites. SEM micrograph shows good wettability of the blend with glass fibers resulting in proper bonding which increase the strength of the composites.

Self-diagnosis of structures strengthened with hybrid carbon-fiber-reinforced polymer sheets

Science.gov (United States)

Wu, Z. S.; Yang, C. Q.; Harada, T.; Ye, L. P.

2005-06-01

The correlation of mechanical and electrical properties of concrete beams strengthened with hybrid carbon-fiber-reinforced polymer (HCFRP) sheets is studied in this paper. Two types of concrete beams, with and without reinforcing bars, are strengthened with externally bonded HCFRP sheets, which have a self-structural health monitoring function due to the electrical conduction and piezoresistivity of carbon fibers. Parameters investigated include the volume fractions and types of carbon fibers. According to the investigation, it is found that the hybridization of uniaxial HCFRP sheets with several different types of carbon fibers is a viable method for enhancing the mechanical properties and obtaining a built-in damage detection function for concrete structures. The changes in electrical resistance during low strain ranges before the rupture of carbon fibers are generally smaller than 1%. Nevertheless, after the gradual ruptures of carbon fibers, the electrical resistance increases remarkably with the strain in a step-wise manner. For the specimens without reinforcing bars, the electrical behaviors are not stable, especially during the low strain ranges. However, the electrical behaviors of the specimens with reinforcing bars are relatively stable, and the whole range of self-sensing function of the HCFRP-strengthened RC structures has realized the conceptual design of the HCFRP sensing models and is confirmed by the experimental investigations. The relationships between the strain/load and the change in electrical resistance show the potential self-monitoring capacity of HCFRP reinforcements used for strengthening concrete structures.

Push-out bond strength of fiber posts to root dentin using glass ionomer and resin modified glass ionomer cements

Directory of Open Access Journals (Sweden)

Jefferson Ricardo PEREIRA

2014-10-01

Full Text Available OBJECTIVE: The purpose of this study was to assess the push-out bond strength of glass fiber posts to root dentin after cementation with glass ionomer (GICs and resinmodified glass ionomer cements (RMGICs. MATERIAL AND METHODS: Fifty human maxillary canines were transversally sectioned at 15 mm from the apex. Canals were prepared with a step back technique until the application of a #55 K-file and filled. Post spaces were prepared and specimens were divided into five groups according to the cement used for post cementation: Luting & Lining Cement; Fuji II LC Improved; RelyX Luting; Ketac Cem; and Ionoseal. After cementation of the glass fiber posts, all roots were stored at 100% humidity until testing. For push-out test, 1-mm thick slices were produced. The push-out test was performed in a universal testing machine at a crosshead speed of 0.5 mm/minute and the values (MPa were analyzed by Kolmogorov-Smirnov and Levene's tests and by two-way ANOVA and Tukey's post hoc test at a significance level of 5%. RESULTS: Fiber posts cemented using Luting & Lining Cement, Fuji II LC Improved, and Ketac Cem presented the highest bond strength to root dentin, followed by RelyX Luting. Ionoseal presented the lowest bond strength values (P>0.05. The post level did not influence the bond strength of fiber posts to root dentin (P=0.148. The major cause of failure was cohesive at the cement for all GICs and RMGICs. CONCLUSIONS: Except for Ionoseal, all cements provided satisfactory bond strength values.

The Determination of the Optimal Material Proportion in Natural Fiber-Cement Composites Using Design of Mixture Experiments

OpenAIRE

Aramphongphun Chuckaphun; Ungtawondee Kampanart; Chaysuwan Duangrudee

2016-01-01

This research aims to determine the optimal material proportion in a natural fiber-cement composite as an alternative to an asbestos fibercement composite while the materials cost is minimized and the properties still comply with Thai Industrial Standard (TIS) for applications of profile sheet roof tiles. Two experimental sets were studied in this research. First, a three-component mixture of (i) virgin natural fiber, (ii) synthetic fiber and (iii) cement was studied while the proportion of c...

Mechanical properties of ramie fiber reinforced epoxy lamina composite for socket prosthesis

Directory of Open Access Journals (Sweden)

Tresna Soemardi

2010-10-01

Full Text Available This paper presents an investigation into the application of natural fiber composite especially ramie fiber reinforced epoxy lamina composite for socket prosthesis. The research focuses on the tensile and shear strength from ramie fiber reinforced epoxy lamina composite which will be applied as alternative material for socket prosthesis. The research based on American Society for Testing Material (ASTM standard D 3039/D 3039M for tensile strength and ASTM D 4255/D 4255M-83 for shear strength. The ramie fiber applied is a fiber continue 100 % Ne14'S with Epoxy Resin Bakelite EPR 174 as matrix and Epoxy Hardener V-140 as hardener. The sample composite test made by hand lay up method. Multiaxial characteristic from ramie fiber reinforced epoxy composite will be compared with ISO standard for plastic/polymer for health application and refers strength of material application at Prosthetics and Orthotics. The analysis was completed with the mode of the failure and the failure criterion observation by using Scanning Electron Microscope (SEM. Based on results of the research could be concluded that ramie fiber reinforced epoxy composite could be developed further as the alternative material for socket prosthesis on Vf 40-50%. Results of the research will be discussed in more detail in this paper.

