• Computers and Concrete
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• 제17권5호
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• pp.655-672
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• 2016

A predictive model for chloride binding isotherms of blended cements with various supplementary cementitious materials (SCMs) was established in this work. Totally 560 data points regarding the chloride binding isotherms of 106 various cements were collected from literature. The total amount of bound chloride for each mixture was expressed a combinational function of the predicted phase assemblage and binding isotherms of various hydrated phases. New quantitative expressions regarding the chloride binding isotherms of calcium-silicate-hydrate (C-S-H), AFm, and hydrotalcite phases were provided. New insights about the roles of SCMs on binding capabilities of ordinary portland cements (OPC) were discussed. The proposed model was verified using separate data from different sources and was shown to be reasonably accurate.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.126-127
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• 2016

In this research, the optimum combination of fly ash (FA) and blast furnace slag (BS) was deduced by analyzing the performance of high volume supplementary cementitious materials (SCMs) cement mortar depending on various combinations of cement, FA, and BS. As a result, increased workability was shown with increased the portion of FA, while air content, setting time, and compressive strength were decreased.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.125-126
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• 2021

Fly ash, has been widely used as one of the main supplementary cementitious materials (SCMs) in the world, to replace part of cement to significantly save energy and reduce greenhouse emission. Via mechanical activation, fly ash can replace more cement without impairing early age compressive strength. This study focuses on the strength-based evaluation of carbon dioxide emission for blended cement composite containing mechanically activated fly ash. Results indicate that under similar compressive strength, a prominent drop has been witnessed in embodied energy of binary cement and CO2 emission of the composite containing mechanically activated fly ash compared with those containing ordinary fly ash.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.315-316
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• 2023

In the present investigation, the chloride ion penetration resistance of nuclear power plant concrete with varying water-to-cement ratios was assessed. A comparative analysis was conducted on concretes that do not incorporate supplementary cementitious materials, such as fly ash, using permanently decommissioned nuclear structures as a reference. The objective is to employ this acquired data as a fundamental resource for the evaluation of the residual service life of nuclear power plant structures in subsequent studies.

• Structural Engineering and Mechanics
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• 제85권2호
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• pp.275-287
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• 2023

The use of environmental-friendly building materials is becoming increasingly popular worldwide. Compared to the normal concrete, rubber-based concrete is considered more durable, environmentally friendly, socially and economically viable. In this investigation, M20 grade concrete was designed and the fine aggregates were replaced with crumb rubber of two different micron sizes (0.221 mm and 0.350 mm). Fly ash (FA) and silica fume (SF) replaces the binder as supplementary cementitious materials at a rate of 0, 5, 10, 15, and 20% by weight. The mechanical properties of concrete including compressive strength, tensile, and flexural strength were determined. The polynomial work expectation validates the response surface approach (RSM) concept for optimizing SF and FA substitution. The maximum compressive strength (22.53 MPa) can be observed for the concrete containing 10% crumb rubber, 15% fly ash and 15% silica fume. The reduced unit weight of the rubberized concrete may be attributed to the lower specific gravity of the rubber particles. Two-way ANOVA with a significance criterion of less than 0.001 has been utilized with modest residual error from the lack of fit and the pure error. The predictive model accurately forecasts the variable-response relationship. Since, the crumb rubber is obtained from wasted tires incorporating FA and SF as a cementitious ingredient, it helps to significantly improve mechanical properties of concrete and reduce environmental degradation.

• International Journal of Concrete Structures and Materials
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• 제7권2호
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• pp.155-163
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• 2013

The use of sustainable technologies such as supplementary cementitious materials (SCMs), and/or recycled materials is expected to positively affect the performance of concrete mixtures. However, it is imperative to qualify and implement such mixtures in practice, if the required specifications of their intended application are met. This paper presents the results of a laboratory investigation of self-consolidating concrete (SCC) containing sustainable technologies. Twelve mixes were prepared with different combinations of fly ash, slag, and recycled asphalt pavement (RAP). Fresh and hardened concrete properties were measured, as expected the inclusion of the sustainable technologies affected both fresh and hardened concrete properties. Analysis of the experimental data indicated that inclusion of RAP not only reduces the ultimate strength, but it also affected the compressive strength development rate. The addition of RAP to mixes showed a consistent effect, with a drop in strength after 3, 14, and 28 days as the RAP content increased from 0 to 50 %. However, most of the mixes satisfied SCC fresh properties requirements, including mixes with up to 50 % RAP. Moreover, several mixes satisfied compressive strength requirement for pavements and bridges, those mixes included relatively high percentages of SCMs and RAP.

