• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.628-631
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• 2004

In this paper, mechanical properties of concrete incorporating CKD are discussed with W/B and fluidity. For setting properties, an increase in W/B retarded setting time greatly in $5^{\circ}C$, while accelerated in $20^{\circ}C$. For fluidity, an increase in slump delayed the setting time with dosage of SP agent. The presence of CKD has little influence on setting time compared with plain concrete. For compressive strength, an increase in maturity enhanced compressive strength. Fluidity had no relation to compressive strength. At low curing temperature, concrete with CKD has slight strength loss compared with plain concrete. However, remarkable strength loss at low curing temperature in early stage was not found, which can be applicable to low temperature environment concrete placing.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.251-252
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• 2012

The exiting studies on the strength prediction by maturity method is mainly focused on concrete using OPC, meanwhile the study on the concrete mixing blast furnace slag powder (BFSP) is insufficient. The purpose of this study is to investigate the relationships between compressive strength and equivalent age by existing Maturity functions, i.e., Nurse-saul function Arrhenius function. This study also compared and examined the strength prediction of concrete mixing BGSP using ACI model and Logistic Curve prediction equation. Therefore, it is intended that fundamental data are presented for quality management and process management of concrete mixing BFSP.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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• pp.77-80
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• 2009

The purpose of the study was to examine engineering characteristics due to fine particle cement and gypsum contents to improve early strength of concrete substituted blast furnace slag powder. The results were as follows. Above all, For fluidity, generally all mixtures had lower fluidity than Plain mixture and was not satisfied target scope, but for mixture substituted the gypsum showed a little increasing trend. For air content, generally all mixtures compared to Plain mixture had decreasing tendency. However, all mixtures were satisfied target scope. For compressive strength, long-term strength was better than early strength according to ternary blast furnace slag contents was increased. For complex mixture was better than individual use of gypsum and fine particle cement.

• 한국건축시공학회지
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• 제14권1호
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• pp.37-44
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• 2014

건설산업에서는 탄산가스 저감을 위해 산업부산물을 다량 활용하는 기술개발을 위한 연구가 이루어지고 있다. 산업부산물 중 특히 고로슬래그 미분말은 잠재수경성에 기인하여 장기강도는 우수하나 초기강도가 낮기 때문에 많은 양을 대체하는데 한계가 있다. 이에 본 연구에서는 철강공정 중 용선예비처리 공정에서 발생하는 슬래그부산물을 활용하여 고활성 고로슬래그 미분말을 시험 제조후 고활성 고로슬래그 미분말의 모르타르 압축강도 강도발현 특성을 검토하였다. 또한, 고활성 고로슬래그 미분말 단독으로도 경화가 가능한 특징을 고려해서 2차 콘크리트 제품용 결합재로서 활용 가능성을 검토하고자 배합조건에 따른 콘크리트 제조 및 압축강도 발현특성을 검토하였다. 실험변수로써 슬래그부산물의 분말도, 치환율, 양생조건 및 W/B를 설정하였다. 그 결과 슬래그부산물을 자극제로 활용한 고활성 고로슬래그 미분말 모르타르의 압축강도 향상을 확인하였으며 고활성 고로슬래그 미분말이 단독으로도 경화가 가능하기 때문에 양생 및 배합조건을 고려하면 고활성 고로슬래그 미분말을 콘크리트 2차 제품용 결합재로서 활용 가능할 것으로 판단된다.

• 한국건축시공학회지
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• 제5권3호
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• pp.101-107
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• 2005

This paper reports the contribution of Shrinkage reducing admixture(SRA) to the physical properties and drying shrinkage of concrete. Dosage of SRA is varied with. For the properties of fresh concrete, an increase in SRA dosage results in a decrease in fluidity and air content, while setting time is accelerated. For the properties of hardened concrete, the incorporation of mineral admixture leads to a decrease in compressive strength at early age, whereas after 28 days, the incorporation of fly ash(FA) and blast furnace slag(BS) has greater compressive strength than conventional concrete without admixture. The use of SRA results in a decrease in compressive strength. The incorporation of SRA with every $1\%$ increase causes the decrease of compressive strength by as much as $3\~6\%$. For drying shrinkage properties, the incorporation of FA and BS reduces drying shrinkage slightly. The use of SRA also decreases drying shrinkage. Every $1\%$ of increase in SRA dosage can reduce drying shrinkage by as much as $10\~15\%$

