The Experts below are selected from a list of 32601 Experts worldwide ranked by ideXlab platform
Yunyong Kim - One of the best experts on this subject based on the ideXlab platform.
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quantitative evaluation technique of polyvinyl alcohol pva Fiber Dispersion in engineered cementitious composites
Cement & Concrete Composites, 2009Co-Authors: Bang Yeon Lee, Jinkeun Kim, Jeongsu Kim, Yunyong KimAbstract:Abstract The Fiber Dispersion in Fiber-reinforced cementitious composites is a crucial factor with respect to achieving desired mechanical performance. However, evaluation of the Fiber Dispersion in the composite Polyvinyl Alcohol-Engineered Cementitious Composite (PVA-ECC) is extremely challenging because of the low contrast of PVA Fibers with the cement-based matrix. In the present work, a new evaluation technique is developed and demonstrated. Using a fluorescence technique on PVA-ECC, PVA Fibers are observed as green dots in the cutting plane of the composite. After capturing the fluorescence image with a Charged Couple Device (CCD) camera through a microscope, the Fiber Dispersion is evaluated using image processing and statistical tools. In the image processing step, the Fibers are more accurately detected by employing a series of processes based on categorization, watershed segmentation, and morphological reconstruction. Test results showed that the Dispersion coefficient α f was calculated reasonably and the Fiber-detection performance was enhanced.
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tensile and Fiber Dispersion performance of ecc engineered cementitious composites produced with ground granulated blast furnace slag
Cement and Concrete Research, 2007Co-Authors: Jinkeun Kim, Jeongsu Kim, Yunyong KimAbstract:An engineered cementitious composite (ECC) produced with ground granulated blast furnace slag was developed for the purpose of achieving moderately high composite strength while maintaining high ductility, represented by strain-hardening behavior in uniaxial tension. In the material development, single Fiber pullout tests and matrix fracture tests were performed, followed by micromechanical analyses to properly select the range of mixture proportion. Subsequent direct tensile tests were employed to assess the strain-hardening behavior of the composite, which exhibited high ductility and strength with the addition of slag. High ductility is most likely due to enhanced workability and Fiber Dispersion performance which is attributed to the oxidized grain surface of slag, as verified by Fiber Dispersion tests. These results suggest that, within the limited slag dosage employed in the present study, the contribution of slag to Fiber Dispersion outweighs the side-effect of decreased potential for saturated multiple cracking, including a slight increase in matrix fracture toughness and Fiber/matrix bond strength.
Surendra P Shah - One of the best experts on this subject based on the ideXlab platform.
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correlation among fresh state behavior Fiber Dispersion and toughness properties of sfrcs
Journal of Materials in Civil Engineering, 2008Co-Authors: Liberato Ferrara, Y D Park, Surendra P ShahAbstract:Effective structural use of steel Fiber-reinforced concrete (SFRC) relies on the assumption of uniform Dispersion of Fibers within the elements. Fiber Dispersion related issues hence stand as a cutting edge research and technology development topic. The use of self-consolidating concrete (SCC), thanks to its rheological stability and self-placability, which leads to the elimination of compaction by vibration, may be helpful in guaranteeing a uniform Dispersion of Fibers. With reference to the latter, several techniques [e.g., based on alternate current impedance spectroscopy (AC-IS), microwave reflectometry etc.] have been developed in the last few years for its nondestructive monitoring. Investigation into the connections between Fiber Dispersion and the performance of the composite in the fresh and hardened state stand as the natural completion for a thorough assessment of the FRC properties, aimed at promoting its wider use for full load bearing structural applications. This paper presents the results of a research project aimed at the above said purpose. Based on a previously calibrated mix-design methodology, suitable specimens were cast with SFRC characterized by different performance in the fresh state (vibration-, self-, and segregation consolidating) and tested in four-point bending, in order to assess the connections among fresh state behavior and Fiber Dispersion, herein investigated by means of AC-IS, and the performance in the hardened state. The results, highlighting this correlation, point out their importance for a design of the material composition “tailored” to the anticipated mechanical performance and to the specific structural application.
