• 한국건설순환자원학회논문집
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• 제9권4호
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• pp.419-424
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• 2021

콘크리트의 압축강도 추정에 널리 사용하는 반발경도법을 이용하여 콘크리트 표면의 동해손상을 초기에 판정할 수 있는 가능성을 검토하고자 하였다. 이를 위하여 동결융해 열화조건에 다면으로 노출된 콘크리트와 단면으로 노출된 콘크리트에 대하여 반발경도와 상대동탄성계수를 측정하여 콘크리트 표면 손상도를 비교하였다. 반발경도에 의한 동해손상이 단면 노출 콘크리트 시험체에 대해서는 150싸이클 빠르게 계측되었으며, 다면 노출 시험체에 대해서는 50싸이클 빠르게 계측되었다. 따라서 반발경도법이 공명진동법보다 콘크리트 표면 손상을 신속하게 판정할 수 있는 것으로 사료된다

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.183-188
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• 2002

When Concrete work during winter is placed, it has anxiety that concrete freeze at low temperature. As concrete's freezing cause reduction of durability, it is necessary for mixing to pay attention to Air content and W/C ratios. Accordingly, in this study, we set up three series and evaluate a frost-resistance of concrete with admixture, like fly-ash and blast-furnace slag, for early curing method and types of chemical admixture..The study is composed as; I series : Analysis for early curing method and types of chemical admixture in laboratory II series : Analysis for early curing method and types of chemical admixture in batcher plant and measured concrete' temperature. The result of this study, it was more effective the use of super-plasticizers than air entraining agent.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.51-52
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• 2011

This study is to propose a curing method for a concrete wall structure under severe cold climate. The curing methods of using heated cable, heated panel and insulated form were applied. Results showed that the concrete cured by the heated cable resulted in the highest temperature history and the highest strength development at 28 days. Further, it is believed that the curing methods of the heated panel and insulated form are also recommendable for the resistance of the early frost damage on the concrete in practice.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3411-3420
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• 2014

Deficiencies in wear and frost resistance as well as mechanical strength constitute the main causes of equipment failure under the harsh climatic conditions of the Earth's polar regions. To improve the properties of the materials used in this equipment, nanoparticle composites have been prepared from clays such as kaolinite, hectorite, and montmorillonite in combination with polytetrafluoroethylene (PTFE) or ultrahigh molecular weight polyethylene (UHMWPE). A number of techniques have been proposed to disperse silicate particles in PTFE or UHMWPE polymer matrices, and several successful processes have even been widely applied. Polymer nanocomposites that exhibit enhanced mechanical and thermal properties are promising materials for replacing metals and glass in the equipment intended for Arctic use. In this article, we will review PTFE- and UHMWPE-based layered silicate nanocomposites.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.193-198
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• 2005

The solar energy floodgate which discusses will minimize a quotient bringing up for discussion friction resistance and it will do to write a disturbance power, with the base which will reach it will be able to use the solar power unit in order. It is a plan which to magnification supply the practicality and will give proof will the effort with the irrigation facility of the farming village. Magnification supply of the solar energy floodgate which it sees hazard the stack supervisor and the possibility the use against the farmer and the easy frost does the monitoring against and the work which it complements is necessary.

• 한국구조물진단유지관리공학회 논문집
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• 제1권2호
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• pp.123-130
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• 1997

The effect of experimental factors on the Freeze-Thaw durability in the High Strength Concrete has been analyzed and investigated with [DESIGN of EXPERIMENT: L16). The Experimental parameters included the type of aggregate and mixer, the conditions of aggregates, and the difference of mixing temperature, procedure and placing, etc. It is aim of this study to provide the fundamental data on the effect of various factors on the frost resistance of high strength concrete for the practical use and research data accumulation of durability inspection. The results of this experiment indicate that the freeze-thaw durability of high strength concrete is markedly affected by the coarse aggregate source, mixing temperature and curing conditions.

• 한국건설순환자원학회논문집
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• 제5권3호
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• pp.275-281
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• 2017

본 연구에서는 플라이애시(FA)의 정제가 시멘트 모르타르의 제반 품질에 미치는 영향을 고찰하고자 하였다. 본 연구에서 사용된 플라이애시는 원분플라이애시, 정제플라이애시, 리젝트애시 및 이들의 조합으로 5수준으로 선정하였고, 모르타르 배합비는 1: 1, 1 : 3 및 1 : 5의 3수준으로 계획하였다. 본 연구의 실험결과로 먼저 플로는 모든 배합비에서 원분인 Ra 사용시 Rf 보다 낮은 유동성을 나타내었다. 또한 Rj의 경우는 낮은 유동성을 보일 것으로 예상하였으나, Rf와 동등하거나 그 이상의 유동성을 나타내었다. 공기량의 경우 Rf와 Rj를 제외한 모든 배합이 목표 범위에 만족하지 못하였다. Ra를 사용한 배합의 경우 정제과정을 거친 Rf보다 약 41% 낮은 공기량을 나타내었으며, Rj의 경우 모르타르 내부 다공질의 이물질 등으로 인해 Rf 보다 약 19% 높은 공기량을 나타내었다. 압축강도의 경우 초기 3, 7일에서는 Plain인 OPC에 비해 낮은 압축강도를 나타내었으나, 28일 이후에는 양호한 품질인 Rf의 포졸란 반응으로 인해 여타의 FA 보다 높은 강도를 발휘하였으며, 배합비 1 : 1 및 1 : 3에서는 OPC보다 높은 강도를 확보할 수 있음을 확인하였다. 내동해성으로 정제되지 않은 FA를 사용한 경우 공기량 감소로 인해 내동해성에 취약한 것으로 분석되었다. 따라서 정제과정을 거친 양질의 FA 사용은 콘크리트의 경제적인 배합과 구조물의 안정성에도 긍정적인 기여를 할 것으로 판단되었다.

