• Title/Summary/Keyword: ordinary portland cement concrete

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Synthesis and Mechanical Properties of Alkali-Activated Slag Concretes (무시멘트 알칼리 활성 고로슬래그 콘크리트의 배합에 따른 재료 역학적 특성)

  • Song, Jin-Kyu;Lee, Kang-Seok;Han, Sun-Ae;Kim, Young-In
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.1005-1008
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    • 2008
  • The purpose of this study is to estimate basic mechanical properties of alkali-activated concretes based on GGBS(Ground Granulated Blast Furnace Slag). In this study, various mix ratios of alkali activated concretes based on sodium silicate and GGBS were set to evaluate concrete's compressive strengths and strains on the basis of results of existing alkali-activated cements and preliminary concrete tests, which were already performed by authors [Ref. 1]. Compressive strengths of concretes of ages 1, 3, 7, 28, 56 and 91 days were tested and investigated, respectively, and at early ages (< 7days) alkali-activated slag concrete (AASC) showed a high strength development, compared to that of Ordinary Portland Cement (OPC). A compressive strengths of AASC at age-3days range between 18 and 24 MPa, while those of OPC range 12 and 15 MPa. The stress-strain curve after maximum stress, on the other hand, is approximately reached at a compressive strain between 0.002 and 0.0025, which mechanical property is very similar to that of OPC.

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Characteristics of Diffusion Coefficient of High Performance Concrete using GGBFS for Road Structures by Accelerating Test Method (슬래그 미분말 혼입률에 따른 도로구조물용 고성능 콘크리트의 압축강도 및 촉진 염소이온 확산 특성)

  • Han, Seong-Woo;Kim, Hong-Sam;Lee, Chan-Young;Cheong, Hai-Moon;Ahn, Tae-Song
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.885-888
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    • 2008
  • In recent years, the terminology "High-Performance Concrete(HPC)" has been introduced into the construction industry. Most high-performance concretes have a high cementitious content and a low water-cementitious material ratio. The proportions of the individual constituents vary depending on local preferences and local materials. Therefore, many trial batches are usually necessary before a successful mix is developed. The objective of this experiments is to investigate the fundamental properties of high performance concrete based binary cimentitious materials such as ordinary portland cement and ground granulated blast furnace slag. The results from the study will be utilized as the basic data and guideline in making standard mixproportions and the manufacture, construction work and quality control of HPC

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Fundamental Properties of MgO Base Ceramic Mortar for Concrete Repair Material (MgO계 세라믹 모르타르를 활용한 콘크리트 보수재료의 기초물성평가)

  • Park, Joon-Woo;Ann, Ki-Yong
    • Journal of the Korea Concrete Institute
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    • v.29 no.4
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    • pp.407-413
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    • 2017
  • The fundamental property of magnesia phosphate cement (MPC) for concrete repair material was investigated in this research. For mechanical properties, setting time, compressive strength and tensile/flexural bond strength were measured, and hydration products were detected by X-ray diffraction. The specimens were manufactured with dead burnt magnesia and potassium dihydrogen phosphate was admixed to activate the hydration of magnesia and a borax was used as a retarder. To observe the pore structure and ionic permeability of MPC mortar, mercury intrusion porosimetry was performed together with rapid chloride penetration test (RCPT). As a result, time to set of Fresh MPC mortar was in range of 16 to 21 min depend on the M/P ratio. Borax helped delaying setting time of MPC to 68 min. The compressive strength of MPC with M/P of 4 was sharply developed to 30 MPa within 12 hours. The compressive strength of MPC mortar was in range of 11.0 to 30.0 MPa depend on the M/P ratio at 12 hours of curing. Both tensile and flexural bond strength of MPC to old substrate (i.e. MPC; New substrate to OPC; Old substrate) were even higher than ordinary Portland cement mortar (i.e. [OPC; New substrate] to [OPC; Old substrate]) does, accounting 19 and 17 MPa, respectively. The total pore volume of MPC mortar was lower than that of OPC mortar. MPC mortar had the entrained air void rather than capillary pore. The RCPT showed that total charge passed of OPC mortar had more than that of MPC mortar, which can be explained by the pore volume and pore distribution.

