• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.303-308
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• 1998

In the concrete structures exposed to environmental conditions at early ages, water movement occurs by moisture diffusion in the concrete, and self-desiccation of concrete is also occurred. Thus the internal relative humidity is changed from moisture diffusion and self-desiccation. Thus the internal relative humidity at each location in concrete includes the decrease by self-desiccation. Especially, for high-strength concrete the much unit cement content is used, so that the non-uniform relative humidity distribution is affected form self-desiccation at early ages. In this study, the internal relative humidity in concrete was measured at early ages, and the moisture diffusion component and self-desiccation component of total relative humidity were discussed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.309-314
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• 1998

The moisture diffusion and self-desiccation cause the differential drying shrinkage and autogenous shrinkage at early ages, respecitvely. Thus total shrinkage strain includes the differential drying shrinkage and self-desiccation shrinkage. Thus in this study the shrinkage strain was measured at various positions in the exposed concrete and in the sealed concrete the self-desiccation shrinkage was measured. In low-strength concrete, the differential drying shrinkage increases very rapidly, but self-desiccation shrinkage is very small. But high-strength concrete shows the reverse result. And the analytical results for differential drying shrinkage were in good agreement with the test results.

• 산업기술연구
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• 제20권A호
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• pp.93-100
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• 2000

This research is to investigate the self-weight consolidation settlement and desiccation shrinkage settlement of soft marine dredging clay by performing numerical and experimental works. Large column test were carried out investigate the consolidation settlement considering effect of the self-weight and desiccation shrinkage, and centrifuge model test was also carried out investigate self-weight consolidation settlement. Results of centrifuge model and large column experiments about changes of settlement with time were analyzed by using the numerical technique of explicit finite difference method considering effect of the self-weight and desiccation based on the finite strain consolidation theory. Centrifuge model test results were in relatively good agreements with analyzed results in terms of self-weight consolidation settlement with time. Large column test results showed quite different values from the numerically estimated one, carried by experimental conditions.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.515-520
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• 2006

Yano method had been used in predicting the settlement of self-weight consolidation of dredged soil in the construction of reclamating the dredged soil. Its estimation was found to show some different results from field measurements. The numerical analysis with PSDDF was peformed find such differences, considering the effect of desiccation on the consolidation during the remaining time after reclamation. For the parametric study, numerical analyses with/without consideration of desiccation were carried out with changing the conditions of desiccation such as the number of placing the fill and the time period between each placement. As results of analysis, estimations about consolidation settlement and distribution of water contents with consideration of desiccation was in good agreements with field measurements. It was also found that the number of placing the fill and the time period between each placement did not affect the behavior of self-weight consolidation as much as the effect of desiccation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.499-506
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• 2004

The use of dredged soft marine clay is increasing due to a shortage of coarse material available. This paper presents a stabilization method that can increase shear strength of the surface layer of a dredged clay deposit at dates much earlier than usual. The desiccation of the upper soft 1-2m layer can be accelerated by interrupting water seeping from its bottom with impervious geotextile. Just below the geotextile, enough pervious material is provided so that the underlying deposit can be drained through it. This scheme is proved to be effective through theoretical analysis.

• 한국방재학회 논문집
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• 제9권2호
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• pp.1-9
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• 2009

물-결합재비 0.4이하의 고성능 콘크리트 수축 변형을 파악하기 위해 전체 수축을 수분의 외부이동에 의한 건조수축과 수분의 내부소모에 의한 자기수축으로 분리한 후, 자기건조에 의한 상대습도 변화와 변형률의 관계를 묘사하기 위하여 계면역학적 접근법에 의한 습도-변형률 관계를 설정하였다. 이에 대한 검증을 위해 자기수축 시험체에서의 습도-수축 측정을 수행하였으며, 기존 연구 모델인 Tazawa, CEB-FIP 모델에 비하여 측정값과 가장 유사한 결과를 나타내어 본 연구에서의 자기수축모델은 자기건조에 따른 자기수축은 선형성을 나타내는 수분의 외부이동에 의한 수축과는 달리 지수적 관계를 갖는 특성과 초기재령에서의 급속한 자기수축 발현 특성을 적절히 묘사하고 있음을 알 수 있었다. 이 후 본 연구의 수분이동-수축 모델을 반영하여 온도, 수분이동, 변형률 해석의 다중물리 모델 해석과 모형시험체 측정을 수행한 결과 매우 유사한 값을 나타내어 본 연구를 통해 측정된 수분의 내부소모에 의한 습도와 수축변형률을 고려한 다중물리모델은 타당할 것으로 판단된다.

