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The last innovation of rock bolts

The advantages of the CT-Bolt®:

  • Combines the benefits of immediate point anchor support and a post groutable fixture

  • The polypropylene sleeve seals the bolt against corrosion when grouted

  • Long term support for fully mechanized or hand installation

Quickly installed, easily grouted
The CT-Bolt® is in many ways a typical combination mechanical bolt, installed as a temporary rock support and later grouted to become permanent. But there are important differences. It’s quick and easy to install, simple to grout even with varying consistency and the polypropylene sleeve seals the bolt against corrosion.

The bolt can be installed manually or fully mechanised with rock bolters, which have been developed for the CT-Bolt®.

Special hemispherical dome
The CT-Bolt® has a special hemispherical dome at the end, which serves both to hold the rock loading on the plate and as a grouting chamber. The grout is pumped into the hemispherical dome and flows through the polypropylene sleeve. At the end of the bolt, the grout flows out of the sleeve and spreads back between the sleeve and the rock.

Unique corrosion protection
When the bolt is grouted, it can take loads along its full length as well as at the bearing plate. The polypropylene sleeve also seals the bolt against corrosion. The buttons on the sleeve transfer the load from the rock to the bolt and centre the bolt in the borehole.

The CT-Bolt® is anchored with an expansion shell and is prestressed during installation. The load is maintained because the bearing plate needn’t be removed for grouting. 

If the area has to be shotcreted before the bolt is grouted, it is possible to attach tubes to the hemispherical dome and the plate and grout the bolt after shotcreting. Many underground rock stabilisation jobs have proved the efficiency and reliability of the CT-Bolt® since its first use in 1993. It has been specified on projects such as sub-sea tunnels, road and rail tunnels, sewer tunnels and mines.


Step 1

The CT-Bolt® is installed in a bore hole of 44-51mm diameter, using the expansion shell. The hole is drilled to at least the length of the bolt. The bolt is pressurised so the plate gives immediate support

Step 2

To grout the bolt, use an injection nozzle on the grout hose. Insert the nozzle in the hole in the hemispherical dome and pump the grout. It flows up inside the  polypropylene sleeve and back down between the sleeve and the drill hole.

Step 3

When the grout flows out trough the hole in the plate and sets, you have solid  full-length anchorage.  The polypropylene sleeve seals the bolt against  corrosion


Per Svein Krøvel
Sales Manager,
+47 913 18 342