Question about moisture infiltration around expansion anchors (KB-TZ for example) was recently brought up regarding use in outdoor or "wet" applications where substrate temperatures could get below freezing conditions. Specifically, is there a concern about moisture getting in the space between the expansion anchor (either the shaft or the expansion cone), freezing, and causing detrimental effects (cracking of concrete, damage to the expansion sleeve, etc.). Information from a competitor indicates that this could be a problem, although gives no quantitative resposne. Appears that this question has been asked before to some degree on Ask Hilti but responses haven't been very clear or applicable (IMO). Should expansion anchors be avoided in these applications (has there been any testing done?) and adhesive anchors be used, or is there a "simplier" solution (using something like silicone around the anchor) after installation to limit/prevent any infiltration? Traditionally, grout may have formed this barrier but there are a number of applications where grout may be omitted for lightly loaded posts (utlity stands) where this situation could potentially occur. Thanks -
Hello,
There is no technical information on the effects of freeze-thaw conditions for Hilti mechanical anchors. Freeze/thaw is a test criterion for adhesive anchors and is tested per ACI 355.4 and AC308 as the freeze / thaw cycles can disrupt the ability of an adhesive anchor to bond to the base material. If there is concern for water penetration over the lifespan of the anchor, especially if freezing water within the anchor hole could cause disruption, an adhesive anchor system may be considered. Hilti's adhesive anchor systems have been tested for freeze-thaw conditions and the adhesive acts as a protective barrier against water infiltration.
Ultimately, all design decisions are at the discretion of the Engineer of Record (EOR) on the project. If you have additional questions, please reach out to hnatechnicalservices@hilti.com.
Kind regards,
Sinan