• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.386-391
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• 1998

Recently, high performance concrete developed has a good quality at fresh and hardened state, but high binder contents results in spending much money on manufacturing and many cracks by drying and autogenous shrinkage. Therefore, in this paper, not only prevention of cracks caused by drying and autogenous shrinkage, but improvement of quality and accmplishment of economy by applying F.A(fly ash), S.F(silica fume) and CSA(calcium sulfa aluminate) expansive additives as an inorganic admixtures in W/B 35% are discussed. According to the experimental results, when 5% of CSA Expansive additives and 15:5 (F.A:S.F)are replaced at unit cement content, high performance concrete with both good compensation of drying and autogenous shrinkage at hardened state is accomplished.

• Computers and Concrete
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• 제24권5호
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• pp.453-458
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• 2019

Today, concrete remains the most important, durable, and reliable material that has been used in the construction sector, making it the most commonly used material after water. However, cement continues to exert many negative effects on the environment, including the production of carbon dioxide (CO2), which pollutes the atmosphere. Cement production is costly, and it also consumes energy and natural non- renewable resources, which are critical for sustainability. These factors represent the motivation for researchers to examine the various alternatives that can reduce the effects on the environment, natural resources, and energy consumption and enhance the mechanical properties of concrete. Geopolymer is one alternative that has been investigated; this can be produced using aluminosilicate materials such as low calcium (class F) FA, Ultra-Fine GGBS, and high calcium FA (class C, which are available worldwide as industrial, agricultural byproducts.). It has a high percentage of silica and alumina, which react with alkaline solution (activators). Aluminosilicate gel, which forms as a result of this reaction, is an effective binding material for the concrete. This paper presents an up-to-date review regarding the important engineering properties of geopolymer formed by FA and slag binders; the findings demonstrate that this type of geopolymer could be an adequate alternative to ordinary Portland cement (OPC). Due to the significant positive mechanical properties of slag-FA geopolymer cements and their positive effects on the environment, it represents a material that could potentially be used in the construction industry.

• 한국건설순환자원학회논문집
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• 제6권3호
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• pp.167-173
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• 2018

일반적으로 고로슬래그 미분말 및 플라이애시의 반응에는 칼슘이 필요하게 된다. 순환골재를 생산하는 과정에서 발생하는 공정부산물은 파쇄단계에 따라 칼슘 함량이 다르며, 공정부산물의 콘크리트 혼합재로서의 활용 가능성도 다르게 된다. 본 연구에서는 공정부산물의 칼슘 함량이 압축강도에 미치는 영향을 확인하고, 이를 활용한 블록을 제작하였다. 공정부산물을 혼합재로 활용하기 위해 칼슘 함량을 분석하였으며 저류블록의 형상에 따른 휨강도 및 표면온도를 측정하였다. 연구 수행을 통해 순환골재 공정부산물을 활용한 블록 제작 가능성을 검증하였으며, 저류량 및 휨강도 확보를 위해 아치형의 저류블록을 제작하였다. 또한, 저류블록의 표면온도는 일반투수블록보다 $9^{\circ}C$ 이상 저감되는 것을 확인하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 추계 학술논문 발표대회
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• pp.213-214
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• 2012

This study is about the assessment of utilization possibility as a material for cementation of ground which is necessary for the reinforcement of soft ground by making environment-friendly inorganic composite utilizing inorganic recycled resources, and it was verified that it showed higher uniaxial compressive strength than the existing cementitious ground solidifier when it was applied as a combination material for soft ground such as dredge reclaimed land, and since an inorganic composite utilizing recycled resources such as high calcium fly ash and blast furnace slag etc. does never use cement, it is considered that it would be safe in the issue of a hexavalent chromium that was recognized as a problem of a cementitious solidifier.

