• Title, Summary, Keyword: Setting Time

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Estimation of the Setting Time of the Super Retarding Concrete Combining Mineral Admixtures (혼화재를 조합 사용한 초지연 콘크리트의 응결시간 추정)

  • Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.3
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    • pp.111-117
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    • 2008
  • This study provides the setting time prediction method of super retarding concrete incorporating mineral admixtures at the same time including fly ash(FA), blast furnace slag(BS) based on maturity method. The setting time was retarded, as super retarding agent contents increase and curing temperature decreases. In addition, apparent activation energy by Arrhenius function was ranged from $24{\sim}35KJ/mol$ with slightly difference along with mixture proportion. This value is smaller than existing value $30{\sim}50KJ/mol$. It is Indicated that equivalent age using setting time can be a proper method to predict setting time and it also exhibited comparable relativity between prediction value and measurement value. Therefore, this study provided setting time prediction value with super retarding agent contents and mineral admixture combination. Setting time prediction equation provided herein is possibly valid for estimating precise setting time of the super retarding concrete at the job site.

Estimation of Setting Time of Cement Mortar combined with Recycled Aggregate Powder and Cement Kiln Dust based on Equivalent Age

  • Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.12 no.1
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    • pp.87-97
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    • 2012
  • This paper presents a method of estimating the setting time of cement mortar incorporating recycled aggregate powder (RP) and cement kiln dust (CKD) at various curing temperatures by applying an equivalent age method. To estimate setting time, the equivalent age using apparent activation energy (Ea) was applied. Increasing RP and CKD leads to a shortened initial and final set. Ea at the initial set and final set obtained by Arrhenius function showed differences in response to mixture type. These were estimated to be from 10~19 KJ/mol in all mixtures, which is smaller than those of conventional mixture ranging from 30~50 KJ/mol. Based on the application of Ea to Freisleben Hansen and Pederson's equivalent age function, equivalent age is nearly constant, regardless of curing temperature and RP contents. This implies that the concept of maturity is applicable in estimating the setting time of concrete containing RP and CKD. A high correlation was observed between estimated setting time and measured setting time. A multiregression model was provided to determine setting time reflecting RP and CKD. Thus, the setting time estimation method studied herein can be applicable to concrete incorporating RP and CKD in the construction field.

Estimation of Setting Time of Chlorine By-pass System Dust Mortar using Setting Time Estimation (현장용 응결시간추정계를 이용한 고염화물 모르타르의 응결시간 추정)

  • Lee, Hyuk-Ju;Han, Jun-Hui;Hyun, Seong Yong;Shin, Yong-Seop;Lee, Jun-Seok;Han, Min-Choel
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.6-7
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    • 2018
  • In the previous study, durometer, namely rubber hardness tester Was used to confirm the possibility of using the setting time of concrete for determination. in this study, the possibility of using condensation time judgment condensation estimation system by comparing the measuring station setting estimation system Measuring needle of the proctor penetration resistance tester by newly making a measurement needle and refining the coagulation estimation system Want to make sure. As a result of this study, it was possible to use one condensation estimation system showing similar correlation between the two types of durometer showing high correlation with the penetration resistance value of proctor testers, It is considered to be fruitful to use the dew condensation estimation system for determining the setting time.

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A Feasibility Analysis of the Durometer for Setting Time Assessment of the High Fluidity Concrete with SCMs (혼화재 치환 고유동 콘크리트에서 응결시간 판정시 듀로메타 사용 가능성 분석)

  • Lee, Hyuk-Ju;Lee, Young-Jun;Kim, Tae-Woo;Min, Byeong-Oh;Lee, Jun-Seok;Han, Min-Choel
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.187-188
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    • 2018
  • For the concrete construction, finishing process is inevitable for crack control and improving permeability. The finishing process is closely related with setting time, but currently, the timing of the finishing process is not managed with scientifically but feeling of the workers. In this research, therefore, by comparing with the setting time measured with penetrating method, the feasibility of durometer for measuring setting time was analyzed. As a result, there was a high relationship between setting time measured with penetration method and durometer. Therefore, it is expected that using durometer can be a good solution for assessing setting time for finishing process.

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An Experimental Study on the Setting of Antiwashout Underwater concrete Using Fly Ash (플라이애쉬를 사용한 수중불분리성 콘크리트의 응결에 관한 실험적 연구)

  • 권중현;김봉익
    • Journal of Ocean Engineering and Technology
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    • v.15 no.4
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    • pp.120-125
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    • 2001
  • This paper describes the effect of fly ash replacement on the setting time of antiwashout underwater concrete, where cement was replaced by 0% to 50%. Experimental work was performed on the condition of sea water and in air to find out the characteristics of setting time between the concretes that were cast in air and cast in 15$^{\circ}C$ of sea water. The experimental results show that the setting time of underwater concrete with 50% replacement was delayed about 10 hours than normal concrete. And it can be concluded that, at the case of underseawater concrete addicted with fly ash, the delayed final setting times are shown as the function Tf=0.069F+7.69, where Tf is the delayed final setting time and F is quantity of fly ash, respectively. These results confirm that the setting time underseawater concrete could be prolonged.

