• Proceedings of the Korean Geotechical Society Conference
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• 2002.11b
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• pp.18-30
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• 2002

이암 및 셰일은 점토를 함유하고 있어 풍화작용을 받을 경우 공학적 성질이 급격히 변화하여 강도 저하, 내구성저하현상 및 토사와 유사한 거동을 보이는 등 토목공사에 위험한 요소가 되고 있다. 풍화된 시료엔 대한 실험용 시료 가공이 어렵고 적용 가능한 실험법이 적어 공학적 특성이나 거동을 정량적으로 파악하는 기법이 다른 암종에 비해 극히 제한된다. 현재까지 강도측정과 같은 일반적인 물성의 단순측정보다는 내구성을 분석하는 슬레이킹 내구성 시험 (Slake durability test), Modified Jar test, 팽창율 측정시험 (Swelling test) 등의 정량화 시험법이 주로 사용되고 있으며 국내 현장에서도 적용을 권장할 수 있다. 이러한 실험치의 해석에서 단일 실험치 (예: 팽창율)만으로 지질공학적 특성을 파악하는 경우 잘못된 판단을 할 수도 있으므로, X선 회절분석시험 (XRD: X-Ray Diffraction Test), TG-DTA분석, 주사전자현미경 (SEM: Scanning Electron Microscope) 이미지 분석, 투수계수 측정실험 등도 함께 수행하여 실험결과를 종합적으로 해석하는 것이 바람직하다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.96-102
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• 2019

When GGBFS(Ground Granulated Blast Furnace Slag) with high blaine is incorporated in concrete, compressive strength in the initial period is improved, but several engineering problems arise such as heat of hydration and quality control. In this paper, compressive strength and durability performance of concrete with 3,000 Grade-low fineness slag are evaluated. Three conditions of concrete mixtures are considered considering workability, and the related durability tests are performed. Although the strength of concrete with 3,000 Grade slag is slightly lower than the OPC(Ordinary Portland Cement) concrete at the age of 28 days, but insignificant difference is observed in long-term compressive strength due to latent hydration activity. The durability performances in concrete with low fineness slag show that the resistances to carbonation and freezing/thawing action are slightly higher than those of concrete with high fineness slag, since reduced unit water content is considered in 3,000 Grade slag mixture. For the long-term age, the chloride diffusion coefficient of the 3000-grade slag mixture is reduced to 20% compared to the OPC mixture, and the excellent chloride resistance are evaluated. Compared with concrete with OPC and high fineness GGBFS, concrete with lower fineness GGBFS can keep reasonable workability and durability performance with reduced water content.

• Journal of the Society of Disaster Information
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• v.10 no.4
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• pp.566-571
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• 2014

Recently, with concentrated social and engineering interests on durability, diversified subsequent researches have been progressed. The Chloride-induced corrosion, carbonation, freeze-thaw etc, deterioration factors of concrete act to concrete not privately but complexly, Fly ash is most frequently used admixture which is using a reduction method of deterioration. And the fly ash effects on improvement of durability with enhancement of fluidity, decrease of crack with reduction of hydration heat, promotion of long-age strength and have a economic advantage which replaces cement as a binding material. But, fly ash have different qualities and occasionally reduce the durability and strength by adhesion of AE admixture with unburned carbon powder etc. In this study, the experiments will take about various replacement ratio of fly ash concrete, and will analyze, consider the results, after these will verify applicability and validity as admixture and binding material.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.397-405
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• 2001

In clod weather regions, a strong seasonal wind brings sea salts to the land. In addition to it, recently, the spreading amount of deicing salts has increased numerously for purpose of removing snow and ice. Thus the salts environment around concrete structures becomes so severe that various damages of concrete due to applied salts will be brought up. Much of countries such as America, Europe etc. is carried out study for effects of deicing salts on concrete. However, there are not test methods for deterioration of concrete subjected to both freezing-thawing and chloride in Korea. In this study, we carried out test for the compound deterioration subjected to both freezing-thawing and chloride attack, to investigate the effects of sodium chloride on the deterioration of concrete. The test was performed to investigate the effects of cement type, strength and air content on the scaling deterioration of concrete. As a result, the scaling deterioration was accelerated in the presence of salts. And the resistance to scaling was strongly influenced by the type of cement, the strength and air content of concrete.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.285-293
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• 2023

In this research, we embarked on a meticulous analysis of the challenges inherent in real-world scenarios relating to the durability design standards of engineered concrete structures and the assessment of carbonation durability in concrete guidelines. Our investigation brought to light substantial issues concerning constructability and quality assurance. The genesis of these problems is the exclusive application of prescribed strength to exterior walls, neglecting other elements to facilitate smoother licensing procedures. While this methodology aims to mitigate financial constraints in alignment with enhanced standards, it invariably invites complications. Furthermore, it is imperative to resolve the uncertainty surrounding durability evaluations by establishing a clear and definitive objective. Alongside this, actionable steps must be formulated to forestall the emergence of fissures between the floors of residential buildings, particularly apartment complexes. It is equally essential to tackle issues connected to application by devising a comprehensive management strategy for potential cracking during the phase of maintenance.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.102-109
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• 2024

