• Title/Summary/Keyword: 촉진양생

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A Study on Properties of Early Strength Development of the Concrete (콘크리트의 조기강도 발현특성에 관한 연구)

  • Kang, Chang-Woon;Lee, Jae-Sam;Kim, Jung-Sik;Sung, Yong-Hwan;Ryu, Deug-Hyun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.541-544
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    • 2008
  • Recently, due to the increase of high-rise buildings construction, many researches for making harden of concrete earlier and remove of forms faster are being performed to reduce construction period. The purpose of this study is to analysis which mixing condition and curing temperature of early strength concrete. Porperties of concrete by the different factors, such as the type of active admixtures, mineral admixtures, curing temperature, the amount of binder, etc. Through the test of concrete using the different type of admixture, PC type was more excellent than PNS type admixture. The concrete Strength remarkably will be able to confirm that decreases from temperature below 12$^{\circ}C$.

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Effect of Types and Replacement Ratio of Alkali Activator on Compressive Strength of Ground Granulated Blast Furnace Slag Mortar (알칼리 자극제의 종류 및 치환율이 고로슬래그 미분말 모르타르의 압축강도에 미치는 영향)

  • Kim, Rae-Hwan;Kim, Gyu-Yong;Kim, Jong-Hee;Lee, Bo-Kyeong;Cho, Bong-Suk
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.2 no.4
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    • pp.360-366
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    • 2014
  • In this study, effect of types and replacement ratio of alkali activator on compressive strength of ground granulated blast furnace slag mortar has been reviewed. Types of alkali activator are NaOH, $Ca(OH)_2$, $Na_2SO_4$, and KOH. Replacement ratio of alkali activator is 7.5, 10, 12.5, and 15%, respectively. As results, under high temperature curing condition, 1 day compressive strength development with NaOH and KOH was higher than that of $Ca(OH)_2$ and $Na_2SO_4$. Regardless of types of alkali activator, compressive strength increased with increasing pH. This can be explained by the fact that impermeable film on the surface of slag which is generated when slag contacts water has been destroyed by alkali activator, and this promotes hydration reaction. Also, 1 day age compressive strength of specimen with high temperature curing was higher than that of specimen with standard curing. 28 days age compressive strength of specimen with high temperature curing was less than or equal to that of specimen with standard curing.

Compressive Strength and Chloride Permeability of High Strength Concrete according to the Variety of Mineral Admixtures (광물질혼화재 종류별 고강도콘크리트의 압축강도 및 촉진 염소이온침투 특성)

  • Moon Han-Young;Kim Byoung-Kwon
    • Journal of the Korea Concrete Institute
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    • v.16 no.3 s.81
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    • pp.407-414
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    • 2004
  • The purpose of this study is to evaluate the ability to resist chloride ions penetration of the concrete structure under marine environment in south-east asia especially. In this study, high strength concrete(HSC) with various combination of ordinary portland cement(OPC), blast-furnace slag(SG) and silica fume(SF) are cured 23 and $35^{\circ}C$ considering the site weather, and are cured in water for 3, 7 or 56 days respectively. And to investigate the fundamental properties and the resistance of chloride penetration of various HSC, setting time, slump flow, compressive strength, void and ASTM C 1202 test were conducted. Test results show that the compressive strength of HSC is similar regardless of SG replacement ratio and total charge passed of chloride is the smallest at 40% replacement of SG. The compressive strength of G4FS HSC is, besides, outstandingly high at early age compare with other HSC, but the compressive strength of G4F HSC, which is vary according to curing temperature and condition, most high at the age after 7 days. Total passed charge of HSC get larger in the order G4FS

Temperature Dependency Affecting the Properties at Early Age of the Concrete Containing High Volume Blast Furnace Slag (고로슬래그 미분말을 다량 치환한 콘크리트의 초기품질에 미치는 온도의존성)

