• Title/Summary/Keyword: Crushed sand ratio

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Mixture Design of High Strength Concrete with Crushed-sand (부순모래를 사용한 고강도 콘크리트의 배합설계에 관한 연구)

  • Lee, Bong-Hak;Kim, Dong-Ho;Hong, Chang-Woo;Lee, Joo-Hyung
    • Journal of Industrial Technology
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    • v.21 no.A
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    • pp.285-292
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    • 2001
  • 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 for mixture of high strength concrete using crushed sands. Mixing design of concretes are various water-cement ratios(w/c) such as 25%, 40%, 55% and different replacement ratio of crushed sands to natural sands such as 0%, 20%, 40%, 60%. As a results, it has been shown that compressive strength of concretes with w/c lower than 40% and 25% is higher than $400kgf/cm^2$ and $600kgf/cm^2$ respectively.

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A Fundamental Study on the Properties of Crushed Aggregates Produced in Busan Suburbs (부산근교에서 생산된 부순골재의 특성에 관한 기초적 연구)

  • Bae Won Mahn;Youm Chi Sun;Lee Hwan Woo;Jang Hui suk;Kim Jong Soo;Kim Myung Sik
    • 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.

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The Influence of the Properties of Crushed Stone Sand on the Mixing Factor and Compressive Strength of Concrete (부순모래의 품질특성이 콘크리트의 배합인자 및 압축강도에 미치는 영향)

  • Hong Ji Hoon;Yum Jun Haun;Choi Jin Man;Jeong Yang;Lee Seong Yeun;Yeo Byung Chul
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.11a
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    • pp.623-626
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    • 2005
  • This study is aimed for investigating the influence of the properties of crushed stone sand on the mixing factor and compressive strength of concrete. The results of this study are as follows; The influence of Particle Shape and Very Fine Sand(VFS) of crushed stone sand on the mixing factor was higher than Fineness Modulus. The demand water of concrete with crushed stone sand was decreased about $12\~18kg/m^3$with increasing $4\%$ of Particle Shape and increased $8\~15kg/m^3$ with increasing $3\%$ of ratio of Very Fine Sand(VFS).

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The Properties of High Flowing Concrete with Fly Ash for CFT Structure (플라이 애쉬를 사용한 CFT 구조용 고유동콘크리트의 강도특성)

  • Ahn, Nam-Shik;Lim, Hong-Chul;Choi, Jae-Gon
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.93-96
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    • 2006
  • To investigate the properties of high flowing concrete with fly ash and crushed sand for CFT structure, many batches were performed by a trial-error method and the results were analyzed by SPSS software program. In the experiment W/B was set up as 0.25 and the variables 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 increase of the substitution ratio of fly ash, the decrease of dosage of SP and the increase of dosage of AEA due to very fine sphere particle of fly ash. 2) The increase of the blend ratio of crushed sand, the increase of dosage of S/a and water content related with viscosity. 3) Made the high flowing concrete, the increase S/a and the increase the water content.

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Importance of particle shape on stress-strain behaviour of crushed stone-sand mixtures

  • Kumara, Janaka J.;Hayano, Kimitoshi
    • Geomechanics and Engineering
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    • v.10 no.4
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    • pp.455-470
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    • 2016
  • In ballasted railway tracks, ballast fouling due to finer material intrusion has been identified as a challenging issue in track maintenance works. In this research, deformation characteristics of crushed stone-sand mixtures, simulating fresh and fouled ballasts were studied from laboratory and a 3-D discrete element method (DEM) triaxial compression tests. The DEM simulation was performed using a recently developed DEM approach, named, Yet Another Dynamic Engine (YADE). First, void ratio characteristics of crushed stone-sand mixtures were studied. Then, triaxial compression tests were conducted on specimens with 80 and 50% of relative densities simulating dense and loose states respectively. Initial DEM simulations were conducted using sphere particles. As stress-strain behaviour of crushed stone-sand mixtures evaluated by sphere particles were different from laboratory specimens, in next DEM simulations, the particles were modeled by a clump particle. The clump shape was selected using shape indexes of the actual particles evaluated by an image analysis. It was observed that the packing behaviour of laboratory crushed stone-sand mixtures were matched well with the DEM simulation with clump particles. The results also showed that the strength properties of crushed stone deteriorate when they are mixed by 30% or more of sand, specially under dense state. The results also showed that clump particles give closer stress-strain behaviour to laboratory specimens than sphere particles.

A Field Test Study on stress concentration ratio of Crushed-Stone Column Pile (쇄석다짐말뚝의 응력분담비에 관한 현장실험 연구)

  • Lee, Min-Hee;Im, Jong-Chul;Hwang, Geun-Bae;Choi, Yong-Kyu
    • Proceedings of the Korean Geotechical Society Conference
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    • 2004.03b
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    • pp.525-532
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    • 2004
  • Among soft ground treatment methods with granular soil used in domestic, the sand compaction pile method has been utilized greatly, but, as a result of exhaustion of sand and increase of unit cost, a necessity of an alternative method is suggested. In this study, the static load tests for crushed-stone compaction piles which were constructed on test field were performed. Based on test results, stress concentration ratios between the crushed-stone compaction pile and the soft ground were investigated and estimated. The stress concentration ratio was the range of 1.7 to 3.0 and the higher it was the more replacement rate was increased.

