Most anchor fasteners are very sensitive to the bore hole condition in terms of the cleaning procedure. For chemical anchors, the brushing and pumping out of the dust is even more critical to ensure a good adhesion of the mortar to the concrete. If the hole is not properly brushed and dust and fragments are not blown out as per the installation procedure, standard bonded anchors can experience a drop in load capacity of up to 70% or higher, and uncontrolled displacement under service conditions might occur.

As an engineer, you can specify the installation process in your project documents and prescribe jobsite inspections to encourage an effective execution. Nevertheless, the installer might overlook this or do it poorly for some fixing points. How do you make it safe? When it comes to fixing an anchor plate, you can rely on systems that do not require this critical step (i.e. Safeset from Hilti).

We take a look at one of these Safeset solutions: the anchor rod HIT-Z in combination with our mortar HIT-HY 200-R.

Two principles in one anchor = Empowered bond strength

No cleaning required: how can this be achieved? The answer lies in combination two anchoring technologies in one system. The HIT-Z system acts as a chemical fixing as well as a mechanical expansion anchor, combining the two working principles of the two technologies: micro-keying (bonding) of the injected mortar and expansion forces due to the helix design of the rod.

The helix-shaped rod HIT-Z, to be used

with injection mortar HIT-HY 200

In this article, we explained the working principals of post-installed anchor systems. Let’s now explain where the expansion comes from without an expansion sleeve like would be present with a stud anchor or sleeve anchor.

As part of the installation steps for the HIT-Z system, a torque is applied after the anchor mortar has cured. The applied torque will cause small cracks in the mortar at the closest annular distance between the rod and the bore hole surface. This allows the elements to act as an expansion anchor with multiple-concentric cones: The pressure generated on the concrete bore-hole surface guarantees that the design load capacity is reached even without cleaning the hole.

Two mechanisms in

one system: expansion and bonding

The two functioning mechanisms combined in this unique technology also result in a higher pull-out resistance compared to most other post-installed mechanical or adhesive systems.

When should you consider HIT-Z technology in your projects?

Firstly, whenever peace of mind is crucial. As mentioned above, the anchor will not experience a drop in load capacity if the drill bit bore holes have not been cleaned, making the installation extremely safe. As well, the installation will be even faster (up to 60% faster compared to traditional methods), since the brushing and blowing of the hole is not required. Note, in some conditions such as diamond drilling, the cleaning procedure is still needed.

Secondly, the HIT-Z system is the ideal problem solver when high pull-out resistance and shallow embedment depth are both required for a post-installed anchor connection.

You can run your next anchor plate anchor design with the HIT-Z and other anchoring technologies in our software PROFIS Engineering. See with your own eyes the upsides of using this solution in your projects.