• 한국방재학회 논문집
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• 제5권1호
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• pp.77-84
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• 2005

콘크리트 구조물의 성능저하, 노후화 및 용도 변경 등으로 구조물을 해체할 경우가 증가하면서 발생되는 폐콘크리트량이 급증하고 있는 추세이지만, 거의 대부분이 단순 매립용 재료로 사용되고 있다. 우리나라와 같이 부존자원이 부족한 나라에서 폐기되는 콘크리트를 포장 콘크리트용 골재로 재활용할 경우 콘크리트용 천연골재의 부족 현상 극본, 자원절약 및 환경보존 등에 크게 기여할 것으로 기대된다. 본 연구에서는 실제 구조물에 사용된 콘크리트를 해체하면서 발생한 폐콘크리트를 파쇄하여 제조한 재생골재의 혼합율을 각각 5단계로 변화시켜 제조한 재생 골재를 포장 콘크리트용 골재로 활용하기 위하여 실시한 실험결과에 대하여 고찰하였다.

• Computers and Concrete
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• 제10권2호
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• pp.197-217
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• 2012

This research deals with the prediction of compressive strength of normal and high strength concrete using neural networks. The compressive strength was modeled as a function of eight variables: quantities of cement, fine aggregate, coarse aggregate, micro-silica, water and super-plasticizer, maximum size of coarse aggregate, fineness modulus of fine aggregate. Two networks, one using raw variables and another using grouped dimensionless variables were constructed, trained and tested using available experimental data, covering a large range of concrete compressive strengths. The neural network models were compared with regression models. The neural networks based model gave high prediction accuracy and the results demonstrated that the use of neural networks in assessing compressive strength of concrete is both practical and beneficial. The performance of model using the grouped dimensionless variables is better than the prediction using raw variables.

• 한국공간구조학회논문집
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• 제9권4호
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• pp.61-72
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• 2009

건축물이 고층화 및 대형화 되어감에 따라 구조물 및 빌딩의 자중을 줄이는 것은 반드시 필요하게 되는데, 이러한 구조물 의 자중을 줄이기 위한 가장 효과적인 방법 중 하나는 경량콘크리트를 사용하는 것이다. 본 연구에서는 경량콘크리트의 단점인 강도를 보완하기 위하여 폴리머를 첨가하였으며, 폴리머 개질 경량콘크리트의 적절한 배합비율을 도출하기 위한 실험을 수행하였다. 또한 경화콘크리트 시험을 통하여 폴리머 개질 경량콘크리트의 물리적 특성을 고찰하였다. 그 결과 소량의 폴리머 첨가로도 휨강도가 증가하였으며, 실험결과를 바탕으로 회귀분석을 통한 압축강도 추정식을 제시하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.151-156
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• 2001

Concrete has excellent characteristics as building material and functions relatively well; but it has many problems concerning too heavy weight of the structures. Accordingly, it is the assignment for study in the part of building materials to lighten and high strengthen the weight of concrete structures in order to improve those weak Points; and it seems one of the representative solutions to develop the high strength lightweight aggregate concrete. Based on the experimental results presented, the following conclusions are drawn. The concrete with unit weight of 1.96~2.03t/$m^{2}$, compressive strength of 322~431kgf/$cm^{2}$ was gained. So, it appears that the lightweight aggregate concrete will be useful for low unit weight and high strength lightweight aggregate concrete. In the end, to manufacture artificial lightweight aggregate concrete for construction work is necessary to develope artificial aggregate which has improved performances physically.

• 한국해양공학회지
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• 제25권1호
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• pp.73-79
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• 2011

The various properties of concrete have been required, as civil engineering structures are getting larger and complicated. Therefore, the high performance of concrete, such as high strength, high fluidity, and low hydration heat, has been investigated largely. In this study, the properties of lightweight concrete-reducing self-weight of structure member have been studied in order to check the applicability of lightweight aggregate concrete to structural material. The experiments on compressive strength, splitting tensile strength, unit weight, and modulus of elasticity have been conducted with varying PLC, LWCI, LWCII, LWCII-SF5, LWCII-SF15 to check the basic properties. The compressive strength of 21MPa was obtained easily by using lightweight aggregate concrete and the addition of silica fume to increase the compressive strength slightly. To use lightweight aggregate concrete for civil engineering structures, systematic and rigorous studies are necessary.