In order to use limestone powder as a material for concrete, the mechanical and durability characteristics of cement matrices manufactured by varying the substitution rate were evaluated. In general, limestone powder did not contribute to the cement hydration reaction, so as a result of the compressive strength test of cement mortar using it, the compressive strength decreased as the substitution rate increased. However, as a result of evaluating the durability performance of cement mortar using limestone powder, such as chloride ion penetration resistance, carbonation resistance, and chemical attack resistance, small particles of limestone powder showed superior results compared to the unsubstituted control mortar due to the micro-filler effect of filling the fine pores inside the cement matrix. Therefore, limestone powder is expected to be used as an effective method for improving the durability of concrete. In this study, the durability was evaluated by changing the mixing amount of limestone powder to 0 %, 5 %, 10 %, and 15 %, but it is judged that it is necessary to study in more detail the effect on the durability by changing the end and mixing amount of limestone powder to various levels in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.207-213
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• 1992

In this study, the strength and durability of compacted coal ash with proper mixing ratio of fly ash to bottom ash, such as 5:5 or 6:4, are examined for use of highway embankment and subgrade materials. Right after compaction, the strength of bituminous mixed coal ash is greater than that of anthracite mixed coal ash. The distinguished increase of strength with curing time is observed only in Ho-nam mixed coal ash that contains a lot of free lime, and the strength increase with curing time are not seen or little in the others. The durability in sinking test is good also in Ho-nam mixed coal ash, but satisfactory by adding 2% cement in the others. And it is seen that the effects of the strength increase with adding cement are greater in coal ash with proper mixing ratio than in fly ash or bottom ash respectly.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2002.11a
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• pp.58-63
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• 2002

콘크리트에 사용되는 재료들은 특성진전에 따라 콘크리트의 경제성에 따른 고내구성은 비교적 용이하게 되었고, 콘크리트 구조물도 대형화, 다양화, 고급화되어 특수한 용도로서의 사용이 늘어나고 있다. 여기에 주안점을 두어 음료병을 파쇄하여 콘크리트에 혼합했을 때 강도에 미치는 영향과 강도 특성을 알아보기 위한 것이다.(중략)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.251-254
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• 2009

건설 분야에서 FRP(Fiber Reinforced Polymers) 부재는 기존의 건설부재에 비해 많은 장점을 가지고 있어 여러 분야에서 연구 및 개발이 이루어지고 있다. 그중 FRP 재료를 이용한 교량 부재들이 해외 뿐만 아니라 국내에서도 연구되고 있으며, FRP 인장재 및 바닥판은 연구 및 개발이 완료돼 현재 시공 중에 있고 FRP 휨 부재 또한 연구가 활발히 진행되고 있다. 이런 FRP 부재는 외부 환경에 그대로 노출됨으로써, 온도 등의 주위 환경의 변화에 많은 영향을 받게 되며, 특히 높은 온도에 취약한 성질을 가지고 있다. 이에 본 연구에서는 FRP 부재의 온도에 따른 역학적 특성을 파악하기위한 실험적 연구로써, $-21^{\circ}C$, $100^{\circ}C$, $200^{\circ}C$에 각각 1시간씩 시험체를 보관한 뒤 내구성 실험을 실시하였다. 각각의 시험체는 FRP 모듈형 박스부재에서 4개씩 채취하였으며, 실험 실시 후 SEM촬영을 실시하여 파괴모드를 분석하였다. 실험 결과 저온일 때는 강도변화가 많이 나타나지 않았으나 고온일 때 압축 및 휨강도의 급격한 저조를 확인할 수 있었다. 고온 보관 시험체의 SEM(Scanning Electron Microscope) 촬영결과 수지의 손상으로 낮은 강도가 측정되는 것을 확인할 수 있었다.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.212-218
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• 2013

Tuff specimens were thermally treated with predetermined temperatures of 200, 400 and $600^{\circ}C$ to construct specimens simulating weathered tuff rocks. Specific gravity, absorption ratio, elastic wave velocity, uniaxial compressive strength, Brazilian tensile strength, Young's modulus, Poisson's ratio and slake-durability index were measured for pre-heated specimens. Heating of rock specimens entailed the degradation of material properties except for slake-durability index. It was found that correlations among P-wave velocity, uniaxial compressive strength, Brazilian tensile strength, Young's modulus and absorption ratio are high. Regression equations which use the P-wave velocity as an independent variable were presented to evaluate uniaxial compressive strength, Brazilian tensile strength, Young's modulus and absorption ratio.