Micromechanical modeling of strength and damage of fiber reinforced composites

Energy Technology Data Exchange (ETDEWEB)

Mishnaevsky, L. Jr.; Broendsted, P.

2007-03-15

The report for the first year of the EU UpWind project includes three parts: overview of concepts and methods of modelling of mechanical behavior, deformation and damage of unidirectional fiber reinforced composites, development of computational tools for the automatic generation of 3D micromechanical models of fiber reinforced composites, and micromechanical modelling of damage in FRC, and phenomenological analysis of the effect of frequency of cyclic loading on the lifetime and damage evolution in materials. (au)

An Investigation of Fiber Reinforced Chemically Bonded Phosphate Ceramic Composites at Room Temperature.

Science.gov (United States)

Ding, Zhu; Li, Yu-Yu; Lu, Can; Liu, Jian

2018-05-21

In this study, chemically bonded phosphate ceramic (CBPC) fiber reinforced composites were made at indoor temperatures. The mechanical properties and microstructure of the CBPC composites were studied. The CBPC matrix of aluminum phosphate binder, metakaolin, and magnesia with different Si/P ratios was prepared. The results show that when the Si/P ratio was 1.2, and magnesia content in the CBPC was 15%, CBPC reached its maximum flexural strength. The fiber reinforced CBPC composites were prepared by mixing short polyvinyl alcohol (PVA) fibers or unidirectional continuous carbon fiber sheets. Flexural strength and dynamic mechanical properties of the composites were determined, and the microstructures of specimens were analyzed by scanning electron micrography, X-ray diffraction, and micro X-ray computed tomography. The flexural performance of continuous carbon fiber reinforced CBPC composites was better than that of PVA fiber composites. The elastic modulus, loss modulus, and loss factor of the fiber composites were measured through dynamic mechanical analysis. The results showed that fiber reinforced CBPC composites are an inorganic polymer viscoelastic material with excellent damping properties. The reaction of magnesia and phosphate in the matrix of CBPC formed a different mineral, newberyite, which was beneficial to the development of the CBPC.

Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide.

Science.gov (United States)

Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

2013-05-10

Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents.

Polymerization of dual cure resin cements applied for luting tooth colored fiber posts

Directory of Open Access Journals (Sweden)

Ghavam M.

2007-05-01

Full Text Available Background and Aim: Insufficient polymerization of resin cements is of considerable clinical importance, because of mechanical deficiencies and biological side effects of uncured resin. Dual cure resin cements are getting popular in luting tooth colored posts and although their curing is claimed to proceed chemically, polymerization efficiency in deep areas of canal is uncertain. The aim of this study was to evaluate degree of polymerization of dual-cure resin cements used for luting translucent and opaque fiber posts in different distances from the light tip. Materials and Methods: In this experimental in vitro study, degree of conversion of two dual cured resin cements, Rely X ARC (3M, ESPE and Nexus 2 (Kerr, USA were measured when used with DT-Light and DT-White posts (RTD, France. The light curing unit used was Optilux 501, with output of 650-700 mw/cm2 with emitting time of 60 seconds. Degree of conversion was measured in three different depths (4, 6, 8 mm by FTIR. The data were analyzed using ANOVA and Post hoc tests. P0.05. Nexus used with DT-Light had lower DC% in 8 mm depth (P<0.05. Nexus used with DT-White showed lower DC% in 8 mm depth compared to 4 mm depth. The control groups of both cements showed significant increased DC% in 4 mm depth compared to 6 and 8 mm depths (P<0.05. DT-White caused decreased DC% in both cements in 4 mm. DT-Light caused increased DC% of Rely X in 6 mm depth compared to DT-White and control. DT-Light increased DC% of Nexus in 6 and 8 mm depths, compared to DT-White and control groups. Conclusion: Based on the results of this study, application of translucent fiber posts has a significant effect on degree of polymerization in dual-cure resin cements, compared to opaque types. Their better light transmission to deep areas due to the effect of optical fibers, can lead to better results.

Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

OpenAIRE

Gao, Lei; Hu, Guohui; Xu, Nan; Fu, Junyi; Xiang, Chao; Yang, Chen

2015-01-01

In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0...

A comparison of tensile properties of polyester composites reinforced with pineapple leaf fiber and pineapple peduncle fiber

Science.gov (United States)

Juraidi, J. M.; Shuhairul, N.; Syed Azuan, S. A.; Intan Saffinaz Anuar, Noor

2013-12-01

Pineapple fiber which is rich in cellulose, relatively inexpensive, and abundantly available has the potential for polymer reinforcement. This research presents a study of the tensile properties of pineapple leaf fiber and pineapple peduncle fiber reinforced polyester composites. Composites were fabricated using leaf fiber and peduncle fiber with varying fiber length and fiber loading. Both fibers were mixed with polyester composites the various fiber volume fractions of 4, 8 and 12% and with three different fiber lengths of 10, 20 and 30 mm. The composites panels were fabricated using hand lay-out technique. The tensile test was carried out in accordance to ASTM D638. The result showed that pineapple peduncle fiber with 4% fiber volume fraction and fiber length of 30 mm give highest tensile properties. From the overall results, pineapple peduncle fiber shown the higher tensile properties compared to pineapple leaf fiber. It is found that by increasing the fiber volume fraction the tensile properties has significantly decreased but by increasing the fiber length, the tensile properties will be increased proportionally. Minitab software is used to perform the two-way ANOVA analysis to measure the significant. From the analysis done, there is a significant effect of fiber volume fraction and fiber length on the tensile properties.

