• Title/Summary/Keyword: Mixing-Strength

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Experiments on Mechanical Characteristics of Anti-Washout Concrete with Mixing and Placing Condition (배합 및 타설조건에 따른 수중불분리성 콘크리트의 역학적특성 변화에 관한 실험)

  • Yang, Eun-Ik;Choi, Hong-Shik;Heo, Gweon;Lee, Si-Woo
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.04a
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    • pp.141-146
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    • 1999
  • An experimental study is carried out to estimate the effects of mixing and placing condition on the mechanical properties of anti-washout concrete. According to the test results, mixing method and placing temperature do affect the characteristics of rrsh concrete, while they do not affect the strength development of anti-washout concrete. But, concrete strength was greatly affected by the placing condition and placing height. Concrete strength decreases linearly as the placing height increased. Compared to the normal concrete, the increase in strength is not associated much with an increase in the elastic modulus of anti-washout concrete.

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Application of Artificial Neural Network Theory for Evaluation of Unconfined Compression Strength of Deep Cement Mixing Treated Soil (심층혼합처리된 개량토의 일축압축강도 추정을 위한 인공신경망의 적용)

  • Kim, Young-Sang;Jeong, Hyun-Chel;Huh, Jung-Won;Jeong, Gyeong-Hwan
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.1159-1164
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    • 2006
  • In this paper an artificial neural network model is developed to estimate the unconfined compression strength of Deep Cement Mixing(DCM) treated soil. A database which consists of a number of unconfined compression test result compiled from 9 clay sites is used to train and test of the artificial neural network model. Developed neural network model requires water content of soil, unit weight of soil, passing percent of #200 sieve, weight of cement, w-c ratio as input variables. It is found that the developed artificial neural network model can predict more precise and reliable unconfined compression strength than the conventional empirical models.

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Strength Properties of Prepacked Polymer Mortar Using MMA-Based Binders (MMA를 이용한 프리팩트 폴리머 모르터의 강도특성)

  • Yeon, Kyu-Seok;Lee, Hyun-Jong;Ryu, Neung-Hwan;Jin, Xing-Qi;Lee, Chi-Won
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2005.10a
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    • pp.117-122
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    • 2005
  • Prepacked polymer mortar that is mainly composed of MMA monomer and used for the patching and restoring materials of concrete structures was developed, and its hardening and strength properties were experimentally surveyed. Results of study show that the permeance of binder into the aggregate was excellent for the case of PMMA mixing ratio of below 10%, the surface hardening inferiority was not generated for the case of the ratio of over 5%. Working time of the prepacked polymer mortar and hardening shrinkage tended to decrease as the PMMA mixing ratio increased. On the other hand, the ratio turned out not to decisively affect on compressive and flexural strengths. Regardless of PMMA mixing content, the adhesive strength was about 2.5 MPa. Occurring the desquamation on the substrate of cement concrete showed the adhesive strength of MMA prepact polymer mortar was excellent.

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Engineering Characteristics of Filling Materials using Lightweight Foamed Concrete (경량콘크리트를 사용한 충전용 재료의 공학적 특성)

  • Do, Jong-Nam;Kang, Hyung-Nam;Seo, Doo-Won;Chun, Byung-Sik
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.519-523
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    • 2009
  • In this study, the base mixing ratio was determinated to estimate the optimal mixing ratio of material with a change of mixing ratio of micro cement, sand, foaming agent, plasticizer by testing the unconfined compressive strength test. The unconfined compressive strength test was performed to grasp a engineering characteristics of with a change of micro cement, bubble. The results of test, the unconfined compressive strength increased with a micro cement's increase and bubble's decrease. In the future, it will be secured that is reliable datas from laboratory of various condition and in-situ tests to develop optimal lightweight foamed concrete.

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The Properties of Foamed Concrete Slurry Using Bottom Ash According to the Methods of Mixing of Foam (기포혼입방법에 따른 바텀애쉬를 사용한 기포 콘크리트의 특성)

  • Kang Cheol;Kang Gi Woong;Kawg Eun Gu;Cho Sung Hyun;Kwon Gi Ju;Kim Jin Man
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.529-532
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    • 2004
  • As the purpose of this study is a research of series to obtain fundamental data on the development of the product of foamed concrete using bottom ash for various applications in the field, the main purpose is the light weight of product of concrete. In this experiment, method of mixing of foam is very important because it control specific gravity and strength of the product. As the test results, it was found that regardless of mixing method the grower the concentration of foaming agent the lower the specific gravity and the compressive strength of the specimen especially pre-foaming method. From a strength point of view, we knew that mix-foaming method and steam curing is efficient to obtain a adequate compressive strength of foamed concrete.

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Effect of Mixing Time of Pre-Mixed Cement and Post-Mixed Cement on the Strength Development of the Concrete (프리믹스 및 포스트믹스 시멘트를 혼입시간이 콘크리트의 압축강도에 미치는 영향)

  • Baek, Sung-Jin;Lee, Hyeok;Han, Jun-Hui;Kim, Jong;Han, Min-Cheol
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.137-138
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    • 2023
  • This study proposed the optimal mixing time for pre-mixed cement and post mixed cement using the statistical analysis method of box plots. Pre-mixed cement can prevent material seegregation, strength loss, and quality variation if mixed for at least 60 seconds, and the data median is shown to be within the box range. Post-mixed cement should be mixed for at least 180 seconds to prevent material segregation, strength loss, and quality variation, and compressive strength tends to increase with longer vibrating times. Therefore, it is suggested that using pre-mixed cement can shorten the vibrating time and increase the productivity of the concrete.

