ACI Adhesive Anchor Installer Certification Practice Exam

What part of the hole should the mixing nozzle or piston plug be placed when injecting adhesive?

1. At the entrance of the hole

2. In the middle of the hole

3. At the bottom of the hole

4. At the deepest part of the hole

The correct answer is: At the deepest part of the hole

The mixing nozzle or piston plug should be placed at the deepest part of the hole when injecting adhesive. This positioning is crucial for several reasons. Injecting adhesive at the deepest part ensures that the adhesive effectively fills the entire volume of the hole from the bottom up, which minimizes air pockets and ensures a strong bond. If the adhesive is introduced at the bottom, it can displace any potential contaminants present in the hole, such as dust, debris, or moisture, thereby enhancing the overall bond strength. Furthermore, starting the injection at the deepest point allows the adhesive to flow upward, pushing out any trapped air and ensuring complete encapsulation of the anchor or rebar. This technique contributes to a more uniform distribution of the adhesive throughout the hole, which is vital for achieving the intended load-bearing performance of the anchor system. Providing a clear path for the adhesive to rise also helps in achieving the necessary chemical mixing and activation, which is essential for optimal curing and strength development. Therefore, placing the nozzle at the deepest part of the hole is essential for the integrity and effectiveness of the adhesive anchoring system.