What is the best practice for ensuring full encapsulation of a through-bolted adhesive anchor? How can you practically ensure that an excessive amount of grout is not pushed out the other side of the hole, leaving voids around the rod?
You are correct that pushing the adhesive out of the hole is a challenge with a through anchor application. This question is typically asked for an anchor that is oriented in the horizontal position and is primarily loaded in shear.
To prevent the adhesive from being pushed out the backside of the hole a temporary form needs to be installed on the backside of the hole. One method that customers have used is to cut a hole (approximately 1/4” larger than the anchor rod) in a piece of plywood and fill the hole with Hilti CF 116 Filling Foam. After the foam has cured, align the plywood over the hole and attach it at each corner with a Hilti fastener such as a power-actuated fastener or Kwik-Con II screw anchor. The form should be sized to provide the required minimum edge distance from the temporary fasteners to the hole in the concrete. For this application either Hilti HIT-HY 200 or HIT-RE 500 V3 could be considered. HIT-HY 200 will provide a faster cure time and the HIT-RE 500 V3 has a longer cure time and is more suitable for an oversized hole. Additional information may be available for oversized holes if you would like to send details for your proposed design. The hole should be cleaned in accordance with the ‘Instructions for Use’ and the adhesive injected using a piston plug and extension hose which will help ensure that no air pockets are created during injection of the adhesive.
The threads on the end of the anchor rod being inserted into the hole/adhesive will need to be protected from accumulating adhesive. Customers have used Teflon tape and/or a combination of Teflon tape and a layer of duct tape. Avoid adding too much tape thickness or the hole in the form may be too small. Mark the exposed end of the anchor rod for alignment. Insert the anchor and when the anchor is at the end of the hole, extra applied force should punch it through the foam in the form. Remove any excess adhesive from the taped end of the anchor and around the hole. Wedges may be used for alignment in a horizontal hole. Allow the adhesive to fully cure before removing the tape and the form.
Let me know if you need further clarification.
Randy