• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.389-392
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• 2008

Electric-furnace-slag has the expansion, due to the reaction with water and free Cao. So compared with the blast-furnace-slag, the recycling range of EFS is subject to restriction. But the expansive reaction of EFS is removed, the it is possible to use aggregate for concrete. This study is the basic properties of concrete to used stabilized EFS(oxidized EFS). The EFS is used fine aggregate in concrete, and replaced by sea-sand(natural sand). The replacement ratio are 0%, 25%, 50%, 75%, 100%. The result of study, to used oxidized EFS-sand, the flowability and the compressive strength is increased. Also it is possible to reduce the Bleeding. It is necessary more study about using the EFS aggregate, like the durability, the mechanical property for concrete

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.409-415
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• 2012

To recycle the steel slag as manufactured composite materials of polymer concretes, we used the atomizing method to make round aggregates from steel slag, which is treated as industrial wastes. A round rapid-cooled steel slag was used to replace fine aggregate (river sand) or coarse aggregate (crushed aggregate), depending on the grain size. To examine general physical properties of polymer concrete composites manufactured from rapid-cooled steel slag, the polymer concrete specimen with various proportions depending on the addition ratio of polymer binder and replacement ratio of rapid-cooled steel slag were manufactured. In the result of the tests, the mechanical strength of the specimen made by replacing the optimum amount of rapid-cooled steel slag increased notably (maximum compressive strength 117.1 MPa), and the use of polymer binder, which had the most impact on the production cost of polymer concrete composites, could be remarkably reduced. However, the mechanical strength of the specimen was markedly reduced in hot water resistance test of polymer concrete composite.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.95-104
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• 2005

The research conducted to study the potential practicability of recycled aggregate concrete by analyzing the characteristics of concretes made of recycled quality aggregates produced by wet and dry process has found the following results. The air content of recycled aggregate concrete increased with increase of the substitut on rate due to mortar included while producing recycled aggregates. However, the concretes with aggregate produced by dry process had relatively low rate of increase in air content. The slump showed generally decreasing trend as the substitution rate of recycled aggregate increased regardless of the wet or dry process. It was assumed that the mortar particles remained in recycled aggregate absorbed the surplus hydration in concrete and decreased fluidity The compressive strength generally decreased as the substitution rate of recycled aggregate increased, however there was an increasing trend as well due to decreasing effect of water-cement ratio when the substitution rate of recycled aggregate reached 25, 50% after mix. This phenomena also appeared in early age, which meant that recycled aggregate concrete should not be retarded in setting when applied in the field. The tensile strength also reached the maximum when wet or dry recycled aggregate replaced with 25%. To conclude, recycled aggregates for concrete produced by wet or dry process are expected to demonstrate essential characteristics of concrete without significant decline in physical or dynamic quality when the substitution rate is below 25% although there are variations subject to water-cement ratio. However, slight differences are expected due to types of recycled aggregate and physical quality.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.147-153
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• 2010

The recycling of demolished concrete as an alternative source of coarse aggregates for the production of new concrete can help to solve the growing waste disposal crisis and the problem of the depletion of natural aggregates. The purpose of this study is to investigate the chloride migration of recycled aggregate concrete containing pozzolanic materials by the chloride migration coefficient. The specimens were made with recycled coarse aggregate at various replacement ratios (10, 30, 50%) and metakaolin, blast furnace slag, and fly ash is replaced for recycled concrete with a mixing ratio of 20%. The major results are as follows. 1) The compressive strength of recycled aggregate concrete containing pozzolanic materials increases as the curing age and chloride diffusivity decreases. 2) When the replacement ratio of recycled coarse aggregate is 30%, the chloride migration coefficient of recycled concrete containing blast furnace slag or metakaolin that shows a value similar to or lower than that of plain concrete at all ages.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.43-50
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• 2008

This paper presents experimental and analytical results on the long-term behavior of the reinforced recycled aggregate concrete beams under sustained loading. In this experimental program, three beams with different conditions of aggregates replacement (natural aggregate 100%, recycled coarse aggregate 100%, recycled fine aggregate 50%) were subjected to the sustained flexural loading that was a half of the nominal flexural capacity over a period of 1 year. The beam were designed with net span of 2,000 mm and rectangular cross-section of 170 mm width and 170 mm effective depth. The beams were instrumented and monitored to observe the change in the long-term behavior due to creep and shrinkage of concrete under sustained loading. The predictions of long-term deflection by ACI code, Branson, Mayer, Neville, EMM and AEMM were compared with the experimental results. From the experimental results, the reinforced concrete beams with recycled aggregates showed the same performance as that of a beam with natural aggregate. The proposed method to predict the long-term deflections of reinforced recycled aggregate concrete beams gives a good estimation for experimental results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.99-107
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• 2014

In this study, the effects of curing procedures on the mechanical properties of recycled aggregate concrete (RAC) were investigated. The replacement ratios by recycled coarse aggregate were 0, 25, 50, 75 and 100% by mass of natural coarse aggregate. Steam curing was adopted to all recycled aggregate concrete mixtures. Compressive and split tensile strength, water porosity, chloride ions penetration resistance and drying shrinkage measurements were carried out to determine performance of the RACs. From the test results, it was found that the mechanical performance of RAC decreased as the recycled aggregate contents increased. Furthermore, steam curing reduced the compressive and split tensile strength, water porosity and total charge of RAC, especially at the early ages. However, at the later ages, the beneficial effect of steam curing was less prominent. This study clearly showed that initial steam curing could be one of practical methods to improve performance of RAC with higher replacement ratio of recycled aggregate.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.237-238
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• 2009

This study presents effect on replacement level of recycled fine aggregates(30% and 50%)instead of silica sand in SHCC with PYA fiber.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.180-181
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• 2021

This study compared and analyzed the fluidity, compressive strength, and unit weight characteristics of mortar using bottom ash aggregates as part of a study to develop alternative aggregates

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.361-368
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• 2003

As the supply of aggregate needed in the construction site becomes difficult due to preservation of environment and exhaust of aggregate resource, a research for replacement aggregate in shortage is being actively progressed and a copper slag is also a kind of replacing aggregate. To use copper slag as fine aggregate of concrete, many studies are already conducted in each of the advanced countries and in the state of applying these at the site. In the year of 2000 a Korea industrial standard of Copper slag aggregate for concrete was established in our country so that this can be applied in the construction site. This study is to find out whether copper slag is equipped with the physical and chemical requirements for the use in concrete aggregate, and to analyze the dynamic properties of copper slag concrete that replaces 25, 50, 75, 100% of fine aggregate. Copper slag study not only satisfies the using condition of fine aggregate, but also reveals high level of physical property compared to ordinary concrete up to 50% of sand replacement rate. In the future after confirming the durability of concrete using copper slag, it is judged to be advantageous for the preservation of environment to use this as a replacement material for natural aggregate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.33-39
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• 2024

This study explores the utilization of common marine wastes, specifically seashells, such as oysters and cockles, as alternative fine aggregates in construction materials. The considered seashells were cleaned and pre-processed for use as a substitute for aggregate in mortar. Cement mortar specimens were prepared under different conditions, such as substitution ratios and the cleaning status of the seashells. The compressive strength of the mortars specimens was evaluated, and the solid and porous structures of each specimen were analyzed using microstructure analysis methods such as XRD, SEM, and micro-CT. The results confirmed that oyster and cockle seashells are composed of different calcium carbonate polymorphs, and their microstructural characteristics influence the mechanical properties of the cement mortar specimens.