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A Study on the Adhesive Performance of High-early Strengthening Polymer Cement Composites for Crack Repair of RC Structures (RC 구조물의 균열보수용 조강성 폴리머 시멘트 복합체의 접착성능에 관한 연구)

  • Park, Dong-Yeop;Kim, Sang-Hyeon;Jo, Young-Kug
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.11a
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    • pp.179-180
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    • 2023
  • The adhesion performance of PCCs for crack repair of RC structures was greater in the case of using ultra high-early strength cement than in the case of using ordinary Portland cement, and the effect of mixing silica fume was higher in the case of ordinary Portland cement than that of ultra high-early strength cement. On the other hand, 130% of W/C was more fluid than 80% of W/C in the same P/C 80%, which increased the fillability and improved the strength, but the strength improvement effect was the greatest in adhesion in flexure. Through this study, the basic characteristics of the adhesion performance of PCCs were identified, and based on this, it is necessary to induce an optimal mixing design that can increase adhesion performance through various mixing designs.

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Temperature Strength of Sawdust-Mixing Concrete (폐톱밥 혼입 콘크리트의 온도 이력에 관한 실험적 연구)

  • Son, Ki-Sang;Hong, Seung-Ryul
    • Journal of the Korean Society of Safety
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    • v.20 no.4 s.72
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    • pp.46-53
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    • 2005
  • Existing study far fire-resistant concrete has been done already. but it is not found out how the waste tyre mixing concrete will be acted against fire. This waste tyre concrete molds under the condition of $0^{\circ}C,\;200^{\circ}C,\;400^{\circ}C,\;600^{\circ}C$ were heated in gas oven. It was worried about that they might be fractured down at about $800^{\circ}C$ so that they can not be tested. compressive strength for the test molds are made with commercially used $180kg/cm^2,\;210kg/cm^2,\;240kg/cm^2,\;270kg/cm^2$ mixing saw dust with proportion such as 0.05%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0% compressive strength at $200^{\circ}C$ was approximately 20% from the original, while approximately 30% deoreased at $400^{\circ}C$. their results are not quite different from the normal concrete condition even though they contains saw dust in it. The higher strength the concrete has, the less strength was decreased. There are almost no difference in strength under the condition of less than $400^{\circ}C$, but damage of concrete structure could be considerable large with more than $400^{\circ}C$.

An Experimental Study on the Strength Properties of Flowing Lightweight Aggregate Concrete with Age (재령에 따른 고유동 경량골재콘크리트의 강도특성에 관한 실험적 연구)

  • Jeon, Hyun-Kyu;Yoo, Taek-Dong;Seo, Chee-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.2 no.4
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    • pp.186-193
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    • 1998
  • The purpose of this research is to seek properties of flowing light-weight aggregate concrete and possibility of application. The experimental analysis results by using light-weight aggregate and industrial waste such flyash, furnace slag are as follow. 1) The research shows that flowing light-weight aggregate concrete of slump 23~27cm, slump flow 58~69 cm is possible, but material segregation is appeared above slump 26.5cm and slump flow 65 cm. 2) If mixing ratio of flyash is increase, strength deterioration is about 25 % in early age. It showed that effectiveness of long time strength improvement because strength manifestation ratio is above 95% in a long term. 3) This research showed possibility of substitution of blast furnace slag because strength deterioration by using mixing of furnace slag was appeared small deterioration range as below 10 %. 4) Each experimental compressive strength ratios were 77 %(1st week), 86 %(2nd week), 109 %(8th week), 115 %(13th week), 125 % (26th week) on the basis of 28 days. If mixing ratio of flyash is increase, long term strength increase ratio is improved.

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Optimum Mix of Extrusion panel Using Low Energy Curing Admixture (LA) based on Ground Granulated Blast-Furnace Slag and Ladle Furnace Slag (고로슬래그와 환원슬래그를 기반으로 한 저에너지양생용 결합재를 사용한 압출성형패널의 최적배합)

  • Kim, Ha-Seog;Baek, Dae-Hyun;Lee, Sea-Hyun
    • Resources Recycling
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    • v.24 no.2
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    • pp.13-22
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    • 2015
  • $CO_2$ emitted from building materials and construction materials industry reaches about 67 million tons, which occupy about 30 % of $CO_2$ emitted from the construction field. Controls on the use of consumed fossil fuels and reduction of emission gases are essential for the reduction of $CO_2$ in the construction area as we reduce the second and third curing to emit $CO_2$ in the construction materials industry. Accordingly, this study applied the low energy curing admixture (hereinafter "LA") to the extruded panels to observe the physical properties, depending on the mixing amount of fiber, type of fiber and mixing ratio of fiber. The type of fiber did not appear to be a main factor to affect strength, while the LA mixing ratio and mixing amount of fiber appeared to be major factors to affect strength. Especially, the highest strength was developed when the LA mixing ratio was 40%, whereas the test object with the mixing ratio of 50% resulted in the decrease of strength. In addition, it appeared that the mixing ratio of fiber greatly affected flexural strength and strength increased as the mixing ratio increased.