• Title/Summary/Keyword: Schmidt hammer strength

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Strength Evaluation of the Plant Facility for Fluid Machinery Using Schmidt Hammer in Cold Regions (극한지에서의 유체기계를 위한 플랜트 설비구조물의 비파괴 건전도 평가)

  • Hong, Seung-Seo;Kim, YoungSeok
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.3
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    • pp.25-28
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    • 2016
  • The Schmidt hammer test is one of the best nondestructive tests to measure the strength without breaking structures, which has been used to measure the strength of concrete structures in a simple way at construction sites. However, the future research is needed to apply Schmidt hammer in cold regions. This study is intended to investigate the correlation between unconfined compression test result of the oil storage facilities foundation taken at the King Sejong Antarctic Station and Schmidt hammer test result at the sample-taking site. Also, the equation for uniaxial compression strength using Schmidt hammer rebound value is proposed.

Influence of Aggregate on the Rebound Value of P Type Schmidt Hammer (P형 슈미트햄머의 반발도에 미치는 골재종류의 영향)

  • 김태현;김기정;이용성;이백수;윤기원;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.239-242
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    • 2002
  • This study is intended to investigate the relationship between rebound value of P type schmidt hammer and the compressive strength with various aggregates, and a series of experiments about early strength quality control by P type schmidt hammer was performed. According to the results, the compressive strength of concrete using basalt and limestone aggregate is higher by 3% and lower by 4% than that of concrete using granite aggregate respectively. Concrete using basalt and lime stone aggregate show high rebound value in vertical strike. Estimation of the compressive strength does not show differences in horizontal strike, but the compressive strength is estimated high in order of granite, basalt and limestone aggregate in vertical strike. A good correlation between the rebound value of schmidt hammer and the compressive strength is confirmed regardless of aggregate types, so it could be possible to control the quality of concrete by P type schmidt hammer test when basalt and limestone aggregates are used at the same time.

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Strength Prediction Equations of High Strength Concrete by Schmidt Hammer Test (슈미트 해머 시험법에 의한 고강도 콘크리트의 강도 추정식)

  • Park Song Chul;Yoo Jae Eun;Kim Min Su;Kwon Young Wung
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.11a
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    • pp.615-618
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    • 2005
  • This study concerns the equation of high strength concrete by schmidt hammer test. There are not only few prediction strength equations of concrete by schmidt hammer test, but also many problems to apply them because of time, cost, easiness, structural damage, reliability and so on. For this study, there performed a series of schmidt hammer test with in existing 1,095days' concrete structures and proposed equations as follows ; Linear: ${\Large f}_{ck}=-45.35+2.44R(r^2=72.7\%)$ Quadratic: ${\Large f}_{ck}=-502.08+24.0R-0.25R^2(r^2=82.4\%)$ here, $f_{ck}$ : Estimated compressive strength of concrete by MPa, R : Rebound index of concrete

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A New Strength Equation of Concrete by Schmidt Hammer Test (슈미트햄머 시험법에 의한 콘크리트 강도 추정식)

  • Park Song-chul;Yoo Jae-Eun;Kim Min-Su;Kwon Young-Wung
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.133-136
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    • 2004
  • This study concerns the. new equation of concrete strength by schmidt hammer test. There are not only few estimate strength equations of concrete by schmidt hammer test, but also many problems to apply them because of time, cost, easiness, structural damage, reliability and so on. For this study, there performed a series of schmidt hammer test with in existing 730days' concrete structures and proposed equations as follows; $$Linear\;:\;f_{ck}=2.18R-40.54\;(r^2=77.7\%)$$ $$Quadratic\;:\;f_{ck}=0.076R^2-2.92R+40.04\;(R^2= 85.5\%)$$ here, fck : Estimated compressive strength of concrete by MPa, R : Rebound index of concrete.

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An Investigation on Estimation of the Compressive strength by P Type Schmidt Hammer (P형 슈미트햄머에 의한 압축강도 추정에 관한 검토)

  • 김기정;이용성;이백수;윤기원;최영화;한천구
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2002.11a
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    • pp.11-15
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    • 2002
  • This study is intended to analyze the relationship between the rebound value of P type schmidt hammer and the compressive strength for a quality control of concrete. According to the results, the compressive strength of standard curing specimen increases in proportion to age, but that of air curing specimen hardly increases after 28 days. The rebound value of P type schmidt hammer, however, increases due to carbonation of concrete in air curing specimen. The correlativity between the rebound value and the compressive strength is very favorable in the case of standard curing specimen, but drops remarkably in the case of air curing specimen. Thus, as application of age coefficient is required for exact estimation of the compressive strength, the age coefficient is derived from this study. The age coefficient of P type schmidt hammer is higher at the age of 3 and 7days, and drops significantly, compared with the age of 28days. And it is lower before 28days than that of N type schmidt hammer suggested in Japan, and shows the similar tendency after 28days.

