• Geomechanics and Engineering
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• 제32권6호
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• pp.601-613
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• 2023

Low liquid limit silt, widely distributed in the middle and down reaches of Yellow River, has the disadvantages of poor grading, less clay content and poor colloidal activity. It is very easy to cause vehicle jumping at the bridge-embankment transition section when the low liquid limit silt used as the backfill at the abutment back. In this paper, a series of laboratory tests were carried out to study the physical and mechanical properties of the low liquid limit silt used as back filling. Ground granulated blast furnace slag (GGBFS) was excited by active MgO and hydrated lime to solidify silt as abutment backfill. The optimum ratio of firming agent and the compaction and mechanical properties of reinforced soil were revealed through compaction test and unconfined compressive strength (UCS) test. Scanning electron microscope (SEM) test was used to study the pore characteristics and hydration products of reinforced soil. 6% hydrated lime and alkali activated slag were used to solidify silt and fill the model of subgrade respectively. The pavement settlement regulation and soil internal stress-strain regulation of subgrade with different materials under uniformly distributed load were studied by model experiment. The effect of alkali activated slag curing agent on curing silt was verified. The research results can provide technical support for highway construction in silt area of the Yellow River alluvial plain.

• 한국건축시공학회지
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• 제17권4호
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• pp.341-348
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• 2017

콘크리트 포장도로는 동절기 제설제에 의한 내구성 저하가 심각한 위협으로 거론되고 있고 그 보수에도 많은 비용이 소요되고 있다. 따라서 이러한 콘크리트 포장재에 대한 적절한 보수 대책의 마련과 이에 활용될 우수한 성능의 보수 재료가 요구되고 있는 상황인데, 본 연구에서는 국내에서 개발된 인산마그네슘 세라믹(Magnesium phosphate ceramics)을 대상으로 압축강도 특성 및 염소이온 침투 저항성, 길이변화 특성을 평가하여 국내 콘크리트 포장 도로의 보수 재료로 적용 가능성을 검토하였다. 평가 결과 모르타르의 유동성은 190mm의 평범한 수준을 나타내었으나 다소 점성이 높고 재료 자체의 흐름성은 크지 않았다. 응결 시간은 12분으로 매우 빠른 경화가 이루어졌으며 이에 따라 신속한 작업이 요구되었다. 모르타르의 압축강도 성능은 2시간에 38.4MPa, 24시간에 73.8MPa, 28일에 111.0MPa로 재령 초기부터 높은 수준을 나타내었다. 염소이온 침투 저항성 시험 결과 모르타르의 경우 143 Coulombs, 콘크리트의 경우 173 Coulombs으로 매우 우수한 수준을 나타내었다. 콘크리트의 길이변화 시험 결과는 재령 40일까지 $60{\times}10^{-6}$ 이하로 완만하게 감소하였으며, 보통의 시멘트 콘크리트의 길이변화 수준과 비교할 때 1/10 이하의 수준으로 우수한 체적안정성을 확보하고 있었다. 이상과 같이 인산마그네슘 세라믹은 우수한 강도 성능과 염소이온 침투 저항성, 체적 안정성을 보유하고 있음을 확인하였고, 향후 작업 시간이나 작업성에 대한 개선이 요구되며, 현장 적용시에는 이러한 부분에 대한 주의가 필요하다.

• Interaction and multiscale mechanics
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• 제3권4호
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• pp.389-403
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• 2010

Based on the Model Coupled Method (MCM), a case study has been carried out on a Concrete-Filled Steel Tubular (CFST) tied arch bridge to investigate the vibration problem. The mathematical model assumed a finite element representation of the bridge together with beam, shell, and link elements, and the vehicle simulation employed a three dimensional linear vehicle model with seven independent degrees-of-freedom. A well-known power spectral density of road pavement profiles defined the road surface roughness for Perfect, Good and Poor roads respectively. In virtue of a home-code program, the dynamic interaction between the bridge and vehicle model was simulated, and the dynamic amplification factors were computed for displacement and internal force. The impact effects of the vehicle on different bridge members and the influencing factors were studied. Meanwhile the acceleration responses of some of the components were analyzed in the frequency domain. From the results some valuable conclusions have been drawn.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.305-308
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• 2008

