• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.147-148
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• 2019

Lack of fine aggregate is adversely affecting the quality of concrete. Due to lack of land sand, EZZ sea sand has been used. However, the use of sea sand is also difficult because of the opposition of fishermen. The purpose of this study was to analysis the effect of slag fine aggregate to durability and compressive strength of concrete. The concrete compressive strength and durability were assessed to derive a proper mix ratio of fine aggregate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.459-462
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• 2005

Recently, interest grew on the quality of aggregates following the diminution of primary resources from river and the growing construction demand which exhausted high-quality sand sources around large cities and incited the use of low grade aggregates like shore sand and sea sand that can be supplied in natural state. Moreover, the most sensitive aspect highlighted by the unstability of aggregate supply is the quality. The extreme insufficiency of quality criteria about the materials currently used as substitute aggregates and about concrete mixed with such materials is also critical. This study investigated influence of qualities of concrete which is using mixed crushed sand and natural sand

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 추계 학술논문 발표대회
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• pp.17-20
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• 2005

This study investigates mock-up test of the concrete containing crushed sands with improved quality and following could be draws as conclusions. The slump satisfies the target value. The air content reaches the goal, however, it decreases by the occurrence of loss with elagse of age. In normal strength region, the setting time of CS24 member is shorter than that of SS24 member. In high strength region, the setting time of SS50 member is make only slower than that of CS5O because of the use of retarding AE agent. The compressive strength of the concrete using crushed sands is little higher than the concrete using washed sea sands, and the compressive strength of core sample increases at lower part. Drying shrinkage of the concrete using crushed sands is larger than that using washed sea sands. At water caring condition, both the concrete using crushed sands and using washed sands expand at first, exhibit to be swelled and with elagse of age, they remain relatirely constant. Also, the drying shrinkage occurred greatly when the width and thickness of a member are small because it is easy to evaporate the inner part vapor in the small width and thickness of a member. there can be little different according to the location of a contact gauge, however it is similar to the change of specimen's length change. The concrete using crushed sands, of which grading, grain shape and fine particle is improved, are comparable to the quality of the concrete using washed sea sand.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.463-466
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• 2005

This study examined the effects of comparatively widely used fine aggregates in the domestic construction fields on the quality of concrete through the analysis of the effects of such fine aggregates on the physical properties of fresh concrete and strength of hardened concrete. Results revealed that crushed sand degrades the fluidity and air entraining of concrete compared to natural aggregates like sea sand and river sand. Especially, the use of crushed sand exhibiting low grain shape and grade was seen to have larger adverse effect on the physical properties of concrete.

• 한국안전학회지
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• 제14권1호
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• pp.124-128
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• 1999

Product background of cement, sand and coarse aggregate differ from country to country, so that thermal behaviour of concrete make a difference in high temperature. To cope with demand, this paper is a study on compressive strength for W/C 45%, 55% and 65% by using domestic portland cement, Han-river sand, sea sand and crushed-coarse aggregate. As a result, it is shown that it is estimating to the mechanical properties of heated concrete specimens under various W/C ratio.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.529-532
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• 2006

In this study, recently it has to be solved urgently the unbalance of demand and supply about the fine aggregate because the sea sand is restricted by exhaustion of river sand and intensification of environmental law. In this background, manufacturing technology which can produce recycled sand from construction and demolition waste concrete mass is developed. However, the existed washing method has the problem which not only impurities but also many other things make poor quality. Therefore, it tries to conform in time necessity, the objective of this study is to develop the Sand Flux system which can product the high-quality recycled sand from wast concrete and high value-added technology of the high-quality recycled sand as basic materials for mortar and concrete. At the same time it will be able to improve the quality of recycled sand products as an experiment of the physical nature and a quality present condition the products of recycled sand from construction waste.

• 한국도로학회논문집
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• 제14권5호
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• pp.67-74
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• 2012

PURPOSES: In this study the influence factors related to abrasion resistance of interlocking concrete block have been evaluated, and comparisons between various domestic and foreign abrasion test methods was also accomplished. METHODS: The modified rotational cutting method suggested in ASTM C 944 was applied. Surface materials with different types of fine aggregate such as crushed sand, sea sand, and mixture of crushed and sea sand were tested to compare the aggregate effect for abrasion resistance. RESULTS: The different surface mixtures with various W/C ratios, mortar and fly ash ratios have been investigated for functional and economical considerations. CONCLUSIONS: This study had obtained reliable results by changing diamond blade of rotating cutter. Therefore, in order to improve the abrasion resistance of interlocking concrete block for road, a new mix design was proposed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.113-117
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• 2000

The objective of this study is to find the long-age strength property and the compressive strength of age which is used as the specified concrete strength. The W/W ratio (45%, 50%, 55%, 60%) fine aggregate of useful river sand or blended sand(river sane : sea sand=1:1) were chosen as the experimental parameters. the experimental results show that pH(it means the material segregation resistance) & suspension were increased larger, so W/C become larger, and slump flow was increased as W/C increased (except W/C=60%), air-contents were decreased as W/C became increase and all of this results are satisfied with the under of 40%. The compressive strength ( a case use only river sand as fine aggregate) is showed less than the case of blended asnd. Because the unit weight of the blended sand is more heavy than the unit weigh of the river sand. The results of the case which haven been used only river sand, and the case have been used blended sand), both case have considered W/C. So it's possible to use the compressive strength of age 28 day like the case of plain concrete.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3719-3725
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• 2012

최근, 건설공사의 급증으로 인한 양질의 하천모래의 고갈로, 콘크리트용 대체골재로서 바다모래, 부순모래 및 순환잔골재 등의 사용이 증가하고 있다. 그러나, 미세척 바다모래는 함유된 염화물로 인하여 철근콘크리트 구조물에 사용할 경우, 철근부식 유발로 구조물의 내구성에 악영향을 미치고, 부순모래는 미립분이 많고 입도조정이 어려워서 철근콘크리트 구조물에 널리 사용되지 못하고 있는 실정이다. 한편, 낙동강 세사는 낙동강 중 하류에 대규모로 분포하고 있고, 입도를 제외하면 콘크리트용 잔골재로서 품질이 우수하므로 이에 관한 연구가 시급히 요구되고 있다. 따라서 본 연구의 목적은 콘크리트 잔골재로서 낙동강 세사를 적극적으로 활용하기 위하여 그것의 물성을 평가하는 것이다. 이를 위하여 낙동강 본류 대표위치별로 시료를 채취하여 이들의 절건밀도, 입도, 단위용적질량 등의 물성을 평가하였는데, 그 결과 낙동강 세사는 입도를 제외하면 잔골재로서의 물성이 우수한 것으로 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.177-180
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• 2004

In these days the exhaustion of natural sand has been highlighted with the environmental damages due to excavating sea-sand. Many researchers and engineers have investigated some materials to replace natural sand with, and were interested in using the basic oxygen furnace-slag, the industrial by-product, as fine aggregate. One of the drawbacks to using BOF-slag as a aggregate is to be gradually expanded, and needed the time-consuming process, but some engineers in Korea tackled it recently. In this study, the stabilized BOF-slag was used for lean concrete under the laboratory condition. After testing the several properties - dry density, compressive strength, and young's modulus-, it was found that the dry density was proportionally governed by BOF-slag content and the 7-day compressive-strength was $110\~120\%$ of the natural sand-made. Therefore, BOF-slag is applicable to the lean concrete because they greatly satisfied the required strength, $50kgf/cm^2$.