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Jay G. Sanjayan - One of the best experts on this subject based on the ideXlab platform.
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unsaturated capillary flow within alkali activated Slag Concrete
Journal of Materials in Civil Engineering, 2008Co-Authors: Francis Gerard Collins, Jay G. SanjayanAbstract:Alkali activated Slag Concrete (AASC), based on a binder that consists of 100% blast furnace Slag that is activated by an alternative alkali to conventional Portland cement, has considerable environmental benefits. Nevertheless, the durability of the exposed surface zone of AASC needs consideration. The ingress of harmful agents is highly influenced by convection-induced effects; e.g., moisture gradients caused by exposure to rainfall or the wetting and drying effects in the splash zone of a marine environment that can lead to high surface concentration of chloride. The convective effects also propagate steel reinforcement corrosion, once initiated, by making available moisture and oxygen for the cathodic reaction at the steel reinforcement, as well as changing the conductivity of the Concrete surface zone. This paper reports the behavior of convection-induced uptake of water into AASC and ordinary Portland cement Concrete. The sensitivity to "exposed," "sealed," and "bath" curing and the resultant pore structure for Concrete made with different water/binder is contrasted.
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microcracking and strength development of alkali activated Slag Concrete
Cement & Concrete Composites, 2001Co-Authors: Francis Gerard Collins, Jay G. SanjayanAbstract:Abstract Alkali activated Slag Concrete (AASC) is made by activating ground granulated blast furnace Slag with alkalis without the use of any Portland cement. This study investigates the level of microcracking which occurs in AASC when subjected to various types of curing regimes. The corresponding compressive strength developments of AASC were monitored. The level of microcracking were measured using three different types of tests: (1) frequency and size of surface cracks using crack-detection microscope (2) water sorptivity tests measuring absorption of water by capillary attraction and (3) mercury intrusion porosimetry (MIP) tests which measured the pore size distribution of AASC and AAS pastes (AASPs). The results show that the lack of moist curing of AASC increased the level of microcracking measured using all three different tests mentioned above. The strength development of AASC is also significantly reduced by lack of moist curing.
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effect of pore size distribution on drying shrinkage of alkali activated Slag Concrete
Cement and Concrete Research, 2000Co-Authors: Frank Collins, Jay G. SanjayanAbstract:Higher drying shrinkage has been observed in alkali-activated Slag Concrete (AASC) than comparable ordinary Portland cement Concrete (OPCC). However, the OPCC samples lost more moisture during the period of shrinkage measurements than the AASC samples. This is contradictory to the commonly accepted relationship between shrinkage and moisture loss. This paper provides an explanation for this phenomenon by studying the effect of pore size distribution on the drying shrinkage. The investigation showed that AAS pastes have a much higher proportion of pore sizes within the mesopore region than OPC pastes. Further, the radius of pores where the meniscus forms seems to be an important parameter in determining the magnitude of shrinkage, rather than the amount of moisture loss. This also supports the theory that the capillary tensile forces set up during drying is an important contributory factor for the drying shrinkage of Concrete.
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Cracking tendency of alkali-activated Slag Concrete subjected to restrained shrinkage
Cement and Concrete Research, 2000Co-Authors: Frank Collins, Jay G. SanjayanAbstract:Alkali-activated Slag Concrete (AASC) has higher drying shrinkage than ordinary Portland cement Concrete (OPCC). However, the cracking tendency of AASC under drying conditions, when restrained, is unreported. AASC has lower elastic modulus, higher creep, and higher tensile strength than OPCC, and the combined effects of these can affect the cracking tendency of AASC. This article reports the results of cracking tendency utilizing restrained ring tests and discusses the development of a restrained beam test. The effects of curing, aggregate type, and incorporation of shrinkage reducing chemical admixture on the cracking tendency of AASC are reported.
