• Title/Summary/Keyword: fresh and hardened concrete property

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An Experimental Study on the Effect for Replacement of Pozzolanic Admixtures Influencing to the Properties of High-Performance Concrete - Part2 : Properties of Fresh Concrete - (고성능콘크리트의 특성에 미치는 혼화재 치환변화의 영향에 관한 실험적 연구 - 제2보 : 경화상태의 특성 -)

  • 윤기원;조병영;최청각;이정희;한천구;반호용
    • Proceedings of the Korea Concrete Institute Conference
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    • 1995.04a
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    • pp.26-29
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    • 1995
  • Continued form part 1, this study is aimed for analyzing the property of hardened concrete According to the replacing change of fly ash and silica fume which has influence on the properties of high performance xoncrete. From the test results, the compressive and the drying shrinkage Strength are high when the replacing ratio of silica fume increases and the tensile strength appears high when the replacing of fly ash increases.

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A Fundamental Study on the Optimal Mix Proportion for Antiwashout Underwater Concrete (수중 비분리 콘크리트의 최적 배합비에 관한 기초적 연구)

  • 진치섭;김희성;한태영
    • Magazine of the Korea Concrete Institute
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    • v.7 no.6
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    • pp.224-232
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    • 1995
  • Recently, in other.view of underwater concrete construction, special admixture agent of concrete has been developed for antiwashout of concrete under water with easy carrying out method in some foreign nations. They had successful cases in experiment and construction and it trend to use in many cases with many scales. However, in domestic, there was rare record in carrying out. In this paper, reference for successful results of experiment and construction about antiwashout underwater concrete, as variable add of special admixture agent and other agents. We have carried out property tests of fresh and hardened concrete, certified the properties and made the antiwashout underwater concrete have enough strength to endure with ea.sy construction. And we have decided the optimal mix proportion for antiwashout underwater concrete under standard state.

An Experimental Study on the Optimal Mix Proportion for Antiwashout Underwater Concrete (수중불분리성 혼화제를 첨가한 콘크리트의 최적배합비에 관한 실험적 연구)

  • 조선규
    • Magazine of the Korea Concrete Institute
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    • v.8 no.5
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    • pp.179-187
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    • 1996
  • Many underwater concrete structures have been constructed recently in proportion to the increase of ocean developments. The research for the underwater concrete construction was mainly focused in view of placing method. Recently, special admixture agents of concrete were developed for antiwashout concrete under water in some foreign nations. They had successful results in experiments and site constructions. However. there are seldom experimental results or placements in domestic contry. In this paper. We had carried out property tests of fresh and hardened concrete with refer to successful results in experiments and site construction and investigated the physical variation of the antiwashout underwater concrete considering the interaction between antiwashout admixture and other ones. We have decided the optimal mix proportion fb;r antiwashout underwater concrete under standerd sea state.

Effect of fly ash and plastic waste on mechanical and durability properties of concrete

  • Paliwal, Gopal;Maru, Savita
    • Advances in concrete construction
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    • v.5 no.6
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    • pp.575-586
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    • 2017
  • The disposal of polythene waste and fly ash is causing serious threat to the environment. Aim of this study is to decrease environmental pollution by using polythene waste and fly ash in concrete. In this study, cement was partially replaced with 0%, 5%, 10%, 15% and 20% fly ash (by weight) and plastic waste was added in shredded form at 0.6% by weight of concrete. The specimens were prepared for the concrete mix of M25 grade and water to cementitious material ratio (w/c) was maintained as 0.45. Fresh concrete property like workability was examined during casting the specimens. Hardened properties were found out by carrying out the experimental work on cubes, cylinders and beams which were cast in laboratory and their behavior under test were observed at 7 & 28 days for compressive strength and at 28 days for density, flexural strength, dynamic modulus of elasticity, abrasion resistance, water permeability and impact resistance. Overall results of this study show that addition of 0.6% (by weight of the concrete) plastic waste with 10% (by weight of cement) replacement of cement by fly ash result an improvement in properties of the concrete than conventional mix.

An Analysis on the Properties of Undispersed Underwater Mortar for Augered Pile with Expansive Additives (팽창재 혼입율 변화에 따른 오거파일용 수중불분리 모르터의 특성 분석)

  • 이광설;이대주;유홍종;권지훈;한일영;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04a
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    • pp.255-260
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    • 1998
  • As a part of the study on the development of augered pile method, this study is intended to investigate the properties of fresh and hardened mortar with the proportion of expansion additives. With the increase of proportion of expansion additives, the fluidity of mortar shows a decrease while air content increases and setting time gets retarded. It show the satisfactory property in strength at 5% of proportion, and shows more expansion with the increase of proportion of expansion additives and sand/cement ratio. In conclusion, both of strength and expansion reveal appropriate at 10% of proportion of expansion additives.

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Evaluation of Quality Properties of Concrete according to Mixing Proportion of Finex Water Granulated Slag Fine Aggregate (파이넥스 수쇄 슬래그 잔골재의 혼합률에 따른 콘크리트의 품질특성 평가)

  • Choi, Yun-Wang;Cho, Bong-Suk;Oh, Sung-Rok;Park, Man-Seok
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.2 no.2
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    • pp.145-151
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    • 2014
  • This paper evaluated the quality properties of Finex Water Granulated Slag fine aggregate as part of a study to recycle the Finex Water Granulated Slag generated in korea, and examined the availability as fine aggregate for concrete by comparing properties (properties of fresh concrete, mechanical properties of hardened concrete) of concrete using Finex Water Granulated Slag fine aggregate with properties of concrete using river sand as fine aggregate. From the results of this study, it was found that quality properties of concrete using finex water granulated slag as fine aggregate and concrete using river sand as fine aggregate are equivalent level.

