• Computers and Concrete
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• 제6권1호
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• pp.19-40
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• 2009

This paper describes the development of modified heat of hydration and maturity-strength models for concrete containing fly ash and slag. The modified models are developed based on laboratory and literature test results, which include different types of cement, fly ash, and slag. The new models consider cement type, water-to-cementitious material ratio (w/cm), mineral admixture, air content, and curing conditions. The results show that the modified models well predict heat evolution and compressive strength development of concrete made with different cementitious materials. Using the newly developed models, the sensitivity analysis was also performed to study the effect of each parameter on the hydration and strength development. The results illustrate that comparing with other parameters studied, w/cm, air content, fly ash, and slag replacement level have more significantly influence on concrete strength at both early and later age.

• 콘크리트학회논문집
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• 제21권6호
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• pp.729-735
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• 2009

이 연구에서는 산업부산물을 재활용하는 차원에서 화학비료공장의 인산제조과정 중 부산물로 발생되는 인산부산석고($CaSO_4/H_2O$)를 이수석고 형태인 건조석고, 반수석고, III형 무수석고, II형 무수석고로 실험용시료를 제조하여 화학분석을 통해 그 석고의 품질특성을 분석하고 조건별로 제조된 석고를 각각 3.0%씩 고로슬래그 시멘트에 첨가하여 시멘트 품질에 미치는 영향을 연구하였다. 그 결과 석고의 제조 조건에서 온도가 높아질수록 석고의 품질이 향상되는 결과가 확인 되었으며 $700^{\circ}C$ 소성조건인 II형 무수석고에서 시멘트 품질에 영향을 미칠 수 있는 수용성인산($S-P_2O_5$)이 현저히 낮아지는 경향이 나타났다. 또한 고로슬래그 시멘트 적용 실험 결과 II형 무수석고에서 재령 3일 압축강도와 건조수축 길이변화가 양호한 것으로 나타났고 재령 56일에서 압축강도는 반수석고, III형 무수석고, 건조석고, II형 무수석고 순으로 높게 나타나는 경향을 보였다.

• 대한건축학회논문집:구조계
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• 제34권5호
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• pp.13-18
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• 2018

In this research, regarding the type three blast furnace slag (BS) regulated by KS F 2563 and supplied to actual ready mixed concrete plant, the fineness on specification and actually measured fineness by Blain test were compared, and by applying the hydrometer method used for early prediction of concrete strength, the feasibility of the hydrometer method for acquisition inspection of BS was analyzed. Additionally, the influence of various fineness of BS on properties of cement mortar was also assessed. According to the experimental results of this research, correlation of fineness values between specification and actually measured data were not matched. In the case of the rapid evaluation method using hydrometer, a good relation was shown between the fineness data obtained from hydrometer and Blain test. furthermore, from the cement mortar properties test, there was a good relation was obtained between fineness data from rapid evaluation method by hydrometer and cement mortar properties, while there was no clear relation between fineness data from specification and cement mortar properties. Hence, as a qulity controlling method of BS fineness, a rapid evaluation method using hydrometer is suggested as a new method.

• 콘크리트학회논문집
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• 제17권3호
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• pp.473-480
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• 2005

In this study, a mix design for self compacting concrete was based on Okamura's method and concrete incorporated just a ground granulated blast furnace slag. Replacement ratio of slag is in the range of $20-80\%$ of cement matrix by volume. For the optimal self compactability in mixture incorporating ground granulated blast furnace slag, the paste and mortar tests were first completed. Then the slump flow, elapsed time of 500mm slump flow, V funnel time and filling height by U type box were conducted in concrete. The volume of coarse aggregate in self compacting concrete was in the range of $50-60\%$ to the solid volume percentage of coarse aggregate. Finally, the compressive and splitting tensile strengths were determined in the hardened self compacting concrete incorporating ground granulated blast furnace slag. From the test results, it is desirable for self compacting concrete that the replacement of ground granulated blast furnace slag is in the range of $40-60\%$ of cement matrix by volume and the volume of coarse aggregate to the solid volume percentage of coarse aggregate with a limit of $55\%$.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.501-504
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• 2006

Recycled aggregate mortar contains plenty of calcium hydroxide to improve the strength of blast furnace slag, although the surface mortar made of recycled aggregate deteriorates adhesion to cement paste and blast furnace slag has a low initial strength. Therefore, this study assumes that the combination with both recycled aggregate and blast furnace slag will produce a better performance. The results of the experiment show that dry mortar made of recycled aggregate provides with higher strength than wet mortar does at the 3-day and 7-day age, while lower at the 28-day age. It indicates that a large amount of cement mortar made of dry recycled aggregate has deteriorated adhesion strength. The mixes with 30% and 50% of blast furnace slag and 50% and 75% of recycled aggregate provide with much better strength at the 7-day age, although they usually have latent hydraulic property at the 28-day age. It indicates that calcium hydroxide($Ca(OH){_2}$) in recycled aggregate has affected ground granulated blast furnace slag.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.556-559
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• 2004

