Wet regeneration of waste artificial sand used in sand casting using chemical solutions

Eun Yeong Ko,Kyeong-Ho Kim,Jae Ho Baek,황인성,이만식 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.6

Natural sand and organic binders have been the main materials used in sand casting. However, inorganic binders are used in novel casting technologies, and research on artificial sand as a substitute of natural sand has been conducted. Herein, the wet regeneration of waste artificial sand was performed using a sodium silicate binder. Acidic, neutral, and basic solutions were used for wet regeneration. The effects of binder removal and reusability of the regenerated sand were investigated by comparing the characteristics and strengths of the artificial and regenerated sand. It was demonstrated that the basic solution effectively removed the binder from the surface of the waste artificial sand. The Si-O-Si bond cleavage in the binder occurred due to the high concentration of hydroxide ions in the basic solution. The strength of the regenerated sand treated with the basic solution and that of the artificial sand were similar. Moreover, the strengths of regenerated sands treated with the acidic or neutral solutions were lower than that of artificial sand due to the presence of residual binder. These results indicated that the basic solution was suitable for removing the sodium silicate binder. The quality of the regenerated sand was similar to that of artificial sand.

Wet regeneration of waste artificial sand used in sand casting using chemical solutions

Eun Yeong Ko,Kyeong Ho Kim,Jae Ho Baek,Inseong Hwang,Man Sig Lee 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.6

Natural sand and organic binders have been the main materials used in sand casting. However, inorganic binders are used in novel casting technologies, and research on artificial sand as a substitute of natural sand has been conducted. Herein, the wet regeneration of waste artificial sand was performed using a sodium silicate binder. Acidic, neutral, and basic solutions were used for wet regeneration. The effects of binder removal and reusability of the regenerated sand were investigated by comparing the characteristics and strengths of the artificial and regenerated sand. It was demonstrated that the basic solution effectively removed the binder from the surface of the waste artificial sand. The Si-O-Si bond cleavage in the binder occurred due to the high concentration of hydroxide ions in the basic solution. The strength of the regenerated sand treated with the basic solution and that of the artificial sand were similar. Moreover, the strengths of regenerated sands treated with the acidic or neutral solutions were lower than that of artificial sand due to the presence of residual binder. These results indicated that the basic solution was suitable for removing the sodium silicate binder. The quality of the regenerated sand was similar to that of artificial sand.

수용성 고화재와 규산염광물 결합재를 활용한 지반개량재의 실험적 연구

김성욱,최은경,조진우,이주형,이규환 한국복합신소재구조학회 2015 복합신소재구조학회논문집 Vol.6 No.4

The demand for environmental consideration is on the increase in civil engineering. This study focuses on the development of technology to reduce the use of carbonate cement and improve its performance by using a silicate mineral and hardening agents, and presents the test results for the demonstrative evaluation of the properties of the raw material. Highly active feldspar was used as a binder to augment the bonding of the carbonate cement, and their change in strength was observed after test piece construction with the addition of soluble hardening agent. The uniaxial compression strength of the test piece of the general Portland cement with the addition of 0.5% soluble hardening agent, showed an increase by 33% and that of the test piece of cement with the addition of 70% substituted with feldspar increased by 28%. The strength of viscous soil; classified as soft ground, showed an increase of a maximum of 1.7 times when it was mixed with cement and solidifier depending on the curing period. These tests confirmed that a soluble solidifier is effective for improving the strength of a cement binder and that the highly active feldspar can be used as a binder.

수용성 고화재와 규산염광물 결합재를 활용한 지반개량재의 실험적 연구

김성욱 ( Sung Wook Kim ),최은경 ( Eun Kyeong Choi ),조진우 ( Jinwoo Cho ),이주형 ( Juhyung Lee ),이규환 ( Kyu Hwan Lee ) 한국복합신소재구조학회 2015 복합신소재구조학회논문집 Vol.6 No.4

The demand for environmental consideration is on the increase in civil engineering. This study focuses on the development of technology to reduce the use of carbonate cement and improve its performance by using a silicate mineral and hardening agents, and presents the test results for the demonstrative evaluation of the properties of the raw material. Highly active feldspar was used as a binder to augment the bonding of the carbonate cement, and their change in strength was observed after test piece construction with the addition of soluble hardening agent. The uniaxial compression strength of the test piece of the general Portland cement with the addition of 0.5% soluble hardening agent, showed an increase by 33% and that of the test piece of cement with the addition of 70% substituted with feldspar increased by 28%. The strength of viscous soil; classified as soft ground, showed an increase of a maximum of 1.7 times when it was mixed with cement and solidifier depending on the curing period. These tests confirmed that a soluble solidifier is effective for improving the strength of a cement binder and that the highly active feldspar can be used as a binder.