• 한국건축시공학회지
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• 제20권1호
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• pp.19-26
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• 2020

본 연구는 소성과정에서 다량의 이산화탄소를 배출하는 포틀랜드 시멘트를 대체할 수 있는 비소성 시멘트 개발을 목표로 하였다. 이를 위해 고로슬래그 미분말과 고칼슘 플라이애시, 소석회를 사용하였다. 또한 실험 결과를 통하여 배합비율에 따른 비소성 시멘트의 특성에 대해서 파악하고, 프리캐스트 콘크리트 제품으로의 적용 가능성을 파악하고자 하였다. 실험방법은 비소성 시멘트를 제작하여 증기양생을 실시하였고 재령 3, 7, 28일의 휨강도와 압축강도를 비교하여 각 배합비의 특성을 파악하였다. 재령 28일에는 흡수율 시험과 X선 회절 분석, 내부 미세구조를 관찰하였다. 시험 결과, NSC 모르타르는 Plain 모르타르에 비해 강도는 낮지만 재령 3일에서 다수의 배합이 품질 최소기준을 만족하였다. 흡수율 시험에서는 재령 28일 기준 모든 배합이 품질 최소기준을 만족하였다. 따라서 NSC 모르타르는 목표 PC제품 생산 원료로서 적용 가능성이 높다고 판단하였다.

• Advances in concrete construction
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• 제13권1호
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• pp.71-81
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• 2022

Aluminosilicate materials as precursors are heterogenous in nature, consisting of inert and partially reactive portion, and have varying proportions depending upon source materials. It is essential to assess the reactivity of precursor prior to synthesize geopolymers. Moreover, reactivity may act as decisive factor for setting molar concentration of NaOH, curing temperature and setting proportion of different precursors. In this experimental work, the reactivities of two precursors, low calcium (fly ash (FA)) and high calcium (ground granulated blast furnace slag (GGBS)), were assessed through the dissolution of aluminosilicate at (i) three molar concentrations (8, 12, and 16 M) of NaOH solution, (ii) 6 to 24 h dissolution time, and (iii) 20-100℃. Based on paratermeters influencing the reactivity, different proportions of ternary binders (two precursors and ordinary cement) were activated by the combined NaOH and Na2SiO3 solutions with two alkaline activators to precursor ratios, to synthesize the geopolymer. Reactivity results revealed that GGBS was 20-30% more reactive than FA at 20℃, at all three molar concentrations, but its reactivity decreased by 32-46% with increasing temperature due to the high calcium content. Setting time of geopolymer paste was reduced by adding GGBS due to its fast reactivity. Both GGBS and cement promoted the formation of all types of gels (i.e., C-S-H, C-A-S-H, and N-A-S-H). As a result, it was found that a specified mixing proportion could be used to improve the compressive strength over 30 MPa at both the ambient and hot curing conditions.

• 한국세라믹학회지
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• 제34권1호
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• pp.45-55
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• 1997

다양한 무정형 실리케이트를 규산칼슘건축재의 규산원료로 사용하여 겔합성의 활성도와 성형성의 관계를 검토하고, 이런 규산원료의 활성도의 차가 수열합성된 규산칼슘성형체의 역학적 특성에 미치는 영향을 생성된 결정형태 및 기공율 등의 미세조직을 조사해 해석하였다. 규산원료의 활성도가 클수록 가압형성이 양호해지며 생성성형체의 결정과 기공율이 커지는 경향이다. 이런 성형체의 미세조직이 역학특성에 미치는 영향을 보면 곡강도는 결정크기가 작고 조직이 치밀할수록 양호한 특성을 가지나, 압축강도는 결정크기보다는 주로 조직의 치밀도에 영향을 받고 있다. 이런 특징을 종합할 때, 규산칼슘복합건재의 적정 규산원료로는 활성이 크고 수화체의 조직을 치밀하게 할 수 있는 규조토의 선정이 바람직하나, 슬래그와 플라이 애쉬의 혼합사용도 상호특성보완과 함께 부산자원의 재활용측면에서 활용이 기대된다.