• 대한건축학회논문집:구조계
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• 제35권12호
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• pp.165-172
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• 2019

본 연구는 물결합재비 40 %인 일반강도 영역에서 FA, BS 및 FA+BS인 광물질 혼화재의 0~30 %의 치환율 변화가 분체계 고유동 콘크리트의 재료분리 저항성 등 제반 특성에 미치는 영향에 대하여 분석하였다. 특히 고유동 콘크리트에서 밀도가 작은 분체의 치환율을 증가시킬 경우 액상 콘크리트의 점성저하로 재료분리가 증대될 수 있지 않은지, 또한 J-ring시험으로 철근 장애부에 의한 재료분리 정도에는 영향을 미치지 않을지 등 제반특성을 검토 분석하였다. 실험연구 결과 Normal 시험의 경우는 기존의 이론과 같이 광물질 혼화재의 치환율이 증가할수록 레올로지적 측면의 점성증가로 재료분리가 방지되었다. 단, J-ring를 이용한 시험의 경우는 액상중 밀도저하로 양호하게 골재를 끌고 철근사이를 통과하지 못해 재료분리 방지에 큰 역할을 하지 못함을 알 수 있었다.

• 한국건설순환자원학회논문집
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• 제4권3호
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• pp.292-298
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• 2016

본 연구에서는 매스 매트 콘크리트에 있어, 상 하부를 구분하여 타설하는 실무조건을 고려하여, 상부 및 하부배합의 혼화재 종류와 치환율을 동일 및 달리하는 배합 조건 변화로부터 최적치를 도출한 다음, 실구조체에 적용하여 해석치와 실측치간을 비교하므로서, 혼화재를 활용한 매스콘크리트의 효율적인 수화열균열 저감방안을 제안하고자 하였다. 연구결과 먼저, 현장적용 전 사전검토를 위해 Midas gen을 이용하여 수화열 해석을 실시한 결과 상부는 OPC : FA = 85 : 15 배합, 하부는 OPC : FA : BS = 50 : 20 : 30 배합을 본 대상 구조물 매스 매트콘크리트의 최적배합으로결정하였다. 이를 적용한 실제 현장의 시험결과 슬럼프, 공기량 및 압축강도는 모두 목표범위를 만족하였다. 또한, 봄철 실제 현장의 매스 매트콘크리트의 온도특성으로 최적배합의 경우는 중심부의 최고 온도 약 $59^{\circ}C$, 표층부 온도 약 $49^{\circ}C$로 나타나, 약 $10^{\circ}C$의 온도차가 나타났으며, 수화열 해석결과 약 1.4의 균열지수를 나타내었다. 따라서, 실무를 고려한 매스 매트콘크리트의 경우 상 하부 타설 콘크리트간의 저발열 배합정도를 달리 고려하는 수화발열량차 공법적용은 침하균열 방지 및 수화열 균열제어에 효과적인 방법이 될 것으로 사료된다.

• 한국건설순환자원학회논문집
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• 제8권2호
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• pp.219-226
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• 2020

지난 수십 년 동안 건축 분야에서 발생하는 이산화탄소 배출을 줄이기 위한 방법으로 다른 산업계의 폐기물 및 부산물을 시멘트의 대체재로 접목하기 위해 많은 노력이 있었다. 양식 산업에서 발생하는 굴 패각 폐기물은 특정 지역에서 대량으로 발생하며, 적절한 처리 방법의 부재로 인하여 일반적으로 매립되어지고 있다. 본 연구에서는 시멘트 대체재로 사용되어지고 있는 석회석 소성 점토 시멘트(LC³)의 주원료인 석회석의 대체재로써 굴 패각의 재활용 가능성을 평가하였다. 굴 패각 소성 점토 시멘트(OC³) 페이스트의 화학적·기계적 특성을 규명하기 위해 X-선 회절 분석, 등온 열량 측정, 압축강도 시험 및 열 중량 분석을 실시하였다. 결과적으로, OC³ 페이스트는 LC³와 동일한 포졸란 반응에 의해 유사한 강도 발현 및 반응성을 보여주었으며, 이를 통해 굴 패각이 LC³의 주 원료인 석회석의 대체재로써 사용할 수 있다는 것을 확인할 수 있었다.

• Advances in concrete construction
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• 제7권2호
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• pp.75-85
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• 2019

The present study is focused on the mechanical and durability properties of ternary blended cement concrete mix of different grades 30 MPa, 50 MPa and 70 MPa. Three mineral admixtures (fly ash, silica fume and lime sludge) were used as a partial replacement of cement in the preparation of blended concrete mix. The durability of ternary blended cement concrete mix was studied by exposing it to acids HCl and $H_2SO_4$ at 5% concentration. Acid mass loss factors (AMLF), acid strength loss factor (ASLF) and acid durability factor (ADF) were determined, and the results were compared with the control mix. Chloride ions penetration was investigated by conducting rapid chlorination penetration test and accelerated corrosion penetration test on control mix and ternary blended cement concrete. From the results, it was evident that the usage of these mineral admixtures is having a beneficiary role on the strength as well as durability properties. The results inferred that the utilization of these materials as a partial replacement of cement have significantly enhanced the compressive strength of blended concrete mix in 30 MPa, 50 MPa and 70 MPa by 42.95%, 32.48% and 22.79%. The blended concrete mix shown greater resistance to acid attack compared to control mix concrete. Chloride ion ingress of the blended cement concrete mix was low compared to control mix implying the beneficiary role of mineral admixtures.