In this Paper, concrete durability, coefficient variation of compressive strength, and hydration heat development characteristics of concrete using different types binder for 2nd Phase Construction in IIA were investigated. The experimental results show that the coefficient variation of compressive strength decreased with the slag cement when compared with the replacement of granulated blast furnace slag powder. And the diffusion coefficient of chloride ion decreased with use of a blended cement when compared with using a only portland cement. Also the type of low heat cement is very suitable to reduce the thermal crack caused by hydration heat development.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.489-492
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• 2006

A chloride is an important deteriorating factor which governs the durability of the reinforced-concrete structures under marine environments. Also, the main penetration mechanism of chloride ion into concrete is a diffusion phenomenon and numerous methods have been proposed to determine the diffusion coefficient of chloride ion quickly. In this study, electrically accelerated experiments were carried out in order to evaluate diffusion coefficient of the chloride ion into concrete. The methods were diffusion cell test method in which the voltage of 15V(DC) was applied. The type of cement is blended cement in which the admixtures of blast-furnace slag and fly ash were used. In conclusion, the diffusion coefficient of chloride ion is much affected according to mineral admixtures and the diffusion coefficient of ternary blended cement showed very low values. it is presumably said that this result is due to highly densified pore structures by the aid of slag substitution and pozzolanic activity of fly ash.

• 한국건축시공학회지
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• 제11권6호
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• pp.547-556
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• 2011

경화 콘크리트의 물성에 있어서 황산염 저항에 가장 큰 영향을 미치는 두 요소로서 포틀랜드 시멘트의 화학적 성분과 그 양을 들 수 있다. 본 연구에서는 황산염 침투에 대한 영향을 고찰하기 위하여 ASTM C1012의 규정을 바탕으로 여러 종류의 모르타르를 제작하여 실험을 수행하였다. 본 연구에서 황산염 침투에 대한 영향을 평가하기 위해 TYPE I, 두 가지의 TYPE I-II 시멘트와 TYPE V의 시멘트 등 네 가지 모르타르를 사용하여 실험을 수행하였다. 또한 각각의 모르타르 혼합물들에 사용된 무기혼합물의 경우에도 세 가지 종류를 사용하였다. F타입 플라이애시와 C타입 플라이애시, 고로슬래그를 부피비를 기준으로 대체하여 사용하였으며, 실험을 통한 콘크리트의 팽창률을 ASTM 규정의 권장 팽창 기준을 바탕으로 비교 분석하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.33-39
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• 1999

This study was conducted to confirm the effect of bypass dust on the hydration and mechanical properties of the cement pastes and mortar obtained from ordinary Portland cement (OPC), OPC-slag and OPC-fly ash system. The rate of heat evolution is accelerated with the content of By-pass Dust(BD). total heat evolution increased because alkali-chlorides activated the hydration of blended cement. Compressive strength and bound water content show maximum value at 5wt% By-pass Dust(BD) on each curing time in ordinary Portland cement and slag blended cement. Ca(OH)2 content of Ordinary Portland Cement increased as the content of BD and curing time. In blended cement, the formation of Ca(OH)2 is active at early hydration stage. By pozzolanic reaction, the content of Ca(OH)2 is decreased as curing time goes by. According to the BD content stable chlorides complex of Friedel's salt (C3A·CaCl2·10H2O) is created. Due to the hydration activation effect of chlorides and alkali we observed Type II C-S-H, which developed into densest microstructure.

• 자원리싸이클링
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• 제33권3호
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• pp.12-20
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• 2024

세계 시멘트 산업의 온실가스 배출량은 약 29억 톤이며, 이중 17.4~18.9억 톤이 시멘트 클링커의 주원료인 석회석으로부터 배출된다. 따라서 비탄산 CaO 원료인 슬래그류 사용이 연구되어야 하며, 이때 시멘트의 물리적 특성도 충분히 발현되어야 한다. 본 연구에서는 슬래그류 사용에 따른 혼합원료 배합 조건과 시멘트 물성을 분석하였다. 슬래그류 단독 사용 시 CaCO₃ 대체율은 한계를 갖으나, 혼합 슬래그 사용 시 CaCO₃ 대체율이 12 % 이상 증가하였다. 단독 슬래그 사용 시멘트의 압축강도는 OPC 대비 감소하였으며, 압축강도 증진을 위해 혼합원료의 LSF 및 시멘트 분말도를 상향시켰다. 분말도 상향 시멘트의 압축강도는 CaCO3₃ 대체율 6 %까지 OPC와 유사하였으나, 9 % 이상에서는 소폭 하락하였다. 하지만 혼합 슬래그 사용 시멘트의 분말도와 LSF를 모두 상향 시, CaCO₃ 대체율 12 % 시멘트도 OPC와 유사한 압축강도가 발현되었다. 또한 CaCO₃ 대체율 12 % 시멘트의 플로우 값도 OPC와 유사하였다.