• 한국지반공학회논문집
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• 제15권6호
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• pp.219-238
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• 1999

본 연구에서는 연약한 점토층 준설매립지반을 대상으로, 비교적 활발히 연구가 진행되고 있는 자중압밀 침하분야에 비해 상대적으로 연구성과가 미흡한 표토층의 건조수축특성 규명에 초점을 두고, 침투압밀시험, 부압시험 및 건조수축시험 등 실내시험을 시행하였다. 실내시험이 시행된 시료는 전라남도에 위치한 해남지구, 고금지구 및 고흥지구 등 3개 지구의 현장시료이며, 실내시험결과를 토대로 건조수축 관련특성을 분석하였다. 또한 Abu-Hejleh % Znidarcic가 제안한 연약한 세립점토 지반의 건조수축 침하이론 지배방정식을 유한차분형태로 표현하고 실내시험을 통해 파악된 해남지구 현장시료의 건조수축특성 등을 입력자료로 하여, 3차원 체적변화에 따른 건조수축침하를 수치적으로 예측하였다. 계속해서 자중압밀침하를 포함한 전체침하 예측치를 해남지구 현장에서의 10년간 실제 관측결과와 서로 비교하였다. 최종적으로는 건조수축특성에 관련된 변수들이 침하 등에 미치는 영향정도를 분석하였다. 특성 (불연속면의 방향 및 강도), 하중조건 및 암반사면의 기하학적 형상 등이다. 확률론적 해석에서 고려할 수 있는 불연속면의 방향 및 마찰각의 통계적 특성이 파괴형태를 고려한 암반사면의 안정에 큰 영향을 보였다. 암반사면의 안정은 굴착면의 방향에 가장 민감하였다. 예제분석을 통하여 개발된 파괴형태를 고려한 암반사면의 신뢰도모델은 암반사면의 안정성 조사에 성공적으로 적용할 수 있었다.

• Architectural research
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• 제14권4호
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• pp.153-161
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• 2012

This paper presents an integrated procedure to predict the temperature and moisture distributions in hardening concrete considering the effects of temperature and aging. The degree of hydration is employed as a fundamental parameter to evaluate hydro-thermal-mechanical properties of hardening concrete. The temperature history and temperature distribution in hardening concrete is evaluated by combining cement hydration model with three-dimensional finite element thermal analysis. On the other hand, the influences of both self-desiccation and moisture diffusion on variation of relative humidity are considered. The self-desiccation is evaluated by using a semi-empirical expression with desorption isotherm and degree of hydration. The moisture diffusivity is expressed as a function of degree of hydration and current relative humidity. The proposed procedure is verified with experimental results and can be used to evaluate the early-age crack of hardening concrete.

• 콘크리트학회논문집
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• 제23권4호
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• pp.441-448
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• 2011

이 연구에서는 실리카퓸 및 수축 저감제, 팽창재, 고성능 감수제의 혼입을 변수로 한 초고성능 시멘트 복합체(UHPCC)의 초기 수축 거동을 평가하기 위하여 화학수축 및 자기수축 실험을 수행하고, 응결 측정 결과와 비교하여 UHPCC의 자기건조 시작 시점에 대하여 분석하였다. 실험 결과, 실리카퓸 및 수축 저감제는 초기 화학수축을 증가시키는 경향을 보였으며, 고성능 감수제는 시멘트와 배합수의 수화 반응을 지연시키고 화학수축을 저감시키는 것으로 나타났다. 수축 저감제와 팽창재를 조합하여 적용한 경우 약 49%의 자기수축 저감 효과를 보였으며, 팽창재는 경화를 촉진 시키는 것으로 나타났다. 또한 UHPCC는 다수의 섬유 혼입과 낮은 물-결합재비에 의해 초결 이전부터 자기건조 현상이 발생하는 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1412-1419
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• 2005

Preventing the infiltration of rainwater into the landfill site is the main purpose of the final cover in landfill sites. Compacted clay layer or geomembrain have been used as a conventional landfill final cover. But they have several disadvantages when damages might occur due to puncturing, differential settlement and desiccation or freeze and thaw. For this reason, as an alternative method SRSL(Self Recovering Sustainable Liner) has been developed. Adopting the precipitation reaction of two chemical material, by forming precipitates that fill the pores, and lower the overall permeability of the liner. The advantage of this method is that when fracture of the liner occurs the remaining reactants of the two layers form precipitates that fill the fracture and recover the low permeability of the liner. In this study, the recovering ability of the SRSL with a crack due to the seasonal variation or differential settlements was investigated by permeability tests. And in order to estimate the durability of the SRSL after freeze/thaw and desiccation, uniaxial compression strength tests were performed.