• Title/Summary/Keyword: mechanical properties of concrete

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Mechanical Properties of Cement Paste with Nanomateirals (나노재료를 혼입한 시멘트 페이스트의 역학적 특성)

  • Choi, Ik-Je;Kim, Ji-Hyun;Chung, Chul-Woo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.06a
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    • pp.193-194
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    • 2020
  • Recently, as the use of high-performance concrete has become common, various problems related to high-performance concrete have become an issue. Among them, self-shrinkage of cement paste due to low water cement ratio is known to cause problems in the volume stability of concrete. To improve this, studies related to the mixing technology of cement-based materials and nano materials have been actively conducted. Looking at the results of prior research related to nano material mixing technology, generally, research results have been reported in which nano materials are incorporated into cement-based materials to improve material properties1). Among them, it was shown that the mechanical performance and various types of functionality of the cement composite are expressed. Among nano materials, carbon nanotubes (hereinafter referred to as CNTs) and graphenes are used in a mixture with cement-based materials. Accordingly, this study intends to compare the mechanical properties by incorporating various CNTs and graphene into cement paste.

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Mechanical Properties and Carbonation Resistance of Water-Soluble Sulfur Concrete (수용성 유황 첨가 콘크리트의 역학 특성 및 탄산화 저항성)

  • Hong, Ki Nam;Ji, Se Young;Park, Jae Kyu;Jung, Kyu San;Han, Sang Hoon
    • Journal of the Korean Society of Safety
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    • v.29 no.4
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    • pp.103-109
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    • 2014
  • In this study, two types of water-soluble sulfur, LSA and LSB, were developed and the influence of the water-soluble sulfur on the mechanical properties and durability of concrete were experimentally evaluated. In order to evaluate mechanical properties and carbonation resistance of concrete with water-soluble sulfur, compressive strength test, flexural strength test, bonding strength test, and carbonation resistance test were performed. Compressive strength of only concrete with 1% LSA was increased while that of concrete with LSB was proportionally increased with the higher LSB dosage. On the other hand, flexural strength of concrete with LSA and LSB was increased by 12-41% and 36-74%, respectively. Carbonation resistance of concrete with water-soluble sulfur were increased by 25-66%. As a result, it should be noted that the water-soluble sulfur can not only solve the demerit of sulfur concrete but also offer the durability of sulfur concrete.

Analysis of the Mechanical Properties of High-Tension Performance Biochar Concrete Reinforced with PVA Fibers Based on Biochar Cement Replacement Ratio

  • Kim, Sangwoo;Lee, Jihyeong;Hong, Yeji;Kim, Jinsup
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.44 no.5
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    • pp.603-613
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    • 2024
  • This study evaluated the mechanical properties of high-tension performance biochar concrete, focusing on the effects of varying biochar cement replacement ratios (0 %, 1 %, 2 %, 3 %, 4 %, and 5 %). Mechanical properties, including compressive strength, tensile strength, and flexural strength, were tested. The results showed a general decrease in compressive strength with increasing biochar replacement, with significant reductions at 1 % to 3 % levels. PVA fiber reinforcement improved long-term compressive strength, particularly at higher biochar levels. Tensile and flexural strength also showed initial reductions with low biochar levels but improved at higher replacement levels. PVA fibers consistently enhanced tensile and flexural strength. SEM images confirmed the integration of biochar and PVA fibers into the cement matrix, enhancing microstructural density and crack resistance.

An Experimental Study on the Mechanical Properties of No-Fines Concrete (No-Fines Concrete의 역학적 특성에 관한 실험적 연구)

  • 홍건호;정일영
    • Magazine of the Korea Concrete Institute
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    • v.6 no.3
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    • pp.190-200
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    • 1994
  • The purpose of this research is to examine experimentally the mechanical properties and economics of No-fines concrete for its application to the low-rise housing construction. Basic mechanical properties of No fines concrete are studied by measuring of compressive, tensile strength and stress-strain relationship, and economics of it is compared with other materials in unit cost and wall construction cost. From the test results, it can be concluded that No-fines concrete has advantages of good workability, light weight and lower construction cost, even though it has lower strength and modulus of elasticity than normal conc:rt:te does.

Mechanical Properties and Frost Resistance of Concrete with Steel and Nylon Fibers (강섬유 및 나일론섬유를 적용한 콘크리트의 역학적 성능 및 내동해성 평가)

  • Dong-Gyou, Kim;Seung-Tae, Lee
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.4
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    • pp.386-394
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    • 2022
  • In this study, the mechanical properties and frost resistance of concrete with steel and nylon fibers were experimentally investigated. Both of OPC concrete with 100 % ordinary portland cement and SGC concrete replaced with 50 % GGBFS were manufactured to evaluate effects of fibers to the performance of concrete. Compressive and split tensile strength, ultrasonic pulse velocity and surface electric resistivity measurements of concrete were carried out at a predetermined interval. In addition, the freezing & thawing resistance of concrete in accordance with ASTM C666 standard was also examined. As a result, it is seemed that the effect of fibers was remarkable to improve the mechanical properties and frost resistance of concrete, especially for the concrete incorporating steel fiber.

Meso-Scale Approach for Prediction of Mechanical Property and Degradation of Concrete

  • Ueda, Tamon
    • Corrosion Science and Technology
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    • v.3 no.3
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    • pp.87-97
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    • 2004
  • This paper presents a new approach with meso scale structure models to express mechanical property, such as stress - strain relationships, of concrete. This approach is successful to represent both uniaxial tension and uniaxial compression stress - strain relationship, which is in macro scale. The meso scale approach is also applied to predict degraded mechanical properties of frost-damaged concrete. The degradation of mechanical properties with frost-damaged concrete was carefully observed. Strength and stiffness in both tension and compression decrease with freezing and thawing cycles (FTC), while stress-free crack opening in tension softening increases. First attempt shows that the numerical simulation can express the experimentally observed degradation by introducing changes in the meso scale structure in concrete, which are assumed based on observed damages in the concrete subjected to FTC. At the end applicability of the meso scale approach to prediction of the degradation by combined effects of salt attack and FTC is discussed. It is shown that clarification of effects of frost damage in concrete on corrosion progress and on crack development in the damaged cover concrete due to corrosion is one of the issues for which the meso scale approach is useful.

Mechanical Properties of Specialty Cellulose Fiber Reinforced Concrete (특수 가공된 셀룰로오스섬유보강 콘크리트의 역학적 특성)

  • 원종필;박찬기
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 1999.10c
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    • pp.307-312
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    • 1999
  • This study has been performed to obtain the mechanical properties of specialty cellulose fiber reinforced concrete. Flexural test is proceeded by third-point loading method and the size of the test specimens is 15${\times}$15${\times}$55mm. The effect of differing volume fraction (0.08%, 0.1%, 0.15%) were studied. The results of tests of the specialty cellulose fiber reinforced concrete were compared with plain and polypropylene fiber reinforced concrete. Results indicated that specialty cellulose fiber reinforcement showed an ability to increase the flexural strength.

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Mechanical Performance Evaluation of Concrete with Recycled Coarse Aggregate Selected by Multi-stage Wind Pressure (다단형 풍압처리에 의해 선별된 순환굵은골재 적용 콘크리트의 역학적 성능 평가)

  • Chu, Young-Kyu;Lee, Seung-Tae;Lee, Se-Hyun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.1
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    • pp.1-8
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    • 2022
  • In this study, the mechanical properties of concrete with recycled coarse aggregate (RG) selected by multi-stage wind pressure (MSWP) treatment were evaluated. After evaluating the basic properties of natural and recycled coarse aggregates, the mechanical performance of the recycled coarse aggregates concrete was experimentally investigated. As a result, it was found that the MSWP technique could improve the fundamental properties such as density and water absorption of RG. In addition, the concrete with RG selected by MSWP showed a better mechanical performance, indicating a higher strength values, surface electric resistivity and a lower absorption. Thus, it seems that the MSWP technique can be effective for the production of high-quality RG.

Experimental investigation on self-compacting concrete reinforced with steel fibers

  • Zarrin, Orod;Khoshnoud, Hamid Reza
    • Structural Engineering and Mechanics
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    • v.59 no.1
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    • pp.133-151
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    • 2016
  • Self-Compacting Concrete (SCC) has been originally developed in Japan to offset a growing shortage of skilled labors, is a highly workable concrete, which is not needed to any vibration or impact during casting. The utilizing of fibers in SCC improves the mechanical properties and durability of hardened concrete such as impact strength, flexural strength, and vulnerability to cracking. The purpose of this investigation is to determine the effect of steel fibers on mechanical performance of traditionally reinforced Self-Competing Concrete beams. In this study, two mixes Mix 1% and Mix 2% containing 1% and 2% volume friction of superplasticizer are considered. For each type of mixture, four different volume percentages of 60/30 (length/diameter) fibers of 0.0%, 1.0%, 1.5% and 2% were used. The mechanical properties were determined through compressive and flexural tests. According to the experimental test results, an increase in the steel fibers volume fraction in Mix 1% and Mix 2% improves compressive strength slightly but decreases the workability and other rheological properties of SCC. On the other hand, results revealed that flexural strength, energy absorption capacity and toughness are increased by increasing the steel fiber volume fraction. The results clearly show that the use of fibers improves the post-cracking behavior. The average spacing of between cracks decrease by increasing the fiber volume fraction. Furthermore, fibers increase the tensile strength by bridging actions through the cracks. Therefore, steel fibers increase the ductility and energy absorption capacity of RC elements subjected to flexure.

Investigation of adding cement kiln dust (CKD) in ordinary and lightweight concrete

  • Shoaei, Parham;Zolfaghary, Sina;Jafari, Navid;Dehestani, Mehdi;Hejazi, Manouchehr
    • Advances in concrete construction
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    • v.5 no.2
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    • pp.101-115
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    • 2017
  • Cement kiln dust (CKD) is one of the most important waste materials in the cement industry. The large amount of this material, has encouraged researchers to propose new ways to recycle and reuse it. In this paper, effects of adding cement kiln dust to the ordinary Portland cement, on the physical and mechanical properties of ordinary and lightweight concrete were investigated. Results showed that concrete containing CKD, presents lower workability and modulus of elasticity; however, improvements in strength was observed by adding particular amounts of CKD. Eventually, it was found that adding 10% of cement weight CKD is the appropriate percentage for utilizing in manufacturing ordinary and lightweight concrete.