• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1211-1214
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• 2000

The purpose of this paper was to study of blast furnace slag cement of high early strength and replacement ordinary portland cement. we prepared the specimens of cement and concrete with various mixing proportions of elementary materials. For example, clinker, gypsum(1~10%), fineness $4, 000~6, 000cm^2/g$ of blast furnace slag(30~50%), limestone etc. As a result of this study, fineness $(4, 000cm^2/g)$ blast furnace slag was of used replacement ordinary portland cement and fineness $(6, 000cm^2/g)$ blast furnace slag was of used blast furnace slag cement of high early strength.

• 한국세라믹학회지
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• 제53권2호
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• pp.215-221
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• 2016

In this study, the utilization of the by-products of various industries was examined using raw materials of CSA high-functional cement such as coal bottom ash, red mud, phosphate gypsum, etc. Technology to improve energy efficiency and reduce $CO_2$ was developed as part of the manufacturing process; this technology included lower temperature sintering ($150{\sim}200^{\circ}C$) than is used in the OPC cement manufacturing process, replacement of CSA cement with the main raw material bauxite, and a determination of the optimum mix condition. In order to develop CSA cement, a manufacturing system was established in the Danyang plant of the HANIL Cement Co. Ltd., in Korea. About 4,200 tons of low purity expansion agent CSA cement (about 16%) and about 850 tons of the lime-based expansion agent dead burned lime (about 8%) were produced at a rate of 60 tons per hour at the HANIL Cement rotary kiln. To improve the OPC cement properties, samples of 10%, 13%, and 16% of CSA cement were mixed with the OPC cement and the compressive strength and length variation rate of the green cement were examined. When green cement was mixed with each ratio of CSA cement and OPC cement, the compressive strength was improved by about 30% and the expansibility of the green cement was also improved. When green cement was mixed with 16% of CSA cement, the compressive strength was excellent compared with that of OPC cement. Therefore, this study indicates the possibility of a practical use of low-cost CSA cement employing industrial wastes only.

• 한국구조물진단유지관리공학회 논문집
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• 제18권1호
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• pp.84-92
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• 2014

본 연구는 조강시멘트와 경화촉진제를 사용하여 조기강도 발현의 메커니즘을 분석하는 것이 목적이다. 연구결과 경화촉진제는 시멘트와의 수화반응시 $Ca(OH)_2$의 촉진시키는 것을 TG/DTA 실험을 통하여 검정하였다. 압축강도 측정결과 경화촉진제의 사용량이 증가 할수록 초기압축강도가 증가하는 것을 알 수 있었다. 또한 미소수화열 측정결과 경화촉진제는 시멘트의 성분중 $C_3S$의 수화반응을 촉진시키는 것으로 나타났다. XRD분석결과 재령별 수화생성물을 확인할 수 있었으며 경화촉진제의 사용량이 증가할수록 수화물들의 피크점이 높게 나타나는 것을 알 수 있었다. SEM찰영을 한 결과 촉진제의 첨가량에 따라 $Ca(OH)_2$의 생성과 재령에 따라 C-S-H의 형상을 관찰할 수 있었다. 따라서 본 연구에서 사용된 경화촉진제는 초기강도발현 시키는 것에 대해 효과적인 것을 확인 할 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.105-110
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• 1998

The purpose of this was to examine the used of fly ash as a type of construction material. In this paper the results from a recent study on development of a cement composite utilizing relatively large amount of fly ash are presented. The flowable fly ash-cement sand composite was investigated for strength and flowability characteristics. The independent variable considered were: fly-ash content, sand content, and ratio of water to cementitious materials. Results of this study show that high volume fly-ash composite can be proportioned to obtain 10~15kg/$\textrm{cm}^2$ compressive strength at 28 days. For applications requiring strength between 10kg/$\textrm{cm}^2$ and 15kg/$\textrm{cm}^2$, the mixture with fly ash-cement ratio of 5.6 and sand-cement ratio of 28 with relatively high water content may be used. Slump was held at 25$\pm$1cm for all mixtures produced compressive strength at 28 days were found to range from 5kg/$\textrm{cm}^2$ to 13.7kg/$\textrm{cm}^2$.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.159-162
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• 2006

This study generally compared and investigated cement type and quality of China and Korea. Cement in Korea is divided into five such as ordinary, high early strength, moderate heat, low heat and sulfate resistance portland cement. However cement in China is divided into portland cement($P{\cdot}I,\;P{\cdot}II$) and ordinary portland cement($P{\cdot}O$) with admixture displacement ratio and it is again divided into 6 level and 7 level with 28 days compressive strength. In addition China classified cement into several standards, such as Mgo, SO3,, igloss, blame, setting time, stability, strength, alkali and sampling test. Therefore it should be careful to conclude so quickly without right understanding whether quality of China cement is bad or good. The better way to evaluate China cement is synthetically understanding a value engineering and consumer awareness.

