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Abstract
Sealants play an important role in weatherproofing structures by filling gaps and preventing air and water intrusion. When incorrectly selected or improperly applied, they may fail quickly, compromising durability of the structure. To ensure reliability and prevent the need for costly repairs to structures, it is necessary to measure durability and predict life expectancy of sealants. Our approach to these challenges is to conduct accelerated testing per designed parameters to populate a predictive model and test this model via outdoor aging with prescribed cyclic displacements and in situ modulus measurements. Accelerated weathering is conducted in environmental chambers connected to an integrating sphere irradiation source at the National Institute of Standards and Technology (NIST). Outdoor durability testing is conducted at the Forest Products Laboratory (FPL) in Madison, WI, with a custom-built computer-controlled instrument. This instrument applies controlled displacement to 16 sealant specimens simultaneously as a function of temperature. Consequently, specimens experience a daily displacement cycle induced by the diurnal temperature change within set strain limits. Cycling is stopped once a week to run a stress relaxation profile allowing measurement of the sealants’ apparent modulus. Weather is recorded during exposure such that a full set of dosage factors (solar irradiance, temperature, % RH, displacement) is captured and compared to changes in modulus. Here we describe results from two sealants exposed to five consecutive months of hot compression cycling and outdoor weathering.
Keywords
Service life,
accelerated life testing,
sealing compounds,
deterioration,
weathering,
mechanical properties,
elasticity,
temperature,
strains,
stresses,
joints,
buildings,
loads,
modulus of elasticity,
ultraviolet radiation,
humidity,
accelerated testing,
fatigue,
failure,
exposure tests,
aging,
durability,
stress analysis
Citation
Schueneman, Gregory T.; Lacher, Steven; Hunt, Christopher G.; White, Christopher C.; Hunston, Donald L. 2011. Durability of sealants exposed to outdoor weathering and hot compression cycles. In: Proceedings of the 34th annual meeting of the Adhesion Society, 2011 February 13-16, Savannah, GA. Blacksburg, VA : The Adhesion Society, 2011: [3] p.
