• Title/Summary/Keyword: 압축강도특성

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A Study on Unconfined Compressive Strength of CLSM with Paper Sludge Ash (제지애쉬가 적용된 CLSM의 일축압축강도 특성에 관한 연구)

  • Park, Jeong-Jun;Lee, In-Hwan;Shin, Eun-Chul;Hong, Gigwon
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.4
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    • pp.253-262
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    • 2019
  • This paper described the evaluation results on unconfined compressive strength characteristics of CLSM with paper sludge ash, in order to develop a CLSM that can prevent sewer pipe damage. The flowability test and the unconfined compressive strength test were performed according to mix design condition of CLSM. The flowability test result showed that the water content, which can satisfy the flowability criteria, was 24% to 32% according to the mix design condition. The results of unconfined compressive strength test showed that the strength incremental ratio was high between 1 and 7 days of curing time, and the strength at this time was more than about 50% of the strength at 28 days of curing time. The strength of CLSM was greatly influenced by fly ash. However, it was analyzed that the mixture of paper sludge ash is required when the reference strength of CLSM is considered. Although the strength of the high cement ratio was higher than that of the low cement, a cement ratio of 5% would be a reasonable mix design condition of CLSM.

Analysis of Compressive Strength of Lightweight Air-mixed Soil According to the Properties of Soil (원료토의 특성에 따른 경량기포혼합토의 압축강도 영향인자 분석)

  • Song, Jun-Ho;Im, Jong-Chul;Hong, Seok-Woo
    • Journal of the Korean Geotechnical Society
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    • v.24 no.11
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    • pp.157-166
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    • 2008
  • To investigate the relationship between compressive strength ($q_u$) of Lightweight Air-mixed soil (LAS) and its physical deformation coefficient ($E_{50}$), a series of unconfined compressive tests have been performed on specimens of LAS according to various dredged soil types by percentage of sand, silt and clay. From the results it was found that the cement content ($C_i$) and unit weight (${\gamma}_m$) are most influence factors on strength, and percentage of sand, silt, clay by grain size analysis (KS F2302) have more effect on compressive strength than other physical properties of soil. It was also found that the rate of strength (a) increases with curing time, but it reduces with the increase of percentage of clay ($C_%$).

An Experimental Study on the Shear Strength of Reinforced High Strength Concrete Beams without Stirrups (스터럽이 없는 고강도 철근콘크리트보의 전단강도 특성에 관한 실험적 연구)

  • 김진근;박연도
    • Magazine of the Korea Concrete Institute
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    • v.5 no.1
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    • pp.103-113
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    • 1993
  • 일반적으로 스터럽이 없는 철근콘크리트 보의 전단강도는 콘크리트 압축강도, 주철근비, 전단스팬비 및 보 유효깊이에 좌우된다는 것이 많은 연구를 통하여 밝혀지고 있다. 따라서, 본 연구에서는 고강도 콘크리트를 사용한 철근콘크리트 보의 거동 및 전단강도 특성을 분석하기 위하여 주철근비, 전단스팬비 및 보 유효깊이를 변수로 두고 총 22개의 단철근 보 실험체를 제작하여 실험을 수행하였다. 실험결과는 ACI규준식, Zsutty식 및 Bazant & Kim식의 예측값들과 함께 비교, 분석되었는데, ACI 규준식은 주철근비 및 전단스팬비의 효과를 과소평가할 뿐만 아니라 유효깊이가 915mm인 큰 보의 경우 안전측이 아니어서 이에 대한 고려가 필요할 것으로 판단된다. Zsutty식은 주철근비의 효과를 적절하게 평가하는 것으로 나타났으며, Bazant & Kim 식은 유효깊이 증가에 따른 전단강도 감소 경향을 잘 예측하는 것으로 나타났다. 또한, 다른 연구자들의 실험치와 비교, 분석해본 결과 주철근비 및 전단스팬비의 효과는 콘크리트 압축강도 수준에 따라 큰 변화가 없는 것으로 판단된다.

