• Title/Summary/Keyword: hardness meter

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Development of a Soil Hardness Meter with Strain Gages (스트레인 게이지를 이용(利用)한 토양(土壤) 경도계(硬度計)의 개발(開發) (I))

  • Kim, Tae Han;Lee, Ki Myung;Jang, Ik Joo
    • Current Research on Agriculture and Life Sciences
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    • v.1
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    • pp.95-100
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    • 1983
  • A soil hardness meter with strain gages was developed in order to measure the hardness of the soil. Soil hardness tests were conducted at the laboratory based on this measuring system. Also, these results were compard with that from the cone penetrometer which is widely used for this purpose. The following conclusions were drawn from the results. 1. Since the correlation coefficient of calibration curve obtained from the soil hardness meter with strain gages was 0.99876 and that of calibration curve obtained from the cone penetrometer with dial gage was 0.97150, the soil hardness meter with strain gages was more recomendable than that with dial gage for this purpose. 2. Standard deviations of soil hardness for sands and soil of paddy field when the soil hardness meter with strain gages was used were 6.794 and 8.271, respectively and that of soil hardness for sands and soil of paddy field when the cone penetrometer with dial gage was used were 7.490 and 9.169, respectively. Thus, the soil hardness meter with strain gages seemed to have lower measuring error than with dial gage.

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Estimation of Setting Time and Compressive Strength of Ternary Blended Concrete Applying Estimator (추정계를 활용한 3성분계 콘크리트의 응결 및 압축강도 추정)

  • Park, Jae-Woong;Lim, Gun-Su;Kim, Jong;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.143-144
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    • 2023
  • This study aimed to evaluate the feasibility of estimating the setting time and compressive strength in Ternary Blended Concrete(TBC) using Settimeter, Strength meter, and Hybrid meter. It was determined that the hardness values at the initial setting time and final setting time of Settimeter, Hybrid meter, and at the 5 MPa of Strength meter were not affected by the mixing ratio of TBC. However, future studies need to consider the errors caused by the instability of the measurement surface during condensation and the state of the measurement surface after hardening.

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Estimation of Setting Time of Concrete Using Rubber Hardness Meter (고무경도계를 이용한 콘크리트의 응결시간 추정 가능성 분석)

  • Han, Min-Cheol;Han, In-Deok;Shin, Yong-Sub
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.4
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    • pp.358-366
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    • 2019
  • The purpose of this study is to explore the possibility of estimating optimum surface finishing work time of the fresh concrete placed at the job site by applying a surface hardness test meter(Durometer). Tests are carried out by measuring and comparing the Proctor penetration resistance test and hardness test by Durometer. Correlations between Procter penetration test and hardness test by Durometer were obtained. Two different types Durometer were applied to estimate setting time. Test results indicate that the measurement of the Durometer and the test of the Proctor penetration resistance are highly correlated. When measuring the initial setting time with Durometer, initial setting time is reached when the hardness value by the type C Durometer is reached around 42HD, and when final setting is measured with the type D Durometer, the surface finishing work time limit and curing time can be estimated with 10HD of Durometer.

Acoustic Property and Hardness of Coatings for Musical Instruments with Various Coating Thicknesses

  • Hwang, Hyeon-Deuk;Lee, Byoung-Hoo;Choi, Jae-Hoon;Kim, Hyun-Joong;Chung, Woo-Yang
    • Journal of the Korean Wood Science and Technology
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    • v.34 no.2
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    • pp.58-67
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    • 2006
  • The relationship between acoustic property and coating hardness of musical instruments was investigated using a sound level meter and a pendulum hardness tester. Urethane topcoat, oil stain, natural oil varnish, and UV-curable epoxy acrylate coatings were applied on four different substrates: Paulownia coreana, Pinus koraiensis, Castanea crenata var. dulcis and Pinus densiflora. The influence of the coating type on the acoustic properties was stronger than that of the substrate. In the case of an oil stain formed with tacky coating layer, the sound pressure level (SPL) and surface hardness decreased with increasing of coating thickness. In the other coatings, SPL decreased and hardness increased as the coating layer thickened. However, SPL began to increase again at coating thickness above $100{\mu}m$.

A Study on the Estimation of Setting Time for High Strength Concrete Using Durometer (개량형 Durometer를 이용한 고강도 콘크리트의 응결시간 추정 가능성 분석)

  • Sin, Se-Jun;Han, Soo-Hwan;Hyun, Seung-Yong;Kim, Jong;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.11a
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    • pp.87-88
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    • 2020
  • The purpose of this study is to explore the possibility of estimating optimum surface finish time of the fresh concrete placed at the job site by applying a surface hardness test meter(Durometer). Tests are carried out by measuring and comparing the Penetration resistance test and hardness test by Durometer. Penetration resistance tester and improved Durometer are similar, but the higher the temperature, the higher the setting time, and the higher the correlation was shown. When the hardness value of the improved Durometer is about 50 HD, it is found that the initial and 80 HD represent the end. It is expected that this will be useful in determining the finish time of the surface at the actual site.

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Estimation of Compressive Strength at Early Age of Hardened Concrete Using Rubber Hardness Meter (고무경도계를 활용한 경화 콘크리트의 초기재령 압축강도 추정)

  • Han, Soo-Hwan;Choi, Yoon-Ho;Hyun, Seung-Yong;Kim, Jong;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.11a
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    • pp.181-182
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    • 2020
  • This study investigates the feasibility tp estimate the compressive strength at early age in hardened concrete by applying Durometer D type. The result of the experiment showed that the compressive strength reached 5MPa 6 hours, and 55 HD when the hardness was measured with the type D of the Duometer. Through this, it is expected that it will be possible to estimate the compressive strength of the initial age and measure it by the age of 28 when using the Durometer D type in the ready-mixed concrete, which will be applied in practice.