This paper describes a research study on the durability and strength properties of thin quiet-permeable asphalt concrete. Such asphalt mixes have high porosity, which offers significantly better drainages than normal mix designs. However, these materials also exhibit poor durability and strength limiting their use in pavement application. To remedy this, fiber and polymer modifiers have been proposed. All samples were added to modified binder which were prepared with or without the modifiers and fiber using Marshall mix procedures and were experimentally tested using various standardized testing procedures including percent air void for porosity, cantabro test and marshall stability. In general, the results of marshall stability showed that modified mixtures were equivalent to unmodified mixtures. Especially, the result of cantabro tested modified mixtures was superior to unmodified mixtures.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• 제2호
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• pp.114-119
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• 2004

By Article two of a Japanese urban park low, it prescribes park facilities strictly, and one of the classifications includes 'path and plaza'. In addition, it is assumed that we divide several kinds different paths of width by size of the park in a path design of a park with a textbook of park design in a trunk line path, the main path, a vice-path or a branch path and design it. From such a thing, in the path of an urban park, a line consists straight of fixed width, and it is most that one pattern is considered to be. Therefore, in modem urban park, a path and division of a plaza are lucid explanation. It is rare that the historical parks which generally former daimyo gardens are shown later, and is used as a kind of an urban park width of the path where was particularly posted in a strolling garden in that is fixed, and width waits straight for even a line and waits, and, for this, there is. As a result, it is a path and the situation that are hard to be distinguished of a plaza. Although there are a difference of design and a difference of pavement materials in modem landscape space when We watch road surface constitution of the path that We did that will let you wait, in gross We are uniform, and it is it with a result to be poor in change nature. From such an observation, this consideration compared traditional landscape space and modem landscape space with path width about two points of road surface constitution through the trial that a graph analyzed the actual place data which measured into and lectured on an ideal method of a park path from this.

• Geomechanics and Engineering
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• 제14권6호
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• pp.553-562
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• 2018

Road construction is becoming increasingly important in marine and desert areas due to population growth and economic development. However, the load carrying capacity of pavement is of gear concern to design and geotechnical engineers because of the poor engineering properties of the soils in these areas. Therefore, stabilization of the soils is regarded as an important issue. Besides, due to the fuels combustion and carbonate decomposition, cement industry generates around 5% of global $CO_2$ emission. Thus, using bentonite as a natural pozzolan in soil stabilization is more eco-friendly than using cement. The aim of this research is to experimentally study of the stabilized marine and desert sands using deep mixing method by ordinary Portland cement and sodium bentonite. Different partial percentages of cement along with different weight percentages of sodium bentonite were added to the sands. Unconfined compression test (UCS), Energy Dispersive X-ray (EDX), and Scanning Electron Microscope (SEM) were conducted on the specimens. Moreover, a mathematical model was developed for predicting the strength of the treated soils.

• 한국도로학회논문집
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• 제17권2호
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• pp.47-53
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• 2015

PURPOSES: The scaling of a concrete surface caused by the combined effects of frost and de-icing salts is one of the main reasons for the need to repair transportation infrastructures in cold-climate regions. This study describes the results of attempts to determine the scaling resistance of concrete incorporating mineral admixtures such as fly ash, GGBFS, and silica fume, and subjected to the actions of frost and salt. METHODS : Conventionally, to evaluate the fundamental properties of concrete, flexural and compressive strength measurements are regularly performed. Based on the ASTM C 672 standard, concrete is subjected to 2%, 4%, and 8% $CaCl_2$ salt solutions along with repeated sets of 50 freeze/thaw cycles, and the scaling resistance was evaluated based on the mass of the scale and a visual examination. RESULTS : It was observed that silica fume is very effective in enhancing the scaling resistance of concrete. Meanwhile, concrete incorporating GGBFS exhibited poor resistance to scaling, especially in the first ten freeze/thaw cycles. However, fly ash concrete generally exhibited the maximum amount of damage as a result of the frost-salt attack, regardless of the concentrations of the solutions. CONCLUSIONS: It can be concluded that the scaling resistance of concrete is highly dependent on the type of the mineral admixture used in the concrete. Therefore, to provide a durable concrete pavement for use in cold-climate regions, the selection of a suitable binder is essential.