• Steel and Composite Structures
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• 제17권6호
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• pp.929-949
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• 2014

Thirty one push-out tests were carried out in order to investigate the bond behavior between shape steel, steel tube (named steels) and recycled aggregate concrete (RAC), including 11 steel reinforced recycled aggregate concrete (SRRAC) columns, 10 recycled aggregate concrete-filled circular steel tube (RACFCST) columns and 10 recycled aggregate concrete-filled square steel tube (RACFSST) columns. Eleven recycled coarse aggregate (RCA) replacement ratios (i.e., 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) were considered for SRRAC specimens, while five RCA replacement ratios (i.e., 0%, 25%, 50%, 75% and 100%), concrete type and length-diameter ratio for recycled aggregate concrete-filled steel tube (RACFST) specimens were designed in this paper. Based on the test results, the influences of all variable parameters on the bond strength between steels and RAC were investigated. It was found that the load-slip curves at the loading end appeared the initial slip earlier than the curves at the free end. In addition, eight practical bond strength models were applied to make checking computations for all the specimens. The theoretical analytical model for interfacial bond shear transmission length in each type of steel-RAC composite columns was established through the mechanical derivation, which can be used to design and evaluate the performance of anchorage zones in steel-RAC composite structures.

• Advances in concrete construction
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• 제5권4호
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• pp.303-311
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• 2017

The concrete industry of developing countries like India consumes majority of natural resources. The increase in population has necessitated the construction of more and more structures. Further many structures have completed their life span or have undergone damages thus warranting the demolition of these structures. India produces approximately 23.75 million tons of recycled concrete aggregate (RCA) annually. The natural resources are depleting at a higher rate with the increasing demand of concrete industry. This difficulty can be reduced with the use of RCA in land fill and concrete manufacturing. Use of RCA can provide cost savings and better energy utilization. This paper presents mechanical behavior of concrete comprising successively recycled concrete aggregate. Mechanical properties of recycled concrete get affected with number of recycling. In mix design successive recycled concrete aggregate (SRCA) was used in place of natural aggregates (NA) with 100% replacement. The test results of the compressive, flexural strength and pulse velocity were obtained for 14 and 28 days of curing age which showed significant improvement in results.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.124-125
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• 2015

Recycled aggregate is not used for structures because of negative awareness of quality. for improving the negative awareness, a concrete structure was built with 100% recycled aggregate and monitoring mechanical properties and durability was conducted. As a result, It was observed that mechanical properties and carbonation of structures with 100% recycled aggregate were fine.

• Computers and Concrete
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• 제12권5호
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• pp.627-650
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• 2013

This paper deals with application of a non-linear continuum model for reinforced concrete affected by alkali-aggregate reaction (AAR) to analysis of some nuclear structures. The macroscopic behaviour of the material affected by AAR is described by incorporating a homogenization/averaging procedure. The formulation addresses the main stages of the deformation process, i.e., a homogeneous deformation mode as well as that involving localized deformation, associated with formation of macrocracks. The formulation is applied to examine the mechanical behaviour of some reinforced concrete structures in nuclear power facilities located in Quebec (Canada). First, a containment structure is analyzed subjected to 45 years of continuing AAR. Later, an inelastic analysis is carried out for the spent fuel pool taking into account the interaction with the adjacent jointed rock mass foundation. In the latter case, the structure is said to be subjected to continuing AAR that is followed by a seismic event.

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2147-2157
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• 2023

The aggregate-forming minerals in concrete undergo volume swelling and microstructure change under neutron irradiation, leading to degradation of physical and mechanical properties of the aggregates and concrete. A comprehensive investigation of volume change and elastic property variation of major aggregate-forming minerals is still lacking, so molecular dynamics simulations have been employed in this paper to improve the understanding of the degradation mechanisms. The results demonstrated that the densities of the selected aggregate-forming minerals of similar atomic structure and chemical composition vary in a similar trend with deposited energy due to the similar amorphization mechanism. The elastic tensors of all silicate minerals are almost isotropic after saturated irradiation, while those of irradiated carbonate minerals remain anisotropic. Moreover, the elastic modulus ratio versus density ratio of irradiated minerals is roughly following the density-modulus scaling relationship. These findings could further provide basis for predicting the volume and elastic properties of irradiated concrete aggregates in nuclear facilities.