The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Kimberly E. Kurtis - One of the best experts on this subject based on the ideXlab platform.
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a probabilistic technique for Entrained Air void analysis in hardened concrete
Cement and Concrete Research, 2014Co-Authors: Nathan P Mayercsik, Robert Felice, Tyler M Ley, Kimberly E. KurtisAbstract:A novel method that utilizes the lineal-path function to ascertain a probability density function for the three-dimensional size distribution of Entrained Air voids directly from plane polished sections of hardened concrete is proposed. The results then treat the spacing factor in terms of a probabilistic maximum distance from a random point in the cement paste matrix to the periphery of an Air void, where Air voids are treated as a polydispersed sphere system. The model was applied to concretes with various Air entrainment admixture types and dosages. The results suggest that the model may offer a better assessment of the system for use in assessing durability and studying admixtures, as well as providing a new tool for spatial characterization of heterogeneous and porous materials.
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Characterization of Multi-scale Porosity in Cement Paste by Advanced Ultrasonic Techniques
Cement and Concrete Research, 2007Co-Authors: Wonsiri Punurai, Jacek Jarzynski, Laurence J. Jacobs, Jin-yeon Kim, Kimberly E. KurtisAbstract:The effectiveness of advanced ultrasonic techniques to quantitatively characterize the capillary porosity and Entrained Air content in hardened cement paste is examined. Direct measurements of ultrasonic attenuation are used to measure the volume fraction and average size of Entrained Air voids and to assess variations in intrinsic porosity – as influenced by water-to-cement ratio (w/c) – in hardened cement paste samples. For the Air Entrained specimens, an inversion procedure based on a theoretical attenuation model is used to predict the average size and volume fraction of Entrained Air voids in each specimen, producing results in very good agreement with results obtained by standard petrographic methods and by gravimetric analysis. In addition, ultrasonic attenuation measurements are related to w/c to quantify the relationship between increasing porosity (with increasing w/c) and ultrasonic wave characteristics.
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Characterization of Entrained Air voids in cement paste with scattered ultrasound
Ndt & E International, 2006Co-Authors: Wonsiri Punurai, Jacek Jarzynski, Kimberly E. Kurtis, Laurence J. JacobsAbstract:This research develops a technique that uses the attenuation of ultrasonic waves to characterize the average size and volume fraction of Entrained Air voids in hardened cement paste. Quantitative knowledge of Entrained Air void size and distribution helps ensure that an adequate design strength is developed, while maintaining resistance to freeze-thaw damage in cement-based materials. Ultrasonic attenuation coefficients obtained from pulse-burst signals are measured in the frequency range of 500 kHz–5 MHz. From these parameters, the average size and the volume fraction of the Entrained Air voids are determined using a combination of an ultrasonic scattering model and an inversion algorithm. Experiments are performed on specimens produced with and without Entrained Air voids. There is a good agreement between the model prediction and the experiments in these systems that contained o10% by volume of Entrained Air voids. r 2006 Elsevier Ltd. All rights reserved.
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Characterization of Entrained Air voids in cement paste with scattered ultrasound
Geotextiles and Geomembranes, 2006Co-Authors: W Punari, Jacek Jarzynski, Kimberly E. Kurtis, Laurence J. JacobsAbstract:This research develops a technique that uses the attenuation of ultrasonic waves to characterize the average size and volume fraction of Entrained Air voids in hardened cement paste. Quantitative knowledge of Entrained Air void size and distribution helps ensure that an adequate design strength is developed, while maintaining resistance to freeze-thaw damage in cement-based materials. Ultrasonic attenuation coefficients obtained from pulse-burst signals are measured in the frequency range of 500 kHz-5 MHz. From these parameters, the average size and the volume fraction of the Entrained Air voids are determined using a combination of an ultrasonic scattering model and an inversion algorithm. Experiments are performed on specimens produced with and without Entrained Air voids. There is a good agreement between the model prediction and the experiments in these systems that contained
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Characterization of Entrained Air Voids Using Scattered Ultrasound
AIP Conference Proceedings, 2006Co-Authors: Wonsiri Punurai, Kimberly E. Kurtis, Laurence J. Jacobs, Jacek JarzynskiAbstract:The passage of ultrasound waves through highly heterogeneous media (e.g. hardened cement pastes that contain Entrained Air voids for protection against damage during freeze‐thaw cycles) leads to significant loss of wave energy and an apparent attenuation of ultrasonic signal emerging from the heterogeneous zone. The size of this attenuation depends on the correlation properties of the medium (e.g. size and volume fraction of Air voids) and the wavelength and frequency content of the incident waves. An estimated of the effect can be obtained using independent scattering theory under dilute concentration assumption. The resulting attenuation characteristics are illustrated numerically. These results are discussed in comparison with experimental data of longitudinal wave attenuation in the hardened cement paste containing a low volume fraction of Entrained Air voids of less than 10% for a large frequency range of 500 kHz–5MHz.