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Strength and shrinkage properties of alkali-activated Slag Concrete containing porous coarse aggregate
Cement and Concrete Research, 1999Co-Authors: Francis Gerard Collins, Jay G. SanjayanAbstract:An investigation was conducted that examined the effects of internal curing of alkali-activated Slag Concrete (AAS) by replacing normal weight coarse aggregate with fully saturated blast-furnace Slag coarse aggregate. The slow release of moisture from the porous aggregate provides ongoing internal curing of Concrete. The study showed that, under drying conditions, the compressive strength was improved and the drying shrinkage was significantly less (40% less than AAS containing normal weight coarse aggregate).
Rae-hwan Kim - One of the best experts on this subject based on the ideXlab platform.
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compressive strength resistance to chloride ion penetration and freezing thawing of Slag replaced Concrete and cementless Slag Concrete containing desulfurization Slag activator
Construction and Building Materials, 2016Co-Authors: Bo-kyeong Lee, Gyu-yong Kim, Jeong-soo Nam, Bong-suk Cho, Yukio Hama, Rae-hwan KimAbstract:Abstract In this research, desulfurization Slag (DS), a byproduct generated during steel production, was used as an activator for ground granulated blast-furnace Slag (GGBS), and the compressive strength, resistance to chloride-ion penetration and freezing/thawing of Slag-replaced Concrete and cementless Slag Concrete containing DS activator was evaluated. The experimental results indicated that DS affects the strength development of Slag-replaced Concrete and cementless Slag Concrete when used as an activator. Moreover, a constant increase in the compressive strength was observed during the long-term aging of cementless Slag Concrete with a DS and anhydrous gypsum mixture. However, the transformation of ettringite to monosulfate was not effective; a large quantity of ettringite was observed at a long-term age of 910 days in the cementless Slag Concrete. In addition, a high resistance to chloride-ion penetration was obtained for high-volume Slag Concrete. The resistance to chloride-ion penetration was greater in cementless Slag Concrete. On the other hand, cementless Slag Concrete, which had a high volume of capillary pores, had the lowest resistance to freezing/thawing.
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Compressive strength, resistance to chloride-ion penetration and freezing/thawing of Slag-replaced Concrete and cementless Slag Concrete containing desulfurization Slag activator
Construction and Building Materials, 2016Co-Authors: Bo-kyeong Lee, Gyu-yong Kim, Jeong-soo Nam, Bong-suk Cho, Yukio Hama, Rae-hwan KimAbstract:Abstract In this research, desulfurization Slag (DS), a byproduct generated during steel production, was used as an activator for ground granulated blast-furnace Slag (GGBS), and the compressive strength, resistance to chloride-ion penetration and freezing/thawing of Slag-replaced Concrete and cementless Slag Concrete containing DS activator was evaluated. The experimental results indicated that DS affects the strength development of Slag-replaced Concrete and cementless Slag Concrete when used as an activator. Moreover, a constant increase in the compressive strength was observed during the long-term aging of cementless Slag Concrete with a DS and anhydrous gypsum mixture. However, the transformation of ettringite to monosulfate was not effective; a large quantity of ettringite was observed at a long-term age of 910 days in the cementless Slag Concrete. In addition, a high resistance to chloride-ion penetration was obtained for high-volume Slag Concrete. The resistance to chloride-ion penetration was greater in cementless Slag Concrete. On the other hand, cementless Slag Concrete, which had a high volume of capillary pores, had the lowest resistance to freezing/thawing.
