• Title/Summary/Keyword: Bond Strength Test

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A Study on Bond Strength between Fiber Sheet and Concrete for Concrete Surface Preparation and Heating Condition (콘크리트 표면처리와 가열조건에 따른 섬유쉬트와 콘크리트의 부착강도에 관한 연구)

  • Ahn, Sang-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.6 no.4
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    • pp.201-207
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    • 2002
  • An advanced fiber sheet has been widely used for strengthening of the concrete structures due to its excellent properties such as high strength and light weight. Bond strength is very important in strengthening the concrete structures using an advanced fiber sheet. This research examines the bond behavior between fiber sheet and concrete, investigates the bond strength by the direct pull-out test and the tensile-shear test. To obtain the tensile-shear strength a double-face shear type bond test is conducted. The primary test variables are the types of concrete surface roughness (disk-grinding/chipping) and retrofitting methods (bonding/injection). Thirty specimens were tested to evaluate the bond strength. It is shown that the average bond strength between fiber sheet and concrete by the direct pull-out test and the tensile-shear test is $22.3{\sim}23.1kgf/cm^2$ $17.92{\sim}19.75kgf/cm^2$, respectively.

Study on bond behavior of steel reinforced high strength concrete after high temperatures

  • Chen, Zongping;Zhou, Ji;Wang, Xinyue
    • Advances in concrete construction
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    • v.10 no.2
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    • pp.113-125
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    • 2020
  • This paper presents experimental results on bond-slip behavior of steel reinforced high-strength concrete (SRHC) after exposure to elevated temperatures. Three parameters were considered in this test: (a) high temperatures (i.e., 20℃, 200℃, 400℃, 600℃, 800℃); (b) concrete strength (i.e., C60, C70, C80); (c) anchorage length (i.e., 250 mm, 400 mm). A total of 17 SRHC specimens subjected to high temperatures were designed for push out test. The load-slip curves at the loading end and free end were obtained, the influence of various variation parameters on the ultimate bond strength and residual bond strength was analyzed, in addition, the influence of elevated temperatures on the invalidation mechanism was researched in details. Test results show that the shapes of load-slip curves at loading ends and free ends are similar. The ultimate bond strength and residual bond strength of SRHC decrease first and then recover partly with the temperature increasing. The bond strength is proportional to the concrete strength, and the bond strength is proportional to the anchoring length when the temperature is low, while the opposite situation occurs when the temperature is high. What's more, the bond damage of specimens with lower temperature develops earlier and faster than the specimens with higher temperature. From these experimental findings, the bond-slip constitutive formula of SRHC subjected to elevated temperatures is proposed, which fills well with test data.

Bond Strength of Reinforcing Steel to High Strength, High Flow Belite Concrete (고강도, 고유동 Belite 콘크리트의 부착성능)

  • 김상준;조필규;이세웅;최완철
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04b
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    • pp.653-660
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    • 1998
  • Bond strength of reinforcing bar to high-performance concrete using belite cement is explored using beam end test specimen. The key parameters for the bond test are slump of concrete, top bar effect, and strength of concrete in addition to concrete covers. Specimen failed in the typical brittle bond failure splitting the concrete cover as the wedging action. The test results show that the specimens with belire cement concrete show higher bond strength than those with portland cement concrete. Bond strength of the top bar is less than bond strength of bottom bar, but the top bar factor satisfies the modification factor for top reinforcement. The results also show that the bond strength is function of the square root of concrete compressive strength and cover thickness. The recently developed high-strength and high-slump concrete with belite cement performs well in terms of bond strength to reinforcing steel.