Fracture Behavior and Properties of Functionally Graded Fiber-Reinforced Concrete

International Nuclear Information System (INIS)

Roesler, Jeffery; Bordelon, Amanda; Gaedicke, Cristian; Park, Kyoungsoo; Paulino, Glaucio

2008-01-01

In concrete pavements, a single concrete mixture design is selected to resist mechanical loading without attempting to adversely affect the concrete pavement shrinkage, ride quality, or noise attenuation. An alternative approach is to design distinct layers within the concrete pavement surface which have specific functions thus achieving higher performance at a lower cost. The objective of this research was to address the structural benefits of functionally graded concrete materials (FGCM) for rigid pavements by testing and modeling the fracture behavior of different combinations of layered plain and synthetic fiber-reinforced concrete materials. Fracture parameters and the post-peak softening behavior were obtained for each FGCM beam configuration by the three point bending beam test. The peak loads and initial fracture energy between the plain, fiber-reinforced, and FGCM signified similar crack initiation. The total fracture energy indicated improvements in fracture behavior of FGCM relative to full-depth plain concrete. The fracture behavior of FGCM depended on the position of the fiber-reinforced layer relative to the starter notch. The fracture parameters of both fiber-reinforced and plain concrete were embedded into a finite element-based cohesive zone model. The model successfully captured the experimental behavior of the FGCMs and predicted the fracture behavior of proposed FGCM configurations and structures. This integrated approach (testing and modeling) demonstrates the viability of FGCM for designing layered concrete pavements system

Improvement of the piezoelectric properties of glass fiber-reinforced epoxy composites by poling treatment

International Nuclear Information System (INIS)

Oh, S M; Hwang, H Y

2013-01-01

Recently, a new non-destructive method has been proposed for damage monitoring of glass fiber-reinforced polymer composite materials using the piezoelectric characteristics of a polymeric matrix. Several studies of the piezoelectric properties of unidirectional glass fiber epoxy composites and damage monitoring of double-cantilever beams have supported the claim that the piezoelectric method is feasible and powerful enough to monitor the damage of glass fiber epoxy composites. Generally, conventional piezoelectric materials have higher piezoelectric characteristics through poling treatment. In this work, we investigated the change of the piezoelectric properties of glass fiber-reinforced epoxy composites before and after poling treatment. The piezoelectric constants (d 33 ) of glass fiber-reinforced epoxy composites increased by more than 400%. Also, x-ray diffraction tests revealed that poling treatment changed the degree of crystallinity of the epoxy matrix, and this led to the improvement of the piezoelectric characteristics of glass fiber-reinforced epoxy composites. (paper)

Study of the Effect of Reinforced Glass Fibers on Fatigue Properties for Composite Materials

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Mohamed G. Hamad

2013-05-01

Full Text Available This  research  included  the  study of  the effect  of  reinforced  glass fibers  on  fatigue  properties  for composite materials. Polyester  resin  is used  as  connective  material(matrix in two types  of  glass  fibers  for reinforced. The  first  type  is regular  glass fibers  (woven  roving with the  directional(0-90, the second  is  glass  fibers  with  the  random  direction. The first type is the panels with regular reinforced (0-90, and with number of layer (1,2.The  second  type  is  the  panels with random  reinforced  and  with  number  of  layers (1,2. The  results  and  the  laboratory  examinations  for  the samples  reinforce  with  fibers  have  manifested (0-90  that there  is  a decrease  in the number  of  cycles  to the  fatigue  limit  when  the  number  of  reinforce  layers  have  increased . And  an elasticity of this  type  of  samples  are decreased  by  increasing  the number  of  reinforced  layers  with  fiber  .We  find  the  random  reinforced  number  of  fatigue  cycles  for the samples  with  two  layers  of  random  reinforced  are  decreased  more  than the samples  with  one  layer of random  reinforced .

Fiber-Reinforced Epoxy Composites and Methods of Making Same Without the Use of Oven or Autoclave

Science.gov (United States)

Barnell, Thomas J. (Inventor); Rauscher, Michael D. (Inventor); Stienecker, Rick D. (Inventor); Nickerson, David M. (Inventor); Tong, Tat H. (Inventor)

2016-01-01

Method embodiments for producing a fiber-reinforced epoxy composite comprise providing a mold defining a shape for a composite, applying a fiber reinforcement over the mold, covering the mold and fiber reinforcement thereon in a vacuum enclosure, performing a vacuum on the vacuum enclosure to produce a pressure gradient, insulating at least a portion of the vacuum enclosure with thermal insulation, infusing the fiber reinforcement with a reactive mixture of uncured epoxy resin and curing agent under vacuum conditions, wherein the reactive mixture of uncured epoxy resin and curing agent generates exothermic heat, and producing the fiber-reinforced epoxy composite having a glass transition temperature of at least about 100.degree. C. by curing the fiber reinforcement infused with the reactive mixture of uncured epoxy resin and curing agent by utilizing the exothermically generated heat, wherein the curing is conducted inside the thermally insulated vacuum enclosure without utilization of an external heat source or an external radiation source.

