• Title/Summary/Keyword: structural lightweight concrete

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Ultrasonic Pulse Velocity of Normal Aggregate Concrete and Lightweight Aggregate Concrete at Early age According to Elapsed Time (초기재령에서 보통골재 및 경량골재 콘크리트의 시간경과에 따른 초음파 속도 변화)

  • Kim, Won Chang;Choi, Hyeong Gil;Nam, Jeong Soo;Kim, Gyu Young;Lee, Tae Gyu
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2021.11a
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    • pp.61-62
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    • 2021
  • Because of the problem of increasing self-weight due to the enlargement and high-rise of buildings using normal aggregate concrete, the need for structural lightweight aggregate concrete increases. However, early strength prediction is required when placing structural lightweight aggregate concrete, but research is insufficient. In this study, the ultrasonic pulse velocity of normal aggregate concrete and lightweight aggregate concrete was measured at early age. As a result, the ultrasonic pulse velocity of lightweight aggregate concrete was lower than normal aggregate concrete according to elapsed time at early age.

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Fuzzy logic approach for estimating bond behavior of lightweight concrete

  • Arslan, Mehmet E.;Durmus, Ahmet
    • Computers and Concrete
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    • v.14 no.3
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    • pp.233-245
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    • 2014
  • In this paper, a rule based Mamdani type fuzzy logic model for prediction of slippage at maximum tensile strength and slippage at rupture of structural lightweight concretes were discussed. In the model steel rebar diameters and development lengths were used as inputs. The FL model and experimental results, the coefficient of determination R2, the Root Mean Square Error were used as evaluation criteria for comparison. It was concluded that FL was practical method for predicting slippage at maximum tensile strength and slippage at rupture of structural lightweight concretes.

An Experimental Study for the Strength Variations of High-strength Lightweight Concrete According to Grain-size of Artificial Lightweight Aggregate (인공경량골재의 입도에 따른 고강도 경량콘크리트의 강도변화에 대한 실험적 연구)

  • Kim, Sung Chil;Park, Ki Chan;Choi, Hyoung Wook
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.5
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    • pp.209-217
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    • 2011
  • In recent days, while taller and more massive structures such as huge bridges and super skyscrapers have been welcomed, the structural stabilization in design and construction have been gradually limited due to the major weakness of current concrete which is relatively heavier when compared with its strength. To improve the weakness of the current concrete, The lightweight concrete with light weight and high strength should be used; however, not many researchers in Korea have studied on the lightweight concrete. Generally, artificial lightweight aggregate produced through high-temperature-plasticization has a possibility of its body-expansion with many bubbles. Therefore, depending on the size of aggregate, the effects of bubbles on the specific weight and strength of the lightweight concrete should be studied. In this study, considering grain-size, the mix design of the artificial lightweight aggregate produced through the high-temperature-plasticization and the body-expansion of waste and clay from the fire power plant in Korea was conducted. The experiment to analyze the variation in specific weight and strength of the lightweight concrete was followed. From these experiments, the optimized grain-size ratio of the artificial lightweight aggregate for the enhancement of high-strength from the lightweight concrete was revealed.

Fundamental Tests of High Strength Lightweight Concrete for Application (고강도-경량콘크리트의 실용화를 위한 기초적 실험 연구)

  • Lee, Jae-Sam;Kim, Jung-Sik;Kang, Hoon;Choi, Myung-Shin;Ahn, Jong-Moon;Shin, Sung-Woo
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.10a
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    • pp.393-400
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    • 1997
  • It is possible to reduce dead load and cross section of structural members by use of lightweight concrete, and also reduce the cost of construction. The mechanical properties of lightweight concrete are lower than that of normal weight concrete having the same compressive strength, then it is necessary to make higher strength of lightweight concrete for structural use, and the objective of this paper is to development and application the highstrength lightweight concrete with lower than 2.0t/$\textrm{m}^3$ of unit weight and over than 350kg/$\textrm{cm}^2$ of compressive strength.

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A Study for Automation of Lightweight Concrete Mix Design (경량 콘크리트 배합설계의 자동화를 위한 연구)

  • Choi, Jae-Jin;Song, Jin-Woo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.329-330
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    • 2010
  • For the computerization of structural lightweight concrete mix design, mix design theories of ACI211.2-98(Standard Practice for Selecting Proportions for Structural Lightweight Concrete) are investigated and the mix design process is mathematized by Table Curve 2D and 3D software of Jandel company.

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Influence of the Mixing Factor on the Properties of Concrete Used Artificial Lightweight Aggregates (인공경량골재를 사용한 콘크리트의 물성에 미치는 배합요인의 영향)

  • Shin, Jae-Kyung;Choi, Jin-Man;Jeong, Yong
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2008.11a
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    • pp.73-77
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    • 2008
  • Structural lightweight concrete will reduced total loads of supporting sections and foundations in archtectural and civil structures. So, the lightweight concrete can be used widely for various purpose in the archtectural and civil structures. This paper were examined the influence of the mixing factor on the fresh and hardened properties of lightweight concrete that are used 2types of the differences properties of lightweight aggregates. According to types of lightweight aggregates, the case of synthetic lightweight aggregate are have need higher s/a; 2~4% on mixing proportion. Lightweight concrete was somewhat exhibit lower compressive strength than ordinary concrete. However it was not showed a marked difference. According to types of lightweight aggregates, the case of synthetic the lightweight aggregate are highest performance in fresh and hardened concrete.