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Determination of concrete quality with destructive and non-destructive methods

  • Kibar, Hakan;Ozturk, Turgut
    • Computers and Concrete
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    • v.15 no.3
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    • pp.473-484
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    • 2015
  • In this study, the availability of Schmidt hammer has been investigated as a reliable method to determine the quality of concrete in irrigation networks. For this purpose, the 28-day compressive strength of concrete material used in the construction irrigation channel of Bafra lowland, which is one of the most fertile plains in Turkey was examined by means of concrete compression and as well as concrete Schmidt hammer in laboratory conditions. This study was carried out on cylindrical samples to represent the everyday concrete party ($150m^3$) produced by contractor firm as 3 replications. The statistical analysis of experimental data showed that the correlations between the values of 28-day compressive strength of Schmidt hammer and the rebound number was found to be 0.98. Differences of the compressive strength between compression testing and Schmidt hammer were statistically significant at P<0.01. In this context, it was found that the reliability of compressive strength of the concrete compression test are excellent, also the reliability of compressive strength of Schmidt hammer are fair in assessing the quality of concrete irrigation channels.

A Prediction of Engineering Properties of Ulsan Sedimentary Rocks with Schmidt Hammer Rebound Number (Schmidt hammer 반발지수로 울산지역 퇴적암의 공학적 특성을 추정하기 위한 연구)

  • Min, Tuk-Ki;Moon, Jong-Kyu
    • Journal of the Korean Geotechnical Society
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    • v.22 no.10
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    • pp.139-150
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    • 2006
  • A study has been made of the Schmidt hammer rebound test for the estimation of engineering and physical characteristics of sedimentary rocks. As there is no universal formular for the estimation of rock strength due to geological conditions, in this study only sedimentary rocks are adopted to testing. The aim of study is to make the information more meaningful and useful for engineers and contractors by providing rapid, cheap and easy method. The obtained parameters were correlated and regression equations were established among Schmidt hammer rebound number, uniaxial compressive strength, tangent Young's modulus, indirect tensile stress, water absorption and porosity of rocks with high coefficients of correlation with each other.

Evaluating the pull-out load capacity of steel bolt using Schmidt hammer and ultrasonic pulse velocity test

  • Saleem, Muhammad
    • Structural Engineering and Mechanics
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    • v.65 no.5
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    • pp.601-609
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    • 2018
  • Steel bolts are used in the construction industry for a large variety of applications that range from fixing permanent installations to temporary fixtures. In the past much research has been focused on developing destructive testing techniques to estimate their pull-out load carrying capacity with very little attention to develop non-destructive techniques. In this regards the presented research work details the combined use of ultrasonic pulse velocity and Schmidt hammer tests to identify anchor bolts with faculty installation and to estimate their pull-out strength by relating it to the Schmidt hammer rebound value. From experimentation, it was observed that the load capacity of bolt depends on its embedment length, diameter, bond quality/concrete strength and alignment. Ultrasonic pulse velocity test is used to judge the quality of bond of embedded anchor bolt by relating the increase in ultrasonic pulse transit time to the presence of internal pours and cracks in the vicinity of steel bolt and the surrounding concrete. This information combined with the Schmidt hammer rebound number, R, can be used to accurately identify defective bolts which resulted in lower pull-out strength. 12 mm diameter bolts with embedment length of 70 mm and 50 mm were investigated using constant strength concrete. Pull-out load capacity versus the Schmidt hammer rebound number for each embedment length is presented.

Determination of Removal Time of the Forms with the Strength Development of High Strength Concrete at Early Age (고강도 콘크리트의 초기강도 발현에 따른 거푸집 탈형시기의 결정)

  • 김은호;김영진;한민철;신병철;한천구
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2003.05a
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    • pp.99-102
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    • 2003
  • This study discusses the determination of removal time of forms with early strength development in high strength concrete. According to the results, as W/B increases by 10%, the setting time is shortened by about 2 hours. The time when compressive strength of 8 MPa is gained is about 20 hours. Bond strength between form and concrete is highest around final setting time, but decreases drastically after that. Amount of concrete sticking on the form is large before setting, but after that, it is little. The rebound value of P type schmidt hammer is measured faster by 2-3 hours than compressive strength. It is also confirmed that the removal of forms is possible when the rebound value of P type schmidt hammer is more than 34

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Strength Estimation of the High Strength Concrete by using Rock Test Hammer (암반용 테스트해머 사용에 의한 고강도콘크리트의 강도추정)

  • Seo, Yun-A;Nam, Kyung-Yong;Park, Soo-Hwa;Kim, Seong-Deok;Lim, Nam-Gi;Jung, Sang-Jin
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2012.11a
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    • pp.77-79
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    • 2012
  • This paper intends to review possible application in the high strength area through compressive strength estimation of the simulated high strength concrete member using Rock Test Hammer and suggest it as a reference data for the strength estimation technique of the ultra high strength concrete in the future. From the results of our test, in the low strength area less than 15MPa and normal strength area in 15~60MPa, as shown on the existing studies, it is indicated that P Type Schmidt Hammer in the low strength area and N Type Schmidt Hammer in the normal strength area have high correlation of rebound-compressive strength. As the Rock Test Hammer indicated more or less reduced accuracy in the low strength area and the normal strength area but high correlation on the high strength area (50~100MPa) defined on this test, it is determined that it would be possible to make the fastest and simplest compressive strength estimation on the site where the high strength concrete is applied.

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