• 한국건축시공학회지
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• 제9권3호
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• pp.65-71
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• 2009

General criteria for the quality of porous concrete have not been established yet in Korea. And yet, pavement and construction have been performed. In this paper, guidelines on the construction site quality control of porous concrete were developed in order to establish criteria for resolving the issues and problems of porous concrete, to establish methods for improving poor performance, and to manage porous concrete more systematically. In addition, a guide for the construction site quality control of porous concrete, which was appropriate for reality, was developed by researching several quality control guides and maintenance at construction sites. The guide consists of a total of nine chapters such as Application Range, Overview, the Structure of Porous Concrete, the Design of Package Thickness, Package Materials for Porous Concrete, Construction Methods, Quality Assurance and Inspections, Construction Site Quality Control, and Maintenance. It describes quality control guidelines in all steps such as methods for transporting porous concrete from the factory to the construction site, cautions for construction work at construction sites, maintenance, and management. The Guide for the Construction Site Quality Control of Porous Concrete is expected to ensure the quality of porous concrete, to reduce national costs for quality assurance, and to help ensure the health and safety of Korean people.

• 한국도로학회논문집
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• 제13권2호
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• pp.125-131
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• 2011

본 연구는 도로 운영시 강우로 인하여 발생하는 배수 취약구간에 대하여 현장 조사를 통하여 도로 배수 취약구간의 발생 원인을 과학적이고 구체적으로 규명하는데 목적이 있다. 도로 배수 취약구간의 발생 원인을 규명하기 위하여 배수취약구간에 대한 기존 연구결과 및 현황 자료를 검토하였으며, 도로 노면 배수시설과 도로 인접지 배수시설에 대한 취약구간을 조사 및 분석한 결과, 시공 및 기타의 원인으로 발생한 배수 취약구간이 45.7%, 도로의 기하구조가 원인이 된 배수 취약구간은 32.3%, 도로의 수리 수문의 원인은 22.0%로 분석되었으며, 분석된 원인 별 개선 방안으로서 i)시공 및 기타 부분에서는 토사측구의 재료 변경, 단면의 크기 상향 및 수리학적 근거를 바탕으로 한 용량의 산정을, ii)도로의 기하구조 측면에서는 편경사 및 종단선형을 고려한 합성경사의 도출 및 범위 산정과 종단 오목부 구간의 배수구조물 적정 간격의 제시를, iii)도로의 수리 수문 측면에서는 1분단위 강우강도식의 사용과 노면 강우의 부등류 흐름 해석 기법의 적용과 선형 배수방식에 따른 도로 노면 강우의 신속배제를 개선 방안으로 제안하였다.

• 한국건설순환자원학회논문집
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• 제4권4호
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• pp.388-395
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• 2016

본 논문에서는 폐수슬러지에서 제조된 재활용 이산화티탄($TiO_2$)을 혼입한 시멘트 모르타르의 NOx 저감 성능에 대해 고찰하였다. 일반적으로, 이산화티탄은 클러스터 형태로 입자가 붙어 있어, 시멘트의 응결과 경화 전에 타설체 하면에 침강하는 특징이 있다. 그 결과로 타설체의 상면과 하면에는 이산화티탄의 분포도가 서로 상당한 차이를 나타내고, 광촉매 효과도 하면에서 우수하게 나타난다. 건물이나 주택과 같은 건축구조물에서는 이를 해결하기 위해, 이산화티탄을 혼입한 프리캐스트 제품을 미리 제작 후, 조립 시에는 타설 시 상면과 하면을 뒤집어 거치하여 상대적으로 높은 이산화티탄 분포면을 대기에 노출시키는 방식을 사용한다. 그러나 콘크리트 도로포장과 같은 현장 타설의 경우, 상면과 하면을 뒤집어 거치할 수 없기 때문에 이산화티탄의 분산성은 중요하다. 이를 개선시키기 위한 본 논문의 결과로 실리카퓸, 고성능감수제, 증점제, 고로슬래그 등 전형적인 시멘트성 재료의 분산에 기여하는 재료는 이산화티탄 클러스터의 분산효과에 미미한 영향을 주었다. 급결제, 발포제, 작은 크기의 잔골재의 조합이 이산화티탄 클러스터의 분산성을 개선하였다. 분산성 개선에도 불구하고, 타설체 상면과 하면의 NOx 제거효율은 하면에 큰 효율을 지속적으로 나타내었고, 이는 표면에 분포하는 공극량에 따라 달라지는 것을 디지털 표면 이미지 분석을 통하여 확인하였다. 많은 공극분포를 갖는 표면은 상대적으로 매끄러운 표면에 비해 NO가스 흡착을 기본적으로 높이게 되고, 이를 기준으로 상대적인 NOx 제거효율이 높아지는 것으로 사료된다.