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effects of micropores on the freezing thawing resistance of high volume Slag Concrete
Journal of the Korea institute for structural maintenance and inspection, 2015Co-Authors: Rae-hwan Kim, Bo-kyeong Lee, Gyu-yong Kim, Kyoungsu Shin, Gwonyong SongAbstract:In this study, effects of micropores on the freezing-thawing resistance of high volume Slag Concrete are reviewed. Concrete was made with Slag which contains the ground granulated blast furnace Slag(GGBS) and the pig iron preliminary treatment Slag(PS) by replacing 0, 40, 70 %, then compressive strength, freezing-thawing resistance, micropores were reviewed. Also, specified design strength, target air contents were set. Deterioration was induced by using 14-day-age specimen which has low compressive strength for evaluating deterioration by freeze-thawing action. As results of the experiment, despite of specified design strength which has been set similarly and ensured target air contents, the pore size distribution of the Concrete showed different results. Micropores in GGBS70 specimen have small amount of water which is likely to freeze because there is small amount of pore volume of 10~100 nm size at 0 cycle which has not been influenced by freezing-thawing. For these reasons, it was confirmed that the freezing-thawing resistance performance of GGBS70 is significantly superior than other specimens because relatively small expansion pressure is generated compared to the other specimens.
Bo-kyeong Lee - One of the best experts on this subject based on the ideXlab platform.
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compressive strength resistance to chloride ion penetration and freezing thawing of Slag replaced Concrete and cementless Slag Concrete containing desulfurization Slag activator
Construction and Building Materials, 2016Co-Authors: Bo-kyeong Lee, Gyu-yong Kim, Jeong-soo Nam, Bong-suk Cho, Yukio Hama, Rae-hwan KimAbstract:Abstract In this research, desulfurization Slag (DS), a byproduct generated during steel production, was used as an activator for ground granulated blast-furnace Slag (GGBS), and the compressive strength, resistance to chloride-ion penetration and freezing/thawing of Slag-replaced Concrete and cementless Slag Concrete containing DS activator was evaluated. The experimental results indicated that DS affects the strength development of Slag-replaced Concrete and cementless Slag Concrete when used as an activator. Moreover, a constant increase in the compressive strength was observed during the long-term aging of cementless Slag Concrete with a DS and anhydrous gypsum mixture. However, the transformation of ettringite to monosulfate was not effective; a large quantity of ettringite was observed at a long-term age of 910 days in the cementless Slag Concrete. In addition, a high resistance to chloride-ion penetration was obtained for high-volume Slag Concrete. The resistance to chloride-ion penetration was greater in cementless Slag Concrete. On the other hand, cementless Slag Concrete, which had a high volume of capillary pores, had the lowest resistance to freezing/thawing.
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Compressive strength, resistance to chloride-ion penetration and freezing/thawing of Slag-replaced Concrete and cementless Slag Concrete containing desulfurization Slag activator
Construction and Building Materials, 2016Co-Authors: Bo-kyeong Lee, Gyu-yong Kim, Jeong-soo Nam, Bong-suk Cho, Yukio Hama, Rae-hwan KimAbstract:Abstract In this research, desulfurization Slag (DS), a byproduct generated during steel production, was used as an activator for ground granulated blast-furnace Slag (GGBS), and the compressive strength, resistance to chloride-ion penetration and freezing/thawing of Slag-replaced Concrete and cementless Slag Concrete containing DS activator was evaluated. The experimental results indicated that DS affects the strength development of Slag-replaced Concrete and cementless Slag Concrete when used as an activator. Moreover, a constant increase in the compressive strength was observed during the long-term aging of cementless Slag Concrete with a DS and anhydrous gypsum mixture. However, the transformation of ettringite to monosulfate was not effective; a large quantity of ettringite was observed at a long-term age of 910 days in the cementless Slag Concrete. In addition, a high resistance to chloride-ion penetration was obtained for high-volume Slag Concrete. The resistance to chloride-ion penetration was greater in cementless Slag Concrete. On the other hand, cementless Slag Concrete, which had a high volume of capillary pores, had the lowest resistance to freezing/thawing.
