• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.187-191
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• 2008

It is necessary to develop a technology for effectively controling explosive spalling of high strength concrete caused increasing construction of high rise building and putting up the fireproof standard of high strength concrete by MLTM (Ministry of Land, Transport and Maritime Affairs). Accordingly, it was investigated basic properties such as slump, air content and compressive strength, and fire resistance properties of high strength concrete using polypropylene fiber for field application as a countermeasure for explosive spalling of concrete on fire in this study, As a test result, it was confirmed that PP fiber is available as fire resistance method of high strength concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.395-398
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• 2005

In recent years, the applications of high-strength concrete have increased, and high-strength concrete has now been used in many parts of the world. The growth has been possible as a. result of recent developments in material technology and a demand for higher-strength concrete in Korea. In this study, we have an object to produce the ultra-high strength concrete(Super-Con) of over 100MPa with low price materials. First, the binders for Super-Con should be selected by the tests; setting time of paste, flow value and strength of mortar. From the test results, the binders are blended with ordinary portland cement, pulverized portland cement and silica fume. Fundamentally the compressive strength, frost resistance and chloride resistance are investigated.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
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• pp.21-25
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• 2008

It is the aim of this study to investigate the fire resistance design Guidelines for high-strength concrete structure for example compressive strength more than 40Mpa. It is well know that explosive spalling due to fire attack of high strength concrete is related to concrete failure. so, the purpose of this study introduce the fire A Studty on the Fire Resistance Design Guidelines for High-Strength Concrete Structures of AIK for the response of explosive spalling of high strength concrete.

• 한국안전학회지
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• 제29권5호
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• pp.116-122
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• 2014

Assessment of setting process of concrete is important as it provides useful information to schedule concreting work in construction site. Electrical impedance measurement method, which utilizes the change of electrical resistance of concrete, has been applied to assess setting process of cement-based materials. However, the applicability of the method has been demonstrated only for cement paste and mortar. The main purpose of this research is to develop the electrical impedance based setting process assessment for concrete. To this end, electrical impedance response model for concrete should be developed in advance since it is essential to estimate the electrical resistance of concrete from measured impedance response. The electrical resistance of concrete is a key parameter for the setting process assessment. In this study electrical impedance responses of the concrete in setting process are measured and analyzed. Thereby, an electrical impedance response model of the liquid state concrete is developed and schematically validated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.75-80
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• 2002

This study is to investigate the characteristic on the resistance of chloride infiltration concrete containing limestone powder The variables are the substitution ratio of slag powder and limestone powder. In order to study the effect slag powder and limestone powder, all mixtures were prepared at a fixed water/cement ratio, slump, and entrained air quantity. As results show that the strength and the resistance of chloride infiltration in concrete substitution 10%, 20% limestone powder, and 30%, 40% slag powder are positive.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.610-613
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• 2006

This paper is the fundamental study for manufacture of spalling resistance concrete and also analyses the mechanism and spalling resistance method with materials, mixture proportion and lateral confinement. The present work with the basic experiment achieved successful method for spalling resistance using both proper amounts of fiber contents and lateral confinement using metal lath. Moreover, the developed spalling resistance method was applied for full sized column construction in the Doosan We've Poseidon I field, located in Busan city. Authors investigated the physical properties examining workability, placeability and pumpability. These studies are continuously processing to develop new technology expecting remarkable impact on the spalling resistance and fire resistance performance of high-raise building construction in the future.

• Structural Engineering and Mechanics
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• 제78권2호
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• pp.199-207
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• 2021

In the present paper, an analytical model is proposed to determine the flexural and shear strength of normal and high-strength reinforced concrete beams with longitudinal bars, in the presence of transverse stirrups. The model is based on evaluation of the resistance contribution due to beam and arch actions including interaction with stirrups. For the resistance contribution of the main bars in tension the residual bond adherence of steel bars, including the effect of stirrups and the crack spacing of R.C. beams, is considered. The compressive strength of the compressed arch is also verified by taking into account the biaxial state of stresses. The model was verified on the basis of experimental data available in the literature and it is able to include the following variables in the resistance provision: - geometrical percentage of steel bars; - depth-to-shear span ratio; - resistance of materials; - crack spacing; - tensile stress in main bars; - residual bond resistance including the presence of stirrups;- size effects. Finally, some of the more recent analytical expressions able to predict shear and flexural resistance of concrete beams are mentioned and a comparison is made with experimental data.