The Analysis of Fundamental Property for Developing High Performance Concrete of Ternary System (3성분계 고성능 콘크리트 개발을 위한 기초 특성 분석)

  • Park, Byung-Kwan;Choi, Sung-Yong;Kim, Soo-Yung;Kim, Bok-Kyu;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.805-808
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    • 2008
  • This study analyzed the basic characteristics of concretes to develop 3 ingredients high performance concrete that displaced BS and FA, and the results are as follows. As part of fresh concrete characteristics, the flow was shown more increase than OPC with increase in admixture material displacement rate, and air amount tended to decrease with increase in admixture displacement rate. As hardened concrete characteristics, compressive strength decreased below OPC at early age with increase in BS and FA displacement rate, however at age 28 days, it was similar to OPC or increased above that. Particularly, at B30F15 with age 28 days, its compressive strength was about 15% higher than OPC

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Efficacy of supplementary cementitious material and hybrid fiber to develop the ultra high performance hybrid fiber reinforced concrete

  • Sharma, Raju;Bansal, Prem Pal
    • Advances in concrete construction
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    • v.8 no.1
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    • pp.21-31
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    • 2019
  • The rich recipe of ultra high performance concrete (UHPC) offers the higher mechanical, durability and dense microstructure property. The variable like cement/sand ratio, amount of supplementary cementitious material, water/binder ratio, amount of fiber etc. alters the UHPC hardened properties to any extent. Therefore, to understand the effects of these variables on the performance of UHPC, inevitably a stage-wise development is required. In the present experimental study, the effect of sand/cement ratio, the addition of finer material (fly ash and quartz powder) and, hybrid fiber on the fresh, compressive and microstructural property of UHPC is evaluated. The experiment is conducted in three phases; the first phase evaluates the flow value and strength attainment of ingredients, the second phase evaluates the efficiency of finer materials (fly ash and quartz powder) to develop the UHPC and the third phase evaluate the effect of hybrid fiber on the flow value and strength of ultra high performance hybrid fiber reinforced concrete (UHP-HFRC). It has been seen that the addition of fly ash improves the flow value and compressive strength of UHPC as compared to quartz powder. Further, the usage of hybrid fiber in fly ash contained matrix decreases the flow value and improves the strength of the UHP-HFRC matrix. The dense interface between matrix and fiber and, a higher amount of calcium silicate hydrate (CSH) in fly ash contained UHP-HFRC is revealed by SEM and XRD respectively. The dense interface (bond between the fiber and the UHPC matrix) and the higher CSH formation are the reason for the improvement in the compressive strength of fly ash based UHP-HFRC. The differential thermal analysis (DTA/TGA) shows the similar type of mass loss pattern, however, the amount of mass loss differs in fly ash and quartz powder contained UHP-HFRC.

Flowability and mechanical characteristics of self-consolidating steel fiber reinforced ultra-high performance concrete

  • Moon, Jiho;Youm, Kwang Soo;Lee, Jong-Sub;Yun, Tae Sup
    • Steel and Composite Structures
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    • v.43 no.3
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    • pp.389-401
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    • 2022
  • This study investigated the flowability and mechanical properties of cost-effective steel fiber reinforced ultra-high performance concrete (UHPC) by using locally available materials for field-cast application. To examine the effect of mixture constituents, five mixtures with different fractions of silica fume, silica powder, ground granulated blast furnace slag (GGBS), silica sand, and crushed natural sand were proportionally prepared. Comprehensive experiments for different mixture designs were conducted to evaluate the fresh- and hardened-state properties of self-consolidating UHPC. The results showed that the proposed UHPC had similar mechanical properties compared with conventional UHPC while the flow retention over time was enhanced so that the field-cast application seemed appropriately cost-effective. The self-consolidating UHPC with high flowability and low viscosity takes less total mixing time than conventional UHPC up to 6.7 times. The X-ray computed tomographic imaging was performed to investigate the steel fiber distribution inside the UHPC by visualizing the spatial distribution of steel fibers well. Finally, the tensile stress-strain curve for the proposed UHPC was proposed for the implementation to the structural analysis and design.

Effect of Fly Ash on Rheology and Strength of Recycled Aggregate Concrete (순환골재와 플라이애쉬가 콘크리트 유동성 및 강도에 미치는 영향)

  • Kim, Kyu-Hun;Shin, Myoung-Su;Kong, Young-Sik;Cha, Soo-Won
    • Journal of the Korea Concrete Institute
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    • v.25 no.2
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    • pp.241-250
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    • 2013
  • As the amount of construction wastes increase, reuse of demolished concrete is being considered in research areas. Reflecting these interests, this experiment was performed to clarify concrete's mechanical property and workability using recycled aggregate as a coarse aggregate. Eleven cases of concrete specimens were produced by changing the rates of replacement of coarse recycled aggregate, replacement of fly ash, design strength, and moisture state of coarse aggregate. Compressive and tensile split strength tests were taken to study the mechanical properties of hardened concrete. To verify flowability of fresh concrete, a slump test and a flow curve test using ICAR Rheometer were performed. It was found that using recycled aggregate and fly ash leads good workability by testing slump and flow curve. The yield stress of fresh concrete decreased with increase of recycled aggregate substitution rate. Through the test, it was confirmed that there is inversely proportional relationship between the slump and yield stress roughly. Recycled aggregate concrete containing fly ash has considerably lower plasticity viscosity than not containing fly ash. Strength test results showed that recycled aggregate tended to decrease compressive and tensile strength of concrete, when recycled aggregate was used as a coarse aggregate. Using over 30% recycled aggregate caused significant decreases in compressive and tensile strength. Replacing 30% cement with fly ash was helpful to improve the long-term strength of concrete.