• Title/Summary/Keyword: Structural Sealants

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Time Dependent Extension and Failure Analysis of Structural Adhesive Assemblies Under Static Load Conditions

  • Young, Patrick H.;Miller, Zachary K.;Gwasdacus, Jeffrey M.
    • Journal of Adhesion and Interface
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    • v.21 no.1
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    • pp.6-13
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    • 2020
  • The objective of the current study is to characterize the long-term stability and efficacy of a structural adhesive assembly under static load. An apparatus was designed to be used in the Instron tensile test machine that would allow for real time modeling of the failure characteristics of an assembly utilizing a moisture- cure adhesive which was bonded to concrete. A regression model was developed that followed a linear - natural log function which was used to predict the expected life of the assembly. Evaluations at different curing times confirmed the structure was more robust with longer cure durations prior to loading. Finally, the results show that under the conditions the assembly was tested, there was only a small amount of inelastic creep and the regression models demonstrated the potential for a stable structure lasting several decades.

A Study on the Perception of Pit and Fissure Sealant using Unstructured Big Data (비정형 빅데이터를 이용한 치면열구전색(치아홈메우기)에 대한 인식분석)

  • Han-A Cho
    • Journal of Korean Dental Hygiene Science
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    • v.6 no.2
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    • pp.101-114
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    • 2023
  • Background: This study aimed to explore the overall perception of pit and fissure sealants and suggest methods to revitalize their current stagnation. Methods: To determine the social perception of the change in coverage policy for pit and fissure sealants, we categorized them into five time periods. The first period (December 1, 2009 to November 30, 2010), the second period (December 1, 2010 to September 30, 2012), the third period (October 1, 2012 to May 5, 2013), the fourth period (May 6, 2013 to September 30, 2017), and the fifth period (October 1, 2017 to December 31, 2022). We utilized text mining, an unstructured big data analysis method. Keywords were collected and analyzed using Textom, and the frequency analysis of the top 30 keywords, structural features of the semantic network, centrality analysis, QAP correlation analysis, and co-occurrence analysis were conducted. Results: The frequency analysis showed that the top keywords for each time period were 'Cavities', 'Treatment', and 'Children'. In the structural features of the semantic network of pit and fissure sealants by time period, the density index was found to be around 1.00 for all time periods. The QAP correlation analysis showed the highest correlation between the first and second periods and the fourth and fifth periods with a correlation coefficient of 0.834. The co-occurrence analysis showed that 'cavities' and 'prevention were the top two words across all time periods. Conclusion: This study showed that pit and fissure sealants are well accepted by the society as a preventive treatment for caries. However, the awareness of health education related to these sealants was found to be low. Efforts to revitalize stagnant pit and fissure sealants need to be strengthened with effective education.

Experimental Study of the Joint Movement Responsiveness Performance to the One-Component Silicon Sealants at Curing Phase (경화단계에서의 1성분형 실리콘 실란트의 거동대응성능에 관한 실험적 연구)

  • Son, Jong-Won;Ono, Tadashi
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2014.11a
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    • pp.63-64
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    • 2014
  • In this study, we has a purpose to estimate the joint movement responsiveness performance for the domestic products of one-component structural silicon sealants. For this purpose, we make a comparative study for the four domestic products focused on tensile properties after allowed the cyclic-movements for three days at initial step of curing phase. A joint movement range ±10% and the rate of compression and extension 3.2mm/h were assumed in those tests. As a result, the large space were induced inside the sealant by rupture, and then adhesion and cohesion failures were caused by stress concentration. The tensile properties were reduced by 15~60% in comparison with physical properties. In this case, the generating defect was caused and the service-life was decreased. Thus, further researches as relationship of test condition and products properties on this behavior would be studied.