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correlation of Fiber Dispersion rheology and mechanical performance of frcs
Cement & Concrete Composites, 2007Co-Authors: Nilufer Ozyurt, Thomas O Mason, Surendra P ShahAbstract:Fresh state properties of Fiber-reinforced concretes (FRCs) were correlated to hardened state properties by quantifying Fiber segregation. Rheological characteristics were evaluated using a custom-designed and built parallel-plate rheometer. Fresh state properties of concrete mixes were varied using different combinations of plasticizing agents and viscosity modifiers. Vibration was applied to the specimens and vibration times were varied to understand the effects of vibration on Fiber segregation. Two sizes of steel Fibers were used. Alternating current-impedance spectroscopy (AC-IS) was employed to non-destructively characterize Fiber segregation in the specimens. In addition, Fiber segregation was experimentally quantified using a destructive technique in which the amount of Fibers in different regions is weighed. A self-compacting concrete (SCC) mix was cast to compare segregation resistance with conventional concretes (CC). Splitting tensile tests were performed to study mechanical performance of FRC specimens. The effects of the rheological characteristics on Fiber segregation and, consequently, on the mechanical performance is discussed.
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fresh state behavior Fiber Dispersion and hardened state properties of self compacting steel Fiber reinforced concrete
Studi e ricerche - Politecnico di Milano. Scuola di specializzazione in costruzioni in cemento armato, 2007Co-Authors: Liberato Ferrara, Y D Park, Surendra P ShahAbstract:The results of a research project focusing on the correlation among fresh and hardened state properties and Fiber Dispersion in Self-Compacting Steel Fiber-Reinforced Concretes (SC-SFRC) are presented. Three SFRCs, containing 50 kg/m 3 hooked end Fibers 35 mm long with an aspect ratio equal to 65, were designed, targeted to different levels of fresh state performance: vibrated, self-consolidating and a third one exhibiting segregation. Thin square plates (600x600x60 mm) were cast for each mix and the Dispersion of Fibers within them was investigated through Alternate Current Impedance Spectroscopy (AC-IS). Beams were cut from the plates and tested in 4-point bending and the mechanical performance in the hardened state was evaluated. The influence of Fiber Dispersion on the mechanical properties is discussed. The results highlight the connections existing among fresh state behavior, Fiber Dispersion and mechanical properties of SFRC, pointing out their importance for a mix-design of a material "tailored" for the specific structural applications.
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non destructive monitoring of Fiber orientation using ac is an industrial scale application
Cement and Concrete Research, 2006Co-Authors: Thomas O Mason, Nilufer Ozyurt, Surendra P ShahAbstract:A comprehensive study has been undertaken to investigate the ability of AC-impedance spectroscopy (AC-IS) to non-destructively monitor the Fiber Dispersion of conductive Fiber-reinforced cement-based materials. Previous work showed that AC-IS effectively monitors various Fiber Dispersion issues in lab-scale steel Fiber-reinforced specimens. In this part of the study, AC-IS was used to study Fiber orientation in an industrial-scale pre-cast concrete beam. A conventional method-image analysis (IA)-was used to verify the results of AC-IS measurements. The results of AC-IS and IA were found to match very well in experimental uncertainty. Splitting tensile tests and bending tests were conducted on the parts of the beam to study the effects of Fiber orientation on the mechanical performance. The results of the mechanical tests also confirmed the results of AC-IS with splitting tensile strengths increasing as the alignment of Fibers increased.
Jinkeun Kim - One of the best experts on this subject based on the ideXlab platform.
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quantitative evaluation technique of polyvinyl alcohol pva Fiber Dispersion in engineered cementitious composites
Cement & Concrete Composites, 2009Co-Authors: Bang Yeon Lee, Jinkeun Kim, Jeongsu Kim, Yunyong KimAbstract:Abstract The Fiber Dispersion in Fiber-reinforced cementitious composites is a crucial factor with respect to achieving desired mechanical performance. However, evaluation of the Fiber Dispersion in the composite Polyvinyl Alcohol-Engineered Cementitious Composite (PVA-ECC) is extremely challenging because of the low contrast of PVA Fibers with the cement-based matrix. In the present work, a new evaluation technique is developed and demonstrated. Using a fluorescence technique on PVA-ECC, PVA Fibers are observed as green dots in the cutting plane of the composite. After capturing the fluorescence image with a Charged Couple Device (CCD) camera through a microscope, the Fiber Dispersion is evaluated using image processing and statistical tools. In the image processing step, the Fibers are more accurately detected by employing a series of processes based on categorization, watershed segmentation, and morphological reconstruction. Test results showed that the Dispersion coefficient α f was calculated reasonably and the Fiber-detection performance was enhanced.
