산업부산물 탈황석고 혼입 레디믹스트콘크리트 회수수를 이용한 콘크리트의 특성

김영엽(Young-Yeop Kim),이한승(Han-Seung Lee) 한국건설순환자원학회 2020 한국건설순환자원학회 논문집 Vol.8 No.4

CaO원 산업부산물은 CaO, SO₃ 및 Al₂O₃ 등으로 구성되어 있어 CaO 화합물의 원료로 사용되고 있다. 이러한 CaO원 산업부산물을 레미콘 회수수에 적용할 경우 슬러지수의 pH를 높여주어 콘크리트 분말 원료의 수화 반응을 촉진하여 콘크리트 조직을 치밀하게 하여 성능 향상이 가능할 것이다. 본 연구에서는 레미콘 회수수에 CaO원 산업부산물 중 하나인 탈황석고를 혼입하여 제조된 활성슬러지의 효과를 확인하기 위해 콘크리트의 특성을 분석하였다. 그 결과 콘크리트에 대한 시험 결과 작업성을 확보하면서 강도 및 건조수축에 대한 문제점이 없는 것을 확인할 수 있었으며, 활성슬러지를 이용한 콘크리트 적용에 대한 가능성을 확인할 수 있었다. CaO-based by-product, which consist of CaO, SO₃, Al₂O₃ and so on, has being used to raw materials of CaO compound. When It was applied to recycling water of remicon, concrete performance can be enhanced because hydration reaction of powder material is accelerated. In this study, activated-sludge, which was putted desulfurization gypsum of CaO-based in recycling water, was manufactured to verify effect of them, and then they was investigated by characteristics of redy-mixde concrete. As a result of concrete tests, it was confirmed that there is no problem of strength or drying shrinkage while ensuring workability. Therefore, the possibility of specific application using activated sludge was confirmed.

C<SUB>12</SUB>A<SUB>7</SUB>을 함유한 열연슬래그를 혼입한 레미콘 회수수 활용 및 시멘트 모르타르의 적용 특성

김영엽(Young-Yeop Kim),이한승(Han-Seung Lee) 한국건설순환자원학회 2021 한국건설순환자원학회 논문집 Vol.9 No.1

CaO 화합물의 원료로는 일반적으로 CaO, SO₃, Al₂O₃ 등으로 구성된 CaO 기반인 산업부산물이 있다. 이러한 CaO 계 산업부산물을 레미콘의 회수수에 적용할 경우 시멘트, 플라이애시, 슬래그미분말 등의 콘크리트 분말 원료의 수화 반응이 가속화되어 콘크리트 성능을 향상시킬 수 있다. 본 연구에서는 레미콘의 회수수에 C12A7을 함유한 열연 슬래그를 혼입하여 레미콘의 회수수에 적용할 수 있는 활성슬러지를 제조하였으며, 시멘트 페이스트 응결시간 및 모르타르 압축강도 성능 테스트를 통해 수화반응에 대한 영향을 확인하고자 하였다. CaO-based by-products composed of CaO, SO₃, Al₂O₃, etc. are generally used as raw materials for CaO compounds. When applied to the recovered water of ready-mixed concrete, the hydration reaction of the powder material is accelerated and concrete performance can be improved. In this study, activated sludge was prepared to apply to the recovered water of ready-mixed concrete by mixing CaO-based hot-rolled slag(C12A7) in the recycling water of ready-mixed concrete. Cement paste setting time and mortar compressive strength performance tests confirmed the effect on the hydration reaction. Therefore, the possibility of concrete application using activated sludge was confirmed.

Effects of CaCl₂ on hydration and properties of lime(CaO)-activated slag/fly ash binder

Yum, W.S.,Jeong, Y.,Yoon, S.,Jeon, D.,Jun, Y.,Oh, J.E. THE CEMENT ASSOCIATION OF JAPAN 2017 CEMENT AND CONCRETE COMPOSITES Vol.84 No.-