Laurence J. Jacobs - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Multi-scale Porosity in Cement Paste by Advanced Ultrasonic Techniques
Cement and Concrete Research, 2007Co-Authors: Wonsiri Punurai, Jacek Jarzynski, Laurence J. Jacobs, Jin-yeon Kim, Kimberly E. KurtisAbstract:The effectiveness of advanced ultrasonic techniques to quantitatively characterize the capillary porosity and Entrained Air content in hardened cement paste is examined. Direct measurements of ultrasonic attenuation are used to measure the volume fraction and average size of Entrained Air voids and to assess variations in intrinsic porosity – as influenced by water-to-cement ratio (w/c) – in hardened cement paste samples. For the Air Entrained specimens, an inversion procedure based on a theoretical attenuation model is used to predict the average size and volume fraction of Entrained Air voids in each specimen, producing results in very good agreement with results obtained by standard petrographic methods and by gravimetric analysis. In addition, ultrasonic attenuation measurements are related to w/c to quantify the relationship between increasing porosity (with increasing w/c) and ultrasonic wave characteristics.
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Characterization of Entrained Air voids in cement paste with scattered ultrasound
Ndt & E International, 2006Co-Authors: Wonsiri Punurai, Jacek Jarzynski, Kimberly E. Kurtis, Laurence J. JacobsAbstract:This research develops a technique that uses the attenuation of ultrasonic waves to characterize the average size and volume fraction of Entrained Air voids in hardened cement paste. Quantitative knowledge of Entrained Air void size and distribution helps ensure that an adequate design strength is developed, while maintaining resistance to freeze-thaw damage in cement-based materials. Ultrasonic attenuation coefficients obtained from pulse-burst signals are measured in the frequency range of 500 kHz–5 MHz. From these parameters, the average size and the volume fraction of the Entrained Air voids are determined using a combination of an ultrasonic scattering model and an inversion algorithm. Experiments are performed on specimens produced with and without Entrained Air voids. There is a good agreement between the model prediction and the experiments in these systems that contained o10% by volume of Entrained Air voids. r 2006 Elsevier Ltd. All rights reserved.
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Characterization of Entrained Air voids in cement paste with scattered ultrasound
Geotextiles and Geomembranes, 2006Co-Authors: W Punari, Jacek Jarzynski, Kimberly E. Kurtis, Laurence J. JacobsAbstract:This research develops a technique that uses the attenuation of ultrasonic waves to characterize the average size and volume fraction of Entrained Air voids in hardened cement paste. Quantitative knowledge of Entrained Air void size and distribution helps ensure that an adequate design strength is developed, while maintaining resistance to freeze-thaw damage in cement-based materials. Ultrasonic attenuation coefficients obtained from pulse-burst signals are measured in the frequency range of 500 kHz-5 MHz. From these parameters, the average size and the volume fraction of the Entrained Air voids are determined using a combination of an ultrasonic scattering model and an inversion algorithm. Experiments are performed on specimens produced with and without Entrained Air voids. There is a good agreement between the model prediction and the experiments in these systems that contained
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Characterization of Entrained Air Voids Using Scattered Ultrasound
AIP Conference Proceedings, 2006Co-Authors: Wonsiri Punurai, Kimberly E. Kurtis, Laurence J. Jacobs, Jacek JarzynskiAbstract:The passage of ultrasound waves through highly heterogeneous media (e.g. hardened cement pastes that contain Entrained Air voids for protection against damage during freeze‐thaw cycles) leads to significant loss of wave energy and an apparent attenuation of ultrasonic signal emerging from the heterogeneous zone. The size of this attenuation depends on the correlation properties of the medium (e.g. size and volume fraction of Air voids) and the wavelength and frequency content of the incident waves. An estimated of the effect can be obtained using independent scattering theory under dilute concentration assumption. The resulting attenuation characteristics are illustrated numerically. These results are discussed in comparison with experimental data of longitudinal wave attenuation in the hardened cement paste containing a low volume fraction of Entrained Air voids of less than 10% for a large frequency range of 500 kHz–5MHz.