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A Study on the Elastic Restoration Characteristics According to Environmental Resistance Condition of Structural Sealing Finishing Materials (구조용 실링마감재의 내환경 조건에 따른 탄성복원 특성 연구)

  • Jang, Pil-Sung;Kang, Dong-Won;Hong, Soon-Gu;Kim, Young-Geun;Kim, Sung-Rae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.1
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    • pp.6-12
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    • 2018
  • Recently, The use of the curtain wall method is increasing in construction. The curtain wall construction is widely applied to the exterior wall of the building for shortening construction period and economical efficiency. However, the replacement of deterioration of the weather resistance and structural behavior of the sealing material connecting the curtain wall method and the glass frame is necessary for introduction of the stable curtain wall method and quality improvement in accordance with KS F 4910 standard. In this study, the elastic restoring force test was performed in the external environment. In this study, the deterioration of the sealant was evaluated for structural sealants. In Korea, studies on the variable displacement behavior of structural sealants are lacked. In this study, the reproduced results in laboratory conditions are compared with the deteriorating conditions exposed to the external environment, and they are reflected in the design of sealing materials in the future. According to the results of the study, it was confirmed that the existing structure sealant meets the quality standard of KS F 4910, but in the conditions performed in this study, adhesion failure of the specimen and cracking of the surface occurred. Especially, in the weather resistance test, it is necessary to evaluate the long-term durability performance of the structural sealant used in the curtain wall method by checking the insoluble state of all the test pieces. Therefore, in order to apply a conventional structural sealant to the site, it is necessary to introduce another durability performance evaluation.

An Experimental Study on the Characteristics of Deformation of Repaired Epoxy Resin by Flexural Strength Test (휨시험에 의한 에폭시 균열주입제의 변형특성에 관한 실험적 연구)

  • Kim Jae Sung;Bae Jun Young;Kim Kyung Deok;Kang Suk Pyo;Kawk Ju Ho;Kim Jung Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05b
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    • pp.269-272
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    • 2005
  • Epoxy resins are gradually becoming some of the most important and versatile polymers in modem civil engineering. Because epoxy resins have some unigue properties, such as toughness, versatility of viscosity and curing conditions, good handling characteristics, high adhesive strength, inertness, low shrinkage compared to most other thermo-setting resins and concrete, and resistance to chemicals, they have found many applications in construction castings, repair materials, road or bridge deck pavements, coatings, and as structural or non structural adhesives. In this applications, epoxy resins are widely used for polymer concretes, grouting materials, injection glues, and sealants. In this paper, characteristics of deformation of repair material after repaired have been investigated by viscosity of repair material and the width of crack. It is believed that flexural strength of epoxy resin with low viscosity is high because tensile strength is high and elongation at break is low, fracture energy is low.

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A Study on Comparison of Outdoor Wind Pressure Performance According to Outdoor Exposure and Acceleration Deterioration Methods of Structural Sealants Applied to Curtain Wall (커튼월에 적용된 구조용 실링재의 옥외폭로와 실내복합열화 처리방법에 따른 내풍압성능 비교연구)

  • Jang, Pil Sung;Hong, Soon Gu;Kim, Sung Rae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.9
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    • pp.279-287
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    • 2018
  • Sealants are an important element of modern architecture and serve as a building protection against weathering by providing barriers against ingress of moisture, air, and other materials. Exposure to a variety of environments often reduces lifespan due to changes in physical, chemical and mechanical characteristics, and UV, humidity, and temperature expansion are important issues that are directly related to durability. In this study, a combined deterioration test chamber was developed to simulate the environment of the open air as an instrument for verifying the durability of structural sealing materials indoors. In order to replicate special weather conditions, such as yellow dust, acid rain, and contamination by microorganisms, it was deemed impossible to replicate the outdoor environment by 100 %, and the results of the results of the results of the external exposure test of the structural sealant and the combined deterioration testing device. As a result of the displacement test of the outdoor exposure test, it was determined that the sealant was breaking apart and that it would be smooth, and the displacement would be up to three times greater than the initial material value of 1 year. The displacement test results of the combined deterioration test device show the tendency to deteriorate, decreasing the elasticity and tensile characteristics. In the case of denatured silicon, the current 400 cycles have been completed to confirm 12 months of degradation of the external exposure. The deformation of the test specimen cannot be verified with the naked eye, so it is considered that the conditions of the specimen are more stable than the silicon sealant. As a result of the outdoor exposure test, if the combined deterioration test device is structured and proposed in the relevant guidance or specification, the anticipated lifespan of 12 months in the actual use environment can be verified indoors and below 3 months later, economically.