Shrinkage modeling of concrete reinforced by palm fibres in hot dry environments

Science.gov (United States)

Akchiche, Hamida; Kriker, Abdelouahed

2017-02-01

The cement materials, such as concrete and conventional mortar present very little resistance to traction and cracking, these hydraulic materials which induces large withdrawals on materials and cracks in structures. The hot dry environments such as: the Saharan regions of Algeria, Indeed, concrete structures in these regions are very fragile, and present high shrinkage. Strengthening of these materials by fibers can provide technical solutions for improving the mechanical performance. The aim of this study is firstly, to reduce the shrinkage of conventional concrete with its reinforcement with date palm fibers. In fact, Algeria has an extraordinary resources in natural fibers (from Palm, Abaca, Hemp) but without valorization in practical areas, especially in building materials. Secondly, to model the shrinkage behavior of concrete was reinforced by date palm fibers. In the literature, several models for still fiber concrete were founded but few are offers for natural fiber concretes. To do so, a still fiber concretes model of YOUNG - CHERN was used. According to the results, a reduction of shrinkage with reinforcement by date palm fibers was showed. A good ability of molding of shrinkage of date palm reinforced concrete with YOUNG - CHERN Modified model was obtained. In fact, a good correlation between experimental data and the model data was recorded.

Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

Science.gov (United States)

Meek, T.T.; Blake, R.D.

1985-04-03

A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

Thermally sprayed prepregs for thixoforging of UD fiber reinforced light metal MMCs

Science.gov (United States)

Silber, Martin; Wenzelburger, Martin; Gadow, Rainer

2007-04-01

Low density and good mechanical properties are the basic requirements for lightweight structures in automotive and aerospace applications. With their high specific strength and strain to failure values, aluminum alloys could be used for such applications. Only the insufficient stiffness and thermal and fatigue strength prevented their usage in high-end applications. One possibility to solve this problem is to reinforce the light metal with unidirectional fibers. The UD fiber allows tailoring of the reinforcement to meet the direction of the component's load. In this study, the production of thermally sprayed prepregs for the manufacturing of continuous fiber reinforced MMC by thixoforging is analysed. The main aim is to optimize the winding procedure, which determines the fiber strand position and tension during the coating process. A method to wind and to coat the continuous fibers with an easy-to-use handling technique for the whole manufacturing process is presented. The prepregs were manufactured by producing arc wire sprayed AlSi6 coatings on fibers bundles. First results of bending experiments showed appropriate mechanical properties.

Fiber reinforced polymer bridge decks : [technical summary].

Science.gov (United States)

2011-01-01

A number of researchers have addressed the use of Fiber Reinforced Polymer (FRP) deck as a replacement solution for deteriorated bridge decks made of traditional materials. The use of new, advanced materials such as FRP is advantageous when the bridg...

Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface-Bonded Carbon Fiber-Reinforced Polymer

Science.gov (United States)

2009-05-01

"This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort...

Micromechanisms of damage in unidirectional fiber reinforced composites

DEFF Research Database (Denmark)

Mishnaevsky, Leon; Brøndsted, Povl

2009-01-01

strength of a composite at the pre-critical load, while the fibers with randomly distributed strengths lead to the higher strength of the composite at post-critical loads. In the case of randomly distributed fiber strengths, the damage growth in fibers seems to be almost independent from the crack length...... in the numerical experiments. The effect of the statistical variability of fiber strengths, viscosity of the polymer matrix as well as the interaction between the damage processes in matrix, fibers and interface are investigated numerically. It is demonstrated that fibers with constant strength ensure higher......Numerical micromechanical investigations of the mechanical behavior and damage evolution of glass fiber reinforced composites are presented. A program code for the automatic generation of 3D micromechanical unit cell models of composites with damageable elements is developed, and used...

Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets.

Science.gov (United States)

Gribniak, Viktor; Tamulenas, Vytautas; Ng, Pui-Lam; Arnautov, Aleksandr K; Gudonis, Eugenijus; Misiunaite, Ieva

2017-06-17

This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly advantageous in avoiding brittle debonding failure, by promoting progressive failure within the hybrid joints. The use of CFRP sheets was also effective in suppressing the localization of the discrete cracks. The development of the crack pattern was monitored using the digital image correlation method. As revealed from the image analyses, with an appropriate layout of the steel pins, brittle failure of the concrete-carbon fiber interface could be effectively prevented. Inverse analysis of the moment-curvature diagrams was conducted, and it was found that a simplified tension-stiffening model with a constant residual stress level at 90% of the strength of the SFRC is adequate for numerically simulating the deformation behavior of beams up to the debonding of the CFRP sheets.

