• Title/Summary/Keyword: Non Steam Curing

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The Strength Properties of Concrete according to Curing Method (양생방법에 따른 콘크리트의 강도특성)

  • Jung, Yong-Wook;Lee, Seung-Han;Yun, Yong-Ho;Son, Sang-Hun;Kim, Jeong-Tai
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.545-548
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    • 2006
  • This study has been carried out to examine the properties of concrete according to replacement ratio and curing method of fly ash, in order to increase utilization of it. As the result of experiments, the 7 days of early age strength presented around 20MPa, up to 20% of replacement ratio, which is almost the same strength as non-replacement. However, when the replacement ratio was 30%, the strength was decreased to 16MPa, as 20% reduction compared to the non-replacement condition. In 365 days of long term aging, the strength was 5% higher, up to 20% of the replacement ratio, due to the pozzolanic reaction of fly ash. When the replacement ratio was 30%, it presented similar strength development as the non-replacement condition. Steam curing and autoclave curing increased the short age strength, regardless of the replacement ratio of fly ash; however, they don't have an effect on increasing the 365 days of long term strength. Water curing showed high strength development after 28 days, 51.81MPa, which is around 30% higher than air curing, 38.9MPa, steam curing, 38.6MPa, and autoclave curing, 39MPa. Therefore, water curing was examined as one of the very effective curing methods for developing long term strength of concrete.

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Physical Properties of Non-sintered Cement Mortar with Heat Treatment after Steam Curing (비소성 시멘트 모르타르의 증기양생 후 열처리에 따른 물리적 특성)

  • Na, Hyeong-Won;Hyung, Won-Gil
    • Journal of the Korea Institute of Building Construction
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    • v.21 no.2
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    • pp.97-104
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    • 2021
  • This study aims to develop non-sintered cement that can replace the Portland cement by utilizing industrial by-products. As a suggestion, the physical properties of non-sintered cement mortar depending on the curing method were investigated with ground granulated blast furnace slag, class C fly ash, and class F fly ash. As a result of the study, it was found that the strength performance and absorption rate were improved through the heat treatment process after steam curing. It was confirmed through crystal phase analysis that the hydration was accelerated after heat treatment, and the bonding material formed a dense internal structure.

Optimum Curing and Full-out Velocity in the Rubber Extrusion Process for Electric Cable Manufacture (전선피복용 고무압출가공 공정의 최적 경화 및 선출 속도)

  • Kim, Duk-Joon;Choi, Sang-Soon;Kim, Tae-Ho
    • Elastomers and Composites
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    • v.33 no.2
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    • pp.93-102
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    • 1998
  • In electric cable industries, the curing extent of the rubber materials covering the electric cores gives an significant effect on their final performance. The curing extent of rubber is controlled mostly by pull-out velocity of cable in the extrusion process. The final curing extent may be different for different radial positions inside the rubber because of the non-uniform temperature distributions during the curing process. In this contribution, the prediction of curing extent distribution throughout the radial direction of rubber is represented when the cable is passing through the steam curing zone with a fixed pull-out velocity. The prediction of the optimum pull-out velocity for the desired curing extent distribution is also reported. The steady-state heat balance was developed for the curing and cooling processes in which the pull-out rubber was cured by high temperature steam and then cooled by ambient water. A few essential material properties such as density, specific heat, and thermal conductivity were measured to analyze the temperature distribution during the curing and cooling processes. The times to reach 90% curing extent at varying temperatures were measured and used to determine the final cure extent distribution inside the rubber.

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Study on the Development of Super-High-Early-Strength Mortar Using the Hardening catalyst and High early strength cement (조강시멘트를 사용한 초조강 모르타르 개발에 관한 연구)

  • Cho, In-Sung;Hur, Yeon-Ok;Min, Tae-Beom;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2012.11a
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    • pp.217-219
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    • 2012
  • In this study, the experiment was conducted in the level of mortar as one of the basic studies on pre-cast concrete which acceleration curing is not done. This study has the purpose to develop the strength of mortar into 20MPa within 6 hours in the condition of room temperature using admixtures which can accelerate C3S hydration reaction. In this experiment, W/C was fixed into 20%, PCE which can stimulate C3S was used as an accelerating admixture. From the results of this experiment, maximum content of accelerating admixture was 1%. Also, as more than 20MPa was measured through 6-hour compressive strength, it can be known that strength can be developed without steam-curing.

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Properties of Alkali-Activated Cement Mortar by Curing Method (양생 방법에 따른 알칼리활성 시멘트 모르타르의 특성)

  • Kim, Ji-Hoon;Lee, Jae-Kyu;Hyung, Won-Gil
    • Journal of the Korea Concrete Institute
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    • v.26 no.2
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    • pp.117-124
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    • 2014
  • Globally, there are environmental problems due to greenhouse gas emissions. $CO_2$ emissions rate of the cement industry is very high, but the continued demand of cement is needed in the future. In this study, in order to reduce the environmental impact of $CO_2$ emissions from cement production. The experiments were carried out for the development of non-sintered cement (have not undergone firing burning) by granulated ground blast furnace slag. In order to compare the characteristics by curing, an experiment was conducted by changing the curing conditions such as atmospheric steam curing, observe the mechanical properties for the measurement of flexural compressive strength by mortar, observe the chemical properties such as acid resistance, $Cl^-$ penetrate resistance and analyzed the mechanism of hydration by XRD, SEM experiments. From the experimental results, as compared with portland cement usually confirm the mechanical and chemical properties excellent, it is expected be possible to apply to the undersea, underwater and underground structures that require superior durability. In addition, based on the excellent compressive strength by steam curing, it is expected to be possible to utilize as a cement replacement material in the secondary product of concrete. In the future, to solve the problem through continued research, it will be expected to reduce the effect of environmental load and to be excellent economics.

