Do you have any guidance, procedures or instructions for installing adhesive anchors when developing a bar that is long (i.e. 18 to 36 inches) and with a large rebar embedment? Do you have extra long mixing nozzles? Or, how do installers typically get the adhesive to the bottom of hole per the instructions?
Hi Eric,
Thank you for reaching out. ACI 318 Chapter 17 for Anchoring to Concrete states a maximum effective embedment is 20d, where d is the diameter of the anchor element. For deeper embedment beyond 20d, engineers tend to begin to look at rebar development. Designing Hilti's adhesive anchor systems with rebar in accordance with Anchoring to Concrete Provisions (ACI 318 Chapter 17) or Rebar Development Theory (ACI 318 Chapter 25) will establish either the necessary embedment depth or development length of the system and is at the discretion of the Engineer of Record (EOR) on the project. The difference between designing with Anchoring to Concrete Provisions and Rebar Development Theory can be further understood using Hilti's Anchor Fastening Technical Guide starting on page 24.
For rebar development lengths with HIT-RE 500 V3 you may reference ESR-3814 starting on page 36. More understanding on designing using anchor-to-concrete provisions for post-installed reinforcing bar design can be found here and the Post-Installed Rebar Design for Structural Joints (REB202) webinar here.
Generally, the installation process is shown in the Instructions for Use. Page 11 section A shows the use of a piston plug (HIT-SZ) needed for embedments deeper than 10". This helps distribute the adhesive within the hole to prevent air gaps.
Additionally, the mixing nozzle that comes with the dispenser can be used for embedments up to approximately 10", but for any deeper an extension tube (HIT-VL) is needed. Please note that this tube is approximately 32' long, so the tube would need to be cut to the desired length to reach the bottom of the hole. The tube is then attached to the mixing nozzle. This configuration together would be: The dispenser with the mixing nozzle, the extension tube attached to the mixing nozzle, and the piston plug attached to the end of the extension tube. It may be helpful to mark the tube to make sure the correct amount of adhesive is inserted into the hole.
Ultimately, the decision and approval of anchor design would be up to the Engineer of Record (EOR) on the project.
Regards,
Katelyn