High Sulfated Calcium Silicate 시멘트 콘크리트의 염소이온침투저항성 평가

정석만,양완희,김현수,이건철 한국건축시공학회 2022 한국건축시공학회지 Vol.22 No.1

The aim of this work was to a comparative review the performance of high calcium silicate cement(HSCSC) and that of ordinary Portland cement(OPC) and blast furnace slag cement(S/C). The result ofthe compressive test confirmed that the compressive strength development rate of high calciumsilicate cement concrete at the age of 3 days was 73.6% that of ordinary Portland cement concrete. However, at the age of 28 days, the strength development rate of high calcium silicate cement increasedto about 107.0% compared to ordinary Portland cement. In addition, the test of the chloride ionpenetration resistance of concrete showed that at the age of 28 days, the passed charge decreased by73.4% and 93.0%, respectively, in blast furnace slag cement and high calcium silicate cement comparedto ordinary Portland cement, and at the age of 56 days, it decreased by 79.1% and 98.3%, exhibitingexcellent resistance to chloride ion penetration. In particular, it was confirmed that the rate of decreasein the passed charge with age was higher in high calcium silicate cement than in ordinary Portlandcement and blast furnace slag cement. High Sulfated Calcium Silicate cement(HSCSC) 콘크리트의 성능을 보통포틀랜드시멘트(OPC), 고로슬래그시멘트(S/C)와 비교 검토하고자 하였다. 콘크리트 압축강도 실험결과 초기 3일 재령에서의 High Sulfated Calcium Silicate cement 콘크리트 압축강도 발현율이 보통포틀랜드시멘트 콘크리트의 73.6% 수준으로 다소 적게 확인되었으나, 28일 재령에서 HighSulfated Calcium Silicate cement의 강도 발현율이 상승하여 보통포틀랜드시멘트 대비 약 107.0% 수준으로 소폭 상승하는것을 확인할 수 있었다. 또한, 콘크리트의 염소이온침투저항성 실험결과 재령 28일의 경우 보통포틀랜드시멘트 대비 고로슬래그시멘트, High Sulfated Calcium Silicate cement 순서로 각각 73.4%, 93.0% 감소하였으며, 재령 56일의 경우 79.1%,98.3% 감소하여, 우수한 염소이온 침투 저항성능을 확인하였다. 특이사항으로는 보통포틀랜드시멘트, 고로슬래그시멘트보다 High Sulfated Calcium Silicate cement의 재령 경과에 따른 통과 전하량 감소율이 더 높은 것을 확인할 수 있었다.

콘크리트 내 실리카퓸을 대체하기 위한 페로실리콘 산업부산물의 활용 적절성에 대한 연구

김한솔,조원정,안기용 한국건설순환자원학회 2019 한국건설순환자원학회 논문집 Vol.7 No.4

A ferrosilicon (FS) by-product was applied into a cementitious binder in concrete substituting the ordinary Portland cement (OPC). The original material characteristic of FS is very identical to silica fume (SF) regarding chemical composition and physical properties such as specific surface area and specific gravity. Therefore, the FS and SF concrete or mortal of which 10% of the material was replaced to total binder weight were fabricated to evaluate the feasibility of using FS as a binder, and the comparative information of OPC, FS and SF concrete was given. The hydration characteristic of FS concrete was analyzed using X-ray diffraction analysis. The FS concrete was beneficial in compressive strength, resistivity against chloride ingress and reducing porosity considering performance of OPC concrete but the advantage was less than using SF. A possibility of alkali-silica expansion was found out from the FS concrete due to the agglomerated size of the silica particles.