This study presented CaCl<SUB>2</SUB> as a potential additive activator to develop a new strong, price-competitive CaO-activated GGBFS binder blended with fly ash (CAS 4:4:2) to commercially replace ternary blended cements, which generally consist of 40% Portland cement, 40% GGBFS, and 20% fly ash (wt.%) (PC 4:4:2), widely used for concrete production. Despite CAS 4:4:2 having no clinker cement compound, the addition of CaCl<SUB>2</SUB> not only significantly accelerated reactions of CAS 4:4:2 binders but also largely increased strengths at all curing days. Up to 72 h, the cumulative reaction heat of CAS 4:4:2 with CaCl<SUB>2</SUB> was also reasonably low. Reaction products and microstructures of hardened CAS 4:4:2 pastes were considerably changed after CaCl<SUB>2</SUB> addition. The CaCl<SUB>2</SUB> presence markedly promoted dissolution of the glass phase of GGBFS and fly ash in early days, resulting in more production of reaction products (e.g., C-S-H, hydrocalumite) and pore-size refinement.

CaO원 활성슬러지를 혼입한 시멘트 경화체 및 모르타르의 특성

이용수(Yong-Soo Lee),유성룡(Seong-Lyong Ryu),신광호(Kwang-Ho Shin),추용식(Yong-Sik Chu),김영엽(Young-Yup Kim) 한국콘크리트학회 2017 콘크리트학회논문집 Vol.29 No.4

Strength enhancement and pore-size refinement in clinker-free CaO-activated GGBFS systems through substitution with gypsum

Park, H.,Jeong, Y.,Jun, Y.,Jeong, J.H.,Oh, J.E. THE CEMENT ASSOCIATION OF JAPAN 2016 CEMENT AND CONCRETE COMPOSITES Vol.68 No.-

This study presents an improvement in the compressive strength of the clinker-free CaO-activated GGBFS system with the addition of gypsum. The compressive strength was primarily governed by the amount of ettringite, but more importantly, the morphology of reaction products (e.g., size, slenderness) is proposed as being a more dominant factor. The gypsum content at the best strength produced fine ettringite crystals and removed large pores that were around 100 μm in diameter, resulting in significant pore-size refinement. However, excessive addition reduced the strength and generated a large volume of detrimental pores with sizes of 0.03-0.4 μm, which were probably due to expansive cracking or large voids between the large sizes of re-precipitated gypsum crystals. The SEM images demonstrated that the fine ettringite crystals at the gypsum dosage of the best strength filled the pores effectively, which led to dense matrices; while the coarse crystals of gypsum or ettringite at the excessive addition level produced porous matrices.

Properties of quicklime(CaO)-activated Class F fly ash with the use of CaCl₂

Jeon, Dongho,Yum, Woo Sung,Jeong, Yeonung,Oh, Jae Eun Elsevier 2018 Cement and concrete research Vol.111 No.-

<P><B>Abstract</B></P> <P>This study reports the significant effect of CaCl<SUB>2</SUB> on strength improvement in CaO-activated Class F fly ash system. In these systems, the presence of CaCl<SUB>2</SUB> promotes (1) a higher degree of fly ash dissolution, (2) increasing C-S-H formation, and (3) an overall reduction of pore size and volume, resulting in increased strength. However, while more C-S-H, which is responsible for strength increase, was produced with higher CaCl<SUB>2</SUB> content, extreme doses of CaCl<SUB>2</SUB> resulted in strength degradation; more importantly, the best quantity of CaCl<SUB>2</SUB> for the greatest strength was dependent on the water-to-binder weight ratio (w/b). This dependency was closely related to the formation of calcium oxychloride, which generally causes severe expansive cracking and depends on w/b.</P>

Ionic Conductivity of Solid Solution Ceramics in The System of Stabilized ZrO₂ Prepared by Self-Propagating High-Temperature Synthesis

Soh, Deawha,Korobova, N. The Korean Institute of Electrical and Electronic 2002 전기전자재료학회논문지 Vol.15 No.4

The ionic conductivity of cubic solid solutions in the systems of CaO-$ZrO_2$, $Y_2O_3-ZrO_2$ prepared by SHS was examined. The higher conductivity appears to be related to a lower activation energy rather than to the number of oxygen vacancies dictated by composition. Conductivity-temperature data was obtained at 1000 $^{\circ}C$ in atmosphere of low oxygen partial pressure (~$10^{-40}$ atm) for $Y_2O_3-ZrO_2$ cubic solid solutions. The data indicated that these materials could be reduced, and the decree of reduction would be related with the measuring electric field.