Properties of Ternary or Quaternary High Strength Concrete Using Silica Fume & Meta Kaolin (실리카퓸과 메타카올린을 사용한 다성분계 고강도콘크리트의 특성)

  • Park, Cho-Bum;Kim, Ho-Su;Jeon, Jun-Young;Kim, Eun-Kyum;Ryu, Deug-Hyun
    • Journal of the Korea Concrete Institute
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    • v.20 no.3
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    • pp.307-315
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    • 2008
  • In this study, it is investigated the properties of high strength concrete using mineral admixture, on the purpose of use of meta kaolin for the substitutive materials to silica fume which is so expensive. The plain mixtures are 3 degrees which are ordinary portland cement, blast furnace slag cement and OPC included fly ash 20%, and silica fume and meta kaolin are substituted for the each plain mixtures in the range of 20%. The results of experiment showed as follows. In case of silica fume was only used, the viscosity and slump flow of fresh concrete were much decreased, on the contrary air content increased. But as usage of meta kaolin increased, to being increase the viscosity of fresh concrete, slump flow increased and air content and usage of super-plasticizer were decreased. Accordingly the workabilities of concrete were against tendency between silica fume and meta kaolin. The compressive strength, velocity of ultrasonic pulse and unit weight were increased according to usage of meta kaolin, the properties of hardened concrete were judged that they are affected with air content of fresh concrete, so it is very important to control air content of high strength concrete. Therefore, the use of meta kaolin is prospected to the substitutive material of silica fume, in case of using silica fume and meta kaolin, it is judged that the optimum usage of silica fume and meta kaolin is about 10% respectively, considering workability and strength of concrete.

Estimation of Air Void System and Permeability of Latex-Modified Concretes by Image Analysis Method (화상분석법을 이용한 라텍스개질 콘크리트의 공극 구조와 투수성의 상관성 분석)

  • Jeong Won-Kyong;Yun Kyong-Ku;Hong Seung-Ho
    • Journal of the Korea Concrete Institute
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    • v.17 no.5 s.89
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    • pp.695-702
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    • 2005
  • It is known that latex-modified concretes were increased their durability and permeability by added latex. The purpose of this study was to analysis the air void systems in latex-modified concretes using a reasonable and objective image analysis method with main experimental variables such as water-cement ratios, latex contents(0%, 15%) and cement types(ordinary portland cement, high-early strength cement and very-early strength cement). The results are analyzed spacing factor, air volume after hardened, air distribution and structure. Also, air void systems and permeability of latex-modified concretes were compared with correlation. The results are as follows; The same w/c ratio LMC showed better air entraining effect than OPC with AE water reducer. The VES-LMC showed that the number of entrained air below $100{\mu}m$ increased more than four times. In the HES-LMC, micro entraining air having range from 50 to $500{\mu}m$ increased above 7 times without antifoamer. Though spacing factor was measured low, latex-modified concretes were showed that permeability was good. It is considered that air void system does not have an effect on the property of latex-modified concretes but latex film is more influenced in the their durability.

An Experimental Study on Mechanical Properties of Ultra-High Strength Powder Concrete (압축강도 300MPa 이상의 초고강도 분체콘크리트 개발을 위한 실험적 연구)

  • Jo, Byung-Wan;Yoon, Kwang-Won;Park, Jung-Hoon;Kim, Heoun
    • Journal of the Korea Concrete Institute
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    • v.22 no.3
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    • pp.287-295
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    • 2010
  • In this study, ordinary Portland cement was used and the air void was minimized by using minute quartz as the filler. In addition, steel fibers were used to mitigate the brittle failure problem associated with high strength concrete. This study is in progress to make an Ultra-high strength powdered concrete (UHSPC) which has compressive strength over 300 MPa. To increase the strength of concrete, we have compared and analyzed the compressive strengths of the concretes with different mix proportions and curing conditions by selecting quartz sand, dolomite, bauxite, ferro silicon which have diameters less than 0.6 mm and can increase the bond strength of the transition zone. Ultra-high strength powdered concrete, which is different from conventional concrete, is highly influenced by the materials in the mix. In the study, the highest compressive strength of the powdered concrete was obtained when it is prepared with ferro silicon, followed in order by Bauxite, Dolomite, and Quartz sand. The amount of ferro silicon, when the highest strength was obtained, was 110%, of the weight of the cement. SEM analysis of the UHSPC showed that significant formation of C-S-H and Tobermorite due to high temperature and pressure curing. Production of Ultrahigh strength powdered concrete which has 28-day compressive strength upto 341MPa has been successfully achieved by the following factors; steel fiber reinforcement, fine particled aggregates, and the filling powder to minimize the void space, and the reactive materials.