• 한국폐기물자원순환학회지
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• 제35권7호
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• pp.670-682
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• 2018

Engineered nanomaterials (ENMs) can be released to humans and the environment through the generation of waste containing engineered nanomaterials (WCNMs) and the use and disposal of nano-products. Nanoparticles can also be introduced intentionally or unintentionally into waste streams. This study examined WCNMs in domestic industries, and target nanomaterials, such as silicon dioxide, titanium oxide, zinc oxide, nano silver, and carbon nanotubes (CNTs), were selected. We tested 48 samples, such as dust, sludge, ash, and by-products from manufacturing facilities and waste treatment facilities. We analyzed leaching and content concentrations for heavy metals and hazardous constituents of the waste. Chemical compositions were also measured by XRD and XRF, and the unique properties of nano-waste were identified by using a particle size distribution analyzer and TEM. The dust and sludge generated from manufacturing facilities and the use of nanomaterials showed higher concentrations of metals such as lead, arsenic, chromium, barium, and zinc. Oiled cloths from facilities using nano silver revealed high concentrations of copper, and the leaching concentrations of copper and lead in fly ash were higher than those in bottom ash. In XRF measurements at the facilities, we detected compounds such as silicon dioxide, sulfur trioxide, calcium oxide, titanium dioxide, and zinc oxide. We found several chemicals such as calcium oxide and silicon dioxide in the bottom ash of waste incinerators.

• 한국구조물진단유지관리공학회 논문집
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• 제21권6호
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• pp.74-82
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• 2017

본 연구는 고로슬래그 미분말(GGBFS), 플라이 애시(FA) 그리고 칼슘설포알리미네이트(CSA)를 혼합한 활성화된 삼성분계 시멘트의 강도와 건조수축에 대한 연구결과이다. 활성화된 삼성분계 시멘트(ATBC) 모르타르의 물-결합재 비는 0.4이다. GGBFS의 치환율은 100%, 80%, 70% 그리고 60%이며, FA는 10%, 20%, 30% 그리고 40%, CSA는 0%, 10%, 20% 그리고 30% 치환비율로 설정하였다. 혼화제는 폴리카르폭실계를 사용하였다. 활성화제는 결합제 질량에 대해 10% 수산화나트륨(NaOH) + 10% 규산나트륨($Na_2SiO_3$)을 사용하였다. 실험은 미니 슬럼프, 응결시간, V-funnel, 물흡수율, 압축강도 그리고 건조수축을 측정하였다. 실험결과 모든 배합에서 혼화제의 양, V-funnel 그리고 압축강도는 CSA 양이 증가함에 따라 증가하였다. 또한 응결시간, 물 흡수율과 건조수축은 CSA가 증가함에 따라 감소하였다. 강도증가와 건조수축 감소의 가장 큰 원인 중 하나는 CSA와 활성화제에 의한 GGBFS의 수화반응 촉진 때문이다. CSA의 혼합양은 활성화된 삼성분계 시멘트의 강도 증가와 건조수축 감소에 중요 영향요인이다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.127-128
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• 2022

In order to realize carbon neutrality in the international society, research on supplementary cementitious materials(SCMs) has been actively conducted as a way to reduce carbon dioxide emissions in the cement industry. However, the use of SCMs causes problems of initial hydration delay and strength reduction due to the reduction of tricalcium silicate(C3S) in the cement clinker. Therefore, in this study, the initial hydration and basic characteristics of cement mortar were confirmed by adding a C-S-H based hardening acceleration to blended cement mixed with Portland cement, blast furnace slag, fly ash, and limestone power. As a result of the heat of hydration and compressive strength test, it was confirmed that when hardening acceleration was added, the initial reactivity was high, so the heat of hydration was promoted, and the initial strength was increased. It is considered to be due to C-S-H seeding effect. Therefore, it is judged that the use of C-S-H based hardening acceleration can supplement the problem of initial hydration delay of blended cement in Korea.