• 한국농공학회지
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• 제14권3호
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• pp.2677-2684
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• 1972

시멘트의결경화촉진(疑結硬化促進)으로 콘크리트의 초기압축강도(初期壓縮强度)를 얻음으로서 한중(寒中)콘크리트 공사시(工事時) 동해(冬害)를 예방(豫防)하고 보다 안전(安全)하게 구조물(構造物)을 축조(築造)하는데 도움을 얻고자 일반(一般) 포트랜드시멘트(TYPE I) 조강(早强)시멘트(TYPE II) 및 포조란시멘트를 사용(使用)하여 본시험(本試驗)을 실시(實施)한 것이다. 이상(以上)의 결과(結果)를 요약(要約)하면 다음과 같다. 1. 보통(普通)포트랜드시멘트(TYPE I) 보다 조강(早强)시멘트(TYPE II)가 초기강도(初期强度)가 높았고, 2. 조강(早强)시멘트로 만든 콘크리트 초기강도(初期强度)의 증진(增進)으로 공기(工期)를 최대한(最大限)으로 단축(短縮)시킬수 있어 한중(寒中)콘크리트 공사시공(工事施工)에 적합(適合)하겠다. 3. 조강(早强) 및 포조란은 높은 분말도(粉末度)로 외기(外氣)에 대(對)한 풍화작용(風化作用)이 촉진(促進)될 우려(憂慮)가 있으므로 저장기간(貯藏期間)이 짧아야 하겠다. 4. 국내(國內)에서 생산(生産)되는 포조란시멘트가 조강현상(早强現象)을 나타냄으로 이에 대(對)한 시험(試驗)이 계속 필요(必要)하겠다. 이상(以上)의 결과(結果)는 공사현장(工事現場)에서 유효하게 적용(適用)될 것으로 믿는다.

• 콘크리트학회논문집
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• 제12권2호
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• pp.79-87
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• 2000

The strength development of concrete is influenced by temperature and cement type which greatly affect hydration degree of cement. There is not pertinent concrete strength management methods for estimating the in-place strength of concrete. One such method is the maturity concept. The maturity concept is based on the fact that concrete gains strength with time as a result of the cement hydration and, thus the rate of hydration, as in any chemical reaction, depends primarily on the concrete temperature during hydration. Thus, the strength of concrete is function of its time-temperature history. This goals of the present study are to investigate a relationship between strength of high-fluidity concrete and maturity that is expressed as a function of an integral of the curing period and temperature, predict strength of concrete.

• 콘크리트학회논문집
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• 제27권2호
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• pp.115-125
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• 2015

본 연구는 물-결합재비 20%를 가지는 고강도 고함량 고로슬래그 혼합 시멘트 페이스트의 유동성, 수화열, 응결시간 그리고 강도 발현 특성, 수화 및 포졸란 반응 특성 등을 실험을 통해 관찰하고, 이를 통해 고로슬래그 미분말의 치환률과 분말도가 수화 및 포졸란 반응에 미치는 영향을 분석하였다. 연구 결과에 따르면 물-결합재비가 낮은 고강도 배합에서는 고로슬래그 미분말로 시멘트를 대체함으로써 시멘트와 결합하는 자유수가 상대적으로 증가하는 dilution effect에 의해 시멘트의 초기 수화가 촉진되어 재령 3일부터 28일까지의 초기 강도는 보통 포틀랜드 시멘트만을 사용한 배합보다 더 높게 나타났다. 반면, 재령이 증가하면서 수화반응속도가 급격히 낮아지고, 고로슬래그 미분말로 시멘트를 대량 치환함에 따라 수산화칼슘이 충분히 공급되지 못하므로 포졸란 반응도가 낮아져 장기강도의 발현이 억제되는 것으로 나타났다. 또한 고로슬래그의 분말도가 높으면 자유수를 더 많이 흡착함으로써 유동성이 저하되고 수화도가 낮아져 강도가 오히려 저하되는 것으로 나타났다. 이와 같은 결과는 보통 강도 콘크리트와는 다른 경향을 나타내는 것으로 향후 콘크리트 배합에 대해 추가 검증이 필요하며, 고로슬래그 미분말을 대량 혼합한 고강도 콘크리트의 개발을 위해서는 장기 강도의 발현율을 더 높일 수 있는 방안에 대한 연구가 필요하다.

• 한국세라믹학회지
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• 제31권12호
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• pp.1536-1544
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• 1994

DSP technique was applied to improve the high strength characteristics of hardened cement paste using pozzolan materials as blending materials, and pozzolan reactivity was investigated. Pozzolanic materials such as diatomaceous earth, fly ash and hydrated silica were used as blending material. And also superplasticizer was added to cement for molding the specimens. After curing for 60 days, the specimens substituted with 10 and 15 wt% of diatomaceous earth showed better strength characteristics than the specimen with fly ash. The specimen substituted 7 wt.% of hydrated silica exhibited excellent strength with above 800 kg/$\textrm{cm}^2$.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.85-88
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• 2006

This study describes the optimum mix proportion of the high strength and self-compacting concrete placed in main structures of LNG above tank. This concrete requires high strength level about $60{\sim}80MPa$, low hydration heat, balance between workability and consistency without vibrating in the actual work. For this purpose, low heat portland cement and fly ash are selected and design factors including water-binder ratio, replacement ratio of fly ash are tested. As experimental results, low heat portland cement shows lower the confined water ratio than another cement type and the optimum replacement ratio of fly ash in order to improve properties of the binder-paste shows 10% by cement weight considering test results of the confined water ratio$({\beta}p)$. Also, flowability of the high strength and self-compacting concrete by using fly ash about $10{\sim}20%$ is improved. The replacement ratio of fly ash 10% and water-binder ratio $25{\sim}27%$ are suitable to the design strength 80MPa and cost, In case of the design strength 60MPa, the replacement ratio of fly ash and water-binder ratio show 20% and $25{\sim}30%$ separately. Based on the results of this study, the optimum mix proportions of the high strength and self-compacting concrete will be applied to the construction of LNG above tank as a new type.