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Effect of Setting Temperatures and Time on the Gelation Properties (Suwari and Modori Phenomena) of Surimi from Mechanically Deboned Chicken Meat

  • Lee, Sung Ki;Min, Byung Jin
    • Asian-Australasian Journal of Animal Sciences
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    • v.17 no.12
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    • pp.1758-1763
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    • 2004
  • This study was carried out to investigate gel forming and degradation properties (suwari and modori phenomena) of chicken surimi from mechanically deboned chicken meat (MDCM) at various setting temperatures and time. Chicken surimi was manufactured by a continuous process including chopping of MDCM, washing with 5% NaCl solution or pure water, standing, straining and centrifuging etc. Total process of washing for the MDCM from chopping to centrifuging was repeated over 3 cycles. Gel from prepared surimi were formed at $90^{\circ}C$ for 30 min after various setting treatments. The textural properties of gels were measured at the temperature ranges of low (10$^{\circ}C$), medium (25$^{\circ}C$ and $30^{\circ}C$) and high (45 to 70$^{\circ}C$). The compressive force (CF), hardness and fracturability of surimi gel at 10$^{\circ}C$ increased as setting time increased, and showed the highest value at 30 h of setting time. The CF and hardness of chicken surimi gel at 25$^{\circ}C$ and 30$^{\circ}C$ showed the highest values at 10 h of setting time. Most of gel strengths including CF, and texture profile analysis (TPA) values showed the highest levels in the range 47.5 to 52.5$^{\circ}C$ (p<0.05). The gel strength at 60$^{\circ}C$ increased slightly at 30 min, but then continued to decrease with longer setting times. There was no increase of gel strength at $70^{\circ}C$, but only a continuous decrease over setting time. In conclusion, suwari (gel setting) and modori (gel degradation) phenomena occur during the gel formation of surimi from MDCM. The temperature range in chicken surimi was 47.5 to 52.5$^{\circ}C$ for suwari and 60 to 70$^{\circ}C$ for modori.

Setting Time Evaluation of Concrete Using Electrical Resistivity Measurement (전기비저항 측정을 이용한 콘크리트 응결시점 평가)

  • Lee, Han Ju;Yim, Hong Jae
    • Journal of the Korea Concrete Institute
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    • v.29 no.4
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    • pp.361-369
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    • 2017
  • Setting time of cement-based materials can represent a developing strength in early-age mixture, and it can be used a significant parameter of high-performance concrete having various mix-proportions. Generally, initial and final setting time of concrete is measured by penetration resistance method that used a wet-sieving mortar mixture, therefore, it hardly represents the setting time of sound concrete including coarse aggregate. Recently, several nondestructive methods, such as ultrasonic velocity and impendence measurement, are proposed to evaluate the setting time of fresh concrete. This study attempts to measure an electrical resistivity using four-electrode method for evaluation of setting time in early-age cement-based materials. For this purpose, total 10 mixtures are prepared as different mix-proportions including chemical admixture. Based on the experimental results, two electrical parameters, such as initial electrical resistivity and rising time, are proposed to reflect a microstructure development by hydration of cement-based materials. As a result, proposed parameter is also discussed with the measured setting time by penetration resistance method.

Super Retarding Agent Affecting Setting Time of Concrete Using Mineral Admixture (혼화재를 사용한 콘크리트의 응결 시간에 미치는 초지연제의 영향)

  • Jeon Chung Keun;Kim Jong;Han Min Cheol;Shin Dong An;Oh Sean Kyo;Han Chean Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.643-646
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    • 2005
  • This paper reports the influence of super retarding agent(SRA) on the setting time of concrete incorporating mineral admixture including fly ash(FA), expansive additive(EA), silica fume(SF), blast furnace slag(BS) and blast furnace slag along with fly ash(BS+FA). An increase in SRA resulted in retarding the setting time of control concrete, while the use of mineral admixture led to a delay of setting time markedly, compared with that of control concrete under no SRA content. Meanwhile, An increase in SRA in concrete with mineral admixture exhibited comparable setting delay with control concrete. Furthermore, in case of the use of BS and SF, acceleration of setting time was observed with increase of SRA content. It is considered that proper dosage of SRA of concrete with SF and BS to secure similar setting delay with control concrete require rather larger than that of control concrete. Accordingly, For concrete with mineral admixture, in order to decide the proper dosage of SRA, application of correction factors is needed.

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Setting Time Prediction of Super Retarding Concrete Using Improved Durometer (개량형 듀로미터를 이용한 초지연 콘크리트의 응결시간 분석)

  • Han, Soo-Hwan;Choi, Yoon-Ho;Yeun, Kyu-Won;Kim, Jong;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.73-74
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    • 2020
  • In this study, the feasibility of the durometer into super retarding concrete was studied by comparing the penetration resistance with the hardness of each durometer using the penetration resistance and the improved Durometer and Durometer A-Type according to the ultra-delay mixture rate. The test results showed that initial setting time by improved Durometer and Durometer A-Type were fixed at 25, 50 HD, respectively, and the 35, 80 HD showed at final setting time. It was also found that the use of the durometer can be available to measure the setting time of the concrete.

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Experimental Study on Setting Time of Cement Paste Mixed Accelerating Admixtures (급결제를 혼합한 시멘트페이스트의 응결시간에 관한 실험적 연구)

  • Heo Gweon;Choi Hong-Shik;Yi Seong-Tae
    • Journal of the Korea Concrete Institute
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    • v.17 no.6
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    • pp.879-884
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    • 2005
  • The setting time is a very important factor affecting the quality of tunnel lining and reinforcement of inclined slope etc. Currently, however, the quality criteria of accelerating admixture to improve it is not established well. In this study, evaluation on setting time measuring methods of cement mixed a accelerating admixture (AA) was performed using Gillmore and Vicat needle test methods. For both test methods, the setting time for addition at a time was better than post addition regardless of initial setting and final setting. For Gillmore needle test method, two types of measuring methods were selected and it is noted that setting time with cement type under the same accelerating admixture can be different. Accordingly, manufacturing company shall develop a less sensitive accelerating admixture to cement type. For Vicat needle test method, six types of measuring methods were used and a proper measuring method of the admixture were proposed as follows: (1) the temperature of materials used shall be controlled exactly and (2) to evaluate its properties, an admixture usage of $5\%$ (ratio of cement weight) is recommended.