• 한국건축시공학회지
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• 제9권5호
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• pp.71-77
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• 2009

시멘트 혼화용 폴리머 디스퍼션은 시멘트 모르타르 및 콘크리트 내부에서 폴리머 필림을 형성하여 각종 역학적성 질 및 내구성을 향상시킨다. 본 연구는 3종류의 폴리머 디스퍼션을 폴리머 시멘트비 0, 5, 10, 20%로 변환한 폴리머 시멘트 모르타르를 제작, 투수시험을 실시하여 투수성능을 실험하였으며, 더욱이 폴리머 시멘트 슬러리를 폴리머 시멘트 모르타르 표면에 도포하여 방수성능의 개선효과를 평가하였다. 또한 보통시멘트 콘크리트 표면에 폴리머 시멘트 슬러리를 도포하여 시멘트 콘크리트와 폴리머 시멘트 슬러리의 건조수축을 측정하였다. 그리고 기본적인 역학적 성상인 휨강도와 압축강도를 측정하여 보통 시멘트 모르타르와 비교 검토하였다. 연구결과, 폴리머 시멘트 모르타르는 보통 시멘트 모르타르에 비해 방수성능과 강도가 크게 개선되었으며, 폴리머 시멘트 슬러리의 건조수축은 시멘트 콘크리트에 비해 4-5배 크게 나타났다. 또한 향후 건조수축에 따른 접착성능의 영향성에 대한 연구가 진행되어야 할 것이다.

• 한국도로학회논문집
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• 제20권2호
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• pp.27-34
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• 2018

PURPOSES : It is necessary to prevent premature failure of concrete pavements caused by durability problems. The purpose of this study was to find factors affecting the durability of concrete pavements, and suggest improvement methods for existing concrete mix design. METHODS : Factors influencing durability were derived from laboratory test data for common field failure conditions and main properties of concrete cores taken from the field. The improvement of concrete properties was investigated by evaluating the performance of existing and proposed mix proportion designs and curing methods. RESULTS : The compressive strength and the absorbing performance of the low Blaine cement and the high-strength mixture were better than those of the Type I cement. Wet curing showed better compressive strength, elastic modulus, coefficient of thermal expansion, and absorption performance than air curing or compound curing. As a result of comparing concrete cores collected in the field, the sections with good durability showed good performance in terms of resistance to chloride ion penetration, absorption, and initial absorption rate. CONCLUSIONS : The absorption performance was considered as a possible foactor affecting durability of cement concrete pavements as a result of field core tests. In order to improve the durability of the pavement concrete, it is necessary to improve the existing mixtures and curing methods.

• Computers and Concrete
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• 제6권4호
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• pp.343-356
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• 2009

Experiments were designed to investigate the flow behavior of portland cement paste and concrete incorporating superplasticizers. The paste and concrete mixtures were subjected to prolonged mixing for up to 110 min at high temperature. The yield stress values of concrete and that of the corresponding cement paste were measured using a rotating rheometer and viscometer, respectively. The results reveal a weak linear correlation between the yield stress of concrete mixtures and that of the corresponding cement pastes. Results also indicate that the yield stress of concrete varies in a linear fashion with the elapsed time, while its variations with the temperature and superplasticizer dosage follow power and inverse power functions, respectively. In this study, the genetic algorithms (GA) technique was used to predict the yield stress of concrete considering various parameters, such as the mixing time, ambient temperature, and superplasticizer dosage. A sensitivity study was conducted to evaluate the ability of the GA equations thus developed to capture the effects of test parameters on the yield stress of concrete. It was found that the GA equations were sensitive to the effects of test parameters and provided yield stress predictions that compared well with corresponding experimental data.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.579-584
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• 2002