Effect of short fiber reinforcement on the properties of recycled poly(ethylene terephthalate)/poly(ethylene naphthalate) blends

International Nuclear Information System (INIS)

Karsli, Nevin Gamze; Yesil, Sertan; Aytac, Ayse

2013-01-01

Highlights: ► Short fiber reinforcement to the r-PET/PEN blend improved to the tensile strength. ► Fiber reinforcement increased the storage modulus of r-PET/PEN blend. ► CF reinforced composite has the highest storage modulus value. - Abstract: In this study, short carbon (CF), glass (GF) and hybrid carbon/glass fiber reinforced recycled poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate) (r-PET/PEN) blends were prepared by melt mixing method. The mechanical, thermal and morphological properties of composites were investigated by using tensile tests, differential scanning calorimeter, dynamic mechanical analyzer and scanning electron microscopy. The microscopic analysis showed that there is a better interfacial interaction between fiber and polymer matrix for CF reinforced composite. It was found that addition of short fiber reinforcement to the r-PET/PEN blend improved the tensile strength and Young’s modulus values more than the addition of PEN into r-PET. According to DMA analysis, fiber reinforcement increased the storage modulus of composites when compared with r-PET/PEN blend and among them storage modulus of CF reinforced composite was the highest. It was concluded that mechanical properties of r-PET can be enhanced with addition of PEN and more efficiently with short fiber reinforcement

Tensile strength and durability characteristics of high-performance fiber reinforced concrete

International Nuclear Information System (INIS)

Ramadoss, P.; Nagamani, K.

2008-01-01

This paper presents investigations towards developing a better understanding of the contribution of steel fibers to the tensile strength of high-performance fiber reinforced concrete (HPFRC). For 32 series of mixes, flexural and splitting tensile strengths were determined at 28 days. The variables investigated were fiber volume fraction (0%, 0.5%, 1% and 1.5% with an aspect of 80), silica fume replacement level (SF/CM=0.05 and 0.10) and matrix composition (w/cm ratios ranging from 0.25 t 0.40). The influence of fiber content in terms of fiber reinforcing index on the flexural and splitting tensile strengths of HPFRC is presented. Comparative studies were performed on the tensile behavior of SFRC measured by two different loading tests: flexural test and splitting test. Based on the test results, using the least square method, empirical expressions were developed to predict 28-day tensile strength of HPFRC in terms of fiber reinforcing index. Durability tests were carried out to examine the performance of the SFRC. Relationship between flexural and splitting tensile strengths has been developed using regression analysis. The experimental values of previous researchers were compared with the values predicted by the empirical equations and the absolute variation obtained was within 6% and 5% for flexural and splitting tensile strengths respectively. (author)

Processing of thermo-structural carbon-fiber reinforced carbon composites

Directory of Open Access Journals (Sweden)

Luiz Cláudio Pardini

2009-06-01

Full Text Available The present work describes the processes used to obtain thermostructural Carbon/Carbon composites. The processing of these materials begins with the definition of the architecture of the carbon fiber reinforcement, in the form of stacked plies or in the form of fabrics or multidirectional reinforcement. Incorporating fiber reinforcement into the carbon matrix, by filling the voids and interstices, leads to the densification of the material and a continuous increase in density. There are two principal processing routes for obtaining these materials: liquid phase processing and gas phase processing. In both cases, thermal processes lead to the formation of a carbon matrix with specific properties related to their precursor. These processes also differ in terms of yield. With liquid phase impregnation the yield is around 45 per cent, while gas phase processing yields around 15 per cent.

Designing the fiber volume ratio in SiC fiber-reinforced SiC ceramic composites under Hertzian stress

International Nuclear Information System (INIS)

Lee, Kee Sung; Jang, Kyung Soon; Park, Jae Hong; Kim, Tae Woo; Han, In Sub; Woo, Sang Kuk

2011-01-01

Highlights: → Optimum fiber volume ratios in the SiC/SiC composite layers were designed under Hertzian stress. → FEM analysis and spherical indentation experiments were undertaken. → Boron nitride-pyrocarbon double coatings on the SiC fiber were effective. → Fiber volume ratio should be designed against flexural stress. -- Abstract: Finite element method (FEM) analysis and experimental studies are undertaken on the design of the fiber volume ratio in silicon carbide (SiC) fiber-reinforced SiC composites under indentation contact stresses. Boron nitride (BN)/Pyrocarbon (PyC) are selected as the coating materials for the SiC fiber. Various SiC matrix/coating/fiber/coating/matrix structures are modeled by introducing a woven fiber layer in the SiC matrix. Especially, this study attempts to find the optimum fiber volume ratio in SiC fiber-reinforced SiC ceramics under Hertzian stress. The analysis is performed by changing the fiber type, fiber volume ratio, coating material, number of coating layers, and stacking sequence of the coating layers. The variation in the stress for composites in relation to the fiber volume ratio in the contact axial or radial direction is also analyzed. The same structures are fabricated experimentally by a hot process, and the mechanical behaviors regarding the load-displacement are evaluated using the Hertzian indentation method. Various SiC matrix/coating/fiber/coating/matrix structures are fabricated, and mechanical characterization is performed by changing the coating layer, according to the introduction (or omission) of the coating layer, and the number of woven fiber mats. The results show that the damage mode changes from Hertzian stress to flexural stress as the fiber volume ratio increases in composites because of the decreased matrix volume fraction, which intensifies the radial crack damage. The result significantly indicates that the optimum fiber volume ratio in SiC fiber-reinforced SiC ceramics should be designed for

Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

Science.gov (United States)

Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

2015-01-01

Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

Structural characterization and mechanical properties of polypropylene reinforced natural fibers

Science.gov (United States)

Karim, M. A. A.; Zaman, I.; Rozlan, S. A. M.; Berhanuddin, N. I. C.; Manshoor, B.; Mustapha, M. S.; Khalid, A.; Chan, S. W.