• 한국산림과학회지
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• 제28권1호
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• pp.31-35
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• 1975

본 실험(實驗)은 단기(短期) 저온처리(低溫處理)가 3개의 사과 품종(品種)과 양앵두의 휴면타파중(休眠打破中)인 가지(枝)의 내한성도(耐寒性度)에 미치는 효과(効果)를 연구하였다. 단기(短期) 저온(低溫)처리 효과는 저온(低溫)처리 후의 해빙(解氷)처리에 따라 다르게 나타났다. 해빙(解氷)처리와 함께 $-9^{\circ}C$까지의 결빙온도(結氷溫度)가 3시간(時問) 및복되어 처리되었을 때 사과 및 양앵도의 내한성도(耐寒性度)는 저온(低溫)처리에 의하여 $3{\sim}9^{\circ}C$ 만큼 뚜렷하게 높아졌다. 이와 반대로 해빙(解氷)처리가 없이 결빙온도(結氷溫度)($-9^{\circ}C$)가 10시간 전처리(前處理)되었을 때 내한성도(耐寒性度)는 저온(低溫)처리에 의하여 아무런 영향을 받지 않았다. 자연(自然)에서 일어나는 온도(溫度)의 결빙(結氷)-해빙(解氷) 반복의 역할은 위와 같은 자연적(自然的)인 온도(溫度) 자극이 휴면(休眠)이 깨어나고 있는 나무의 내한성(耐寒性)을 증진(增進)하여 초봄에 일어나는 만상(晩霜)의 피해(被害)에 적응(適應)할 수 있도록 하는데 있다고 고찰(考察)되었다.

• Structural Engineering and Mechanics
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• 제90권5호
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• pp.467-480
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• 2024

The mechanical properties and durability of concrete pavements may be degraded in extreme situations, resulting in the need for partial repair or total replacement. During the past few decades, there has been a growing body of research on substituting a portion of Portland cement with alternative cementitious materials for improving concrete properties. In this study, two different configurations of powdered and granulated blast furnace slag were implemented, replacing fine aggregates (by 12 wt.%) and Portland cement (by 0, 20, 40, and 60 wt.%) in the making of roller-compacted concrete (RCC) mixes. The specimens were fabricated to investigate the mechanical properties and durability specifications, involving freeze-thaw, salt-scaling, and water absorption resistance. The experimental results indicated that the optimum mechanical properties of RCC mixes could be achieved when 20-40 wt.% of powdered slag was added to concrete mixes containing slag aggregates. Accordingly, the increases in compressive, tensile, and flexural strengths were 45, 50, and 28%, in comparison to the control specimen at the age of 90 days. Also, incorporating 60 wt.% of powdered slag gave rise to the optimum mix plan in terms of freeze-thaw resistance such that a negligible strength degradation was experienced after 300 cycles. In addition, the optimal moisture content of the proposed RCC mixtures was measured to be in the range of 5 to 6.56%. Furthermore, the partial addition of granulated slag was found to be more advantageous than using entirely natural sand in the improvement of the mechanical and durability characteristics of all mixture plans.

• 한국건축시공학회지
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• 제1권2호
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• pp.146-153
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• 2001

Radical development has been made in the every field of our society for the past scores of year. Radical development of industry and lining environment has mass-produced various toxic wastes . Which comes to the fore as a serious environmental problem. The purpose of this is to suggest the optima mix design by studying the utility of a toxic waste, plated sludge as a building material and deciding the standards of quality and use of cement and evaluating the properties of mortar and concrete in which plated sludge mixed. From an experiment, compressive strength required high early strength cement or special cement. Watertightness proved to be excellent. Heavy metals, such as Cd, Pb, Cu came out below an environmental standard. Cr+6 exceeded an environmental standard under a steam curing, but came out below an environmental under a standard curing. The higher replacement rate was, the lower frost, fusion and resistance were. Thus, got better results above the goal by condition. It was possible that plated sludge was replaced and solidified to aggregate. Therefore, it is necessary to define the standards of quality on strength, replacement rate of wastes, water permeability, endurance in other to solidify plated sludge to concrete products.