• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.168-176
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• 2017

This study, as a research for using crushed sand as a fine aggregate of concrete for nuclear structures, we improved the performance of impact crusher in the existing crushed sand production process and adjusted grain size to conform to ASTM C 33 The shape and grain size characteristics of a crushed sand were examined and concrete was prepared according to the substitution ratio of the sand to investigate the properties of fresh concrete and hardened concrete. The experimental results show that most of the concrete characteristics are equivalent to those of concrete using only heavy sand. However, when the substitution rate of steel sand exceeds 50%, the amount of air, compressive strength and tensile strength are somewhat reduced.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.7
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• pp.25-33
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• 2005

This study was performed to develop environment-friendly porous polymer concrete utilizing recycled aggregates [RPPC] for permeable pavement of uniform quality with high permeability and flexural strength as well as excellent freezing and thawing resistance. The void ratios of RPPC are in the range of 15$\sim$$24\%$, showing the tendency that it is reduced to a great extent as the mixing ratio of the binder increases. The compressive and flexural strength of RPPC are in the range of 19$\sim$26 MPa and 6.2$\sim$7.4 MPa, respectively. Also, it shows a tendency to increase as the mixing ratio of the binder and filler increases. The permeability coefficients of RPPC are in the range of $6.3\times$$10_{-1}$$\sim$$1.5\times$$10_{-2}$cm/s. The flexural loads of RPPC are in the range of 18$\sim$32 KN. The weight reduction ratios obtained from the test for freezing and thawing resistance are in the range of 1.1$\sim$$2.4\%$ after 300 cycles of repeated freezing and thawing of the specimen for all mixes. The relative compressive strengths of RPPC after 300 cycles of freezing and thawing against the compressive strength before freezing and thawing test are in the range of 89$\sim$$96\%$.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.785-788
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• 2008

This study is focused on applying heavyweight concrete to ballast used to have stability of a ship. Generally, heavyweight concrete is made from a high density aggregate like magnetite or limonite. However, these materials are hard to obtain them from relevant companies and so expensive. Therefore, this study plans to product heavyweight ballast concrete which is easy to obtain by recycled iron slag. Heavyweight ballast concrete isn't required to meet some compressive strength in use, but it is required to have high flowable and 2.7t/m3 of bulk density to fill the ballast tank densely. The designed field mix proportion of concrete based on the results of pre-experiment shows it can control the temperature crack and has superior chloride corrosion resistance after conducting chloride corrosion experiment. Also, it is prefer that before airtightness voltile corrosion inhibiter(VCI) is added in airtight space of shipyard.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.55-62
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• 2010

This is an experimental research in order to judge the applicability of sewage sludge incineration ash having applied the mixing proportion needed to manufacture bricks and to do plaster work with addition of hwangtoh and slaked lime as a part of the methods for utilizing the wastes produced from sewage sludge incineration ash. Based on the results from experiment and analysis, it is judged that, in case of mixing proportion of 1:2 for the purpose of plastering and masonry work, the cement mortar produced by using a 10% addition ratio of sewage sludge incineration ash with mixture of hwangtoh covering all range of addition ratio, and also the cement mortar produced by using a 20% of sewage sludge incineration ash together with 0% and 10% addition ratio of hwangtoh, was possible to be applied to the practical use. In case of mixing proportion of 1:7 for manufacture of bricks and blocks, if such brick and block products are produced with 10% and 20% addition ratio of sewage sludge incineration ash having added aggregate fines or stone dust that has been actually used in brick and block manufacturing, it is judged that these bricks and blocks could be practically used in the job sites, although strength development is a little bit lower.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.712-715
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• 2008

The construction wastes rapidly increase because of redevelopment, the development of new urbanization of large-scale land development, the expansion of social infrastructure. As one of the ways to recycle construction waste to be recycled directly. This case, recycling of materials uses up most of recycled aggregate can be secured reliably. As a result, a decrease in the amount of materials brought in or taken out of the site, the cost of transportation, carbon dioxide emission, and traffic can be reduced. Economic, social and environmental effects can be expected. Therefore, this study of the construction waste "Site-Recycling" to enable the construction waste from the occurrence of "site-recycling" that can be processed in batches to apply the "Site-Recycling Simulation Program" is to develop the algorithms.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.244-251
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• 2015

