• 한국건축시공학회지
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• 제7권1호
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• pp.57-62
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• 2007

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. And recently, it has increased the using of crushed sand for concrete due to the exhaustion of good natural aggregate. In case of Korea, in 2004, the using ratio of crushed sand occupies about 28% of whole fine aggregate. This is an experimental study to compare and analyze the influence of W/B ratio and replacement ratio of crushed sand on the fluidity and compressive strength of high strength concrete. For this purpose, the mix proportions of concrete according to the W/B (31.5, 27.5, 23.5%) and replacement ratio of crushed sand (0, 20, 40%) was selected. And then air content, slump-flow, a-lot, compressive strength test were performed.

• 한국건축시공학회지
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• 제5권1호
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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.

• 한국산업융합학회 논문집
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• 제2권1호
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• pp.45-52
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• 1999

It is difficult to keep the balance of supply and demand for natural aggregates in recent years, because natural resources have become to be almost exhausted. Crushed stone is already used for coarse aggregate instead of river gravel at present. Now, crushed sand or sea sand should be used for fine aggregate, because natural sand also has been exhausted with a few exceptions around Nakdong River. The sea sand has a lot of problems which are the corrosion of reinforcement bars, the investment of facility for cleansing salt and the cost increase due to the insufficiency of industrial water. Therefore, it is necessary to produce and to utilize the crushed sand very actively, but some material properties which are related to water absorption, strength and chemical durability, prevent from determining the generalized criteria because its rocks make much differences in its physical and chemical characteristics. In this paper, fundamental physical properties of crushed sand, which comes from Daegu Subway construction fields, have been investigated for the usability on basic material of concrete. The optimum replacement ratio and the strength estimation method of crushed sand replacing natural sand also have been presented here through the compressive strength test of ready-mixed concrete cylinders.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.117-122
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• 1998

Concrete structures has been deteriorated by the freezing and thawing due to temperature gap. This study was conducted to evaluate durabilite of concrete which are increasingly demanded recently. Therefore the research of durability must be executed for application of waste foundry sand concrete real structures. Concrete durability must be executed for application of waste foundry sand concrete real structures. Concrete durability properties incorporating waste foundry sand was performed with the variable of W/C ratio, Sand/Waste foundry sand ratio and Air entrainment-Non air entrainment. Cylinder specimens were made and subjected to freezing and thawing cycle at $-18^{\cire}C$ and $4^{\cire}C$. Dynamic modulus of elasticity were evaluated as F/T cycle increase. The results show that strength of concrete is increased the W/C ratio decrease, the Sand/Waste foundry sand ratio increase when the concrete contains AE agent and decreasing WC ratio and AE concrete makes improved resistance of freezing and thawing improved. Especially, resistance of freezing and thawing is improved by Fine aggregate/Waste foundry sand ratio which is 50%, 25%, 0% in a row. Therefore it is turn out the waste foundry sand could be applied to concrete from the experiment.

• Structural Engineering and Mechanics
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• 제53권6호
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• pp.1241-1251
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• 2015

Faced with the growing needs of material resources and requirements of environmental protection for achieving sustainable development, it has become necessary to study and investigate all possibilities of exploring crushed and dune sand, reusing industrial wastes and by-product, and also applying new technologies including sand concrete which can replace the conventional concretes in certain structures to surmount the deficit on construction materials, conserve natural resources, lessen the burden of pollutants to protect the environment and reduce the consumption of energy sources. This experimental study is a part of development and valorization of local materials project in Skikda region (East of Algeria). It aims at studying the effects of partial replacement of sand with marble waste as fines on several fresh and hardened properties of sand concrete in order to reuse these wastes in the concrete manufacturing, resolve the environmental problems caused by them and find another source of construction materials. To achieve these objectives, an experimental program has been carried out; it was consisted to incorporate different percentages of marble waste fines (2, 4, 6, 8, 10 and 12%) in the formulations of sand concrete and study the development of several mechanical and rheological properties. We are also trying to find the optimal percentage of marble waste fine replaced in sand concrete that makes the strength of the concrete maximum. Obtained results showed that marble waste fines improve the properties of sand concrete and can be used as an additive material in sand concrete formulation.

