• Magazine of the Korea Concrete Institute
• /
• v.14 no.2
• /
• pp.37-44
• /
• 2002

콘크리트의 내화성능에 대한 다각적인 연구가 1970년대부터 원자로의 안정성 확보차원에서 진행되어 왔으며 특히 콘크리트의 취성파괴(brittle failure)등에 대한 연구가 많다. 콘크리트의 내화성이란 화재로부터 보호되고 고열환경에 견디는 재료적 특성 즉 화재온도 1,00$0^{\circ}C$ 정도의 고온을 30분에서 3시간 정도를 받은 경우 콘크리트 중에 매립된 철근 등 철강을 소정의 온도 이하고 유지하기 위한 피복 역할을 유지하면서 구조물의 큰 변형이나 붕괴 등을 막기 위한 소요 압축강도 및 영계수 등의 성능을 가지고 있는 성질을 말한다.(중략)

• Magazine of the Korea Concrete Institute
• /
• v.14 no.4
• /
• pp.14-21
• /
• 2002

국내에서 시공되는 콘크리트 구조물의 대부분은 레미콘(ready-mixed concrete)으로 시공되고 있기 때문에 레미콘의 품질관리(quality control) 및 품질확보(quality security)는 곧 콘크리트 구조물의 품질과 내구성의 확보를 위해 매우 중요한 사항이다. 최근 콘크리트 구조물의 잦은 사고로 인해 콘크리트의 품질문제가 사회문제로 나타나고 있으며 이에 대비한 콘크리트 품질보증 시스템의 확립이 시급한 실정이다. 그러나 레미콘의 품질환경은 원재료의 품질저하, 레미콘 운반시간의 증대 및 기술개발의 미흡 등 주변여건이 좋은 편은 아니며 레미콘 산업도 경쟁시대에 돌입하면서 레미콘 품질이나 기술우위의 시대로 변화되고 있다.(중략)

• Journal of the Korea Concrete Institute
• /
• v.25 no.5
• /
• pp.539-546
• /
• 2013

Cement industry in 1997 began to use industrial waste in cement factory for purpose of resource recycling. However recently, environmental hazard of the cement in accordance with recycling of industrial waste have been raised a problem by contamination around the cement factory and heavy metal leaching in cement. In particular, the presence of $Cr^{6+}$ in cement has become a critical issue, the studies for minimizing of $Cr^{6+}$ in cement have been performed. But, in domestic, most of the research on heavy metal leaching was carried out from the perspective of the cement. Environmental safety assessment in terms of concrete is needed because cement is used to the concrete material. Therefore, this paper was evaluated heavy metals leaching of deteriorated concrete by severe conditions. test result showed that $Cr^{6+}$ were not detected from all the variables.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.7 no.2
• /
• pp.123-130
• /
• 2019

The purpose of this study is to confirm the strength characteristics of concrete according to the mixing ratio of recycled fine aggregates and to use it as basic data for the use of recycled fine aggregates in concrete. For this purpose, the target design compression strength was set at 27MPa. Considering practical use of recycled aggregate, the mixing ratio of recycled fine aggregate was set at 0, 30, 60, and 100%, and the unconfined concrete and hardened concrete were tested. The LCA method was used to evaluate the environmental impact of recycled fine aggregate concrete, and the effectiveness of recycled fine aggregate in the production of concrete was verified.

• Journal of the Korea Institute of Building Construction
• /
• v.9 no.6
• /
• pp.71-78
• /
• 2009

The analysis of the effect of loading on chloride penetration into concrete is very important. In this study, we confirmed that the chloride penetration rates for plain and BFS concrete were increased by 47% and 89% under compressive stress, respectively. The diffusion coefficient of BFS concrete was lower than for conventional concrete with no BFS, no loads, and under stressed states. Therefore, BFS substitution plays an important role in the repression of chloride penetration even under compressive stress. Under compressive stress,the diffusion coefficient for BFS concrete was higher with increasing stress, and this was also the case for plain concrete. However, BFS concrete was strongly influenced by compressive stress in comparison to plain concrete. We investigated the effect of the difference of specific surfaces on the diffusion coefficient. As a result, the larger specific surface of BFS exhibited a lower diffusion coefficient. This tendency was most pronounced under the high stress conditions.