Anuwat Attachaiyawuth - One of the best experts on this subject based on the ideXlab platform.
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Effects of fly ash, mixing procedure and type of Air-entraining agent on coalescence of Entrained Air bubbles in mortar of self-compacting concrete at fresh state
Construction and Building Materials, 2018Co-Authors: Nipat Puthipad, Masahiro Ouchi, Anuwat AttachaiyawuthAbstract:Abstract In this paper, an empirical study aimed at preventing the coalescence of fine Entrained Air bubbles in the fresh mortar of self-compacting concrete (SCC) containing fly ash is reported. The time of addition of the Air-entraining agent (AEA) during mixing is also investigated. Various types of AEA are also studied. In implementing the experiment, mortar flowability is assumed to affect the coalescence of fine Air bubbles. The Air size distribution of the Air-Entrained SCC mortar in the fresh state is determined by an Air Void Analyser (AVA). Changes in the Air size distribution over a 120 min period are analysed to evaluate bubble coalescence. The results suggest that the use of fly ash in the SCC can result in a higher degree of coalescence of the fine Air bubbles. The various types of AEA resulted in Air bubbles with different degrees of coalescence. Further, adding the AEA to the mix after the superplasticiser (SP) inhibits the coalescence of Air bubbles. Evidently, the degree of coalescence of Air bubbles can be reduced by careful selection of the AEA and the mixing procedure.
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Improving the stability of Entrained Air in self-compacting concrete by optimizing the mix viscosity and Air entraining agent dosage
Construction and Building Materials, 2017Co-Authors: Sovannsathya Rath, Masahiro Ouchi, Nipat Puthipad, Anuwat AttachaiyawuthAbstract:Abstract The purpose of this study is to clarify the role of mixing procedure and Air entraining agent (AE) on the Entrained volume of fine and coarse Air bubbles with the aim of improving the stability of Entrained Air in self-compacting concrete (SCC). Experiments were conducted in which the Air bubbles size distribution of fresh mortars was measured with an Air-void analyzer (AVA). Critical size of Air bubble was defined as the size below which the bubble volume remains stable as time pass. This critical size, defined in terms of chord length, was found to be 500 μm from the correlation between the volume of larger bubbles and the reduction in volume two hours after mixing. A lower mortar viscosity, obtained using a mixing procedure in which water additions were divided, reduced the total volume of both fine and coarse Air bubbles. With a higher dosage of AE, a higher volume of fine Air bubbles and a lower volume of coarse Air bubbles were Entrained. An upper limit volume of fine Air was defined as the maximum volume of fine Air bubbles Entrained with a longer mixing time. This upper limit is proportional to the AE dosage multiplied by the funnel speed of the mortar as an index of viscosity.
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Enhanced entrainment of fine Air bubbles in self-compacting concrete with high volume of fly ash using defoaming agent for improved Entrained Air stability and higher aggregate content
Construction and Building Materials, 2017Co-Authors: Nipat Puthipad, Masahiro Ouchi, Sovannsathya Rath, Anuwat AttachaiyawuthAbstract:Abstract This paper presents an experimental study on the use of a defoaming agent (DA) to promote entrainment of fine Air bubbles for improved volumetric stability of Entrained Air in self-compacting concrete (SCC) with fly ash. The possibility of increasing the aggregate content of self-compacting concrete with fly ash through the ball-bearing effect of fine Entrained Air bubbles is also investigated. Lower water retention and the ball-bearing effect of both fly ash and Entrained Air bubbles are considered to affect the self-compactability of fresh concrete. The results suggest that, generally, the employment of DA improves the stability of Entrained Air bubbles owing to the reduced entrainment of large Air bubbles. The self-compactability of fresh concrete with fly ash is found to improve as dosage of DA increases, due to the ball-bearing effect of fine Entrained Air bubbles. Evidently, a higher aggregate content is also made possible through use of a certain type of Air-entraining agent (AEA), due to the lower amount of large Entrained Air bubbles.
