• Title/Summary/Keyword: Crushed sand ratio

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Field Test Study on Stress Concentration Ratio of Composited soft ground with Crushed-stone Compaction Pile (쇄석다짐말뚝 복합지반의 응력분담에 관한 현장실험 연구)

  • 김태훈;이민희;최용규
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.717-724
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    • 2003
  • Although sand compaction pile is applied considerably for increase of hearing capacity in domestic, it is getting more necessary to develope the alternative materials because of exhaustion and increase of unit cost of sand. In this study, stress concentration ratio between crushed-stone pile and soft ground was measured and, a displacement ratio 30, 40 and 50%, variation of stress concentration ratio was analyzed. As an increase displacement ratio, the stress concentration effect of crushed-stone compaction pile doesn't increase proportionally and effect of ground improvement in case of ground was good at displacement ratio 30% or 40%. The stress concentration ratio of crushed-stone compaction pile in group piles is 1.5 times that of crushed-stone compaction pile in single pile.

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Properties of High Strength Concrete Using Fly Ash and Crushed Sand (플라이 애시와 부순모래를 사용한 고강도 콘크리트의 특성)

  • 이봉학;김동호;전인구
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.44 no.2
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    • pp.107-116
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    • 2002
  • The amount used of aggregates for concrete is increasing rapidly since the mid-1980s in Korea. The natural gravels from river are already displaced with crushed stone, and use of crushed sand as a substitute of natural river sands, also, is getting increased day by day. This paper is presented fur analysis on mechanical properties of high strength concrete using fly ash and crushed sand. The material functions in mixing design of concretes are various water-cement ratios(w/c) such as 0.25, 0.40, 0.55 and different replacement ratio of crushed sand to natural sands such as 0%, 20%, 40%, 60%. As a results, it has been shown that compressive strengths of concretes with W/C lower than 0.40 and 0.25 are higher than 400 kgf/$\textrm{cm}^2$ and 600 kgf/$\textrm{cm}^2$ respectively. It is also concluded that the results of rapid chloride permeability tests of concrete are evaluated to negligible. The conclusions of this study is that it is possible to use fly ash and crushed sand fur high strength concrete.

The Properties of High Flowing and Strength Concrete Utilizing Crushed Sand for CFT Structure (부순모래를 사용한 CFT 구조용 고유동.고강도콘크리트의 물성 변화)

  • Ahn Nam-Shik;Rhim Hong-Chul;Lim Hye-Sun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2006.05a
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    • pp.89-92
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    • 2006
  • To investigate the properties of high flowing and high strength concrete with crushed sand and fly ash for CFT structure, many batches were performed by a trial-error method. In the experiment W/B was set up three levels as 0.25, 0.30 and 0.35. Also the variables of the experiment were a substitution ratio of fly ash, a blend ratio of crushed sand and the ages of specimens(3, 7, 28 days). The results of this study are summarized as the follows; 1) The effect a substitution ratio of fly ash on the compressive strength was not consistent with age. For twenty-eight day compressive strength, the best result was come out when cement was substituted by 10% of fly ash. 2) The decrease of the water binder ratio, the increase of compressive strength and elastic modulus. Also the relationship is very similar to the case of a normal concrete

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A Study on the Fluidity and Compressive Strength of HPC according to the Replacement Ratio of Crushed Sand (부순모래 대체율에 따른 고강도콘크리트의 유동특성 및 강도특성에 관한 연구)

  • Choi, Se-Jin;Kang, Won-Seok;Park, Chang-Soo;Lee, Seong-Yeon;Lee, Sang-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.437-440
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    • 2006
  • 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. This is an experimental study to compare and analyze the fluidity and compressive strength of ultra-high strength concrete according to the replacement ratio of crushed sand. For this purpose, the mix proportions of concrete according to the W/B ratio and replacement ratio of crushed sand was selected. And then air content, slump-flow, O-lot, compressive strength test were performed.

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An Experimental Study on the Properties of Fresh and Hardened Ready Mixed Concrete Using EEZ sand and Crush sand (EEZ모래와 부순모래를 사용한 레미콘의 굳지않은 성상 및 경화성상에 관한 연구)

  • Shin Seung-Bong;Koo Kyung-Mo;Na Chul-Sung;Ryu Jae-Chul;Kim Gyu-Yong;Kim Moo-Han
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2006.05a
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    • pp.53-56
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    • 2006
  • Recently, trouble of sand supplying is occurred according to exhaustion of natural sand resources. Therefore various measures are proposed for solution of trouble of sand supply and crushed sand among measures is used as one of most universal measures. But because crushed sand have poor particle shape and plenty of makes micro particle, the quality of concrete using crushed sand deteriorated. Therefore, this study evaluated engineering property of concrete with replacement ratio of crushed sand and EEZ sand and applied evaluation result to fundamental data for quality control of concrete using crushed sand and EEZ sand. The result of this study have shown that quality of concrete using crushed sand and EEZ sand and The compressive strength of concrete up to 50, 70% EEZ sand replacement by crush sand, nearly equal to that of general sand.