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Life-Cycle Cost Optimization of Slab Bridges with Lightweight Concrete (경량 콘크리트를 이용한 슬래브교의 생애주기비용 최적설계)

  • 정지승;조효남;최연왕;민대홍;이종순
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.257-264
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    • 2002
  • This study presents a life-cycle cost (LCC) effectiveness of a concrete with lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. In this study, an optimum design for minimizing the life-cycle cost of concrete slab bridges is performed to evaluate the life cycle cost effectiveness of the lightweight concrete relative to conventional one from the standpoint of the value engineering. The data of physical properties for new concrete can be obtained from basic experimental researches. The material properties of conventional one are acquired by various reports. This study presents a LCC effectiveness of newly developed concrete, which is made by artificial lightweight aggregate. A number of researchers have made their efforts to develop a lightweight concrete, since it is difficult to apply conventional concrete using general aggregate to heavy self-weight structures such as long span bridges. From the results of the numerical investigation, it may be positively stated that the new concrete lead to, the longer span length, the more economical slab bridges compared with structures using general concrete.

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Manufacturing of Lightweight Aggregate using Sewage Sludge by a Pilot Plant(10ton/day) (Pilot Plant(10톤/일)를 이용한 하수슬러지 인공경량골재의 제조)

  • Mun, Kyoung-Ju;Lee, Hwa-Young;So, Seung-Young;Soh, Yang-Seob
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.117-120
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    • 2006
  • The purpose of this study is to efficiently treat the sewage sludge discharged from sewage treatment plants and evaluate the feasibility of the manufacture of lightweight aggregates(LWA) using a large quantity of sewage sludge. Sintered lightweight aggregate from sewage sludge is experimentally manufactured with various mass ratios of clay to sewage sludge by a pilot plant, and is tested for density, water absorption and crushing value. Their physical properties are compared to those of a commercial sintered lightweight aggregate. As a result, an experimentally manufactured lightweight aggregate is similar or superior in physical properties to the commercial lightweight aggregate. The manufactured lightweight aggregate could be used for structural concrete and non-structural concrete.

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Manufacturing of Sintered Lightweight Aggregate using Paper Mill Sludge Ash (제지 슬러지 소각재를 이용한 소성 경량골재의 제조)

  • 문경주;김재신;소양섭
    • Journal of the Korea Concrete Institute
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    • v.13 no.2
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    • pp.114-122
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    • 2001
  • The purpose of this study was to manufacture sintered lightweight aggregate using paper sludge ash and to evaluate the qualities of the aggregate according to various mix proportions, conditions of pelletization and sintering. The paper sludge ash alone, due to its mineral and chemical compositions could not gain suitable expansion and strength. Hence, it was essential to add mineral additives such as clay, fly ash etc. The optimum muting ratio range determined in this study is as follows , paper sludge ash 30∼50 %, clay 30∼50 %, fay ash 0∼40 %, Paper sludge 0∼10% and hematite 2∼3 %(for manufacturing lightweight aggregate both for non-structural and structural concrete). It was possible to manufacture various lightweight aggregate whose dry specific gravity ranged about from 0.6 to 1.4 by using this optimum mixing ratio. From the test results of the qualities of aggregate, it showed that the 10% granules crushing value test and water absorption percentage ranged about 5∼10 ton and 10∼20%. Thus, it was favorably comparable to those of the imported aggregate. The manufactured lightweight aggregate could be used for structural concrete and non-structural concrete.

Time-dependent properties of lightweight concrete using sedimentary lightweight aggregate and its application in prestressed concrete beams

  • Chen, How-Ji;Tsai, Wen-Po;Tang, Chao-Wei;Liu, Te-Hung
    • Structural Engineering and Mechanics
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    • v.39 no.6
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    • pp.833-847
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    • 2011
  • We have developed a lightweight aggregate (LWA) concrete made by expanding fine sediments dredged from the Shihmen Reservoir (Taiwan) with high heat. In this study, the performance of the concrete and of prestressed concrete beams made of the sedimentary LWA were tested and compared with those made of normal-weight concrete (NC). The test results show that the lightweight concrete (LWAC) exhibited comparable time-dependent properties (i.e., compressive strength, elastic modulus, drying shrinkage, and creep) as compared with the NC samples. In addition, the LWAC beams exhibited a smaller percentage of prestress loss compared with the NC beams. Moreover, on average, the LWAC beams could resist loading up to 96% of that of the NC beams, and the experimental strengths were greater than the nominal strengths calculated by the ACI Code method. This investigation thus established that sedimentary LWA can be recommended for structural concrete applications.