The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
Mehmet Ali Tasdemir - One of the best experts on this subject based on the ideXlab platform.
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mechanical behaviour and fibre dispersion of hybrid steel fibre reinforced self compacting concrete
Construction and Building Materials, 2012Co-Authors: Burcu Akcay, Mehmet Ali TasdemirAbstract:Abstract In this study, mixture design, workability, fibre dispersion/orientation, mechanical properties and fracture behaviour of hybrid steel fibre reinforced self-compacting concretes (HSFRSCCs) were investigated. Three different types of steel fibres with and/or without hooked-ends were added to the mixtures in two different volume fractions (0.75 and 1.5% of the total volume of concrete). The results of slump flow, U-box, V-funnel and J-Ring Tests have shown that increasing the fibre content of the concretes slightly reduced the workability of HSFRSCC, and the main influencing factor on flowability is the geometry of fibres. The addition of fibres, although did not change the final flowability, decreased the rate of flowability. The results from the experimental Tests showed that the flexural strengths increased slightly with increasing strength of long fibres, whereas the splitting tensile strength remained unchanged. The concretes with high strength, long steel fibres show behaviour of enhanced toughness and ductility compared to that with normal strength steel fibres. The orientation and distribution of fibres in concrete have been investigated by image analysis and it was observed that fibres dispersed homogeneously in all concrete series without any clumping. With increasing the amount of fibres, the fibres were more vertically orientated relative to the bending loading direction, resulting in enhancement in the mechanical properties of concrete.
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Mechanical behaviour and fibre dispersion of hybrid steel fibre reinforced self-compacting concrete
Construction and Building Materials, 2012Co-Authors: Burcu Akcay, Mehmet Ali TasdemirAbstract:In this study, mixture design, workability, fibre dispersion/orientation, mechanical properties and fracture behaviour of hybrid steel fibre reinforced self-compacting concretes (HSFRSCCs) were investigated. Three different types of steel fibres with and/or without hooked-ends were added to the mixtures in two different volume fractions (0.75 and 1.5% of the total volume of concrete). The results of slump flow, U-box, V-funnel and J-Ring Tests have shown that increasing the fibre content of the concretes slightly reduced the workability of HSFRSCC, and the main influencing factor on flowability is the geometry of fibres. The addition of fibres, although did not change the final flowability, decreased the rate of flowability. The results from the experimental Tests showed that the flexural strengths increased slightly with increasing strength of long fibres, whereas the splitting tensile strength remained unchanged. The concretes with high strength, long steel fibres show behaviour of enhanced toughness and ductility compared to that with normal strength steel fibres. The orientation and distribution of fibres in concrete have been investigated by image analysis and it was observed that fibres dispersed homogeneously in all concrete series without any clumping. With increasing the amount of fibres, the fibres were more vertically orientated relative to the bending loading direction, resulting in enhancement in the mechanical properties of concrete. © 2011 Elsevier Ltd. All rights reserved.
Burcu Akcay - One of the best experts on this subject based on the ideXlab platform.
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mechanical behaviour and fibre dispersion of hybrid steel fibre reinforced self compacting concrete
Construction and Building Materials, 2012Co-Authors: Burcu Akcay, Mehmet Ali TasdemirAbstract:Abstract In this study, mixture design, workability, fibre dispersion/orientation, mechanical properties and fracture behaviour of hybrid steel fibre reinforced self-compacting concretes (HSFRSCCs) were investigated. Three different types of steel fibres with and/or without hooked-ends were added to the mixtures in two different volume fractions (0.75 and 1.5% of the total volume of concrete). The results of slump flow, U-box, V-funnel and J-Ring Tests have shown that increasing the fibre content of the concretes slightly reduced the workability of HSFRSCC, and the main influencing factor on flowability is the geometry of fibres. The addition of fibres, although did not change the final flowability, decreased the rate of flowability. The results from the experimental Tests showed that the flexural strengths increased slightly with increasing strength of long fibres, whereas the splitting tensile strength remained unchanged. The concretes with high strength, long steel fibres show behaviour of enhanced toughness and ductility compared to that with normal strength steel fibres. The orientation and distribution of fibres in concrete have been investigated by image analysis and it was observed that fibres dispersed homogeneously in all concrete series without any clumping. With increasing the amount of fibres, the fibres were more vertically orientated relative to the bending loading direction, resulting in enhancement in the mechanical properties of concrete.