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effects of micropores on the freezing thawing resistance of high volume Slag Concrete
Journal of the Korea institute for structural maintenance and inspection, 2015Co-Authors: Rae-hwan Kim, Bo-kyeong Lee, Gyu-yong Kim, Kyoungsu Shin, Gwonyong SongAbstract:In this study, effects of micropores on the freezing-thawing resistance of high volume Slag Concrete are reviewed. Concrete was made with Slag which contains the ground granulated blast furnace Slag(GGBS) and the pig iron preliminary treatment Slag(PS) by replacing 0, 40, 70 %, then compressive strength, freezing-thawing resistance, micropores were reviewed. Also, specified design strength, target air contents were set. Deterioration was induced by using 14-day-age specimen which has low compressive strength for evaluating deterioration by freeze-thawing action. As results of the experiment, despite of specified design strength which has been set similarly and ensured target air contents, the pore size distribution of the Concrete showed different results. Micropores in GGBS70 specimen have small amount of water which is likely to freeze because there is small amount of pore volume of 10~100 nm size at 0 cycle which has not been influenced by freezing-thawing. For these reasons, it was confirmed that the freezing-thawing resistance performance of GGBS70 is significantly superior than other specimens because relatively small expansion pressure is generated compared to the other specimens.
Haengki Lee - One of the best experts on this subject based on the ideXlab platform.
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setting and mechanical properties of alkali activated fly ash Slag Concrete manufactured at room temperature
Construction and Building Materials, 2013Co-Authors: N K Lee, Haengki LeeAbstract:Abstract This study aims to investigate the setting and mechanical properties of alkali-activated fly ash/Slag Concrete manufactured at room temperature. It also examines to what extent the Slag in the alkali-activated fly ash/Slag mixture improves the mechanical properties of the mixture under room-temperature curing conditions. A series of tests of the compressive strength, elastic modulus, splitting tensile strength, flow, setting time, and porosity of the alkali-activated fly ash/Slag Concrete were carried out. The test results showed that the setting time decreased as the amount of Slag and the concentration of the NaOH solution increased. The proper Slag content in an alkali-activated fly ash/Slag mixture was determined to be 15–20% of total binder by weight considering the setting time and compressive strength of the alkali-activated fly ash/Slag Concrete cured at room temperature. In addition, the modulus of elasticity and splitting tensile strength of the alkali-activated fly ash/Slag Concrete were slightly lower than those of ordinary Concrete as predicted by the ACI code and Eurocode 2. The total porosity of the alkali-activated fly ash/Slag mortar was similar to that of ordinary cement mortar, whereas the mean pore size tended to be smaller than that of ordinary cement mortar.
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Setting and mechanical properties of alkali-activated fly ash/Slag Concrete manufactured at room temperature
Construction and Building Materials, 2013Co-Authors: Namkon Lee, Haengki LeeAbstract:Abstract This study aims to investigate the setting and mechanical properties of alkali-activated fly ash/Slag Concrete manufactured at room temperature. It also examines to what extent the Slag in the alkali-activated fly ash/Slag mixture improves the mechanical properties of the mixture under room-temperature curing conditions. A series of tests of the compressive strength, elastic modulus, splitting tensile strength, flow, setting time, and porosity of the alkali-activated fly ash/Slag Concrete were carried out. The test results showed that the setting time decreased as the amount of Slag and the concentration of the NaOH solution increased. The proper Slag content in an alkali-activated fly ash/Slag mixture was determined to be 15–20% of total binder by weight considering the setting time and compressive strength of the alkali-activated fly ash/Slag Concrete cured at room temperature. In addition, the modulus of elasticity and splitting tensile strength of the alkali-activated fly ash/Slag Concrete were slightly lower than those of ordinary Concrete as predicted by the ACI code and Eurocode 2. The total porosity of the alkali-activated fly ash/Slag mortar was similar to that of ordinary cement mortar, whereas the mean pore size tended to be smaller than that of ordinary cement mortar.
Gyu-yong Kim - One of the best experts on this subject based on the ideXlab platform.