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enhancement in self compactability and stability in volume of Entrained Air in self compacting concrete with high volume fly ash
Construction and Building Materials, 2016Co-Authors: Nipat Puthipad, Masahiro Ouchi, Sovannsathya Rath, Anuwat AttachaiyawuthAbstract:Abstract An experimental study on the effect of Entrained Air bubbles on the enhancement of self-compactability in fresh concrete with high volume fly ash was investigated. The stability in terms of volume of Entrained Air bubbles was also analysed. In this paper, lower water retention and ball-bearing effect of fly ash and Entrained Air bubbles were considered to affect the self-compactability of fresh concrete. The results showed that higher fine aggregate content in mortar ( s/m) of SCC can be employed as replacement ratio of cement with fly ash ( fa/p ) increases owing to the higher ball-bearing effect of fly ash, in spite of reduction in water to powder ratio ( w/p ). The ball-bearing effect of Entrained Air bubbles, with certain type of Air-entraining agent (AEA), was also found to further enhance the self-compactability of fresh concrete with fly ash. However, the stability in volume of Entrained Air bubbles tended to be reduced as fa/p increased, due to higher amount of large Entrained Air bubbles produced. Apparently, the spherical shape of fly ash tended to cause the unification and escape of Entrained Air bubbles in SCC.
Jacek Jarzynski - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Multi-scale Porosity in Cement Paste by Advanced Ultrasonic Techniques
Cement and Concrete Research, 2007Co-Authors: Wonsiri Punurai, Jacek Jarzynski, Laurence J. Jacobs, Jin-yeon Kim, Kimberly E. KurtisAbstract:The effectiveness of advanced ultrasonic techniques to quantitatively characterize the capillary porosity and Entrained Air content in hardened cement paste is examined. Direct measurements of ultrasonic attenuation are used to measure the volume fraction and average size of Entrained Air voids and to assess variations in intrinsic porosity – as influenced by water-to-cement ratio (w/c) – in hardened cement paste samples. For the Air Entrained specimens, an inversion procedure based on a theoretical attenuation model is used to predict the average size and volume fraction of Entrained Air voids in each specimen, producing results in very good agreement with results obtained by standard petrographic methods and by gravimetric analysis. In addition, ultrasonic attenuation measurements are related to w/c to quantify the relationship between increasing porosity (with increasing w/c) and ultrasonic wave characteristics.
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Characterization of Entrained Air voids in cement paste with scattered ultrasound
Ndt & E International, 2006Co-Authors: Wonsiri Punurai, Jacek Jarzynski, Kimberly E. Kurtis, Laurence J. JacobsAbstract:This research develops a technique that uses the attenuation of ultrasonic waves to characterize the average size and volume fraction of Entrained Air voids in hardened cement paste. Quantitative knowledge of Entrained Air void size and distribution helps ensure that an adequate design strength is developed, while maintaining resistance to freeze-thaw damage in cement-based materials. Ultrasonic attenuation coefficients obtained from pulse-burst signals are measured in the frequency range of 500 kHz–5 MHz. From these parameters, the average size and the volume fraction of the Entrained Air voids are determined using a combination of an ultrasonic scattering model and an inversion algorithm. Experiments are performed on specimens produced with and without Entrained Air voids. There is a good agreement between the model prediction and the experiments in these systems that contained o10% by volume of Entrained Air voids. r 2006 Elsevier Ltd. All rights reserved.