• Journal of the Korea Concrete Institute
• /
• v.14 no.4
• /
• pp.623-629
• /
• 2002

Porous concrete enables water and air to pass through a firmly hardened material and allows required nutrients to reach roots of plants. The purpose of this study is to analyze void ratio, strength property and planting ability when using silica fume and fly ash, the change of aggregate gradation and ratio of paste to aggregate. The results of an experiment from the planting ability of the porous concrete to its influence on the compressive strength are reported in this paper. As a result of the experiment, the compressive strength is higher when the gradation of aggregate is smaller, and it also goes higher when the ratio of paste to aggregate gets larger. The planting ability of porous concrete is decided by the germination and the grass length of perennial ryegrass. The grass length of perennial ryegrass is longer when the gradation of aggregate is greater and the ratio of paste to aggregate gets smaller. Therefore the efficiency of planting goes through the perennial ryegrass is in compliance with the void ratio, aggregate gradation.

• Journal of the Korea Concrete Institute
• /
• v.22 no.4
• /
• pp.547-557
• /
• 2010

This paper presents a study on the development of next generation smart concrete in an eco-friendly manner using micro-biologically induced calcite precipitation (MICP) via microbial biomineralization. It seems that currently, the reformation and functional improvement of concrete using MICP can be achieved using Sporosarcina pasteurii, which is a representative microorganism that produces calcite precipitation. Based on previous studies on MICP the biochemical tests and crystallinity evaluation of cement using sporoasrcina pasteurii and four additional micro-organisms from the concrete structures as identified by 16S rDNA sequence analysis were conducted. Also by applying the Sporosarcina pasteurii and separated four effective micro-organisms from the concrete structures to mortar, the compressive strength improvement by varying curing conditions, repair of crack were examined, and plans for future study were suggested. The effect of the application of effective micro-organisms can lead to the development of a new material that will contribute to resolution of environmental problems and facilitate repair work, and this can also serve as a new research theme in the future. In addition, the importance of this study is to use micro-organism, which is found common in concrete structures, this new microbial is not only environmentally safe but also persists in the natural environment for an extended period of time. Therefore, it seems to have a great potential to became a new environmentally low-burdened functional material.

• Korean Journal of Construction Engineering and Management
• /
• v.7 no.2 s.30
• /
• pp.71-80
• /
• 2006

It is required to study systematical on the concrete quality management to extend structure life because rebuilding effect is reducing under present condition of large sized and high stories structure. Concrete, which shows its intensity by hydrating action and a big change in quality according to hot weather and temperature, produces a lot of quality problem under hot and cold weather. Because of each specification and construction plan which does not have basic standard on site, concrete's quality is irregular and makes some defect. As a result, Dae-gu is fumed out to be the longest area after investigating application period and days focused on 8 cities weather information about t relationship between hot weather circumstance and construction environment. Therefore, we first surveyed the curing construction processing in the region and found out the problem of quality management. Then figure out the way of solution. Moreover, we integrated curing quality management, which is applied differently to each site, to have equal quality and to reduce defect from construction site. And then, based on various test of construction condition and analysis of quality management item, we suggest effective concrete quality management to make curing construction standard guide and plan under hot weather.

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

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.757-760
• /
• 2008

Recently, improvements in the standard of living in industrial area require establishment of a convenient residential environment in order to enhance the quality of living, To achieve such an environment, it is necessary to effectively reduce or prevent various environmental problems occurring in and around residential areas. In this study, We focused on the water-purification properties of concrete using effective micro-organisms. Such as SS, BOD, COD, T-P, T-N. The ability of the removal of SS, T-P, T-N in the test water is superior to concrete using effective micro-organisms. As a result, concrete using effective micro-organisms has sufficient performance of water-purification.