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Installing sealants for long service lifeAuthor(s): Gregory T. Schueneman; Steven J. Lacher; Christopher G. Hunt
Source: Gen. Tech. Rep. FPL-GTR-267. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory: 1-11.
Publication Series: General Technical Report (GTR)
Station: Forest Products Laboratory
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DescriptionSealants are critical components of building construction. They must prevent air and water leaks in the building envelope to prevent moisture damage and maintain comfort and energy efficiency. Simultaneously, they must absorb relative motion between the building components as materials expand and contract due to changes in environmental conditions. Repairing failed sealant is an expensive, labor-intensive operation. Common understanding is that sealants fail under tension as they age and stiffen. Experiments at the Forest Products Laboratory using outdoor exposure with movement, laboratory tests, and finite element models with butt joints showed that compression results in significantly higher loads than tension and that the stress is concentrated at the bondline. The amount of tension and compression deformation experienced by a sealant in service depends on both the overall movement of the building joint and the state of the gap when the sealant was installed. Sealants installed when the gap is decreased (typically summer) will experience mostly tension, and sealants installed when the gap is increased (typically winter) will experience mostly compression. Therefore, sealant installation temperature sets the strain profile the sealants will experience and likely has a significant impact on durability. Methods for minimizing the resulting stress are provided.
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CitationSchueneman, Gregory T.; Lacher, Steven J.; Hunt, Christopher G. 2019. Installing sealants for long service life. Gen. Tech. Rep. FPL-GTR-267. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory: 1-11.
KeywordsBuilding sealant, installation condition, backer rod, surface tooling, cyclic strain testing, high compression loads, finite element analysis
- Durability of sealants exposed to outdoor weathering and hot compression cycles
- Effects of prestrain, outdoor aging, and simultaneous strain cycling on the durability of building sealants
- Durability of building joint sealants
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