In this research, the physical properties of self compacting concrete using ground granulated blast furnace slag as a part of cement were investigated. Concrete using ground granulated blast furnace slag was prepared with various ground granulated blast furnace slag replacement(20~80 volume %) for cement and the quantities of coarse aggregate in concrete were 50%, 55% and 60% of ratio of absolute volume of coarse aggregate. The workability, flowing characteristics, air content and compressive strength of concrete using ground granulated blast furnace slag were tested and the results were compared with those of ordinary portland cement concrete. In the experiment, we acquired satisfactory results at the point of flowing characteristics and strengths of concrete using ground granulated blast furnace slag within tile replacement ratio of 50% and the optimum quantity of coarse aggregate in concrete was found to be 50%~55% of ratio of absolute volume of coarse aggregate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.163-166
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• 1999

In this paper, strength development of concrete using blast-furnace slag cement(BSC) and ordinary portland cement(OPC) are discussed under varius W/C and curing temperatures. According to the experimental results, strength development of BSC concrete is lower than that of OPC concrete in low temperature at early age and maturity. In high curing temperature, BSC concrete has higher strength development than that of low temperature regardless of the elapse of age and maturity. BSC has much effect on the strength development of concrete at the condition of mass concrete, hot weather concreting and the concrete products with the steam curing, which is influenced by high temperature.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.271-276
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• 1999

This study is performed to evaluate an elastic properties and acid-resistance of concrete using pine needle ash(PNA). Materials used for this experiment are PNA , normal portland cement, natural fine and coarse aggregate. Test results show that the highest ultrasonic pulse velocity , dynamic and static modulus of elasticity is achieved by 5% PNA filled PNA concrete, which has showed similar with those of thei normal cement concrete. Acid-resistance of PNA concrete is increased with increase of the contnet of PNA , it is 1.29 times of the normal cement concrete by 5% PNA fille PNA concrete an d2.57 times by 15% PNA filled PNA concrete . Accordingly , PNA concrete wil greatly improve the properties of concrete.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.319-323
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• 1999

This study is performed to evaluate the physical and mechanical properties and acid-resistance of oyster shell concrete. The result shows that the unit weights of concrete with oyster shell are decreased by 1∼2% than that of the normla cement concrete. The highest strength is achieved by 2.5% oyster shell filled oyster shell concrete, it is increased compressive strength by 4% , tensile strength by 6% and bending strength by7% than that of the normal cement concrete, respectively . The acid-resistanceis increased with increase of the content of oyster shell. It is 1.6 times of the normal cement concrete by 15% oyster shell filled oyster shell concrete. Accordingly, oyster shell concrete will improve the properties of concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.301-307
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• 1996

High flowing concrete has been made using a combination of much amount cementitious materials and addition of SP agents, so that it makes possible to high flowing properties of fresh concrete. In the fluid mechanical and rheological point of view, high flowing concrete is affected on the relation between cement paste and aggregate of volume. In this experimental study, it is measured high flowing concrete of slump-flow about 65$\pm$5cm according to 0.54~0.80 of volume ratio and to analysed the properties of high flowing concrete in fresh and hardened concrete. It is the aim of this study to consider the affection of high flowing properties accoring to cement paste to aggregate ratio of volume on the combination of concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.305-308
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• 2004

Cold weather concrete is the concrete which is used during construction under low-temperature' environment, and this kind of concrete has to be taken care not to be frozen in early ages of setting-hardening, It is specified in the Concrete Standard Specification(2003) as 'the cold weather concrete must be used on the weather condition under the average daily outdoor temperature below $4^{\circ}C$.' In this research, the mechanical characteristics and hydration heat on the cold weather concrete using high early strength portland cement were studied. As a result, the excellent quality was obtained and high early strength portland cement is expected to be used widely as the cold weather concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.285-286
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• 2009

고로슬래그미분말을 사용한 도로포장용 초속정시멘트 콘크리트의 염소이온 침투저항성을 실험적으로 고찰하였으며, 본 연구에서 얻은 데이터를 활용하여 고성능 시멘트콘크리트포장의 내구성 확보를 위한 재료개발을 목표로 한다.