A Study on Durability of High Strength Concrete (고강도(高强度)콘크리트의 내구성(耐久性)에 관한 연구(研究))

  • Kim, Saeng Bin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.1 no.1
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    • pp.9-19
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    • 1981
  • Using superplasticizer or the methods of autoclave curing is the most typical and practical of the ways to make high strength concrete. In this study the high strength concrete piles by way of centrifugal forming and hand compacting, are put to the freezing and thawing test after the process of autoclave curing, water curing after steam curing, or stand water curing. And the relation of such piles to durability, the rate of strength decrease, and the rate of weight variation is shown. The durability of those test piles throughout freezing and thawing test proves to be comparatively sufficient in the above-mentioned curings when the piles contain a proper quantity of air. But it is also acknowledged that without A.E agent, the high strength concrete piles of autoclave curing is higher than those of the other curing in strength, but lower in modulus of dynamic elasticity and their durability factor after the test is much lower.

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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.

A Study on the Development of Non-PC High-Early-Strength Concrete Without Steam Curing (증기양생이 불필요한 PC부재용 조강형 콘크리트 개발에 관한 연구)

  • Jun, Woo-Chul;Lee, Ji-Hwan;Park, Hee-Gon;Lee, Jae-Sam;Kim, Kyung-Min;Cho, In-Sung
    • Journal of the Korea Institute of Building Construction
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    • v.14 no.2
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    • pp.156-162
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    • 2014
  • This study aims to develop a rapidly hardening type of concrete to achieve the removal of form intensity (more than 10MPa) using the method of curing at room temperature in order to solve some economic environmental problems by omitting the steam curing process involved in producing PC (Precast Concrete). Therefore, this study evaluated a rapidly hardening cement containing a high amunt of C3S, which is very responsive in expressing early intensity, and a rapidly hardening type of concrete which uses some hardening accelerator to increase thehydration reaction of $C_3S$. The results of the experiment on concrete using some hardening accelerator are asfollows. In the slump flow experiment for identifying the liquidity and the air test, the desired values were met. The compression strength showed rapid expression response by 12 hours, and met the desired value within 6~9 hours. Its drying shrinkage value and Autogenous shrinkage value were measured as below ($-754.5{\times}10^{-6}$),and satisfied the requirements. In addition, in the Semi-Adiabatic Temperature Test, it was found that the concrete rose to its peak temperature within 24 hours and then its temperature dropped.

Strength Characteristics of Non-Sintered Cement Mortar Utilizing Ferro-Nickel Slag as Fine Aggregate (페로니켈슬래그를 잔골재로 사용한 비소성 시멘트 모르타르의 강도 특성)

  • Ryu, Ji-Su;Jang, Kyung-Su;Na, Hyeong-Won;Hyung, Won-Gil
    • Journal of the Korea Institute of Building Construction
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    • v.23 no.4
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    • pp.359-367
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    • 2023
  • This experimental study investigates the replacement of conventional Portland cement and sand with non-sintered cement and ferro-nickel slag to formulate eco-friendly cement mortar. The examination aimed to understand the strength properties of non-sintered cement mortar using ferro-nickel slag as fine aggregate by classifying mortar production types, fine aggregates, and curing methodologies. From flexural and compressive strength tests, it was observed that non-sintered cement mortars, incorporating ferro-nickel slag as fine aggregate, exhibited superior strength when compared to both plain mortar and steam-cured non-sintered mortar. This increased strength is attributed to the influence of the particle size, density, and absorption capabilities of the ferro-nickel slag. Furthermore, X-ray Diffraction(XRD) analyses of the mortars verified the presence of MgO, a component of ferro-nickel slag, in the form of a composite oxide. This finding substantiates the consistent strength manifestation of non-sintered cement mortars utilizing ferro-nickel slag as a fine aggregate.

A Study on Improving the Non-Combustible Properties of High-Density Fiber Cement Composites (고밀도 섬유 시멘트 복합체 불연특성 개선에 관한 연구)

  • Song, Tae-Hyeob;Jang, Kyong-Pil
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.4
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    • pp.521-528
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    • 2021
  • The high-density fiber composite manufacturing method by the extrusion molding method has the characteristic that continuous production is possible, and the product is molded through a mold forming a specific cross-section. OPC is used as a defect material, an appropriate amount of SiO2 is supplied for CaO reaction activity, and high density and high strength are expressed through steam and autoclave curing. However, due to the use of organic reinforcing fibers, the flame duration exceeds the regulations during the non-combustible performance test, making it difficult to secure performance. In this study, the product was produced by mixing alkali-resistant organic fiber and fly ash having voids as a binder by replacing the existing polypropylene fiber. appeared to be possible.