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Characterization of Entrained Air voids in cement paste with scattered ultrasound
Geotextiles and Geomembranes, 2006Co-Authors: W Punari, Jacek Jarzynski, Kimberly E. Kurtis, Laurence J. JacobsAbstract:This research develops a technique that uses the attenuation of ultrasonic waves to characterize the average size and volume fraction of Entrained Air voids in hardened cement paste. Quantitative knowledge of Entrained Air void size and distribution helps ensure that an adequate design strength is developed, while maintaining resistance to freeze-thaw damage in cement-based materials. Ultrasonic attenuation coefficients obtained from pulse-burst signals are measured in the frequency range of 500 kHz-5 MHz. From these parameters, the average size and the volume fraction of the Entrained Air voids are determined using a combination of an ultrasonic scattering model and an inversion algorithm. Experiments are performed on specimens produced with and without Entrained Air voids. There is a good agreement between the model prediction and the experiments in these systems that contained
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Characterization of Entrained Air Voids Using Scattered Ultrasound
AIP Conference Proceedings, 2006Co-Authors: Wonsiri Punurai, Kimberly E. Kurtis, Laurence J. Jacobs, Jacek JarzynskiAbstract:The passage of ultrasound waves through highly heterogeneous media (e.g. hardened cement pastes that contain Entrained Air voids for protection against damage during freeze‐thaw cycles) leads to significant loss of wave energy and an apparent attenuation of ultrasonic signal emerging from the heterogeneous zone. The size of this attenuation depends on the correlation properties of the medium (e.g. size and volume fraction of Air voids) and the wavelength and frequency content of the incident waves. An estimated of the effect can be obtained using independent scattering theory under dilute concentration assumption. The resulting attenuation characteristics are illustrated numerically. These results are discussed in comparison with experimental data of longitudinal wave attenuation in the hardened cement paste containing a low volume fraction of Entrained Air voids of less than 10% for a large frequency range of 500 kHz–5MHz.
Wonsiri Punurai - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Multi-scale Porosity in Cement Paste by Advanced Ultrasonic Techniques
Cement and Concrete Research, 2007Co-Authors: Wonsiri Punurai, Jacek Jarzynski, Laurence J. Jacobs, Jin-yeon Kim, Kimberly E. KurtisAbstract:The effectiveness of advanced ultrasonic techniques to quantitatively characterize the capillary porosity and Entrained Air content in hardened cement paste is examined. Direct measurements of ultrasonic attenuation are used to measure the volume fraction and average size of Entrained Air voids and to assess variations in intrinsic porosity – as influenced by water-to-cement ratio (w/c) – in hardened cement paste samples. For the Air Entrained specimens, an inversion procedure based on a theoretical attenuation model is used to predict the average size and volume fraction of Entrained Air voids in each specimen, producing results in very good agreement with results obtained by standard petrographic methods and by gravimetric analysis. In addition, ultrasonic attenuation measurements are related to w/c to quantify the relationship between increasing porosity (with increasing w/c) and ultrasonic wave characteristics.
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Characterization of Entrained Air voids in cement paste with scattered ultrasound
Ndt & E International, 2006Co-Authors: Wonsiri Punurai, Jacek Jarzynski, Kimberly E. Kurtis, Laurence J. JacobsAbstract:This research develops a technique that uses the attenuation of ultrasonic waves to characterize the average size and volume fraction of Entrained Air voids in hardened cement paste. Quantitative knowledge of Entrained Air void size and distribution helps ensure that an adequate design strength is developed, while maintaining resistance to freeze-thaw damage in cement-based materials. Ultrasonic attenuation coefficients obtained from pulse-burst signals are measured in the frequency range of 500 kHz–5 MHz. From these parameters, the average size and the volume fraction of the Entrained Air voids are determined using a combination of an ultrasonic scattering model and an inversion algorithm. Experiments are performed on specimens produced with and without Entrained Air voids. There is a good agreement between the model prediction and the experiments in these systems that contained o10% by volume of Entrained Air voids. r 2006 Elsevier Ltd. All rights reserved.
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Characterization of Entrained Air Voids Using Scattered Ultrasound
AIP Conference Proceedings, 2006Co-Authors: Wonsiri Punurai, Kimberly E. Kurtis, Laurence J. Jacobs, Jacek JarzynskiAbstract:The passage of ultrasound waves through highly heterogeneous media (e.g. hardened cement pastes that contain Entrained Air voids for protection against damage during freeze‐thaw cycles) leads to significant loss of wave energy and an apparent attenuation of ultrasonic signal emerging from the heterogeneous zone. The size of this attenuation depends on the correlation properties of the medium (e.g. size and volume fraction of Air voids) and the wavelength and frequency content of the incident waves. An estimated of the effect can be obtained using independent scattering theory under dilute concentration assumption. The resulting attenuation characteristics are illustrated numerically. These results are discussed in comparison with experimental data of longitudinal wave attenuation in the hardened cement paste containing a low volume fraction of Entrained Air voids of less than 10% for a large frequency range of 500 kHz–5MHz.