• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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• pp.81-85
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• 2009

This study was to execute the basic property evaluation of recycled sand which produced by the sand flux device in order to evaluate the performance of differences between small large sand flux device. As a result, this study has found out that the recycled sand after passing the sand flux device had excellent quality characteristics compared with the One before passing the device. In additional experiment On the basic material properties, this study showed a tendency to improve the quality and performance significantly in case of fineness modulus, absolute surface dried density, 0.08mm sieve throughput, volume of clay lumps, and content of organic foreign matter. In conclusion, it was considered as various quality performances of recycled sand were improved through the production stage of prototype.

• 한국건축시공학회지
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• 제3권3호
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• pp.107-112
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• 2003

This study is to investigate the properties of concrete with crushed sand on site and to propose a quality guideline for its use as artificial sand and concrete. From our experimental result in laboratory and site, we found that demand water of concrete with crushed sand for target slump increased by 18kg/m3 compared to mixed sand and l8kg/m3 compared to sea sand respectively. The compressive strength increased by around 3∼6% when compared to concrete with sea sand. Accordingly, our study showed that the combined sand mixed with sea sand would be desirable to obtain workability and strength of concrete including dry shrinkage and bleeding test. Furthermore, the optimal replacement percentage of crushed sand was 50% with sea sand. As such, crushed sand would be sufficient as fine aggregate for concrete in terms of economic efficiency and quality. Crushed sand, on the other hand can only be used as fine aggregate when VFS(Very Fine Sand) is below 3.5 percentage of weight of sand and particle shape is above 55 percentage. Also, the particle shape and microsand passing NO.200 sieve should continually be improved to increase workability of concrete on site.

• 콘크리트학회논문집
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• 제18권3호
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• pp.415-423
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• 2006

콘크리트용 골재로 양질의 골재가 부족함에 따라 대체 골재의 개발이 요구되어, 현재에는 대체 골재로서 부순모래가 가장 많이 사용되고 있으며, 그 사용량은 더욱 늘어날 전망이다. 국내에서는 대부분의 회사가 습식공정으로 부순모래를 생산하지만, 지역적인 조건과 부지의 제약에 의해서 건식 공정으로 부순모래를 생산하는 회사도 있다. 본 연구에서는 건식 공정 부순모래의 콘크리트의 적용성을 평가하기 위한 기초적인 연구로서, 건식공정으로 부순모래를 생산하고 있는 회사의 제조 설비를 분석하고, 부순모래를 대상으로 한국산업규격에 의거하여 품질특성 시험을 실시하였으며, 그 결과를 바탕으로 부순모래를 바다모래에 대체하여 콘크리트 실험을 실시하였다. 실험 결과, 건식 부순모래 품질 특성 중에서 0.08mm 체 통과량이 KS 규정을 초과하였으며, 조립률도 천연모래에 비하여 다소 높게 나타났고, 다른 물리적 특성은 바다 모래와 유사하였다. 콘크리트 실험에서는 부순모래의 대체율이 증가함에 따라 슬럼프와 공기량이 미립분량 증가에 의해서 감소하였으며, 단위용적질량, 압축강도, 인장강도는 증가하는 것으로 나타났다. 따라서 건식 부순모래의 미립분 함유량을 감소시키면 콘크리트용 골재로서 사용하는 데에는 큰 문제가 없을 것으로 판단되며, 향후 건식공정으로 생산한 부순모래의 사용량도 증대될 것으로 전망된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.352-355
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• 2004

Crushed sand is made by crushing the rocks artificially. With a wide shortage of natural river sand all over the region in Korea, demand for crushed sand are becoming increased. However, Informations as to crushed sand are insufficient. In this paper, the actual conditions of crushed sand related to producing and quality variation are investigated. 29 manufacturing company of crushed sand are reviewed. According to results, density of most crushed sand tested exceeded 2.5g/cm3, and absorption ratio meet the requirement of KS except one sample. For grain properties, passing amount of 0.08mm sieve satisfied the requirement of KS except one sample. Grain distribution of most crushed sand is estimated $54.26\%$. But 6 crushed sand sample did not meet the requirement of KS. Fineness modulus and grading are varied from manufacturing region. 18 samples of crushed sand among 29 samples deviated the minimum level of standard grading range by KS. Therefore, improvement of grain properties of crushed sand is urgently needed to manufacture better crushed sand.

• 수산해양교육연구
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• 제25권3호
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• pp.677-689
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• 2013

Recently, the supplying of basic materials for construction of building as sand is big issues due to lack of shoreside supply. For solving this problem, many suppliers attempt to gather aggregate from the sea bottom of the EEZ & west coastal area of Korea. In this regard, the 'Jangantoe' which exists in the westside of the Daesan port is worth noticing as good seasand supplying areas. The Chungnam Aggregate Association have plan to gather of seasand from 'Gaduckdo 5 regions & Igok 3 regions' which lies westside about 6 miles off from the Jangantoe areas. This designated area also locates upper parts of the Gadaeam TSS(Traffic Separation Scheme) which is very useful passing routes for the sailing vessels of Inchon & Daesan ports. In this study, the evaluation of the safety for passing vessels in the vicinity of the seasand gathering area was performed by various methods of radar observations & GICOMS AIS data for marine traffics and vessel traffic-flow simulation of the 'Marine Traffic Safety Diagnostic Scheme'. By the results of this evaluation, I suggested comprehensive countermeasures for the safety of passing vessels in the near the seasand gathering area.

