Papers by Keyword: Fiber Reinforced Concrete

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Authors: Adam Podstawka, Martin Kovar, Marek Foglar, Vladimir Kristek
Abstract: Paper compares and discusses two different layouts of testing of mechanical and fracture properties of FRC, the three-point bending test and four-point bending test. The basis is extensive experimental program and analytical and statistical evaluation.
Authors: Martin Kovar, Marek Foglar
Abstract: Fiber-reinforced concrete (FRC) has mechanical properties that enhance its suitability for use in structures subjected to high strain rates, e.g. blast or impact loading. The fracture energy value is the decisive material characteristic for assessing the damage to concrete structures due to loadings with high strain rates. An analytical description of the force-deflection diagram of FRC can be a very efficient instrument for making a preliminary estimate of the fracture and mechanical properties of FRC. On the basis of our experiments and experiments from other authors, a tool for an analytical description of the force-deflection diagram for various strength classes, fiber types, etc. is proposed and evaluated.
Authors: Siti Asmahani Saad, Farah Nora Aznieta Abdul Aziz, Maisarah Ali
Abstract: Additional of fiber in concrete creates fiber reinforced concrete (FRC) with an improvement of the mechanical properties of the concrete. However, fiber incorporation in FRC is limited to 2% to allow normal mixing procedure. To address this issue, high performance fiber reinforced concrete (HPFRC) is introduced and it is relatively new in construction industry. Since very limited information on its capacity in tropical climate condition exposure, this research focuses on investigation of compressive strength and microstructure properties of the produced concrete in tropical climate condition. In order to complete this research, grade 80 cement slurry is used with 3%, 4% and 5% hooked-end steel fiber. Total numbers of 56 samples which are divided into 4 sets and exposed to two different curing methods namely water curing method and steam curing method at 80°C. Out of the 4 sets, 2 sets are exposed to tropical climate condition using climatic chamber at 80% relative humidity (RH) and constant temperature of 35°C for 30 days. Compression and ultrasonic pulse velocity (UPV) tests are carried out at 28 days to identify its strength as well as integrity of the concrete produced. Scanning electron microscopy (SEM) analysis is done to ascertain the microstructure properties of HPFRC. The highest compressive strength of 152.2 MPa was recorded for steam curing samples after exposed to tropical climate condition for 30 days with 5% steel fiber volume.
Authors: Vladimír Suchánek, Matěj Slováček
Abstract: This report deals with the description of development of waterproof steel fibre reinforced concrete (suitable for concrete lining of tunnel constructions in particular) in cooperation with the concrete supplier. With regard to newly released documents, two formulas of waterproof concrete supplemented with steel and polypropylene fibres were suggested. The formulas were designed according to different approaches (standards / Austrian Directive), and they differ only in various weight doses of the individual components. With regard to the general requirements for the tunnel lining (fire resistance tests, chemical stability, strength, impermeability and adhesion), strength and plastic properties, durability parameters (depth of penetration of water under pressure, depth of penetration of standing water, frost resistance, resistance of cement concrete surface to water and defrosting chemicals, depth of penetration of chloride) and the resistance to extreme thermal stress were determined in both the formulas. Standardized tests and non-standard testing have been completed.
Authors: Asif Jalal, Nasir Shafiq, Ehsan Nikbakht, Rabinder Kumar, Muhammad Zahid
Abstract: This study focuses on the study of the mechanical behavior of non-metallic hybrid Basalt-PVA fiber reinforced concrete. Total five mixes were investigated with one control plain concrete and four with fiber volume fraction of 0.3%, 0.6%, 0.9% and 1.2%. Basalt and PVA were used in same quantity. Fiber decreased workability, therefore superplasticizer was used to maintain workability constant. The increase in superplasticizer and fiber content decreased compression, split tensile and flexure strengths because of formation of big size pores. Whereas fiber enhanced the post peak load zone in the load-deflection curve. Fiber improved the bridging action by increasing energy absorption. Fiber vanished the brittle behavior of high strength concrete and increased first crack toughness, flexure toughness and also maximum deflection. 0.3% volume fraction of fiber was found to be optimum with the negligible decrease in compression, split tensile and flexure strength while caused the considerable increase in first crack toughness, flexure toughness, and maximum deflection.
Authors: Naima Belhadj, Youcef Bouafia, Rebiha Smahi
Abstract: The damage mechanics allows a detailed modeling of reinforced concrete’s degradation phenomenon. The theory of isotropic damage leads to quite satisfactory results in the description of both in the local and the global behavior. It is within the scope of this work to provide a model of damage based on the non-linear mechanical behavior of fiber concrete. This model takes into account the ductile nature of the observed during testing of material and direct tension after cracking. The modeling will be done while checking the principles of damage mechanics using the fundamentals of continuous mechanics of materials to propose a law of damage variation in unidirectional compression and tension. Confrontations with experimental test results are established.
Authors: Martin Tipka, Jitka Vašková
Abstract: The paper deals with the determination of the modulus of elasticity in tension for cementitious composites and comparing these values with the values of modulus in compression. It describes several methods, which are usually used for determination of modulus of elasticity of concrete and fibre reinforced concrete. In the experimental program modulus of elasticity in compression and tension of various types of concrete and fibre reinforced concrete were compared. The classic test with prismatic specimens was used for determination of the modulus in compression; a new arrangement of uniaxial tension test of cementitious composites was used for determination of the modulus of elasticity in tension.
Authors: Josef Novak, Alena Kohoutkova
Abstract: The building industry offers a wide range of materials which can be used for the production of various structural elements. Fibre reinforced concrete (FRC) is a material which is more frequently utilized for concrete structures. The reason is its physical and mechanical properties which contribute to traditional concrete elements and structures various economical benefits such as structure subtlety, part or full elimination of conventional reinforcement, resistance to mechanical loading and surrounding environment. Therefore, it is necessary to search for appropriate structures where the benefits of FRC could be used. First of all it is necessary to seek for structures which owing to their geometry and intended use seem to be appropriate for FRC application. It can be either new structural elements or existing structural elements made of a different material. During a material optimization there are many parameters to take into account which include production costs, manufacturing technology, structural behaviour, ultimate bearing capacity and durability of proposed member. The efficiency of material optimization is determined by comparing these parameters. While it is relatively easy and cost efficient to determine and evaluate the production costs, structure durability and manufacturing technology, to describe the structural behaviour of innovative elements is a complex task. However there are many sophisticated software which are capable to accurately simulate the behaviour of structural elements by using modern computational methods. At the end of feasibility study, experimental testing is conducted on full-scale pilot elements with the aim to verify their real behaviour as well as to optimize the computational model. As a result, many innovative FRC based structural elements have been developed at Czech Technical University in Prague in cooperation with construction companies.
Authors: Jan Trejbal, Lubomír Kopecký, Jozef Fládr, Pavel Tesárek, Václav Nežerka, Zdeněk Prošek
Abstract: This work deals with determination of location of micro fibers positions in fiber-reinforced concrete. The digital images of sectioned cement-paste samples with dimension equal to 40 × 40 mm were used as an information source about the monofilaments positions. Properly acquired digital image of high resolution allows to determinate the number of fibers in samples cross sections and relate theirs coordinates to any point. Optical microscope Carl Zeiss Axio Zoom.V16 with camera and software allowing individual shots composition of examined samples surface was used to obtain these parameters. Cement pastes reinforced with PET (polyethylene terephthalate) micro fibers having diameter equal to 0.4 mm were studied. The total number and the fibers distribution along the height and width of the sample cross section were examined.
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