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    STP1583

    Reliability Assessment of Structural Sealant Durability

    Published: 16 February 2015


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    Abstract

    Many questions have been raised on how we can practically measure and predict the durability and service life of structural silicone sealants. Meanwhile, facade engineers have many requirements for the reliability of structural silicone sealants. Thus, accelerated reliability engineering was employed in order to assess the durability of structural silicone sealants in terms of 30-year service life. Firstly, the environmental and application conditions of structural silicone sealants need to be defined. Some of the major factors that significantly influence the degradation of structural silicone sealant includes temperature change, movement of joints, stress induced by wind pressure, load stress on glass, humidity, solar UV radiation, etc. For this study, temperature, humidity, and the movement of joints were chosen as failure-causing factors since they are considered to the most predominant in structural silicone sealants. The stress level was selected to reflect extremely severe weathering conditions (ISO28278-1, Class T1, T2, T3). For the design of the accelerated life time test, stress levels of 2 as well as three stress factors were used. In our experiments, indoor accelerated weathering tests were performed to obtain coefficients such as an acceleration factor and shape parameter for service-life prediction. The results exhibited a strong linear regression to calculated fit based on statistical methods. Each factor was thus shown to correlate with others using the Mini-tab toolkit. The test results were also analyzed by the commercially available reliability software, ALTA 7, in which B10 life values were obtained with a 90 % confidence level and a 30-year service-life prediction. The failure-mode test lasted until the complete failure of structural silicone sealants. The failure mode was defined as a tensile strength value of 40 % the strength, which is widely used in many industry standards (500 kPa). Considering the relationship between the experimental parameters and the failure mode of the sealants, a higher chance of failure was observed with higher temperature, humidity, and greater joint movement. In particular, joint movement was found to be the most significant factor in causing failure.

    Keywords:

    sealant, structural silicone glazing, reliability, service life prediction


    Author Information:

    Lee, Sang Kook
    Senior Research Engineer, Advanced Material Reliability Center, Korea Conformity Laboratories, Geumcheon-gu, Seoul,

    Hirouki, Miyauchi
    Senior Research Engineer, Department of Building Materials and Components, Building Research Institute (BRI), Tsukuba-shi, Ibaraki,

    Jeong, Jin Young
    R&D Technical Manager, Sealant Technology & Development Department, Jeonbuk,


    Committee/Subcommittee: C24.87

    DOI: 10.1520/STP158320140084