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Hydraulic Characteristics of Crushed Stone Mat Considering Mixed Ratio (혼합비를 고려한 쇄석매트의 수리특성)

  • Lee, Jun-Hun;Chae, Chang-Woo;Lee, Ju-Hyeong;Lee, Myung-Goo;Lim, Seong-Yoon;Choi, Young-Chul;Song, Chang-Seob
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.1250-1255
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    • 2010
  • In this study, in order to examine the hydraulic characteristics for a crushed stone mat. it was accomplished discharge capacity test and soil-water characteristic curve(SWCC) with the object of the research. From the test result, it produced propriety mixed ratio of the crushed stone which mixes the sand. at the time of crushed stone 100% where it does not mixes the sand it appeared that permeability was biggest. increase of shock and content of the sand showed decrease of air entry value.

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An Experimental Study on the Engineering Properties of Concrete with Kind of Fine Aggregate and Addition Ratio of Water Reducing Agents (잔골재 종류 및 감소제 첨가율에 따른 콘크리트의 공학적 특성에 관한 실험적 연구)

  • Shin, Kwan-Soo;Na, Chul-Sung;Paek, Yong-Lak;Choi, Se-Jin;Kim, Gyu-Yong;Kim, Moo-Han
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.157-160
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    • 2006
  • Recently, trouble of sand supply is occurred according to exhaustion of natural sand resources. To solve this problem, sea sand and crushed sand are used. But, necessity of water reducing agent because quality of concrete that use sea sand and crushed sand is deteriorated. Therefore in this study was examined on the engineering properties of concrete with kind of fine aggregate and addition ratio of water reducing agents. As a result, compressive strength appeared similar standard regardless of kind of fine aggregate. Compressive strength, durability was similar in decrease of the unit water content by increase of addition ratio of the water reducing agent. Also, drying shrinkage resistivity was improved because the unit water content decreased.

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Comparison of rheological properties containing natural and crushed sands in self-compacting concretes (잔골재 종류에 따른 고유동 콘크리트의 유동 특성)

  • Lee, Keun-Su;Choi, Yeol;Jung, Woong;Lee, Jae-Ik
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.365-368
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    • 2008
  • In recent, the crushed sand as a fine aggregate has increasingly used for concrete industry due to the shortage of natural sand from river and the growing demand for protection of natural environments. Aggregates may have a significant influence on the properties of self-compacting concrete (SCC) including self-compacting mortar (SCM). The rheological properties of SCC and SCM using crushed sand as a fine aggregate has been compared to that of SCC and SCM using natural sand and mixed sand of both. Test results indicate that the yield stress of SCM containing 50% of mixed sand present higher than those prepared with natural sand and crushed sand according to SP content. the slump values of SCC with natural sand have approximately 5-15% higher than those of SCC with crushed sand. Also the L-box test values ($H_2/H_1$) of SCC with natural sand have approximately 20-30 higher than those of SCC with crushed sand under same water/cement ratio and viscosity enhancing admixture.

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Performance of self-compacting concrete with manufactured crushed sand

  • Benyamina, Smain;Menadi, Belkacem;Bernard, Siham Kamali;Kenai, Said
    • Advances in concrete construction
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    • v.7 no.2
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    • pp.87-96
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    • 2019
  • Self-compacting concretes (SCC) are highly fluid concrete which can flow without any vibration. Their composition requires a large quantity of fines to limit the risk of bleeding and segregation. The use of crushed sand rich in limestone fines could be an adequate solution for both economic and environmental reasons. This paper investigates the influence of quarry limestone fines from manufactured crushed sand on rheological, mechanical and durability properties of SCC. For this purpose, five mixtures of SCC with different limestone fines content as substitution of crushed sand (0, 5, 10, 15 and 20%) were prepared at constant water-to-cement ratio of 0.40 and $490kg/m^3$ of cement content. Fresh SCC mixtures were tested by slump flow test, V-funnel flow time test, L-box height ratio, segregation resistance and rheological test using a rheometer. Compressive and flexural strengths of SCC mixtures were evaluated at 28 days. Regarding durability properties, total porosity, capillary water absorption and chloride-ion migration were studied at 180 days. For the two test modes in fresh state, the results indicated compatibility between slump flow/yield stress (${\tau}_0$) and V-funnel flow time/plastic viscosity (${\mu}$). Increasing the substitution level of limestone fines in SCC mixtures, contributes to the decrease of the slump flow and the yield stress. All SCC mixtures investigated achieved adequate filling, adequate passing ability and exhibit no segregation. Moreover, the inclusion of limestone fines as crushed sand substitution reduces the capillary water absorption, chloride-ion migration and consequently enhances the durability performance.