• 콘크리트학회지
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• 제10권6호
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• pp.191-202
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• 1998

콘크리트의 강도발현을 양생온도와 재령의 함수로 나타내는 적산온도 방법은 시멘트 콘크리트의 강도추정에 폭넓게 사용되어 왔다. 본 연구에서는 열경화성인 불포화 폴리에스터 수지를 결합재로 한 경량 폴리머 모르터를 대상으로 하여 적산온도법에 의한 초기강도 추정방법을 구명하였다. 폴리머 모르터의 압축강도는 가사시간 및 강도발현성에 영향을 미치는 촉매 및 촉진제 첨가량을 변화시켜 실험하였으며, 또한 적산온도 이론식에 사용되는 기준온도를 산출하였다. 적산온도는 추정된 기준온도를 적용시킨 적산온도 이론식에의해 산출하였으며 경량폴리머 모르터의 압축강도는 적산온도-압축강도의 관계로부터 추정할 수 있었다. 이 연구에서 얻어진 적산온도법에 의한 경량 폴리머 모르터의 강도추정식은 열경화성 수지를 이용한 각종 폴리머 모르터나 콘크리트에도 적용가능할 것으로 판단된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.468-476
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• 2007

Generally, the strength of the field shotcrete is heavily dependent on the field mixing and spraying conditions so that it is different from the strength of the shotcrete mixed in laboratories. As a support member, the early strength of shotcrete unlike concrete as structural material is very important to the initial stabilization of the excavation face in tunnels. Therefore, the field methods to efficiently test the early strength of shotcrete have been highly required. This paper aimed to verify the pneumatic pin penetration test and the point load test for measuring the early strength of the field shotcrete. Through a series of uniaxial compression, pin penetration, and point load tests for the range of the early shotcrete strength, two equations to estimate reliably the uniaxial compressive strength by the pin penetration and the point load tests were derived. Field tests in working tunnel were carried out in order to estimate the economic efficiency. As a result, pin penetration method was proved to be the most effective method for testing the early strength of the field shotcrete.

• 한국농공학회논문집
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• 제59권6호
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• pp.19-27
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• 2017

This study investigated to predict the compressive strength of unsaturated polyester resin based polymer concrete using the maturity method. The test results show that the development of the compressive strength increased exponentially until an age of 24 hours. After 24 hours, the development of the compressive strength just increased gradually. This test result shows that the strength of unsaturated polyester resin based polymer concrete was developed mainly at the early age. Estimated datum temperature of unsaturated polyester resin based polymer concrete was $-20.67^{\circ}C$ which was much lower than of datum temperature ($-10^{\circ}C$) of Portland cement concrete. Also, this study result shows that the existing maturity index associated with Portland cement concrete was not applicable for polymer concrete because curing time of Portland cement concrete is different clearly with curing time of polymer concrete. The cause of different curing time was that there were different curing mechanisms between Portland cement concrete and polymer concrete. In order to best apply the experimental data to a model, CurveExpert Professional, the commercial software, was used to determine the predictive model regarding the compressive strength of unsaturated polyester resin based polymer concrete. As a result, Gompertz Relation or Weibull Model was an appropriate model as a predictive model. The proposed model can be used to predict the compressive strength, especially, it is more useful when the maturity is in the range between $40^{\circ}C{\cdot}h^{0.4}$ and $900^{\circ}C{\cdot}h^{0.4}$.