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compressive strength resistance to chloride ion penetration and freezing thawing of Slag replaced Concrete and cementless Slag Concrete containing desulfurization Slag activator
Construction and Building Materials, 2016Co-Authors: Bo-kyeong Lee, Gyu-yong Kim, Jeong-soo Nam, Bong-suk Cho, Yukio Hama, Rae-hwan KimAbstract:Abstract In this research, desulfurization Slag (DS), a byproduct generated during steel production, was used as an activator for ground granulated blast-furnace Slag (GGBS), and the compressive strength, resistance to chloride-ion penetration and freezing/thawing of Slag-replaced Concrete and cementless Slag Concrete containing DS activator was evaluated. The experimental results indicated that DS affects the strength development of Slag-replaced Concrete and cementless Slag Concrete when used as an activator. Moreover, a constant increase in the compressive strength was observed during the long-term aging of cementless Slag Concrete with a DS and anhydrous gypsum mixture. However, the transformation of ettringite to monosulfate was not effective; a large quantity of ettringite was observed at a long-term age of 910 days in the cementless Slag Concrete. In addition, a high resistance to chloride-ion penetration was obtained for high-volume Slag Concrete. The resistance to chloride-ion penetration was greater in cementless Slag Concrete. On the other hand, cementless Slag Concrete, which had a high volume of capillary pores, had the lowest resistance to freezing/thawing.
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Compressive strength, resistance to chloride-ion penetration and freezing/thawing of Slag-replaced Concrete and cementless Slag Concrete containing desulfurization Slag activator
Construction and Building Materials, 2016Co-Authors: Bo-kyeong Lee, Gyu-yong Kim, Jeong-soo Nam, Bong-suk Cho, Yukio Hama, Rae-hwan KimAbstract:Abstract In this research, desulfurization Slag (DS), a byproduct generated during steel production, was used as an activator for ground granulated blast-furnace Slag (GGBS), and the compressive strength, resistance to chloride-ion penetration and freezing/thawing of Slag-replaced Concrete and cementless Slag Concrete containing DS activator was evaluated. The experimental results indicated that DS affects the strength development of Slag-replaced Concrete and cementless Slag Concrete when used as an activator. Moreover, a constant increase in the compressive strength was observed during the long-term aging of cementless Slag Concrete with a DS and anhydrous gypsum mixture. However, the transformation of ettringite to monosulfate was not effective; a large quantity of ettringite was observed at a long-term age of 910 days in the cementless Slag Concrete. In addition, a high resistance to chloride-ion penetration was obtained for high-volume Slag Concrete. The resistance to chloride-ion penetration was greater in cementless Slag Concrete. On the other hand, cementless Slag Concrete, which had a high volume of capillary pores, had the lowest resistance to freezing/thawing.
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effects of micropores on the freezing thawing resistance of high volume Slag Concrete
Journal of the Korea institute for structural maintenance and inspection, 2015Co-Authors: Rae-hwan Kim, Bo-kyeong Lee, Gyu-yong Kim, Kyoungsu Shin, Gwonyong SongAbstract:In this study, effects of micropores on the freezing-thawing resistance of high volume Slag Concrete are reviewed. Concrete was made with Slag which contains the ground granulated blast furnace Slag(GGBS) and the pig iron preliminary treatment Slag(PS) by replacing 0, 40, 70 %, then compressive strength, freezing-thawing resistance, micropores were reviewed. Also, specified design strength, target air contents were set. Deterioration was induced by using 14-day-age specimen which has low compressive strength for evaluating deterioration by freeze-thawing action. As results of the experiment, despite of specified design strength which has been set similarly and ensured target air contents, the pore size distribution of the Concrete showed different results. Micropores in GGBS70 specimen have small amount of water which is likely to freeze because there is small amount of pore volume of 10~100 nm size at 0 cycle which has not been influenced by freezing-thawing. For these reasons, it was confirmed that the freezing-thawing resistance performance of GGBS70 is significantly superior than other specimens because relatively small expansion pressure is generated compared to the other specimens.