• Journal of the Korea Institute of Building Construction
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• v.5 no.1 s.15
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• pp.63-68
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• 2005

Generally, aggregate may limit the workability, strength and durability of concrete, and good concrete cannot be made with aggregate of bad property including low strength, bad shape and grading. But recently, it has been insufficient in quantity to collect good natural aggregate because of exhaustion of aggregate resources. In case of Korea, the using ratio of crushed stone occupies about 97 percent of total coarse aggregate, and ratio of crushed sand occupies about 18.3 percent of total fine aggregate. This is an experimental study to compare and analyze the properties of crushed sand for concrete in capital region and concrete according to the replacement ratio of crushed sand to improve quality and mix design of concrete using crushed sand. According to test results, it was found that nearly all the properties of crushed sand satisfied with the value recommended by KS. And it is recommended that FM of crushed sand should be lowered by improvement of manufacture system or grading adjustment should be used because FM of crushed sand was a bit higher.

• Journal of the Korea Institute of Building Construction
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• v.20 no.4
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• pp.331-338
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• 2020

The aim of the research is to evaluate the possibility of using coal gasification slag (CGS) as a combined aggregate for concrete mixture. To achieve this goal, the fundamental properties and the durability of concrete were analyzed depending on various combining ratio of CGS into both fine aggregate with favorable gradation and relatively coarse particles. According to the results of the experiment, slump and slump flow were increased with content of CGS regardless of crushed fine aggregate with good and poor gradations while the air content was decreased. For the compressive strength of the concrete, in the case of using the crushed aggregate with good gradation, increasing CGS content decreased compressive strength of the concrete, while when the concrete used crushed aggregate with poor gradation, the compressive strength was the maximum at 50% of CGS content. As a durability assessment, drying shrinkage was decreased and carbonation resistance was improved by increasing CGS content. On the other hand, for freeze-thawing resistance, CGS influenced adverse effect on freeze-thawing resistance. Therefore, it is known that an additional air entrainer is needed to increase the freeze-thawing resistance when CGS was used as a combined aggregate for concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.169-176
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• 2023

This study aims to develop a thermally conductive backfill by applying the prepacked concrete concept, in which a coarse aggregate with relatively high thermal conductivity was first filled and then the voild filled with grout. Backfill with improved thermal conductivity can increase the heat exchange efficiency of underground heat exchangers or underground transmission facilities. The backfills was prepared by using crushed concrete as the coarse aggregate, fly ash-based grout, and a small amount of cement for solidification. The results of this study showed that the fly ash-cement-sand-based grout with a flow of at least 450 mm accor ding to ASTM D 6103 could fill the void of pr epactked coar se aggr egates with a maximum size of 25 mm. The thermal conductivity of the backfil with coarse aggregate was over 1.7 W/m·K, which was higher than that of grout-type backfills.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.376-379
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• 2004

The objective of in this study makes investigation into the characteristics of concrete as to properties and blended ratio of crushed aggregates through experimental researches. In this study, river sand is blended with crushed sand as to investigate the quality change and characteristics of concrete with variation of blend ratio of crushed sand(50, 60, 70, 80, 90, $100\%$). Measured the air contents and slump to investigate properties of fresh concrete, and unit weight and compressive strength in age of 7, 28days to investigate properties of hardened concrete. The experimental results of crushed aggregates' qualities were all satisfied with Korea Standard's values.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.193-197
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• 2008

This study enforced to produce the planting concrete block which could be applied to various slopes economically. First of all, the physical properties was investigated with the various types of aggregate and aggregate ratio of the paste for the lead to mixture proportion of the planting concrete. As a result, the orchid stone as aggregate and 30% of aggregate ratio of the paste were used as the basic mixture proportion considering 20~30% of maintained void ratio for the growth of plant, over 20% of capillary suction for holding water, and 3MPa as the minimum strength. For the result of the test to the new planting block which was quite different from existing planting concrete block, it could complement the problems and be possible to produce effectively and economically because various slopes like 40ﾟ~75ﾟ, continual produce by extrusion, and pumping out were possible were possible.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.112-115
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• 2003

Aggregate may limit the strength of concrete, and aggregate with undesirable properties cannot produces strong concrete. Also, the properties of aggregate greatly affect the durability and structural performance of concrete. Recently, it has increased the using of crushed aggregate for concrete due to the exhaustion of good natural aggregate. In case of Korea, in 2002, the using ration of crushed stone occupies about 97% of whole coarse aggregate, and ratio of crushed sand occupies about 18.3% of whole fine aggregate. This is a study to compare and analyze the properties of crushed aggregate for concrete to do mix proportion and improve the concrete quality. According to results, it was found that nearly all the properties of crushed aggregate satisfied with the value recommended by KS.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.193-196
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• 2004

The objective of in this study makes investigation into the characteristics of concrete as to properties and blended ratio of crushed aggregates through experimental researches. In this research observed crushed quality characteristic of crushed aggregates that is produced in representative stony mountains of Busan suburbs (Yang-san, Kim-hea, Jin-hea). And wished to investigate the quality change and characteristics of concrete with variation of blend ratio of crushed sand(50, 60, 70, 80, 90, $100\%$). Measured the air contents and slump to investigate properties of fresh concrete, and unit weight and compressive strength in age of 7, 28, 60, 90 days to investigate properties of hardened concrete.

• 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

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.327-334
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• 2022

In this study, in order to evaluate the characteristics of mortar and concrete using wood chip cogeneration plant flooring as fine aggregate, mortar characteristics according to wood chip aggregate replacement rate and water-cement ratio as a substitute for crushed sand, and concrete characteristics according to wood chip aggregate replacement rate were compared and evaluated. The cement mortar flow according to the wood chip aggregate replacement rate showed a tendency to increase as the wood chip aggregate replacement rate increased, and the compressive strength and flexural strength increased as the wood chip aggregate replacement rate increased. The slump and air content of concrete increased as the aggregate replacement rate increased, and the compressive strength and tensile splitting strength of concrete tended to increase as the wood chip aggregate replacement rate increased. Accordingly, the possibility of using the flooring by the cogeneration plant as a fine aggregate for concrete was confirmed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.178-185
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• 2011

Recently depletion of natural resources makes a deficiency of sand aggregation in the concrete works. In this study, the quality characteristics of concrete and aggregate according to blending fine aggregate in the river sand and the crash sand was analyzed by Normal method and Driscoll method which has used mixing of fine aggregate for asphalt mostly. Application of Discoll method to blend fine aggregate for concrete was studied in the first step to blend fine aggregates concrete. The fineness modulus, grading, slump, air content and compressive strength were tested by the two method, the results of Driscoll method was very similar to degree of err limits in comparison with those of Normal method in the same condition. As a result, Driscoll method is reasonable to use the fine aggregates mixture for concrete in river sand and crash sand.