Hello - I am working on a project in DC where they want to install a solar system spanning between CMU walls. The anchorage of the system would solely be to the exterior CMU parapet walls. We are unsure if these are fully grouted or not...likely not given that they are in DC. The contractor wants to use Hilti HIT-HY 270 and says that it's a viable option for hollow core CMU walls. The ICC report for it (attached) seems to only have published values for anchorage in the face of the CMU block, not the top. The contractor is saying that the epoxy fills the void of the block, allowing for a tension application in the top of a CMU block. I'm not sure that's true? I thought I'd ask you guys for some clarity and see if we can't come up with a design for this one.
AOstructures,
Hilti HIT-HY 270 has testing for use in face of hollow CMU walls, but does not have testing for the top of a hollow CMU wall. HIT-HY 270 has testing for top of wall applications but only when the wall is fully grouted, thus providing a material for the anchor to interact with.
The video found here provides an example of an HIT-HY 270 installation into the face of a hollow block, presenting the mechanism discussed below.
In regards to the HIT-HY 270’s use in the face of hollow CMU wall, the adhesive is used with a mesh plastic sleeve known as the HIT-SC expand and cure within the hollow section of the wall to create a keying effect behind the concrete web of the CMU to prevent a tension load from pulling the anchor through once set. Note that – this would not be intended to fill a large cavity and is a limited amount of adhesive used in combination with a mesh sleeve to form a solid adhesive section on the other side of the web
Regards,
Aidan