The paper evaluates the effect of the physical property, fineness modulus (FM) and replacement ratio of crushed sand on the characteristics of concrete. This is intended to use crushed sand from Daegu-Kyungbuk region as the fine aggregate of concrete. The experimental result indicates that the replacement ratio of crushed sand needs to be less than 50% to satisfy the mixed gradation of both natural and crushed sand when their FMs are 2.0 and 3.2, respectively. The slump of concrete with crushed sand increased as the replacement ratio of crushed sand increased, while the workability of concrete with the replacement ratio of more than 75% was significantly reduced. The air content and bleeding rate of concrete was reduced as the replacement ratio increased. Furthermore, due to the enhancement of the concrete adhesive regardless of the FM of crushed sand, compressive strength of concrete tended to improve as the replacement ratio increased.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.342-347
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• 2015

This study is basic experiment which prevents indiscriminate reclamation and recycles the wasted tire in order to solve environmental pollution according to generation rate of the wasted tire from recently industrial development. By applying as the substitute material of the lightweight aggregate among the constructional materials in order to evaluate the lightness of the wasted tire chip and suggest the recycling plan of the wasted tire chip. The prior experiment did the replacement ratio of the wasted tire with 20%, 40%, 60%, 80%, 100%, etc. and made a study on the strength and density properties. Based on the prior experiment of wasted tire, the replacement ratio was fixed at 15, 20, 25%, particle size of wasted tire was fixed at 0.2, 0.8, 1~2, 3~5, 5~7(mm). As a result, it is supposed that the best replacement ratio and particle size are 15% and 1~2mm, respectively.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.165-171
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• 2016

The objective of this study is to evaluate the compressive strength development and ecological characteristics of mortars using expanded vermiculite absorbing bacteria as a fundamental investigation to develop precast eco-concrete products. For bacterial growth under the high-alkalinity and high-dried environments within hardened mortars and for creating plant growth function to mortars, Bacillus alcalophilus and Rhodoblastus acidophilus were separated and cultured. The cultured bacteria were absorbed into expanded vermiculite selected for bacteria shelter. The expanded vermiculite absorbing bacteria was then added into mortar mixture as a volumetric replacement of fine aggregate. Test results showed that the developed technology is very effective in enhancing the plant growth onto the hardened mortars and reducing the COD and T-N concentration in raw water. The optimum replacement level of expanded vermiculite absorbing bacteria can be recommended to be less than 10% considering the compressive strength development and cost of mortars along with the ecological effectiveness.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.367-374
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• 2019

Drying shrinkage in the hardened cement is known to change in volume by decreasing the moisture content in the hardened body, and it is known that the higher the W / C and the higher the content of the paste, the larger the drying shrinkage. In the case of ECC, more drying shrinkage occurs compared to concrete, since it does not contain coarse aggregate. Since ECC is an important material for tensile performance, the effect of restrained tensile stress on mechanical tensile behavior should be considered. The purpose of this study is to analyze the effect of stress caused by restraint on the tensile behavior of ECC. The mechanical properties of the specimens were tested by uniaxial tension tests with different restraints. As a result, the difference of tensile behavior according to restraint stress was observed and the cause was analyzed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.202-209
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• 2019

The objective of this study is to examine the reproducibility for compressive strength development and mechanical properties of lightweight concrete made using bottom ash aggregates and foam(LWC-BF). Based on the mix proportions conducted by Ji et al., six identical mixes were prepared with different actual foam volume ratios from 0% to 25% and water-to-binder ratios from 25% to 30%. The presently measured properties, including initial slump, slurry density, compressive strength gains at different ages, splitting tensile strength, and modulus of rupture, were very close to those determined in the previous tests by Ji et al. Thus, the developed LWC-BF has a good potential in obtaining a reproducibility for compressive strength development and mechanical properties even though the troubles of mixing control owing to the addition of preformed foam.