Utilization of precipitated CaCO₃ from carbon sequestration of industrially emitted CO₂ in cementless CaO-activated blast-furnace slag binder system

Jeong, Yeonung,Yum, Woo Sung,Moon, Juhyuk,Oh, Jae Eun ELSEVIER 2017 JOURNAL OF CLEANER PRODUCTION Vol.166 No.-

<P><B>Abstract</B></P> <P>This study explores the use of precipitated calcium carbonate (PCC), an industrial by-product from the carbon sequestration process for emitted CO<SUB>2</SUB> from factories, in the cementless CaO-activated ground-granulated blast-furnace slag (GGBFS) system in an aim not only to improve the strength but also to develop more sustainable structural binder for concrete. The 28-day strength improved with increasing PCC content up to 20 wt%, and its highest strength showed an ∼23% increase from the original strength of the sample without PCC. The analysis revealed that the PCC was not a simple inert filler, but it might promote more dissolution of GGBFS, resulting in a higher strength from additional formation of reaction products. In particular, even the sample with 50 wt% PCC yielded a very similar strength compared to the sample without PCC at 28 days. Thus, this binder system could be a decent solution that can store a large amount of PCC without a significant strength reduction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The PCC from CO<SUB>2</SUB> uptake process was used in CaSO<SUB>4</SUB>-blended CaO-activated GGBFS. </LI> <LI> This study discussed characteristics of strength and microstructure of the pastes. </LI> <LI> The 28-day strength increased ∼23% at 20 wt% of the PCC content. </LI> <LI> There was no significant strength reduction even at 50 wt% of PCC usage. </LI> <LI> The PCC was not a simple inert filler, but it might promote dissolution of GGBFS. </LI> </UL> </P>

Characteristics of GGBFS-Based Pervious Concrete Considering Rheological Properties of the Binder

Yanchen Oinam,주수환,권성우,신명수,표석훈 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.1

To mitigate environmental challenges, such as urban flooding, noise pollution, and the urban heat island effect, pervious concrete has been developed. This research was intended to develop pervious concrete made from ground granulated blast furnace slag (GGBFS) to further decrease the environmental impact of the construction sector by reducing the content of ordinary Portland cement (OPC). The primary objective of the mix proportion was to maximize water permeability while meeting the required compressive strength. Two levels (60 and 100%) of OPC replacement by GGBFS were evaluated and compared to OPC-only concrete, and two target porosities (10 and 15%) were achieved by modifying the binder-to-aggregate ratio. CaO and CaCl2 were utilized as an activator and an accelerator, respectively, for the GGBFS only binder. Characteristics of the pervious concrete were determined with the compressive strength, porosity and water permeability test. Meanwhile, the effects of the rheological properties of binders on the water permeability and compressive strength of pervious concretes was evaluated. According to the results, the permeability of pervious concretes always exhibited a positive correlation with porosity, regardless of binder type. Although, the pervious concrete made with CaO-activated GGBFS has a lower compressive strength than the other two cases (60% GGBFS and only OPC), it still meets the minimum strength requirement. Based on the rheology studies of binder, it was found that, the adhesion force of the binder and the compressive strength of the pervious concrete decreases, as evaluated by rheology studies on binders. The CT scan revealed that when the adhesive force of the binder was weaker, the local porosity was higher (i.e., pore volume was larger) at the bottom of the specimen, which might be due to the limited consolidation and compaction of the binder between aggregate particles at the bottom due to its higher plastic viscosity.

산업부산물을 이용한 저시멘트계 지반개량재의 강도 특성

조진우,이용수,유준,김세호 한국지반공학회 2006 한국지반공학회논문집 Vol.22 No.4

An experimental investigation was carried out to evaluate the strength characteristics of low cement ratio soil stabilizer. The low cement ratio soil stabilizer has been developed by the replacement of certain part of cement with by-product pozzolanic materials such as blast furnace slag, fly ash, waste gypsum and by using activator. A series of unconfined compressive strength tests were performed to investigate and obtain high-strength composite soil stabilizer with large amounts of blast furnace slag and fly ash. Test results show that there were better properties when blast furnace slag, fly ash, waste gypsum, and activator were added in proper ratio. The replacement of certain part of cement with by-product pozzolanic materials improved the strength and pore structure properties.