• Title/Summary/Keyword: non-sintered hwangto

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Analysis of Non-Sintered Hwangto Replacement Rate in Structural Concrete on Ultrasonic Pulse Velocity (비소성 황토의 치환율에 따른 구조용 콘크리트의 초음파 속도 분석)

  • Kim, Won-Chang;Choi, Hee-Yong;Choi, Hyeong-Gil;Nam, Jeong-Soo;Lee, Tae-Gyu
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2022.04a
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    • pp.45-46
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    • 2022
  • In this study, ultrasonic pulse velocity is compared on non-sintered hwangto concrete(NHTC) and normal concrete(NC) at ages. Strength of specimens set up 30MPa. Cement is replaced with 15 and 30% non-sintered hwangto. UPV is tested at 1, 3, 7, 28, 56, 91 days. As a result, UPV increases as the age and strength increase, but decreases as the non-sintered hwangto replacement increases. Although ultrasonic pulse velocity of NHTC was 72% lower than NC, after that, difference tends to decrease

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Analyzing the Strength Development of Concrete with Function of Non-Sintered Hwangto Admixture Ratio at Early Ages (초기 재령에서 비소성 황토 혼입율에 따른 콘크리트의 강도 발현 분석)

  • Kim, Tae-Hyung;Kim, Won-Chang;Choi, Hyung-Gil;Choi, Hee-Yong;Lee, Tae-Gyu
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.39-40
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    • 2023
  • In this study, the compressive strength development was analyzed at early ages of concrete specimens admixed with non-sintered hwangto to reduce the CO2 emissions generated during cement production. The W/B of the specimens was set at 0.41, the percentage of non-sintered hwangto admixture was set at three levels of 15, 30, and 45%, and the compressive strength were measured at 1, 3, 7, and 28 days. The results showed that the compressive strength decreases as the percentage of non-sintered hwangto increases, but the strength development rate increases, and the NHTC41-15 test specimen developed a compressive strength close to NC41 at 28 days.

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Ultrasonic pulse velocity analysis for high- temperature mechanical properties of high strength concrete replacing non-sintered hwangto (비소성 황토를 치환한 고강도 콘크리트의 고온 역학적 특성 평가를 위한 초음파 속도 분석)

  • Hong, Kil-Dong;Lim, Gguk-Jeong;Jang, Kil-San
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.11a
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    • pp.273-274
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    • 2023
  • In this study, ultrasonic pulse velocity was analyzed to evaluate the high-temperature mechanical properties of concrete mixed with non-sintered hwangto. The W/B of the specimens was set at 0.41, the percentage of non-sintered hwangto admixture was set at two levels of 15,30%. The target temperature of the specimen is set to 6 levels of 20, 100, 200, 300, 500, 700 ℃, and the heating rate is set to 1℃/min. The result showed that the amount of non-sintered hwangto incorporated into the concrete tends to results in lower compressive strength. Ultrasonic pulse velocity showed similar trends, but differed in some areas.

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UPV Prediction Method on Compressive Strength of High Strength Concrete Mixed with Non-Sintered Hwangto at Early Age (초기 재령에서 비소성 황토 혼입 고강도 콘크리트의 압축강도 발현 예측을 위한 초음파 속도법 검토)

  • Young-Jin Nam;Won-Chang Kim;Hyeong-Gil Choi;Gyu-Yong Kim;Tae-Gyu Lee
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.11 no.2
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    • pp.105-111
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    • 2023
  • In this study, the mechanical properties of high-strength concrete according to the substitution rate of NSH(Non-sintered Hwangto) as an alternative material for cement were measured and evaluated. Through UPV(Ultrasonic pulse velocity) analysis, the compressive strength prediction equation was proposed, and the substitution rate of NSH was set at 15 % and 30 %. The evaluation items were compressive strength and UPV, and the curing period was set to 24 hours. In compressive strength and UPV, as the NSH substitution rate increased, lower strength and lower UPV were shown. In addition, the correlation number(R2 ) between compressive strength and UPV was 0.99 for NC(Normal Concrete), 0.97 for NSHC(Non-sintered Hwangto Concrete)33-15, and 0.94 for NSHC33-30.

Regression analysis of the correlation between ultrasonic pulse velocity and strength to examine the demoulding time of non-sintered hwangto concrete (비소성 황토 콘크리트의 거푸집 탈형 시점 검토를 위한 초음파속도와 강도의 상관관계 회귀 분석)

  • Nam, Young-Jin;Kim, Won-Chang;Ryu, Jung-Lim;Choi, Hee-Yong;Choi, Hyeong-Gil;Lee, Tae-Gyu
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.11a
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    • pp.159-160
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    • 2023
  • Recently, interest in reducing cement has been growing. Hwangto, an eco-friendly material, has advantages such as air purification effect and humidity control, but when used, accidents such as form collapse may occur due to low strength and reduced durability. In order to quantitatively evaluate the timing of mold demolding, we would like to evaluate the timing of mold demolding through correlation with compressive strength using ultrasonic pulse velocity. As a result, the time at which 5 MPa is developed is after 20 hours for the test specimen of W/B 41 , in the case of W/B 33, NC33 and HTC33-15 were equally expressed at 12 hours, and HTC33-30 was expressed at 16 hours.

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A Study on Evaluating the Compressive Strength Development of Concrete Mixed with Non-sintered Hwangto Admixture by an Ultrasonic Method (비소성 황토 결합재를 혼합한 콘크리트의 강도 발현 평가를 위한 초음파 속도법의 검토)

  • Kim, Jeong-Wook;Kim, Won-Chang;Kim, Gyu-Yong;Lee, Tae-Gyu
    • Journal of the Korea Institute of Building Construction
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    • v.23 no.1
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    • pp.35-43
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    • 2023
  • In this study, the mechanical properties of concrete mixed with non-sintered hwangto(NHT) as an alternate material for cement were evaluated, and the compressive strength prediction equation of concrete based on ultrasonic pulse velocity analysis was proposed. Cement replacement rates for mixed NHT were set to 0, 15, and 30%, and design compressive strength was set to 30 and 45MPa to evaluate the effect on the amount of cement and NHT powder. The mechanical properties items analyzed were compressive strength, ultrasonic pulse velocity, and elastic modulus, and were measured on days 1, 3, 7, and 28. As the replacement rate of NHT increased, the mechanical properties tended to decrease. In addition, as a result of analyzing the correlation between compressive strength and ultrasonic pulse velocity, the correlation coefficient(R2) showed a high relationship(R2=0.95) on concrete mixed with NHT.