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Study on the Properties of Antiwashout Underwater Concrete with Variation of Mixing Proportion of Fine Aggregate Types (잔골재의 혼합비율 변화에 따른 수중불분리성 콘크리트의 특성에 관한 연구)

  • 배원만;박세윤;백동일;김명식
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.533-536
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    • 2003
  • The objective of in this study makes investigation into the characteristics of antiwashout underwater concrete as to mix proportion, casting and curing water through experimental researches. in this study, sea sand is blended with river sand, crushed sand is blended with river sand and sea sand as to investigate the quality change and characteristics of antiwashout underwater concrete with variation of blend ratio of sea sand and crushed sand(0, 20, 40, 60, 80, 100%). Higher compressive strength is measured following the order of river sand, sea sand, crushed sand regardless of age and casting condition. Except for case of using river sand, blended ratio of 40% is appeared on most compressive strength.

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Strength Estimation of Ready-Mixed Concrete Using Crushed Sand (부순모래를 사용한 레디믹스트 콘크리트의 배합설계 및 강도추정방법)

  • Suh, Jin-Kook
    • Journal of the Korean Society of Industry Convergence
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    • v.2 no.1
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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.

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A Study on the Influence of the Physical Properties of Mortar on Surface Shape of Crushed Sand (부순모래의 표면형상이 모르터의 물성에 미치는 영향)

  • 이승한;김종인;윤용호;한형섭
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.10a
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    • pp.51-56
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    • 1997
  • This study is aimed for investigating the influence of mortar on improved of surface shape of crushed sand, and analyzing the physical properties of fresh state and hardened state. By the test results, it was found that the flow value and bleeding ratio was increased, but the change of flow value according to time was decreased with the improved surface shape of crushed sand. Also, comparing improved of surface shape of crushed sand with not improved of surface shape of crushed sand on strength, compressive strength is about the same and flexural strength decrease in case of improved of surface shape of crushed sand.

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A Study On The Engineering Properties of Rammed Aggregate and Sand Mixture Piers (쇄석과 모래 혼합다짐말뚝의 공학적 특성에 관한 연구)

  • Chun, Byung-Sik;Kim, Baek-Young;Do, Jong-Nam;Kuk, Kil-Keun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.03a
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    • pp.119-122
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    • 2009
  • The gravel compaction pile method has been used as a soft foundation improvement method because bearing capacity and discharge capacity is excellent. But the discharge capacity decreased when the clogging was generated because the clay penetrate into a void of gravel compaction pile. Accordingly, the purpose of this study is to reduce the clogging generation in gravel compaction pile constructing in the soft ground and take a step to minimize a void of gravel compaction pile. And the proper mixing ratio was determined with the large scale direct shear test performed to get strength and permeability with mixing ratio of crushed stone and sand(100:0, 90:10, 85:15, 80:20, 75:25). As a result of the test, it was showed that internal friction angle was the highest at 85:15 mixing ratio of crushed stone and sand and we can make sure a tendency of internal friction angle's decrease when the mixing ratio of crushed stone and sand passed 15%.

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Fundamental Characteristics of Concrete for Nuclear Power Plant Using Crushed Sand (부순모래 사용에 따른 원전 구조물용 콘크리트의 기초적 특성)

  • Park, Sung-Hak;Kim, Kyung-Hwan;Choi, Byung-Keol;Choi, Yun-Wang
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.2
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    • pp.168-176
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    • 2017
  • This study, as a research for using crushed sand as a fine aggregate of concrete for nuclear structures, we improved the performance of impact crusher in the existing crushed sand production process and adjusted grain size to conform to ASTM C 33 The shape and grain size characteristics of a crushed sand were examined and concrete was prepared according to the substitution ratio of the sand to investigate the properties of fresh concrete and hardened concrete. The experimental results show that most of the concrete characteristics are equivalent to those of concrete using only heavy sand. However, when the substitution rate of steel sand exceeds 50%, the amount of air, compressive strength and tensile strength are somewhat reduced.