  • Han, Cheon-Goo;Lee, Jang-Hwa;Koh, Kyung-Taek;Han, Min-Cheol;Lee, Ju-Sun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.4 no.1
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    • pp.74-80
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    • 2009
  • This study analysis the fundamental properties of temperature-dependence corresponding the change of curing temperature classified by the replacement ratio of BS, and the results are summarized as following. As the properties of flow, plain satisfied with the target slump, and as the replacement ratio of BS increased, the flow increased, but the air content slightly decreased. The time of set delayed as the replacement ratio of BS increased, but the curing temperature $35^{\circ}C$, even with 80% BS replaced concrete, the time of set was faster than $5^{\circ}C$, $20^{\circ}C$ plain, so the temperature-dependence was much greater. The compressive strength was decreased as the replacement ratio of BS increased, especially as the curing temperature lower, the compressive strength was lower comparatively. Also as the age increased, the plain developed more strength, therefore it show the temperature-dependence is much larger.

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Influence of Water-Cement Ratios and Curing Conditions on the Diffusion Characteristics of Chloride Ion in Concrete (콘크리트의 염소이온 확산특성에 미치는 물-시멘트비 및 양생조건의 영향)

  • Bae, Su-Ho;Lee, Kwang-Myong;Kim, Jee-Sang;Jung, Sang-Hwa
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.4A
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    • pp.753-759
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    • 2006
  • To predict service life of concrete structures exposed to chloride attack, surface chloride concentration, diffusion coefficient of chloride ion, and chloride corrosion threshold value in concrete, are used as important factors. Of these, as the diffusion coefficient of chloride ion for concrete is strongly influenced by concrete quality and environmental conditions of structures and may significantly change the service life of structures, it is considered as the most important factor for service life prediction. The qualitative factors affecting the penetration and diffusion of chloride ion into concrete are water-cement (W/C) ratio, age, curing conditions, chloride ion concentration of given environment, wet and dry conditions, etc. In this paper the influence of W/C ratio and curing conditions on the diffusion characteristics of chloride ion in concrete was investigated through the chloride ion diffusion test. In the test, the voltages passing through the diffusion cell were measured by accelerated test method using potential difference, and then with the consideration of IR drop ratio the diffusion coefficient of chloride ion for concrete with different W/C ratios were estimated by Andrade's model. Furthermore, under different curing conditions formulas for the estimation of the diffusion coefficient of chloride ion have been proposed by the regression analysis considering the effect of W/C ratio and age.

Fundamental Study on the Strength Development of Cement Paste using Hardening Accelerator and High-Early-Strength Cement (경화촉진제와 조강시멘트를 사용한 시멘트 페이스트의 강도발현에 대한 기초적 연구)

  • Min, Tae-Beom;Cho, In-Sung;Lee, Han-Seung
    • Journal of the Korea Institute of Building Construction
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    • v.13 no.4
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    • pp.407-415
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    • 2013
  • The purpose of this research is to verify the performance of hardening accelerator in cement paste through mechanical performance evaluation and micro structure analysis on hardening accelerator for development of super high early strength concrete. The research results showed that hardening accelerator produced $Ca(OH)_2$ when hydrated with cement, enhancing the degree of saturation of Ca ion by using differential thermal analysis. Moreover, porosity was reduced rapidly as capillary pores were filled by hydration products of $C_3S$. According to the experiment using hydration measurement testing, when 1% and 3% of accelerator were mixed, hydration rate increased toward the second peak point compared to high early strength cement, before the first peak point disappeared. It turned out that adding accelerator accelerated the hydration rate of cement, especially $C_3S$. The shape of C-S-H is shown depending on the amounts of accelerator added and the production and age of $Ca(OH)_2$ by using SEM to observes hydration products. Therefore, it's evident that hardening accelerator used in this research increases amounts of $Ca(OH)_2$ and accelerates $C_3S$, it is effective for the strength development on early age.

An experimental study on carbonation resistance of Mg(OH)2 mixed cement paste (Mg(OH)2 혼입 시멘트 페이스트의 탄산화 저항성에 관한 실험적 연구)

  • Chen, Zheng-Xin;Lee, Yun-Su;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2017.05a
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    • pp.165-166
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    • 2017
  • Corrosion of reinforcement is the main factors affecting the durability of reinforced concrete in the world which lead to the failure of structures of reinforced concrete buildings. In this research, mixed brucite(Mg(OH)2) into ordinary portland cement paste in ratio of 5, 10 and 15% as a kind of CO2 fixation material. Samples were exposed to an accelerated carbonation enslavement of 20% CO2 concentration, 60% relative humidity, and a temperature of 20℃ until tested at 3d, 7d, 14d and 28d. After 28d CO2 accelerated curing, in the paste containing MH megnesian calcite was found by XRD and SEM-EDX. Meanwhile, paste containing Mg(OH)2 exhibit the better pore distribution than ordinary portland cement paste and relatively good compressive strength.