2017-10-01

Recently the development of natural fiber composite instead of synthetics fiber has lead to eco-friendly product manufacturing to meet various applications in the field of automotive, construction and manufacturing. The use of natural fibers offer an alternative to the reinforcing fibers because of their good mechanical properties, low density, renewability, and biodegradability. In this present research, the effects of maleic anhydride polypropylene (MAPP) on the mechanical properties and material characterization behaviour of kenaf fiber and coir fiber reinforced polypropylene were investigated. Different fractions of composites with 10wt%, 20wt% and 30wt% fiber content were prepared by using brabender mixer at 190°C. The 3wt% MAPP was added during the mixing. The composites were subsequently molded with injection molding to prepare the test specimens. The mechanical properties of the samples were investigated according to ISO 527 to determine the tensile strength and modulus. These results were also confirmed by the SEM machine observations of fracture surface of composites and FTIR analysis of the chemical structure. As the results, the presence of MAPP helps increasing the mechanical properties of both fibers and 30wt% kenaf fiber with 3wt% MAPP gives the best result compare to others.

Numerical simulation of a high velocity impact on fiber reinforced materials

International Nuclear Information System (INIS)

Thoma, Klaus; Vinckier, David

1994-01-01

Whereas the calculation of a high velocity impact on isotropical materials can be done on a routine basis, the simulation of the impact and penetration process into nonisotropical materials such as reinforced concrete or fiber reinforced materials still is a research task.We present the calculation of an impact of a metallic fragment on a modern protective wall structure. Such lightweight protective walls typically consist of two layers, a first outer layer made out of a material with high hardness and a backing layer. The materials for the backing layer are preferably fiber reinforced materials. Such types of walls offer a protection against fragments in a wide velocity range.For our calculations we used a non-linear finite element Lagrange code with explicit time integration. To be able to simulate the high velocity penetration process with a continuous erosion of the impacting metallic fragment, we used our newly developed contact algorithm with eroding surfaces. This contact algorithm is vectorized to a high degree and especially robust as it was developed to work for a wide range of contact-impact problems. To model the behavior of the fiber reinforced material under the highly dynamic loads, we present a material model which initially was developed to calculate the crash behavior (automotive applications) of modern high strength fiber-matrix systems. The model can describe the failure and the postfailure behavior up to complete material crushing.A detailed simulation shows the impact of a metallic fragment with a velocity of 750ms -1 on a protective wall with two layers, the deformation and erosion of fragment and wall material and the failure of the fiber reinforced material. ((orig.))

Design and analysis of a novel latch system implementing fiber-reinforced composite materials

Science.gov (United States)

Guevara Arreola, Francisco Javier

The use of fiber-reinforced composite materials have increased in the last four decades in high technology applications due to their exceptional mechanical properties and low weight. In the automotive industry carbon fiber have become popular exclusively in luxury cars because of its high cost. However, Carbon-glass hybrid composites offer an effective alternative to designers to implement fiber-reinforced composites into several conventional applications without a considerable price increase maintaining most of their mechanical properties. A door latch system is a complex mechanism that is under high loading conditions during car accidents such as side impacts and rollovers. Therefore, the Department of Transportation in The United States developed a series of tests that every door latch system comply in order to be installed in a vehicle. The implementation of fiber-reinforced composite materials in a door latch system was studied by analyzing the material behavior during the FMVSS No. 206 transverse test using computational efforts and experimental testing. Firstly, a computational model of the current forkbolt and detent structure was developed. Several efforts were conducted in order to create an effective and time efficient model. Two simplified models were implemented with two different contact interaction approaches. 9 composite materials were studied in forkbolt and 5 in detent including woven carbon fiber, unidirectional carbon fiber, woven carbon-glass fiber hybrid composites and unidirectional carbon-glass fiber hybrid composites. The computational model results showed that woven fiber-reinforced composite materials were stiffer than the unidirectional fiber-reinforced composite materials. For instance, a forkbolt made of woven carbon fibers was 20% stiffer than a forkbolt made of unidirectional fibers symmetrically stacked in 0° and 90° alternating directions. Furthermore, Hybrid composite materials behaved as expected in forkbolt noticing a decline

Low Velocity Impact Behavior of Basalt Fiber-Reinforced Polymer Composites

Science.gov (United States)

Shishevan, Farzin Azimpour; Akbulut, Hamid; Mohtadi-Bonab, M. A.