A Crushability Index of Sands Using Particle Strengths and Compressibility Characteristics (흙입자 강도와 압축특성을 이용한 모래의 파쇄성 지표)

  • 곽정민
    • Journal of the Korean Geotechnical Society
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    • v.15 no.5
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    • pp.205-215
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    • 1999
  • Crushable sandy soil grounds are widely found along the coast throughout the world. The ground composed of lime sand, which is characterized by the material with high compressibility due to particle crushing contains carbonate calcium. In this study, in order to clarify the characteristics of the particle crushing as related to the strength and deformation properties of sands, isotropic compression test was carried out on three different types of carbonate sands and a silica sand. A crushability index, K, is proposed in connection with the yielding and particle crushing stress of sands at various relative densities under isotropic compression. It is concluded that the representative crushability index, K, associated with the soil particle strength, can be a key factor in preliminary parameters in evaluating soil crushability.

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A study on the Effects of Superplasticizres on the Engineering Properties of Plain Concrete(II) (고성능감수제가 콘크리트의 공학적 특성에 미치는 영향(II))

  • 박승범
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.28 no.2
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    • pp.74-86
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    • 1986
  • 유동화콘크리트의 공학적 특성에서 시간-의존거동을 확인하기 위하여,나프타렌 설폰산염 폴리머 고축합물인 Rheobuild 1000과 메라민 설폰산염 고축합물인 NP-20의 고성능감수제를 사용한 유동화콘크리트와 보통콘크리트를 제조하여 비교.고찰을 행하였으며, 고성능감수제의 종류 및 함량이 콘크리트의 공학적 특성에 미치는 영향을 구명하기 위하여 재령 3일, 14일, 28일, 60일, 90일, 180일의 압축강도를 측정, 조기 및 장기압축강도를 조사하였고, 인장강도 및 탄성 변형에 미치는 영향을 조사하였다. 또한 습윤 및 에어콘디션의 양생조건하에서 시간의 경과에 따른 건조수축 및 크리이프 변형을 조사.분석함으로써 유동화콘크리트의 시간-의존거동을 확인하였다. 실험결과, 사용 고성능 감수제의 종류에 따라 차이는 있으나, 고성능 감수제의 사용은 일반적으로 워커빌리티 성능을 개선하고 압축 및 인장도를 크게 향상시키며, 탄성계수는 보통의 콘크리트에 비하여 높게 나타났다. 또한 건조수축 및 크리프 변형의 감소에 매우 양호한 결과를 나타내어 앞으로 건설용 용도로써 효과적인 것으로 판단되었다.

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Experimental Study on the Material Properties of Unreinforced Masonry Considering Earthquake Load (지진하중을 고려한 비보강 조적조의 재료특성 평가에 관한 실험연구)

  • 김희철;김관중;박진호;홍원기
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.2
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    • pp.93-101
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    • 2001
  • 본 논문은 국내의 비보강 조적조에 대해 내진성능을 조사하기 위하여 재료측성 평가를 위한 실험연구를 수행하였다. 실험결과를 바탕으로 조적용 모르터의 압축강도식을 제안하였다. 또한 조적용 모르터의 배합비에 따른 조적조 프리즘의 압축강도 특성을 비교하였다. 조적조 프리즘의 압축강도로써 조적조의 탄성계수를 구할 수 있는 약산식을 제시하였으며, 약산식을 사인장 조적조 실험을 통하여 구한 전단탄성계수값과 비교하여 볼 때 타당성을 가지고 있다고 판단된다. 실험결과로써 나온 재료특성 값을 바탕으로 2층 조적조 다세대 주택에 대한 유사동적해석을 수행하였다. 해석결과로 얻은 전단응력과 전단파괴가 나타난 사인장 조적조의 허용전단응력은 유사한 것으로 확인되었다.