• International Journal of Concrete Structures and Materials
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• 제3권1호
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• pp.11-14
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• 2009

This paper is interested in the incorporation of crushed sand and desert sand in the composition the self compacting concretes (SCC). Desert dune sand, which has a fine extra granulometry, and the crushed sand, which contains an important content of fines, can constitute interesting components for SCC. Part II consists in studying the behaviour of SCC containing various sands with different origins. These sands, with different sizes, consist of several combinations of rolled sand (RS), crushed sand (CS) and desert sand (DS). The study examines the influence of the granular combination of sands on the characteristics in the fresh and the hardened state of SCC. The results of the experimental tests showed an improvement of the workability of the fresh SCC by combining sands of varied granulometry. The addition of the DS to CS or to RS allowed the increase of the mixture viscosity but decreased the mechanical strengths. Furthermore, the CS-RS combinations increased the compressive and the tensile strengths of the studied SCC. The optimized formulations of sands gave the highest performances of the SCC.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.23-26
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• 2007

In this study, recently it is urgently required that demolition waste concrete has to be recycled on the construction because urban development is accelerated and redevelopment project is rapidly expanded, production quantity of construction and demolition waste concrete is being increased. On the other hand, 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 environment influence evaluation. Therefore, the purpose of the study was to show the performance of the apparatus developed by the study and to propose the direction of the optimum operating conditions by having an experimental and positive evaluation about quality of recycled sand produced to develop a separating and selecting device of impurities for recycling of construction wastes which can have a bigger improvement of economical efficiency, productivity, environmental property and quality through a basic property of matter of recycled sand by each operating condition of sand flux in comparison with the existing production system of recycled sand.

• 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.

• 자원리싸이클링
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• 제16권2호
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• pp.40-47
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• 2007

생활폐기물 소각장에서 발생되는 바닥재를 콘크리트 잔골재로 재활용하기 위해서, 기준모르타르에 모래 10%를 바닥재로 대체 하고 시멘트 10%를 포졸란성 규조토로 대체한 후, KS L 5105와 TCLP에 따라 시험하였다. 결과에 의하면, 바닥재의 유해중금속들은 TCLP 허용치 범위에 있었다. 포졸란성 규조토와 바닥재를 혼합한 모르타르 압축강도는 기준모르타르보다 높았으며 동시에 모든 유해중금속들은 TCLP 기준치 범위에 들어 있었다. 따라서 포졸란성 규조토를 안정재로 사용하게 되면 바닥재를 콘크리트 잔골재로 재활용할 수 있다.

• 물과 미래
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• 제10권2호
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• pp.91-100
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• 1977

This is an experimental study to raise higher efficiency of filteration than conve ntional filteration by increasing of filteration capacity for per unit area and by extending of filteration lasting time with biflow filter system which was improved from the conventional rapid sand filteration method in the process of water purification treatment. In order to raise more efficient function of filteration and giving consideration to the filter layer at upper and lower parts of the filter, the fine sand & an thracite were used as a filter medium. Although there is some difficulty than previous fine sand in procurement, it could confirm that such filter medium (fine sand & anthracite) was more effective in the field of load, lasting time and back wash, etc. In consideration of practical effect of filteration. The raw water which was used for this experimental study was not coagulated. As a result of this experiment, the filteration volume could increase more than 2 times than that of conventional method. Besides, much more advantages could be obtained for instance, the requirement of installation area was not much and installation cost could economize. On the other hand, the following results were found. The quality of filtered water became worse as time goes by and the turbidity of filtered water was more influenced by raw water turbidity than by rate of filteration. Lasting time of filteration on change of filteration rate in the filter layer reached 2 times in comparison with previous filter basin, and until loss gead reached to 1.0 meter and 1.5 meter, the following relate formulas between lasting time and rate of filteration were formed. ($T_{1.5}=181.96V^{-0.46},\;T_{1.0}=121.31V^{-0.46}$) Even though the lasting time can be shorten in case of the increase of the filteration rate, but the lasting time was prolonged more than 2 times than of previous method. With taking aim at contribution to the development of water treatment technique, we are planning to study continuously for the future study basing on the results in this papers.