2017-06-01

In this research, we studied low velocity impact response of homogenous basalt fiber-reinforced polymer (BFRP) composites and then compared the impact key parameters with carbon fiber-reinforced polymer (CFRP) homogenous composites. BFRPs and CFRPs were fabricated by vacuum-assisted resin transfer molding (VARTM) method. Fabricated composites included 60% fiber and 40% epoxy matrix. Basalt and carbon fibers used as reinforcement materials were weaved in 2/2 twill textile tip in the structures of BFRP and CFRP composites. We also utilized the energy profile method to determine penetration and perforation threshold energies. The low velocity impact tests were carried out in 30, 60, 80, 100, 120 and 160 J energy magnitudes, and impact response of BFRPs was investigated by related force-deflection, force-time, deflection-time and absorbed energy-time graphics. The related impact key parameters such as maximum contact force, absorbed energy, deflection and duration time were compared with CFRPs for various impact energy levels. As a result, due to the higher toughness of basalt fibers, a better low velocity impact performance of BFRP than that of CFRP was observed. The effects of fabrication parameters, such as curing process, were studied on the low velocity impact behavior of BFRP. The results of tested new fabricated materials show that the change of fabrication process and curing conditions improves the impact behavior of BFRPs up to 13%.

Preparation and characterization of corn reinforced polymer sheet of fibers

International Nuclear Information System (INIS)

Moreira, Tatiana Martinez; Seo, Emilia Satoshi Miyamaru

2016-01-01

There is a global trend in seeking plant fibers to replace the synthetic fibers to obtain reinforced composites aimed at the use of renewable resources. In this context, this paper aims to develop the process of preparing maize leaf fibers, characterizing them and adapting them for applications in the construction industry and develop a reinforced polymer composite with these fibers. Corn leaves were dried in environmental temperature, treated by mercerizing, then neutralized with acid solution and washed in running water. The characterization of the corn leaf fibers was carried out by X-ray diffraction, X-ray fluorescence, scanning electron microscopy, specific surface area, thermogravimetry and specific mass. The mercerizing treatment was effective, because the maize fibers have characteristics similar to synthetic fibers, leading to a possibility of new technological uses. The polymeric composite material was developed by extrusion processes and injection and tested for tensile testing, differential scanning calorimetry and scanning electron microscopy, thus reused an organic waste that would be disposed of by inserting it in a technological process, contributing to the research and development of new polymeric materials as well as to reduce waste discarded as scrap. (author)

Wear Characterization of Aluminium/Basalt Fiber Reinforced Metal Matrix Composites - A Novel Material

Directory of Open Access Journals (Sweden)

P. Amuthakkannan

2017-06-01

Full Text Available Aluminum alloy based metal matrix composite participate have a wider applications in wear resistance applications. Attempt made in current study is that, basalt fiber reinforced aluminum metal matrix composite have been prepared using stir casting method. Different weight percentage of basalt fiber reinforced with Al (6061 metal matrix composites are used to study the wear resistance of the composites. For wear study, percentage of reinforcement, normal load and sliding velocity are the considered as important parameters. To study the effect of basalt fiber reinforcement on the dry sliding wear of Al6061 alloy composites the Pin On wear tester is used. Initially hardness of the composites was tested, it was found that increasing reinforcement in the composite hardness value of the composites also increased. Based on the Grey relation analysis (GRA the effects of wear resistance of the composites were studied.

Effect of Anatomical Customization of the Fiber Post on the Bond Strength of a Self-Adhesive Resin Cement.

Science.gov (United States)

Rocha, Adricyla Teixeira; Gonçalves, Leticia Machado; Vasconcelos, Ana Júlia de Carvalho; Matos Maia Filho, Etevaldo; Nunes Carvalho, Ceci; De Jesus Tavarez, Rudys Rodolfo

2017-01-01

The aim of the study was to evaluate, by means of the push-out test, the effect of the anatomical customization of the fiber post on the bond strength of a self-adhesive resin cement. Twelve endodontically treated, human, upper central incisors were randomly divided into two groups ( n = 6): control (glass fiber posts cemented with Relyx® U200) and customized (glass fiber posts anatomically customized with translucent composite resin cemented with Relyx U200). The roots were sectioned into three slices, cervical, middle, and apical, and photographed with a digital camera attached to a stereomicroscopic loupe. The images were analyzed by software, for evaluation of the cement line. The slices were subsequently submitted to the push-out test until the post had completely extruded, and the fracture mode was analyzed with a stereomicroscopic loupe. The results showed significant differences between the groups in the different root thirds in relation to the area occupied by air bubbles ( p customized group. The customized group showed greater bond resistance than the control group and a more uniform cement layer.

A note on the effect of the fiber curvature on the micromechanical behavior of natural fiber reinforced thermoplastic composites

Directory of Open Access Journals (Sweden)

M. A. Escalante-Solis

2015-12-01

Full Text Available To better understand the role of the fiber curvature on the tensile properties of short-natural-fiber reinforced composites, a photoelastic model and a finite element analysis were performed in a well characterized henequen fiber-high density polyethylene composite material. It was hypothesized that the angle of orientation of the inclusion and the principal material orientation with respect to the applied load was very important in the reinforcement mechanics. From the photoelastic and finite element analysis it was found that the stress distribution around the fiber inclusion was different on the concave side from that observed on the convex side and an efficient length of stress transfer was estimated to be approximately equal to one third the average fiber length. This approach was used to predict the short-natural-fiber reinforced composite mechanical properties using probabilistic functions modifications of the rule of mixtures models developed by Fukuda-Chow and the Fukuda-Kawata. Recognizing the inherent flexibility that curves the natural fibers during processing, the consideration of a length of one third of the average length l should improve the accuracy of the calculations of the mechanical properties using theoretical models.