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Mechanical Characteristics of Ultra High Strength Concrete with Steel Fiber Under Uniaxial Compressive Stress (강섬유로 보강된 초고강도 콘크리트의 일축압축 상태에서의 기계적 특성)

  • Choi, Hyun-Ki;Bae, Baek-Il;Choi, Chang-Sik
    • Journal of the Korea Concrete Institute
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    • v.27 no.5
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    • pp.521-530
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    • 2015
  • Design of fiber reinforced ultra-high strength concrete members should be verified with analytical or experimental methods for safety. Members with compressive strength larger than limitation of current design code usually be designed with analytical verification using stress-strain relation of concrete and reinforcements. For this purpose, mechanical characteristics of steel fiber reinforced ultra-high strength concrete were defined under uniaxial compression. Mix proportions of test specimens were based on reactive powder concrete and straight steel fibers were mixed with different volume fraction. Compressive strength of matrix were distributed from 80 MPa to 200 MPa. Effect of fiber inclusion were investigated : increase of compressive strength of concrete, elastic modulus and strain corresponding to peak stress. For the wide range application of investigation, previously tested test specimens were collected and used for investigation and estimation equation. Based on the investigation and evaluation of previous research results and estimation equation of mechanical characteristics of concrete, regression equations were suggested.

Evaluation on Mechanical and Mixing Properties of Ultra-high Strength Concrete with fck=150MPa (150MPa 초고강도 콘크리트의 배합 및 재료역학특성 평가 연구)

  • Kang, Hoon;Ahn, Jong-Mun;Shin, Sung-Woo
    • Journal of the Korea Institute of Building Construction
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    • v.10 no.3
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    • pp.113-120
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    • 2010
  • Ultra-High Strength Concrete (UHSC) demands a clear presentation of its mechanical properties, as distinct from normal strength concrete, and an evaluation of the serviceability of high-rise buildings that use ultra-high strength concrete. Ultra-high strength concrete fck=150MPa was manufactured with pre-mix cement, and an experimental study was conducted to evaluate the mixing properties and compressive strength, with the major variables being unit cement contents, water-binder ratio, and type of pre-mix cement. The test result showed that 150MPa concrete requires about 6~7 minutes of mixing time until each of the materials (ordinary Portland cement, silica fume, blast-furnace slag powder and anhydrite) are sufficiently revitalized. The slump flow of fresh concrete was shown to be about 700~800mm with the proper viscosity. The average value of concrete compressive strength was shown to be about 70% in 7 days, 85% in 14 days, and 95% in 28 days, for 56 days of concrete material age.

Thermal and Mechanical Properties of Alumina Cementitious Composite Materials (알루미나 시멘트에 기반한 복합재료의 열역학적 특성)

  • Yang, In-Hwan;Lee, Jung-Hwan;Choi, Young-Cheol
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.3 no.3
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    • pp.199-205
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    • 2015
  • The mechanical and thermal properties of high temperature aluminate cementitious thermal storage materials were investigated in this paper. Alumina cement was used as basic binder and the effect of the replacement of fly ash, silica fume, calcium sulfo-aluminate and graphite for alumina cement was investigated. Experiments were performed to measure mechanical properties including compressive strength before and after thermal cycling, and split tensile strength, and to measure thermal properties including thermal conductivity and specific heat. Test results show that the residual compressive strengths of mixtures with alumina cement only, or alumina cement and silica fume were greater than those of the others. Additionally, the specific heat of mixture with graphite was largest in all the mixtures used in the study. The results of this study could be used to provide realistic information for material properties in thermal energy storage concrete in the future.

Effect of Bottom Ash Aggregate Contents on Mechanical Properties of Concrete (콘크리트의 역학적 특성에 대한 바텀애시 골재 양의 영향)

  • Ahn, Tae-Ho;Yang, Keun-Hyeok;Ha, Jung-Soo
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.4
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    • pp.379-386
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    • 2020
  • The present study examined the effect of bottom ash aggregate contents on the compressive strength gain and mechanical properties(modulus of elasticity and rupture and splitting tensile strength) of concrete. Main test parameters were water-to-cement ratio and bottom ash aggregate contents for replacement of natural sand. Test results showed that the 28-days compressive strength of concrete and mechanical properties normalized by the compressive strength tended to decrease with the increase in bottom ash fine aggregate content. When compared with fib 2010 model equations, bottom ash aggregate concrete exhibited the following performances: lower rates of compressive strength gain at early ages but greater rates at long-term ages; slightly higher measurements for modulus of elasticity and rupture; and lower measurements for splitting tensile strength.