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Evaluation of Bond Strength Characteristic of Moisture Induced Asphalt Mixtures using ABS Test (ABS Test를 이용한 아스팔트 혼합물의 수분에 의한 점착특성 평가)

  • Son, Jeong Tan;Yang, Sung Lin;Shin, O-Cheol;Rhee, Suk Keun;Im, Jeong Hyuk
    • International Journal of Highway Engineering
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    • v.19 no.2
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    • pp.87-95
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    • 2017
  • PURPOSES : The objectives of this study are to evaluate moisture sensitivity of various asphalt mixtures and to suggest an alternate method for the dynamic immersion test, which is used to determine the application of anti-stripping agent, by analyzing bond strength. METHODS : The bond strength of various asphalt mixtures such as hot mix asphalt, warm mix asphalt, and polymer-modified asphalt was evaluated by the ABS test. In order to characterize moisture sensitivity at different temperatures of the mixtures, the ABS test was conducted at $-10^{\circ}C$, $5^{\circ}C$, $20^{\circ}C$, $40^{\circ}C$, and $54^{\circ}C$ under both dry and wet conditions. The concept of the bond strength ratio was applied for objective moisture sensitivity analysis. Moreover, the bond strength characteristic was compared to the dynamic immersion test to suggest an alternate method to determine the application of anti-stripping agent. RESULTS AND CONCLUSIONS : Overall, the polymer-modified asphalt demonstrates the highest bond strength characteristic regardless of moisture condition and temperature. The bond strength characteristic displays a highly reliable linear relationship from $5^{\circ}C$ to $40^{\circ}C$, and the relationship could be used to predict bond strength at any intermediate temperature. Based on the analysis of bond strength and retained asphalt ratio, the bond strength value of 1254 kPa could be applied as a criterion for anti-stripping agent.

Evaluation of Bond Strength Properties with Changing the Aspect Ratio and Temperature of Concrete (콘크리트의 형상비 및 온도변화에 따른 부착강도 특성평가)

  • Kim, Hyun Seok;Jung, Won Kyong;Oh, Han Jin;Park, Jun Young;Kim, Hyung Bae
    • International Journal of Highway Engineering
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    • v.20 no.3
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    • pp.19-26
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    • 2018
  • PURPOSES : The main purpose of this study is suggest of field bond strength evaluation method for more objective evaluation method through Evaluation of Bond Strength Properties with changing aspect ratio and temperature. METHODS : The evaluation is laboratory bond strength test. Using the core machine, the pull-off test method ; the bond strength test of interface layer the universal testing machine. RESULTS : As a result of the laboratory bond strength evaluation, it was verified that the bond strength by aspect ratio decreases linearly with increasing aspect ratio and the bond strength properties by temperature change existed at high and low temperature condition relative to odinary temperature condition. CONCLUSIONS : According to the results of laboratory bond strength evaluation, the field bond strength evaluation results suggest applying the proposed correction factor (0.8, 1.0, 1.4, 1.9) according to aspect ratio(0.5, 0.1, 1.5, 2.0), For more objective evaluation of the bond strength, it is analyzed that the evaluation value is within $6{\sim}32^{\circ}C$ and the result can be obtained within 5% of the coefficient of variation.

Bond behaviour at concrete-concrete interface with quantitative roughness tooth

  • Ayinde, Olawale O.;Wu, Erjun;Zhou, Guangdong
    • Advances in concrete construction
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    • v.13 no.3
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    • pp.265-279
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    • 2022
  • The roughness of substrate concrete interfaces before new concrete placement has a major effect on the interface bond behaviour. However, there are challenges associated with the consistency of the final roughness interface prepared using conventional roughness preparation methods which influences the interface bond performance. In this study, five quantitative interface roughness textures with different roughness tooth angles, depths, and tooth distribution were created to ensure consistency of interface roughness and to evaluate the bond behaviour at a precast and new concrete interface using the splitting tensile test, slant shear test, and double-shear test. In addition, smooth interface specimens and two separate the pitting interface roughness were also utilized. Obtained results indicate that the quantitative roughness has a very limited effect on the interface tensile bond strength if no extra micro-roughness or bonding agent is added at the interface. The roughness method however causes enhanced shear bond strength at the interface. Increased tooth depth improved both the tensile and shear bond strength of the interfaces, while the tooth distribution mainly influenced the shear bond strength. Major failure modes of the test specimens include interface failure, splitting cracks, and sliding failure, and are influenced by the tooth depth and tooth distribution. Furthermore, the interface properties were obtained and presented while a comparison between the different testing methods, in terms of bond strength, was performed.