규산칼륨으로 표면 처리한 순환골재의 물리화학적 특성

서영화(Young-Hwa Seo),이배식(Bae-Sik Lee) 한국환경관리학회 2007 環境管理學會誌 Vol.13 No.3

폐콘크리트는 대부분 건설폐기물 처리 업체의 재생 골재 생산시설을 통하여 성토용이나 매립용과 같은 초보적인 활용용 골재로 사용되고 있으나 각종 새로운 건설사업과 건축 리모델링으로 하루 10만 여 톤 이상 발생되는 폐 콘크리트를 처리하기 위하여 꾸준한 재생 골재 생산 기술 개발이 필요하다. 근래에는 미소하나마 품질이 우수한 골재도 생산되고 있으나 아직 순환골재의 제조기술은 폐콘크리트에 부착되어 있는 시멘트나 모르타르 및 각종 이물질을 제거하는 기술과 2차 환경오염을 저감하는 데에 그치고 있다, 본 연구에서는 규산(SiO₂)과 산화칼륨(K₂O)를 무게 비율 2.1~2.5로 혼합하여 물에 용해하여 얻은 혼합물을 바로 첨가하거나, 분사하여 코팅 막을 형성하게 함으로서 단단하고 높은 점성으로 무기성 물질들이 서로 엉기게 하여 강도를 증가시키고, 마모, 수분 저항력을 향상시키는 특성을 가진 규산칼륨 용액을 폐콘크리트 골재에 코팅하여 골재의 강도와 입형 등 물리화학적 특성을 강화하고 골재의 표면을 코팅함으로서 폐콘크리트가 가진 화학성분들의 용출이 저감되고 미세먼지 발생이 억제되어 환경친화적인 순환골재를 생산하는 골재의 품질을 향상 시키는 연구를 수행하였으며 도출된 연구 결과를 순환골재 생산 현장 시스템에 적용하여 고강도의 순환골재를 생산하였다. Construction waste has been tremendously increased due to the construction development and remodelling of the old buildings, but recycling construction waste has been limited to the landfill. To increase the recycling it is necessary to improve a quality of recycled aggregates in the construction waste recycling process. Potassium silicate solution which mixed with silicate (SiO₂) and potassium oxide (K₂O) was used to coat the surface of the recycled aggregates to increase the physicochemical properties, to decrease the production of the fine particles during the production line and also to decrease the leaching of the chemical from the recycled aggregates. As performing likely waterglass as binders that adheres material being agglomerated at a low cost, recycled aggregates coated with potassium silicate solution has a high quality in terms of strength, good shape of forming, and lower water absorption capacity.

고방열 세라믹 그래뉼용 첨가제 및 바인더 개발

정대용,김민규,김승욱,지성엽 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11

전자기기의 소형화와 함께 기기 작동 시 발생하는 열을 효과적으로 방출시키기 위한 고열전도성 소재 연구가 활발히 진행되고 있다. Boron nitride(BN)은 높은 열전도도를 갖는 소재로 최근 많은 관심을 받고 있다. 한편, 고열전도성 세라믹소재를 포함한 폴리머 복합체를 제조할 때, 세라믹 분말 크기가 작아질수록 응집이 잘 되므로 균일한 혼합을 위해서 세라믹 분말은 일정 크기의 과립으로 제조되어야 한다. 세라믹 분말을 과립화하기 위해서는 세라믹 분말을 결합할 수 있는 바인더가 필요한데 이때 사용되는 바인더는 세라믹과 같이 높은 열전도도를 가져야 하며, 과립 세라믹 분말 사이의 공극을 채울 수 있어야 한다. 본 연구에서는 BN granule 결합에 도움을 주는 고열전도도를 가지는 바인더를 개발하고 열특성 및 과립의 결합특성을 평가하였다. 고열전도도의 세라믹 필러가 첨가된 silicate 기반의 바인더를 사용하여 BN granule의 결합력을 향상시켰고 세라믹 필러의 비율 조절을 통해 공극을 최소화하여 높은 열전도도를 확보했다. 또한 매트릭스로 사용되는 폴리머 소재와 동일한 소재를 사용하여 진공 와류 함침공정을 수행했고 그 결과, 바인더 혼합 후 용제 제거 시 발생하는 미세 공극을 최소화했다. 이를 통해 BN granule의 열전도 특성이 증가하였고 BN granule과 매트릭스 폴리머 소재 간의 분산도가 증가하는 것을 확인할 수 있었다.

Comparison of Carbon Dioxide Adsorption Capacity between Adsorbents Utilizing Kaolin and Metakaolin

신지원,배민아,김경호,제정호,백재호 한국공업화학회 2023 한국공업화학회 연구논문 초록집 Vol.2023 No.0

SrRuO₃ 분말의 성형 및 소결에 미치는 CaSiO₃ 첨가량 영향

권선길,강대승,홍순석,허진목,이일희 한국공업화학회 2009 한국공업화학회 연구논문 초록집 Vol.2009 No.1