• Advances in concrete construction
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• 제2권4호
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• pp.249-259
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• 2014

Mortar is a masonry product which is matrix of concrete. It consists of binder and fine aggregate and moreover, it is an essential associate in any reinforced structural construction. The strength of mortar is a special concern to the engineer because mortar is responsible to give protection in the outer part of the structure as well as at a brick joint in masonry wall system. The purpose of this research is to investigate the compressive strength and tensile strength of mortar, which are important mechanical properties, by replacing the cement and sand by stone dust. Moreover, to minimize the increasing demand of cement and sand, checking of appropriateness of stone dust as a construction material is necessary to ensure both solid waste minimization and recovery by exchanging stone dust with cement and sand. Stone dust passing by No. 200 sieve, is used as cement replacing material and retained by No. 100 sieve is used for sand replacement. Sand was replaced by stone dust of 15%, 20%, 25%, 30%, 35%, 40%, 45% and 50% by weight of sand while cement was replaced by stone dust of 3%, 5%, and 7% by weight of cement. Test result indicates that, compressive strength of specimen mix with 35% of sand replacing stone dust and 3% of cement replacing stone dust increases 21.33% and 22.76% respectively than the normal mortar specimen at 7 and 28 days while for tensile it increases up to 13.47%. At the end, optimum dose was selected and crack analysis as well as discussion also included.

• 청정기술
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• 제8권3호
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• pp.129-139
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• 2002

This is the study for recycling waste foundry sand. Authors studied about main subject of grading of aggregate and three experimental items such as physical properties of waste foundry sand, optimum grading for concrete products of low water ratio, and quality variations of concrete products according to substitution proportion of fine aggregate as waste foundry sand. We were convinced of following results by experimental study. The first was that waste foundry sand was not fit as the aggregate for concrete because of bad qualities such as grading, unit weight, solid volume and passing 0.08 mm seive, so it is proper to composition using with other fine aggregetes. The second was that optimum grading is fineness modulus of 2.77 to 3.28 And the last is that optimum condition about substitution proportion as waste foundry sand is 10% fine aggregate.

• 한국해안해양공학회지
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• 제10권4호
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• pp.187-196
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• 1998

해안 구조물인 돌제(groins)의 축조로 인한 해안 지형 변화를 수치모델을 통하여 살펴보았다. 수치모델은 크게 파랑과 흐름을 계산하는 동수력학적 부분과 이로부터 구해진 외력을 이용하여 지형변화를 계산하는 퇴적물 이동부분으로 구성된다. 본 연구에서 일정한 경사를 갖는 해안에 축조된 한 개의 돌제 및 3개의 돌제 시스템에 수치모델을 적용하여 파랑 및 흐름 양상의 변화로 인한 퇴적물 이동 양상과 150일간에 걸친 해안지형 변화를 계산하였다. 또한 시간에 따른 돌제 통과 퇴적물 이동량 변화도 살펴보았다

• Advances in materials Research
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• 제4권1호
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• pp.45-60
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• 2015

This paper aimed to investigate the effect of MWCNTs on properties of slag Geopolymeric mortar. Geopolymeric matrices containing different MWCNTs concentrations (0.0, 0.1, 0.2, 0.3 and 0.4 % by weight of the used binder) were synthesized. The Geopolymer mortar composed of aluminosilicate slag to sand (1:2), while the alumino silicate source binder composed of 50% air cooled slag and 50%water cooled slag both passing a sieve of $90{\mu}m$, while the sand passing a sieve of 1 ml. The materials prepared at water/binder ratios in a range of 0.34-0.39% depending on the added MWCNT, whereas the Gelenium Ace-30 superplasticizer used in the ratio of 1.4-2.2% from the total dry weight for better dispersion of MWCNT under sonication for 15 min. Alkaline activation of the Geopolymer mortar was carried by using of 6% NaOH. Curing was performed under temperature of $40^{\circ}C$ and 100% R.H. Results showed that the addition of MWCNTs enhanced the resulting amorphous geopolymer structure with marked decrease in the drying shrinkage as well as water absorption specially when using 0.1% MWCNT, while further increase in MWCNTs results in agglomeration in MWCNT within the matrix and so hinder the propagation of Geopolymerization reaction and negatively affect the formed geopolymer structure.

• 물과 미래
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• 제6권2호
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• pp.12-18
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• 1973

본 논문은 동기에 사역을 성토하기 위한 가능성을 검토하여 실제시공에 공헌하자는 데에 기 목적이 있다. 평상시의 성토기측은 다음과 같다. 1) 재료의 최대경은 30cm 이하로 하고 사분함유율은 중량비로서 60% 이하여야 한다. 2) 산포두께는 60cm 이하로 하고 각층마다 11ton 진동로 라로 칠회이상 다져서 상대밀도가 60%이상이 되게 하여야 한다. 그러나 동기의 사역성토를 가능하게 하기 위하여 상기의 평상시 기준에 아래와 같은 조건을 첨가하였다. 3) 사분함유율은 25% 이하로 하고 함수비는 4% 이하로 할 것. 4) 작업중에는 최대의 온도가 최소영하 $7^{\circ}C$이며 평균으로 영하 $3^{\circ}C$로하여 지속작업을 시행할 것 이상과 같은 기준하에서 각종 시험을 실시하고 기결과로서 댐의 안정성을 검토하여 본기준의 타당성을 입증하고 실제성토에 적용할 수 있음을 확인하였다.