• Nuclear Engineering and Technology
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• v.55 no.6
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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.

• The Journal of Engineering Geology
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• v.13 no.3
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• pp.345-358
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• 2003

Recently, the reuse of coarse aggregate derived from demolished concrete was introduced into practice with two environmental aspects: protection of natural sources of aggregate and recycling of construction waste. However, recycled aggregate has been used for the very limited application such as subbase material for pavement and constructional filling material because it was considered as low quality constructional materials. In the present study, in order to examine the possibility that recycled aggregate can be used for concrete mixing, we conducted various experimental tests to identify mineralogical, chemical and mechanical properties of recycled aggregate and to determine the workability and mechanical properties of recycled aggregate concrete (RAC). The cement paste and mortar contained in recycled aggregate significantly affect the basic mechanical properties of aggregate and the workability and mechanical properties of RAC. However, RCA mixed with the proper replacement ratio of recycled aggregate shows the comparable compressive strength and freeze and thaw resistance to those of normal concrete. Therefore, it is considered that recycled aggregate can be widely used for concrete if the cement paste and mortar can be efficiently removed from recycled aggregate and/or if the effective replacement ratios of recycled aggregate are applied for mixing concrete.

• Journal of the Korea Institute of Building Construction
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• v.12 no.1
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• pp.73-86
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• 2012

In this research, the possible applicability of mixture blended with natural, crushed, and recycled fine aggregate are discussed. The fresh and hardened properties of mortar using blended fine aggregates are monitored depending on various blending ratio of fine aggregates. Newly developed ternary diagram was also utilized for better interpretation of the data. It was found that air content increased and unit weight decreased as recycled fine aggregate content increased. With moisture type processing of recycled fine aggregate, the mortar flow was not negatively affected by increase in the recycled fine aggregate content. The ternary diagram is found to be an effective graphical presentation tool that can be used for the quality evaluation of mortar using blended fine aggregate.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.177-182
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• 1995

Large-scaling recycling of demolished concrete will contribute not only to the solution of a growing waste disposal problem. it will also help to conserve natural resoures of sand and gravel and to secure future supply of reasonly priced aggregates for builiding and other construction purposes within large urban areas. because recycled aggregate particles consist of substaintial amount of relatively soft cement paste component, it is less resistant to mechanical actions. With this view in mind, to obtain a reference data for the development of recycling system and to a basic data the guideline of recycled aggregate concrete construction and mix design, this study deals with the comparative analysis of the workability and engineering properties of recycled aggregate concrete according to the factors, such as blending ratio of recycled aggregate with the natural aggregate, addition of flyash, water cement ration.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.415-418
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• 2003

This study is performed to examine properties of polymer permeability concrete using recycled coarse aggregate and blast furnace slag for application of structures needed permeability. Tests for compressive strength, flexural strength and pulse velocity with replacement ratio of recycled coarse aggregate are performed. As a result, compressive strength, flexural strength and coefficient of permeability of polymer permeability concrete containing recycled coarse aggregate are in the range of $180{\sim}200kgf/cm^2,\;58{\sim}64kgf/cm^2\;and\;4.6{\times}10^{-2}{\sim}6.9{\times}10^{-2}cm/s$, respectively. Compressive strength, flexural strength and pulse velocity of polymer concrete containing crushed stone only are $192kgf/cm^2,\;65kgf/cm^2\;and\;6.1{\times}10^{-2}cm/s$, respectively. Accordingly, recycled coarse aggregate is expected that can be utilizing as an aggregate of polymer permeability concrete.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.411-414
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• 2003

This study is performed to examine the physical and mechanical properties of recycled polymer concrete using recycled coarse aggregate and recycled fine aggregate. Tests for compressive strength, flexural strength and pulse velocity with replacement ratio of recycled coarse aggregate and recycled fine aggregate are performed. As a result, compressive strength, flexural strength and pulse velocity of polymer concrete containing recycled coarse aggregate are in the range of $826{\sim}849kgf/cm^2,\;192{\sim}200kgf/cm^2\;and\;3,932{\sim}4,000m/s$, respectively. Compressive strength, flexural strength and pulse velocity of polymer concrete containing crushed stone only are $805kgf/cm^2,\;197kgf/cm^2$ and 3,931 m/s, respectively. Accordingly, recycled aggregates is expected that can be utilizing as an aggregate of polymer concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.501-504
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• 2006

Recently, the Ceramic Bricks are getting increased due to demolishing aged buildings. But, disposal of the waste ceramic bricks has been relied on just burying into the ground. Regardless they can be used with recycled thick aggregate. Therefore the range of this study includes the experiment of slump test, compression, strength test and stress-strain analysis to the concrete the recycled thick aggregate with made by ceramic bricks. The reducing method of fine aggregate will be reviewed stand on analysis of this experimental result.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.521-526
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• 2000

The structural behavior of the members using recycled coarse aggregate is investigated in this papers. The members considered this study are subjected to shear ad bending simultaneously. A series of test beam specimens using recycled coarse aggregate is made for the structural test. These specimens are manufactured using the concrete for the compressive strength of 280kg/$\textrm{cm}^2$ with recycled aggregate ratio of 0%, 20%, 40%, 60%, 80% of total aggregate volume, respectively. The main object of this test is to investigate the influence of the using recycled aggregate to the cracking strength of the member subjected to flexure and shear and the post cracking behavior.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.178-179
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• 2017

In this study, the fundamental properties of cement mortar in relation to the change of the replacement ratio of the RA(Reject-Ash) were analyzed by mixing RA to the mixed aggregate consisting of poorly graded fine rock aggregate and marine aggregate for quality improvement. It was found that replacing 5% of the mixed aggregate with RA could improve the quality of the aggregate to the degree of fine rock aggregates.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.97-100
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• 2008

In order to recycled wast concrete which is occurred from demolition of the old building, it is effective that the recycled aggregate used as structural concrete aggregate. For used recycled aggregate with structural concrete, the structural capacity must be confirmed. This Study investigated bond capacity which follows in difference of absorption of the aggregate between rebar and concrete. Test results show that there are not a difference of bond strength and slip behavior according to absorption ratio of natural and recycled coarse aggregate.