Using scratch test to evaluate cohesive bond strength of Mo composite coating

  • Koiprasert, Hathaipat;Thaiwatthana, Sirinee;Sheppard, Panadda
    • International Journal of Advanced Culture Technology
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    • v.3 no.2
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    • pp.34-41
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    • 2015
  • Bonding strength of a thermal sprayed coating is difficult to measure using a conventional pull-off test method. Scratch test is a potential alternative testing method. An adhesive and a cohesive bond strength of the coating can be measured by the pull-off test while the scratch test performed on the cross-section of the thermal sprayed coating can only demonstrate the cohesive bond strength of the coating. Nevertheless, it is still beneficial to perform the scratch testing on the cross-section of the coating for the sake of comparison thus providing an alternative to the pull-off test. The scratch test method can reduce testing time and cost in the long run due to a significant cost reduction in consumables and energy and time saving from the curing step of the glue used in the pull-off test. This research investigates the possibility of using the scratch test to measure the cohesive bond strength of Mo/NiCrBSi composite coating. The results from the pull-off test and the scratch test indicate that the cohesive bond strengths of the Mo composite coating show similar trend and that the cohesive bond strength are increased when increasing NiCrBSi content.

An experimental study on Bond strength of Reinforcing steel to High-performance Concrete using Belite Cement (Belite 시멘트를 이용한 고성능 콘크리트의 철근 부착성능 실험연구)

  • 조필규;김상준;강지훈;김영식;최완철
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.10a
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    • pp.408-415
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    • 1997
  • Bond strength of reinforcing bar to high-performance concrete using Belite cement is explored using beam end test specimen. The key parameters for the bond test are slump of concrete, top bar effect, and strength of concrete in addition to concrete covers. Specimen failed in the typical brittle bond failure splitting the concrete cover as the wedging action. The test results show that for the group with portland cement I using superplasticizer additional slump does not decrease the bond strength of the top bar is less than bond strength of bottom bar, but the top bar factor satisfy the modification factor for top reinforcement. The result also show that bond strength is function of square root of concrete compressive strength and cover thickness. More detailed evaluation will be conducted from the test specimen with high strength concrete using the belite cement.

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Parametric Study on Test Method for Pull-off Strength of FRP Composite Material used in Strengthening RC Members (FRP 복합체의 콘크리트에 대한 접착강도 시험방법 변수 연구)

  • Choi, Ki-Sun;You, Young-Chan;Lee, Han-Seung;Kim, Keung-Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05a
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    • pp.222-225
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    • 2006
  • Pull-off test is widely used to evaluate bond performance between concrete and FRP composite. However, reliability of experiment result declines due to many difference between test methods of each national standards. This study analyzed problems of various existing test methods for pull-off test and suggested standardized test method. In addition, since tensile strength of concrete is smaller than bond strength of epoxy resin, maximum bond strength of epoxy resin shall be limited within tensile strength of concrete. Alternative testing method, therefore, which decrease FRP adhesion areas than concrete adhesion areas is suggested to widen test range of bond strength in pull-off test. In the experimental results, bond performance can be estimated up to two times of tensile strength of concrete by reducing FRP adhesion areas by 1/3.

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An Experimental Study on the Bond Split Mechanism of High Strength Concrete (고강도 콘크리트의 부착할렬기구에 관한 실험적 연구)

  • 장일영
    • Journal of the Korea Concrete Institute
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    • v.11 no.4
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    • pp.129-136
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    • 1999
  • For the prediction of concrete-steel bond ability in reinforced concrete, many countries establish specifications for the pullout test. But these methods hardly to consider many parameters such as strength, shape, diameter and location of steel, concrete restrict condition by loading plate, strength of concrete and cover depth etc, and it is difficult to solve concentration and disturbance of stress. The purpose of this study is to propose a New Ring Test method which can be rational quantity evaluations of bond splitting mechanism. For this purpose, pullout test was carried out to assess the effect of several variables on bond splitting properties between reinforcing bar and concrete. Key variables are concrete compressive strength, concrete cover, bar diameter and rib spacing. Failure mode was examined and maximum bond stress-slip relationships were presented to show the effect of above variables. As the result, it appropriately expressed general characteristics of bond splitting mechanism, and it proved capability for standard test method.