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A Study on the Estimation of Setting Time for Concrete Using Durometer (개량형 Durometer를 이용한 콘크리트의 응결시간 추정 가능성 분석)

  • Sin, Se-Jun;Han, Soo-Hwan;Hyun, Seung-Yong;Kim, Jong;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.11a
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    • pp.169-170
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    • 2020
  • The purpose of this study is to explore the possibility of estimating optimum surface finish time of the fresh concrete placed at the job site by applying a surface hardness test meter(Durometer). Tests are carried out by measuring and comparing the Penetration resistance test and hardness test by Durometer. Penetration resistance tester and improved Durometer are similar, but the higher the temperature, the higher the setting time, and the higher the correlation was shown. When the hardness value of the improved Durometer is about 50 HD, it is found that the initial and 80 HD represent the end. It is expected that this will be useful in determining the finish time of the surface at the actual site.

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A Study on the Mechanical Properties of Organo-clay Filled NR/MMT Nanocomposites (Organo-Clay를 이용한 NR/MMT 나노복합체의 기계적 물성에 관한 연구)

  • Oh, Woo-Taek;Lee, Eun-Kyoung;Choi, Sei-Young
    • Elastomers and Composites
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    • v.44 no.4
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    • pp.455-465
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    • 2009
  • In this study, Organo-montmorillonite(MMT) was synthesized by intercalation of various amine(Octylamine, Dodecylamine, Dimethyldodecylamine, Octadecylamine) compounds into layered silicate. Natural Rubber(NR)/MMT nanocomposites were prepared by reinforcement of Organo-MMT. X-ray diffraction(XRD) and Scanning electron microscope(SEM) were employed to characterize the layer distance of Organo-MMT and the morphology of the NR/MMT nanocomposites. The structures of the synthesized Organo-MMTs were analyzed by the measurement of FT-IR. Cure characteristics, surface free energy and mechanical properties such as tensile strength, modulus and hardness of NR/MMT nanocomposites were carefully studied by contact angle meter, ODR, UTM, and hardness tester. FT-IR analysis showed a insertion of the alkyl and amine chains into the interlayers of the MMT. It was shown that the cure time of the organo-MMT was more decreased than that of $Na^+$-MMT. Surface free energy and tensile strength of the NR/DDA-MMT nanocomposite were the highest. NR/ODA-MMT nanocomposite was the highest in hardness.

Development of Travelling Cone-Penetrometer (주행형(走行型) Cone-Penetrometer 개발(開發)에 관(關)한 연구(硏究))

  • Lee, K.M.;Song, J.G.;Chang, D.C.;Chung, S.W.
    • Journal of Biosystems Engineering
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    • v.12 no.3
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    • pp.1-6
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    • 1987
  • The objective of this study is to develop a soil hardness tester which can estimate tillage resistance with tae travelling cone-penetrometer. For the study, a series of tests was performed using the cone penetrating in the horizontal direction. Based on the tests above, soil hardness was represented by travelling cone-index vs depth of cone penetration, travelling speed and moisture contents of the soil Resistance characteristics obtained from the experiments were compared with those by a vertical cone-penetrometer and the Yamanaka's soil hardness tester. Following conclusions were made from the study. 1. 8 to 9 peaks per one meter were detected in the resistance curve of cone penetration regardless of the travelling speed of cone-penetrometer when it penetrated the soil in the horizontal direction. This phenomenon seemed to be a similar one noticed in shearing pitch of plowing. 2. Cone index increased as travelling speed increased from 0.08m/sec to 0.5m/sec. 3. Linear relationship was found between the cone indices measured by the travelling coe-penetrometer and Yamanaka's hardness tester. 4. Increasing rate of the cone indices measured by vertical cone-penetrometer decreased as the depth of soil increased while the cone indices by the travelling cone-pentrometer increased linearly.

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Effect of fluorine gas addition for improvement of surface wear property of DLC thin film deposited by using PECVD (PECVD를 이용한 DLC 박막의 표면 마모 특성 향상을 위한 플루오린 첨가의 영향)

  • Park, Hyun-Jun;Kim, Jun-Hyung;Moon, Kyoung-Il
    • Journal of the Korean institute of surface engineering
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    • v.54 no.6
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    • pp.357-364
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    • 2021
  • In this study, DLC films deposited by PECVD were evaluated to the properties of super-hydrophobic by CF4 treatment. The structure of DLC films were confirmed by Raman Spectra whether or not mixed sp3 (like diamond) peak and sp2 (like graphite) peak. And the hydrogen contents in the DLC films (F-DLC) were measured by RBS analysis. In addition, DLC films were analyzed by scratch test for adhesion, nano-indentation for hardness and tribo-meter of Ball-on-disc type for friction coefficient. In the result of analysis, DLC films had traditional structure regardless of variation of hardness at constant conditions. Also adhesion of DLC film was increased as higher material hardness. Otherwise, friction coefficient was increased as lower material hardness. The DLC films were treated by CF4 plasma treatment to enhance the properties of super-hydrophobic. And the DLC films were measured by ESEM(Enviromental Scanning Electron Microscope) for water condensation.