Structural Analysis of Basalt Fiber Reinforced Plastic Wind Turbine Blade

Directory of Open Access Journals (Sweden)

Mengal Ali Nawaz

2014-07-01

Full Text Available In this study, Basalt fiber reinforced plastic (BFRP wind turbine blade was analyzed and compared with Glass fiber reinforced plastic blade (GFRP. Finite element analysis (FEA of blade was carried out using ANSYS. Data for FEA was obtained by using rule of mixture. The shell element in ANSYS was used to simulate the wind turbine blade and to conduct its strength analysis. The structural analysis and comparison of blade deformations proved that BFRP wind turbine blade has better strength compared to GFRP wind turbine blade.

Overall mechanical properties of fiber-reinforced metal matrix composites for fusion applications

International Nuclear Information System (INIS)

You, J.H.; Bolt, H.

2002-01-01

The high-temperature strength and creep properties are among the crucial criteria for the structural materials of plasma facing components (PFC) of fusion reactors, as they will be subjected to severe thermal stresses. The fiber-reinforced metal matrix composites are a potential heat sink material for the PFC application, since the combination of different material properties can lead to versatile performances. In this article, the overall mechanical properties of two model composites based on theoretical predictions are presented. The matrix materials considered were a precipitation hardened CuCrZr alloy and reduced activation martensitic steel 'Eurofer'. Continuous SiC fibers were used for the reinforcement. The results demonstrate that yield stress, ultimate tensile strength, work hardening rate and creep resistance could be extensively improved by the fiber reinforcement up to fiber content of 40 vol.%. The influence of the residual stresses on the plastic behavior of the composites is also discussed

Behavior of Fiber-Reinforced Smart Soft Composite Actuators According to Material Composition

Energy Technology Data Exchange (ETDEWEB)

Han, Min-Woo; Kim, Hyung-Il; Song, Sung-Hyuk; Ahn, Sung-Hoon [Seoul Nat’l Univ., Seoul (Korea, Republic of)

2017-02-15

Fiber-reinforced polymer composites, which are made by combining a continuous fiber that acts as reinforcement and a homogeneous polymeric material that acts as a host, are engineering materials with high strength and stiffness and a lightweight structure. In this study, a shape memory alloy(SMA) reinforced composite actuator is presented. This actuator is used to generate large deformations in single lightweight structures and can be used in applications requiring a high degree of adaptability to various external conditions. The proposed actuator consists of numerous individual laminas of the glass-fiber fabric that are embedded in a polymeric matrix. To characterize its deformation behavior, the composition of the actuator was changed by changing the matrix material and the number of the glass-fiber fabric layers. In addition, current of various magnitudes were applied to each actuator to study the effect of the heating of SMA wires on applying current.

Mechano-Physical Properties and Microstructure of Carbon Nanotube Reinforced Cement Paste after Thermal Load.

Science.gov (United States)

Szeląg, Maciej

2017-09-11

The article presents the results obtained in the course of a study on the use of carbon nanotubes (CNTs) for the modification of a cement matrix. Carbon nanotubes were introduced into a cement paste in the form of an aqueous dispersion in the presence of a surfactant (SDS-sodium dodecyl sulfate), which was sonicated. The selected physical and mechanical parameters were examined, and the correlations between these parameters were determined. An analysis of the local microstructure of the modified cement pastes has been carried out using scanning electron microscope (SEM) and X-ray microanalysis (EDS). In addition, the effect of carbon nanotubes on the change in characteristics of the cementitious material exposed to the sudden, short-term thermal load, was determined. The obtained material was characterized by a much lower density than a traditional cement matrix because the phenomenon of foaming occurred. The material was also characterized by reduced durability, higher shrinkage, and higher resistance to the effect of elevated temperature. Further research on the carbon nanotube reinforced cement paste, with SDS, may contribute to the development of a modified cement binder for the production of a lightweight or an aerated concrete.

Mechano-Physical Properties and Microstructure of Carbon Nanotube Reinforced Cement Paste after Thermal Load

Science.gov (United States)

2017-01-01

The article presents the results obtained in the course of a study on the use of carbon nanotubes (CNTs) for the modification of a cement matrix. Carbon nanotubes were introduced into a cement paste in the form of an aqueous dispersion in the presence of a surfactant (SDS—sodium dodecyl sulfate), which was sonicated. The selected physical and mechanical parameters were examined, and the correlations between these parameters were determined. An analysis of the local microstructure of the modified cement pastes has been carried out using scanning electron microscope (SEM) and X-ray microanalysis (EDS). In addition, the effect of carbon nanotubes on the change in characteristics of the cementitious material exposed to the sudden, short-term thermal load, was determined. The obtained material was characterized by a much lower density than a traditional cement matrix because the phenomenon of foaming occurred. The material was also characterized by reduced durability, higher shrinkage, and higher resistance to the effect of elevated temperature. Further research on the carbon nanotube reinforced cement paste, with SDS, may contribute to the development of a modified cement binder for the production of a lightweight or an aerated concrete. PMID:28891976

Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete.

Science.gov (United States)

Nam, Jeongsoo; Kim, Gyuyong; Yoo, Jaechul; Choe, Gyeongcheol; Kim, Hongseop; Choi, Hyeonggil; Kim, Youngduck

2016-02-26

This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber-polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance.