• Title/Summary/Keyword: sprayed concrete

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Dispersibility and Flexural Toughness Evaluation of Fiber Reinforcement Cellular Sprayed Concrete by added Foam (기포를 혼입한 섬유보강 셀룰러 스프레이 콘크리트 공법의 분산성 및 휨인성 평가)

  • Lee, Kyeo-Re;Han, Seung-Yeon;Nam-Gung, Kyeong;Yun, Kyong-Ku
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.6
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    • pp.4192-4200
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    • 2015
  • In this paper, dispersibility of steel fiber is improved mixing with form for material development of protection and blast resistant structure sprayed concrete. And it is developed a high toughness cellular sprayed concrete material using steel fiber. Oversupply form for dispersibility improvement of steel fiber is mostly fade away through sprayed, finally it is satisfied with the proper mixing ratio under 3 % ~ 6 %. This is considered for compressive strength and flexural toughness. Test results of compressive strength showed superior strength capability in 28, 56 days, also flexural strength and flexural toughness is great. Then oversupply form is enhanced for dispersibility of steel fiber and I think that it did not cause decreasing of strength. But analysis results of pore structure through image analysis failed for a great spacing factor and specific surface area. This is largely measured in spacing factor because air content have a grate evaporation effect for sprayed.

Mechanical and Repair Performance of Sprayed Ductile Fiber Reinforced Cememtitious Composite(ECC) (습식스프레이공법으로 타설된 고인성 섬유보강 모르타르(ECC)의 역학적 특성과 보수 성능)

  • Kim, Yun-Yong
    • Journal of the Korea Concrete Institute
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    • v.15 no.3
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    • pp.462-469
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    • 2003
  • This paper presents an experimental study on the potential durability enhancement of infrastructures repaired by a sprayed high ductile fiber-reinforced cementitious composite (ECC). For this study, a PVA-ECC which exhibits sprayable properties in the fresh state and tensile strain-hardening behavior in hardened state was sprayed and tested. The experimental results show that the sprayed ECC exhibits mechanical properties with strain capacity comparable to the cast ECC with the same mix design. During loading, the crack widths of ECC are tightly controlled with an average of 30${\mu}m$. It is also revealed that when sprayed ECC is used as a repair material, ductility represented by deformation capacity at peak load of repaired beams in flexure are obviously increased in comparison to those of commercial prepackaged mortar (PM) repaired beams. In addition to high delamination resistance, the significant enhancement of energy absorption capacity and crack width control in ECC repair system suggest that sprayed ECC can be effective in extending the service life of rehabilitated infrastructures.

Evaluation of physical properties of Zn-Al metal spray coating according to concrete surface and treatment method (콘크리트 표면 처리 방법 및 용사면에 따른 Zn-Al 금속 용사 피막의 물리적 특성 평가)

  • Jang, Jong-Min;Yang, Hyun Min;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2022.04a
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    • pp.59-60
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    • 2022
  • When a metal sprayed film of several hundred ㎛ on the concrete surface is possible to 80 dB of shielding effect electromagnetic waves (ElectroMagnetic Pulse, EMP). Therefore, in this study, as a way to secure EMP shielding performance by applying a metal spray coating showing excellent EMP shielding performance to a concrete structure, the metal spray welding efficiency and thin film adhesion performance according to the concrete spray direction and surface treatment method were evaluated. Metal sprayed efficieny according to the metal spraying direction and method was confirmed that the difference was insignificant by applying the roughening agent. However, the method of strengthening the concrete surface and applying the sealing agent show maximum adhesion strength of 3.98 MPa compared to other methods, and it is judged that this method can be utilized for the metal spraying method for concrete EMP shielding.

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Evaluation on Strengthening Capacities and Rebound Rate of Structures with Sprayed FRP (분사식 FRP에 의한 구조물의 보강 성능 및 반발률 평가)

  • Han, Seung-Chul;Yang, Jun-Mo;Yoon, Young-Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.1
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    • pp.193-202
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    • 2008
  • This paper investigates experimentally the confining effect, strengthening capacity and rebound rate of sprayed Fiber-Reinforced-Polymer (SFRP). From the method, resin and chopped fibers are sprayed separately from the nozzle with high pressure, and then they are attached to the concrete surface, so structure could be repaired. To evaluate the strengthening effect of sprayed FRP, cylindrical specimens and beam specimens were strengthening with SFRP. As main material of FRP, glass fiber and polyester resin are used. To investigate the optimum condition of sprayed FRP, the effects of fiber length, coating thickness, fiber volume ratio and concrete strength were examined. Capacities of sprayed FRP method were also compared to the FRP sheet method. In case of the sprayed FRP, rebound rate is important parameter considering economical efficiency and constructibility, so rebound rate of was discussed. From the test results, optimum conditions of sprayed FRP were determined. SFRP method showed superior strengthening capacities than FRP sheet method.

Algorithms to measure carbonation depth in concrete structures sprayed with a phenolphthalein solution

  • Ruiz, Christian C.;Caballero, Jose L.;Martinez, Juan H.;Aperador, Willian A.
    • Advances in concrete construction
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    • v.9 no.3
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    • pp.257-265
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    • 2020
  • Many failures of concrete structures are related to steel corrosion. For this reason, it is important to recognize how the carbonation can affect the durability of reinforced concrete structures. The repeatability of the carbonation depth measure in a specimen of concrete sprayed with a phenolphthalein solution is consistently low whereby it is necessary to have an impartial method to measure the carbonation depth. This study presents two automatic algorithms to detect the non-carbonated zone in concrete specimens. The first algorithm is based solely on digital processing image (DPI), mainly morphological and threshold techniques. The second algorithm is based on artificial intelligence, more specifically on an array of Kohonen networks, but also using some DPI techniques to refine the results. Moreover, another algorithm was developed with the purpose of measure the carbonation depth from the image obtained previously.

Applicability of Colormetric Method for Estimation of Chloride Penetration in Concrete Structure (콘크리트의 염화물 침투 특성 평가를 위한 변색법의 적용성)

  • Kim Myung yu;Yang Eun Ik;Lee Kwang Gyo;Min Seok Hong
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.798-801
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    • 2004
  • Silver nitrate colored method that measure easily penetration depth of chloride ion has been used, recently. But, characteristics of silver nitrate colored method hasn't examined well. Therefore, we are aim to examine characteristics of colored method. According to experiment results, when the colored method was applied in concrete, it is reasonable that $AgNO_3$ solution more than 0.05N concentration was sprayed. Chloride concentration difference in colored parts was about 20ppm when $AgNO_3$ of two concentration (0.05N, 0.1N) in concrete was sprayed.

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Performance Evaluation of Sprayed Ductile Fiber-Reinforced Mortar as a Repairing Material

  • Kang, Su-Tae;Koh, Kyung-Taek;Ryu, Gum-Sung;Kim, Jin-Soo;Han, Cheon-Goo
    • International Journal of Concrete Structures and Materials
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    • v.2 no.1
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    • pp.27-33
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    • 2008
  • Most of existing repair materials have some shortcomings such as brittle fracture, imperfect interface bonding and marked difference in modulus of elasticity compared with the structures. These problems make their repair inefficient. Some researches on using a fiber-reinforced mortar as an alternative to enhance the efficiency have been carried out recently. This paper presents the results of an experimental study on the performance of sprayed PVA fiber-reinforced mortar as a repair material. We evaluated its mechanical properties, durability and strengthening effect. This study shows that the sprayed PVA fiber-reinforced mortar is remarkably effective as a repair material.

Performance Evaluation of Structure Strengthening Using Sprayed FRP Technique (분사식 FRP공법을 이용한 구조물 보강 성능평가)

  • Chang, Chun-Ho;Jang, Kwang-Seok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.4 s.56
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    • pp.126-136
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    • 2009
  • The sprayed FRP strengthening technique is combining the Glass fiber and Polyester resin in open air and spraying randomly at concrete's surface with high-speed compressed air. Then it strengthens the structures with a new technique evaluated the structural performance. We applied it to concrete beam and tested for flexural strength, depended on Korea Standard(KS F 2408). Then based on the result of flexural strength, the properties were proposed that applying to structures. Based on the experiment, we have evaluated structural performance by the experiment. 1/5 scale prestressed concrete I-beam were made by Korean Highway's typical drawing in 1993. With these test results, 49.8% increased in flexural strength, improvement of the behavior of serviceability state, and strengthening was surely effective for controlling deflection and crack of structure. Consequently, it can be summarized that Sprayed FRP technique has prospect to improve the performance of structure.