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Mechanical behaviour and fibre dispersion of hybrid steel fibre reinforced self-compacting concrete
Construction and Building Materials, 2012Co-Authors: Burcu Akcay, Mehmet Ali TasdemirAbstract:In this study, mixture design, workability, fibre dispersion/orientation, mechanical properties and fracture behaviour of hybrid steel fibre reinforced self-compacting concretes (HSFRSCCs) were investigated. Three different types of steel fibres with and/or without hooked-ends were added to the mixtures in two different volume fractions (0.75 and 1.5% of the total volume of concrete). The results of slump flow, U-box, V-funnel and J-Ring Tests have shown that increasing the fibre content of the concretes slightly reduced the workability of HSFRSCC, and the main influencing factor on flowability is the geometry of fibres. The addition of fibres, although did not change the final flowability, decreased the rate of flowability. The results from the experimental Tests showed that the flexural strengths increased slightly with increasing strength of long fibres, whereas the splitting tensile strength remained unchanged. The concretes with high strength, long steel fibres show behaviour of enhanced toughness and ductility compared to that with normal strength steel fibres. The orientation and distribution of fibres in concrete have been investigated by image analysis and it was observed that fibres dispersed homogeneously in all concrete series without any clumping. With increasing the amount of fibres, the fibres were more vertically orientated relative to the bending loading direction, resulting in enhancement in the mechanical properties of concrete. © 2011 Elsevier Ltd. All rights reserved.
Corinne Leyval - One of the best experts on this subject based on the ideXlab platform.
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inter laboratory evaluation of the iso standard 11063 soil quality method to directly extract dna from soil samples
Journal of Microbiological Methods, 2011Co-Authors: Ines Petrić, Karine Laval, Philippe Lemanceau, Thierry Lebeau, Cristina Abbate, Antonio Bispo, Laurent Philippot, Sara Hallin, Thierry Chesnot, Corinne LeyvalAbstract:Extracting DNA directly from micro-organisms living in soil is a crucial step for the molecular analysis of soil microbial communities. However, the use of a plethora of different soil DNA extraction protocols, each with its own bias, makes accurate data comparison difficult. To overcome this problem, a method for soil DNA extraction was proposed to the International Organization for Standardization (ISO) in 2006. This method was evaluated by 13 independent European laboratories actively participating in national and international Ring Tests. The reproducibility of the standardized method for molecular analyses was evaluated by compaRing the amount of DNA extracted, as well as the abundance and genetic structure of the total bacterial community in the DNA extracted from 12 different soils by the 13 laboratories. High quality DNA was successfully extracted from all 12 soils, despite different physical and chemical characteristics and a range of origins from arable soils, through forests to industrial sites. Quantification of the 16S rRNA gene abundances by real time PCR and analysis of the total bacterial community structure by automated ribosomal intergenic spacer analysis (A-RISA) showed acceptable to good levels of reproducibility. Based on the results of both Ring-Tests, the method was unanimously approved by the ISO as an international standard method and the normative protocol will now be disseminated within the scientific community. Standardization of a soil DNA extraction method will improve data comparison, facilitating our understanding of soil microbial diversity and soil quality monitoRing.
L Ceschini - One of the best experts on this subject based on the ideXlab platform.
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dry sliding behavior block on Ring Tests of aisi 420 martensitic stainless steel surface hardened by low temperature plasma assisted carburizing
Tribology International, 2016Co-Authors: Valerio Angelini, Iuri Boromei, C Martini, Cristiano Jose Scheuer, Rodrigo Perito Cardoso, Silvio Francisco Brunatto, L CeschiniAbstract:Abstract This paper reports on the dry sliding behavior (block-on-Ring Tests) of Low-Temperature Plasma Carburized (LTPC) AISI 420 martensitic stainless steel, treated under different times (4–16 h) and temperatures (350–500 °C), so as to identify the relationships between microstructure, micro-hardness and tribological behavior. In particular, LTPC was effective in decreasing wear when treatment conditions led to the highest diffusion layer thickness combined with absence of a thick outer layer (i.e. at 450 °C for a treatment time of 12 h). The dominant wear mechanism was mild tribo-oxidation, with the protective oxide tribolayer being partly removed by abrasive debris in samples treated at 500 °C.
M K Ferber - One of the best experts on this subject based on the ideXlab platform.
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stress distributions in thin bilayer discs subjected to ball on Ring Tests
Journal of the American Ceramic Society, 2005Co-Authors: C H Hsueh, Michael J Lance, M K FerberAbstract:Ball-on-Ring Tests have been used extensively to measure the biaxial strength of brittle materials. However, the Tests and analyses are limited to materials of uniform properties. An analytical model is developed in the present study to analyze thin bilayer discs subjected to ball-on-Ring Tests. It is found that closed-form solutions for bilayer discs can be obtained from existing solutions for monolayer discs by replacing the position of the neutral surface and the flexural rigidity of monolayers with those of bilayers. To validate the analytical solutions for bilayers, ball-on-Ring Tests are performed on a thin Al2O3 scale grown on an oxide dispersion-strengthened FeCrAl alloy disc and photo-stimulated luminescence spectroscopy is used to measure the stress distributions in the Al2O3 layer. In this case, the stress-induced peak shift of the R lines emitted by the Al2O3 scale is used to determine the average stress through the scale thickness. Good agreement between predictions and measurements is obtained.