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Properties of Non-Sintered Cement Mortar using Alkali and Sulfate Mixed Stimulants Accroding to Curing Method (양생방법에 따른 알칼리 및 황산염 복합자극제를 사용한 비소성 시멘트 모르타르의 특성)

  • Park, Sung-Joon;Kim, Ji-Hoon;Hyung, Won-Gil
    • Journal of the Korea Concrete Institute
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    • v.27 no.3
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    • pp.237-244
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    • 2015
  • Entering the 20th century since the industrial revolution, the cement has been widely used in the field of construction and civil engineering due to the remarkable development of construction industry. However, result from that development, each kind of industrial by-products and waste and the carbon dioxide generated in the process of cement production cause air pollution and environmental damage so earth is getting sick now slowly. Therefore, we have to recognize importance about this. It means that the time taking specific and long-term measures have come. In this research paper, as substitution of the cement generating environmental pollution, we investigate the hydration reaction of non-Sintered Cement mortar mixed with GBFS, active stimulant of alkaline and sulphate series by using SEM and XRD, mechanical and chemical properties according to the curing method. As a result of this experiment, NSC realized outstanding strength for water curing and steam curing. It means that it has a good possibility as substitution of cement. From now on, it can be used for structure satisfying specific standard. We expect to find a substitution of outstanding cement by progressing continuous research making the best use of pros and cons according to the curing method.

Effect of Cement Contents and Combinations of Accelerators on Strength Development of Concrete Cured at 10℃ (10℃ 양생조건에서 단위 시멘트량 변화 및 경화촉진제의 복합사용에 따른 강도발현 성능에 관한 연구)

  • Song, Young-Chan;Lee, Tea-Gyu;Kim, Yong-Ro;Seo, Chi-Ho
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.2
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    • pp.94-99
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    • 2018
  • The purpose of this study is to investigate the effect of combinations of different accelerators mixed on the early age strength development of concrete of 21 to 27MPa in the curing temperature of $10^{\circ}C$ compared with existing early strength agent. The present study was assessed the early strength development of combinations of three different accelerating admixtures with early strength type agent comparing to single accelerating admixture with early strength type agent. As a result of this study, the effect of $CaBr_2+NaSCN+DEA$ combination on strength development showed better than $CaBr_2$ or NaSCN alone with early strength type agent. Therefore, we observed that concrete using $CaBr_2+NaSCN+DEA$ combination with early strength agent was achieved 5MPa 12hours earlier than use of $CaBr_2$ or NaSCN alone.

Effect of Hardening Accelerators on the Adiabatic Temperature property Properties of Precast Concrete and FEM analysis for Evaluating the Crack Performance (경화촉진제를 사용한 프리캐스트 콘크리트의 단열온도특성 및 FEM해석에 의한 균열성능 평가에 관한 연구)

  • Min, Tae-Beom;Cho, In-Sung;Mun, Young-Bum;Lee, Han-Seung
    • Journal of the Korea Institute of Building Construction
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    • v.15 no.1
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    • pp.25-33
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    • 2015
  • In this study, initial crack index was evaluated by FEM analysis to find the crack propagation from hydration heat in precast concrete. As results, as the usage of hardening accelerator increased, initial compressive strength increased and setting time was shortened. Additionally, as amounts of hardening accelerators increased, the central temperature of concrete increased and the time to reach the highest temperature was shortened. It was demonstrated that the hardening accelerators accelerated the hydration reaction of cement, and caused the increase of hydration heat within the short period of time. Furthermore, the crack index for evaluating the heat level was performed by FEM. As results, there was no problem about the cracks, despite of the growth of initial high hydration heat. This is because of the increased tensile strength that is large enough to sustain the thermally induced-stress.