• Cement
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• s.173
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• pp.78-83
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• 2006

국내 건설산업의 축소에 따라 수요가 감소하고, 외국산 시멘트의 수입량이 증가하며, 시멘트 콘크리트가 환경문제와 연관이 있다는 인식이 확산되는 등 위기에 직면해 있는 국내 시멘트 산업은 재도약을 위하여 노력하고 있다. 한국양회공업협회, 산업자원부, 건설교통부 등의 후원으로 한국콘크리트학회에서 이러한 시멘트 및 콘크리트 관련산업의 환경 및 품질과 관련한 당면과제를 극복하고, 선진외국의 사례를 참고하여 국내 시멘트, 레미콘 등 콘크리트 관련산업의 경쟁력 제고를 도모하고자 지난 2006년 11월 17일(금)에 한양대학교 백남학술정보관 국제회의실에서 "환경과 콘크리트"를 주제로 시멘트 및 콘크리트 산업 경쟁력 향상을 위한 국제 심포지엄을 개최하였다. 이번 국제 심포지엄은 최근 산업폐기물을 시멘트 제조원료로 사용하는 것과 관련, 많은 논란이 일어나고 있는 가운데, 최근 언론보도에서는 다소 간과된 지구환경 보전측면에서 시멘트 콘크리트 산업이 공헌하는 측면에 대해서 활발한 주제 발표가 있어, 많은 주목을 받았다. 먼저, 외국연사로서 초청된 미국 시멘트협회(Portland Cement Association)의 Thomas B. Carter 부회장은 시멘트 산업이 반환경적인 측면으로 비추어지는 부분을 최소화할 수 있는 다양한 방안을 제시하였고, 일본 태평양시멘트 중앙연구소의 토미타 로쿠로 소장은 일본에서의 산업폐기물 사용 현황 및 다양한 산업폐기물 재활용 기술을 소개하였다. 특히, 일본에서 생산된 시멘트 1톤에 활용되는 폐재료 및 부산물의 양이 평균 400kg에 이르고, 생활쓰레기를 사용한 Eco-Cement의 생산현황 및 지방자치단체의 협조체제 등을 볼 때, 자연환경을 훼손하는 일부 부정적인 이미지만 부각되어 환경파괴의 주범으로까지 잘못 인식되고 있는 우리 현실과 극명하게 대비되어 눈길을 끌었다. 이어서 국내 연사로 나선 군산대학교 이승헌 교수는 "최근 일각에서 제기하고 있는 시멘트중의 미량성분으로 포함돼 있는 6가 크롬에 대한 유해성 여부에 대해 문제제기 차원에서는 바람직하나 시멘트를 유해물질이라고 단정짓는 감성적인 접근보다는 좀더 다양한 실험을 통해 이의 유해성 여부를 규명짓는 것이 선결되어야 한다" 고 언급하였다. 이에 심포지 엄에서 많은 관심을 불러일으킨 토미타로쿠로 일본 태평양시멘트 연구소장의 연구논문과 이승헌 교수의 연구논문을 중심으로 심포지엄의 성과를 간략하게 소개하고 시멘트 콘크리트 관련 전문가가 참석한 종합토론을 정리, 요약 게재한다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.541-544
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• 2008

Recently, due to the increase of high-rise buildings construction, many researches for making harden of concrete earlier and remove of forms faster are being performed to reduce construction period. The purpose of this study is to analysis which mixing condition and curing temperature of early strength concrete. Porperties of concrete by the different factors, such as the type of active admixtures, mineral admixtures, curing temperature, the amount of binder, etc. Through the test of concrete using the different type of admixture, PC type was more excellent than PNS type admixture. The concrete Strength remarkably will be able to confirm that decreases from temperature below 12$^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.609-612
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• 2008

This study investigated effect of recycled fine aggregate quality on strength properties of concrete. Some investigations have been carried out to study the strength properties of recycled aggregate concrete. But these have some limitation due to small-scale test in the laboratory. Therefore concrete using this study were fabricated by ready-mix concrete. Variables were quality of recycled fine aggregate(high and low quality) and replacement ratio of 0%, 30%, 60%, 100%(high quality), 35, 70%(low quality). The change of air content of recycled aggregate concrete were similar to natural aggregate concrete. Replacement ratio of recycled aggregate was not necessarily correlated with compressive strength and modulus of rupture of recycled aggregate concrete.