• 한국구조물진단유지관리공학회 논문집
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• 제23권7호
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• pp.113-119
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• 2019

해안매립지에 건설되는 구조물은 해수로부터 유입되는 염소 및 황산염 이온 등의 화학적 침식에 의한 영향을 복합적으로 받는다. 염해는 콘크리트 내부의 철근을 부식시켜 구조물의 성능을 저하시킨다. 또한, 하수처리시설에서는 내부에서 발생되는 황산염에 의해 콘크리트가 열화되는 문제점을 가진다. 따라서 본 연구에서는 해안매립지에 건설되는 하수처리구조물에 적용할 수 있는 혼합형 저발열시멘트의 특성 및 내화학성을 평가하였다. 실험결과, 모든 배합조건에서 목표슬럼프 및 공기량을 모두 만족하였다. 동일 배합조건에서 LHC사용시 OPC 보다 슬럼프는 증가되고, 공기량은 감소하는 경향을 나타내었다. 압축강도 시험결과, 초기재령에서는 OPC의 강도발현이 빨랐으며, 28일 이후 LHC가 OPC보다 높은 강도를 나타내었다. 염소이온침투저항성 평가결과, LHC-B의 경우 56일 재령에서, "매우낮음" 단계의 염소이온침투저항성을 나타내 LHC의 내염해성을 확인하였다. 내화학성 평가 결과, 에폭시 처리 하지 않은 경우 LHC를 적용한 경우, OPC보다 약 18%정도 내화학성이 개선되는 것으로 나타났으며, 콘크리트 표면에 에폭시 공법 적용시 강도보존율이 95% 이상 확보 가능한 것으로 확인되었다.

• 한국도로학회논문집
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• 제14권4호
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• pp.1-8
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• 2012

PURPOSES : Skid resistance on pavements plays an important role in reducing the risk of vehicle skidding on wet surface particularly. Almost 9.3 percent of traffic accidents were occurred under rainy condition and these are over-represented in terms of the severity of the crashes. Recently, unusual weather conditions referred widely as the intensified rainfalls justify the need of a systematic management of skid resistance. In this context, the study carried out the observational study on the skid resistance characteristics of different types of pavement with the time passage. METHODS : This study measured the skid resistance with Pavement Friction Tester at three times within five years. The skid resistance measurement has followed the method suggested by ASTM. RESULTS : As the main results under the scope of this study, skid resistance of asphalt concrete has not nearly reduced with time. On the contrary, skid resistance of cement concrete has been rapidly reduced with time though the highest resistance was gained at the early observation. Porous asphalt concrete shows a steady decrease of skid resistance with time, anyway, the reduction rate according to the increase of measurement speeds is relatively lower than the others. CONCLUSIONS : Based on our study, skid resistance of the pavement should be regarded as one of the pavement management system, so periodic measurement should be made to assure road safety as a whole.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 봄 학술발표회 논문집
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• pp.152-157
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• 1994

Due to the recent shortage of river sand resulting from a rapid growth of concrete construction, sea sand is increasingly used in stead. It is, however, well noted that non-washed sea sand used in reinforced concrete causes to corrode reinforcing steel and to incur cracks in concrete, and thus eventually result in damage to concrete. In this study, therefore, measeres that increase the quality of concrete were used to protect the reinforcing steel against corrosion in reinforced concrete construction, and then the corrosion resistance of reinforcing steel compared and analyzed from low quality concrete to high quality concrete.