• 한국농공학회지
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• 제27권2호
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• pp.57-71
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• 1985

The characteristics of compaction and unconfined compressive strength were investigated by mixing with lime to all soils adjusted by given percentages of two kinds of clays to sand to obtain the most effective distribution of grain size and the optimum lime content for soil stabilization. In addition, unconfined compressive strength and durability tested by adding of sodium metasilicate, sodium sulfate, sodium carbonate, sodium gydroxide and magnesium oxide to lime-soil mixture mixed with 8 percent lime to adjusted soil having the mixing percentage of 60 percent of cohesive black clay and 40 percent of sand by weight to get the effect and the optimum content of chemicals. The results obtained were as follows; 1.With the addition of more lime, the optimum moisture content was increased, and the maximum dry density was decreased, whereas the more the amount of clay and the less was the maximum drt density. 2. In the soil having more fine grain size the unconfined compressive strength was larger in the earlier stage of curing period, in accordance with the longer period, the mixing percentages of sand to clay showing the maximum unconfined compressive strength, on the basis of 28-day strength, were 60% : 40% (black clay) and 40% : 60% (brown clay) respectively. 3. The reason why the soil adjusted with black clay was remarkably bigger in the unconfined compressive strength than ones adjusted with brown clay for all specimen of lime-soil mixture was the difference in the kind of clay, the amount of chemical compositions the value of pH. Black clay was mainly composed of halloysite that reacted with lime satisfactorily, whereas the main composition of brown clay was kaolinite that was less effect in the enhance of unconfined compressive strength. Also the difference of unconfined compressive strength was because black clay was larger in the amount of composition of calcium oxide and magnesium oxide in the value of pH affecting directly on the unconfined compressive strength of lime-soil mixture than brown clay. 4. In the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40%, on the standard of 7-day strength, the effect of chemical was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium hydroxide and sodium metasilicate. 5. The optimum amount of chemical being applicable to the maximum unconfined compressive strength of lime-chemical-soil mixture was 1 percent by weight for air dry soil in the case of adding sodium carbonated and 0.75 percent on sodium hydroxide, the unconfined compressive strength was increased continuously with increase of the amount of chemical up to 2 percent of chemical content is the lime-chemical-soil mixture added sodium metasilicate, sodium sulfate and magnesium oxide. 6. It was considered that the chemical played and accelerant role of early revelation of strength because the rate of increase of unconfined compressive strength of all of lime-chemical-soil mixtures was largest on the 7-day cured specimen. 7. The effect of test on freezing and thawing after adding suitable amount of chemical on the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40% was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium metasilicate and sodium hydroxide.

• 한국건설순환자원학회논문집
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• 제4권3호
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• pp.90-97
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• 2009

본 연구에서는 고로슬래그 미분말(이하 BS)사용 모르타르의 초기강도가 저하하는 문제점을 해결하고자 BS 20%치환 시멘트 모르타르에 자극제로 석고(이하 CS)와 고분말도의 미분시멘트(이하 FC)를 치환 사용한 경우의 기초적 물성을 검토한 것으로, 그 결과를 요약하면 다음과 같다. 먼저, 굳지않은 모르타르의 특성으로 유동성은 BS 치환율이 증가할수록 감소하였고, BS 20%에 CS를 치환한 경우는 치환율에 관계없이 큰 영향을 미치지 않은 것으로 나타났으며, FC를 치환한 경우는 치환율이 증가할수록 감소하는 것으로 나타났다. 압축강도는 BS 치환율이 증가할수록 초기재령에서 강도가 저하하는 것으로 나타났고, 재령 28일에서는 잠재수경성 반응에 기인하여 약간 증가하는 것으로 나타났다. BS 20 % 치환 모르타르의 초기 압축 및 휨 강도향상에 대하여 CS를 치환한 경우는 치환율이 증가함에 따라 초기재령에서 미소하게 증가하는 것으로 나타났고, FC를 치환한 경우는 치환율이 증가할수록 초기 및 28일 재령에서 강도가 크게 증가하는 것으로 나타났다. 종합적으로 BS 20% 치환 모르타르의 초기 강도 저하 문제의 해결로서 CS의 치환은 효과가 적고, FC 25%를 치환하여 사용하게 되면 OPC만을 사용한 Plain과 유사한 것으로 나타나 양호한 품질의 향상을 기대할 수 있을 것으로 분석된다.