An Experimental Study for Improving the Durability of Concrete Bridge Decks (교량 바닥판 콘크리트의 내구성 증진을 위한 실험적 연구)

  • Suh, Jin-Won;Rhee, Ji-Young;Ku, Bon-Sung;Shin, Do-Chul
    • Journal of the Korea Concrete Institute
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    • v.19 no.4
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    • pp.393-399
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    • 2007
  • Concrete bridge decks are directly exposed to the severe environmental conditions such as rain water and deicing chemicals resulting in the freeze-thaw action and the rebar corrosion during their service lift. These deteriorations of bridge decks shorten the service lift and consequently they are the major concerns of the maintenance. The high performance concrete (HPC) deck is proposed as the alternative to minimize the deterioration problems. To develop more durable concrete deck, the performance characteristic tests of HPC mixtures were carried out. In this study, 4 different concrete mixtures were used varying the mineral admixtures as the cement replacement; ordinary portland cement (OPC), 20% fly ash (FA),20% fly ash with 4% silica fume (FS), and 40% ground granulated blast-furnace slag (BS). The design compressive strengths of HPC specimens were 27 MPa and 35 MPa, respectively. The results showed that the compressive strength of concrete did not much affect the durability of concrete. HPC with fly ash and silica lune (FS) were turned out to have the good durability and crack resistance.

The Property Evaluation of the Marine Concrete Structure Constructed in the Period of Japanese Occupancy (YoungDo Bridge) (일제시대 건설된 해양 콘크리트구조물의 물성 평가(영도대교))

  • Park, Dong-Cheon;Ahn, Jae-Cheol
    • Journal of Navigation and Port Research
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    • v.37 no.2
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    • pp.165-171
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    • 2013
  • YoungDo bridge is the first suspension bridge in Busan which experienced several times repair and reinforcement after completion in 1934. The bridge is under demolition for extension and restoration work since 2011. The purpose of this research is to establish data base about modern concrete. The mix design of the concrete is like that cement : fine aggregate : coarse aggregate = 1 : 2 : 4 or 1 : 3 : 6 by the parts. The compressive strength is in the ranges from 50 to 55 MPa and the elastic modulus is in the ranges from 25 to 35 GPa. From the fact that the deviation is less than 10 %, considerably high quality control was conducted in those days. The carbonation depth is 5.92 cm at the bridge post and 14.3 cm at the machine room. That is why ocean environment keeps the high humidity. The diffusion coefficient of chloride ion through the pores in concrete is 1.052e-12 $m^2/s$ from the regression analysis using the experiment data. The water cement ration is estimated at approximately 35 % in case if the concrete using ordinary Portland cement.

Basic Properties of Latex-Modified Concrete Using Fly-ash (플라이애쉬를 이용한 라텍스개질 콘크리즈의 기초물성 연구)

  • Hong, Chang-Woo;Jeong, won-Kyong;Kim, Kyong-jin;Yun, Kyong-ku
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1A
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    • pp.205-211
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    • 2006
  • The purpose of this study was to evaluate the effects of fly-ash on strength development and durability of latex-modified concrete (LMC) and ordinary portland cement concrete (OPC). Main experimental variables were latex contents (0%, 10%, 15%) and fly-ash content (0, 10%, 20%, 30%). Air content and slump tests were performed to check the basic properties of fresh concretes, and compressive strength, flexural strength, rapid chloride ion permeability and chemical resistance were measured to analyze the basic properties of hardened concretes. The test results showed that air contents of LMC with fly ash decreased as fly-ash contents increased from 0% to 30%. Compressive and flexural strength developments of LMC with fly ash were quite similar to those of LMC without fly ash. However, the long-term flexural strength development of LMC with fly ash after 90 days were bigger than that of LMC without fly ash. Chloride ion permeability and chemical resistance decreased rapidly as the content of fly ash increased. Thus, fly ash could be used at LMC in order to reduce water permeability.

A Study on Performance Evaluation of Early-age Concrete with EOS Fine Aggregate and GGBFS (EOS 잔골재 및 GGBFS를 혼입한 초기재령 콘크리트의 성능 평가에 관한 연구)

  • Kwon, Seung Jun;Cho, Sung Jun;Lim, Hee Seob
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.4
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    • pp.113-119
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    • 2019
  • Many researches on alternative materials as construction materials is continuing by recycling industrial byproducts due to shortage of sitereclamation and natural aggregates. In this paper, engineering properties in early-aged OPC (Ordinary Portland Cement) and GGBFS (Ground Granulated Blast Furnace Slag) concrete are evaluated with EOS aggregate replacement. The related experiments were carried out with 0.6 of water to binder ratio, three levels of EOS replacement ratios (0%, 30% and 50%) for fine aggregate, and two levels of cement replacement with GGBFS (0% and 40%). Several tests such as slump air content, and unit mass measurement are performed for fresh concrete, and compressive strength and diffusion coefficient referred to NT BUILD 492 method are measured for hardened concrete. Through the tests, it was evaluated that the compressive strength in concrete with EOS aggregate increased to 3 days and 7 days but slightly decreased at the age of 28 days. In the accelerated chloride penetration test, GGBFS concrete showed reduced diffusion coefficients by 60 - 67% compared with OPC concrete. The lowest chloride diffusion coefficient was evaluated in the 50% replacement with EOS aggregate, which showed an applicability of EOS aggregate to concrete production.