• Journal of the Korea Institute of Building Construction
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• v.14 no.6
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• pp.515-522
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• 2014

In order to quantitatively evaluate the effect of fly ash (FA) as partial replacement of cement on the life-cycle environmental impact of concrete, a comprehensive database including 4023 laboratory mixes and 2120 plant mixes was analyzed. The environmental loads on the life-cycle assessment were quantitatively converted into environmental impact indicators through categorization, characterization, normalization and weighting process. The life-cycle environmental impacts of concrete could be classified into three categories including global warming, photochemical oxidant creation and abiotic resource depletion. Furthermore, these environmental impacts of concrete was decreased with the increase of the replacement level of FA and governed by the unit content of ordinary portland cement (OPC). As a result, simple equations to assess the environmental impact indicators could be formulated as a function of the unit content of binder and the replacement level of FA.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.561-569
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• 2016

Concrete is cheap, easy to deal with, and the quality is satisfactory. Also, it is one of the easiest materials to get because chemical composition of cement is similar to chemical composition of surface. On the other hand, it is so vulnerable to transform because of weak binding capacity and low binding energy that it produces cracks. Cracks decline durability, usability, safety of structures and damage exterior. In order to decline drying shrinkage crack, this study used shrinkage reducing typed Superplasticizer, which is combination of and water-reducing agent for convenience, different with existing study using AE agent, water-reducing agent, shrinkage reducing agent,. Considering SRS field application possibility, this study planned to mix concrete and mortar generally used in ready-mixed concrete company and did basic experiment depending on a change of SRS content ratio and admixture. Based on the experiment result. It is judged that SRS admixture 2% is proper ratio when Given the intensity and length change. Also mass combination will conduct follow-up studies.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.43-49
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• 2015

The objective of this paper is to investigate experimentally the effect of the substitution of recycled aggregates under 13mm on the properties of the concrete using coarse aggregate with size of 13~25mm. Recycled aggregate under 13mm were substituted to the concrete ranged from 10% to 100%. To compare the properties with the case of recycled aggregate, crushed stone with smaller than 13mm was also substituted to the concrete by 20% and 40%. Test results showed that increase of recycled aggregate under 13mm resulted in the increase of slump and compressive strength compared with plain mixture, which was made with only aggregate with 13~25mm size. This is due to the dense gradation of aggregate in association with addition of relatively small particle. It is thought that the use of recycled aggregate under 13mm along with 30% contributes to the quality improvement of the concrete made with only 13~25mm aggregate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.2
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• pp.297-305
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• 2016

This study aims to analyze characteristics of environmental load for the construction phase of PSC beam bridge based on Life Cycle Assessment. For detail computation of environmental load, the construction materials and energy consumption are derived from the BOQ, also connecting with environmental load by Korea LCI Database Information Network. The characteristic of environmental impact was analyzed by 25 cases and cut-off ratio was 80% to 94%. The result sorted by construction materials revealed that environmental load were 53.3% for ready-mixed concrete, 9.6% for wire rod, 7.8% for rebar, 6.8% for cement, 5.5% for plywood, and 5.2% for energy. Furthermore, the result of environmental impact revealed that 45.5% for global warming, 30.4% for abiotic resources depletion, 10.5% for human toxicity, and 8.9% for photochemical oxidant creation. In the future, we can make a decision considering environmental load based on LCA at design phase.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.78-85
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• 2020

Shotcrete concrete is generally used in the form of ready-mixed concrete products using type I ordinary portland cement(hereinafter referred to as OPC) and about 5% of accelerator mixed separately in the field. In this study, we tested the effect of OPC fineness and SO₃ content on a penetration resistance, compressive strength of binder for shotcrete using calcium aluminate type accerlerator. And we analysed hydrates and pore structure effects on mortar performance. In the future, it is expected to be useful for manufacturing optimized OPC as a binder for shotcrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.86-93
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• 2020

Shotcrete concrete is generally used in the form of ready-mixed concrete products using type I ordinary portland cement(hereinafter referred to as OPC) and about 5% of accelerator mixed separately in the field. In this study, we tested the effect of addition of slag powder(SP) and limestone powder(LSP) on a penetration resistance, compressive strength of binder for shotcrete using calcium aluminate type accerlerator. And we analysed hydrates and pore structure effects on mortar performance. In the future, it is expected to be useful for manufacturing optimized composite cement as a binder for shotcrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.25-28
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• 2007

In this study we measured the changes according to time respectively on the basis of 0, 30, 60 and 90 minutes, taking into consideration the decline in fluidity of concrete according to elapsed time to analyze manufacturing capability of batcher plant according to elapsed time of ready-mixed concrete manufactured in batcher plant, and offer basic data for mixture design of ultra-high strength concrete. The proportion of water-binder was 23.55, water content was 160kg/m3, proportion of replacement of crushed sand was 0, 20 and 40% at 3 level, and we applied to the same condition of triaxial component using blast furnace slag powder and silica fume as admixture. And to meet the demand of certain fluidity, we measured respectively on property before and after hardening of ultra-high strength concrete using superplasticizer. As a result of experiment, before hardening of ultra-high strength concrete showed the best fluidity in conditions of crushed sand replacement rates of 20% and superplasticizer composition of 1.95%, but it appeared that fluidity drops as time goes by in the same composition condition. And it appeared that when it comes to hardened, the changes of compression strength according to elapsed time by crushed sand replacement rates were within 1MPa. Therefore, it turned out that the difference of strength according to elapsed time was low and compression strength of 280dys in composition mentioned above appeared highly as 88MPa.