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tensile and Fiber Dispersion performance of ecc engineered cementitious composites produced with ground granulated blast furnace slag
Cement and Concrete Research, 2007Co-Authors: Jinkeun Kim, Jeongsu Kim, Yunyong KimAbstract:An engineered cementitious composite (ECC) produced with ground granulated blast furnace slag was developed for the purpose of achieving moderately high composite strength while maintaining high ductility, represented by strain-hardening behavior in uniaxial tension. In the material development, single Fiber pullout tests and matrix fracture tests were performed, followed by micromechanical analyses to properly select the range of mixture proportion. Subsequent direct tensile tests were employed to assess the strain-hardening behavior of the composite, which exhibited high ductility and strength with the addition of slag. High ductility is most likely due to enhanced workability and Fiber Dispersion performance which is attributed to the oxidized grain surface of slag, as verified by Fiber Dispersion tests. These results suggest that, within the limited slag dosage employed in the present study, the contribution of slag to Fiber Dispersion outweighs the side-effect of decreased potential for saturated multiple cracking, including a slight increase in matrix fracture toughness and Fiber/matrix bond strength.
Gee Joo Ha - One of the best experts on this subject based on the ideXlab platform.
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tensile and Fiber Dispersion performance of ecc engineered cementitious composites produced with ground granulated blast furnace slag
Cement and Concrete Research, 2007Co-Authors: Gee Joo HaAbstract:An engineered cementitious composite (ECC) produced with ground granulated blast furnace slag was developed for the purpose of achieving moderately high composite strength while maintaining high ductility, represented by strain-hardening behavior in uniaxial tension. In the material development, single Fiber pullout tests and matrix fracture tests were performed, followed by micromechanical analyses to properly select the range of mixture proportion. Subsequent direct tensile tests were employed to assess the strain-hardening behavior of the composite, which exhibited high ductility and strength with the addition of slag. High ductility is most likely due to enhanced workability and Fiber Dispersion performance which is attributed to the oxidized grain surface of slag, as verified by Fiber Dispersion tests. These results suggest that, within the limited slag dosage employed in the present study, the contribution of slag to Fiber Dispersion outweighs the side-effect of decreased potential for saturated multiple cracking, including a slight increase in matrix fracture toughness and Fiber/matrix bond strength.
Jeongsu Kim - One of the best experts on this subject based on the ideXlab platform.
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quantitative evaluation technique of polyvinyl alcohol pva Fiber Dispersion in engineered cementitious composites
Cement & Concrete Composites, 2009Co-Authors: Bang Yeon Lee, Jinkeun Kim, Jeongsu Kim, Yunyong KimAbstract:Abstract The Fiber Dispersion in Fiber-reinforced cementitious composites is a crucial factor with respect to achieving desired mechanical performance. However, evaluation of the Fiber Dispersion in the composite Polyvinyl Alcohol-Engineered Cementitious Composite (PVA-ECC) is extremely challenging because of the low contrast of PVA Fibers with the cement-based matrix. In the present work, a new evaluation technique is developed and demonstrated. Using a fluorescence technique on PVA-ECC, PVA Fibers are observed as green dots in the cutting plane of the composite. After capturing the fluorescence image with a Charged Couple Device (CCD) camera through a microscope, the Fiber Dispersion is evaluated using image processing and statistical tools. In the image processing step, the Fibers are more accurately detected by employing a series of processes based on categorization, watershed segmentation, and morphological reconstruction. Test results showed that the Dispersion coefficient α f was calculated reasonably and the Fiber-detection performance was enhanced.
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tensile and Fiber Dispersion performance of ecc engineered cementitious composites produced with ground granulated blast furnace slag
Cement and Concrete Research, 2007Co-Authors: Jinkeun Kim, Jeongsu Kim, Yunyong KimAbstract:An engineered cementitious composite (ECC) produced with ground granulated blast furnace slag was developed for the purpose of achieving moderately high composite strength while maintaining high ductility, represented by strain-hardening behavior in uniaxial tension. In the material development, single Fiber pullout tests and matrix fracture tests were performed, followed by micromechanical analyses to properly select the range of mixture proportion. Subsequent direct tensile tests were employed to assess the strain-hardening behavior of the composite, which exhibited high ductility and strength with the addition of slag. High ductility is most likely due to enhanced workability and Fiber Dispersion performance which is attributed to the oxidized grain surface of slag, as verified by Fiber Dispersion tests. These results suggest that, within the limited slag dosage employed in the present study, the contribution of slag to Fiber Dispersion outweighs the side-effect of decreased potential for saturated multiple cracking, including a slight increase in matrix fracture toughness and Fiber/matrix bond strength.