CT-Bolt ^TM

System Description

• Combination rock bolt
• Application as temporary and long-term ground control system
• Immediate point anchorage in terms of an expansion shell anchor
• Post-grouting assembly features double corrosion protection
• Fully automated or manual bolt installation

Anchor nut Dome-shaped grouting adapter (with grouting hole and welded-on sleeve) Polyethylene sleeve (with ribbed geometry for an optimum load transfer and inner centralizers) Bolt plate (incl. bore for grout discharge) Rebar rock bolt (with cold-rolled threads on both ends for mounting the expansion shell and the anchor nut) Expansion shell

Field of Applications

Main applications of the CT-Bolt ^TM:

• Systematic permanent reinforcement of underground excavations
• Ground support for areas with limited or no access during operational lifetime
• Mining: permanent roadways and excavations
• Hydropower and underground oil or gas storage caverns
• Sub-sea and sewer tunnels

Installation Procedure

• Borehole drilling
• Drilling of a borehole Ø 44-51 mm
• Recommended borehole length: about 100 mm longer than the bolt length

• Bolt installation
• Insertion of the assembled CT-Bolt ^TM into the pre-drilled borehole
• Pressing the bolt plate firmly against the excavation surface
• Activation of the expansion anchor by pre-stressing of the anchor nut provides immediate point anchorage
• Typical required torque: 200-300 Nm

• Flexible bolt grouting
• Preparation of either mortar or cement according the given specifications
• Connection of an injection adapter to the grouting adapter of the CT-Bolt ^TM
• Primary grout flow inside the polyethylene sleeve towards the bolt’s toe (expansion shell) - complete grout coverage of the rebar
• Secondary grout flow outside the polyethylene sleeve until the grouting medium flows out at the bore for grout discharge at the hemispherical bolt plate

• Fully automated installation
• Optional automation unit available

Technical Features

• Combination rock bolt
• Active reinforcement by pre-stressing of the expansion anchor
• Allowance of a certain amount of elastic deformation of the rebar induced by displacements of the rock mass
• Flexible grouting behind the working face allows an optimum adoption of the CT-Bolt ^TM to given ground and operating conditions
• Optimum alignment and assurance of complete grout coverage of the of the rock bolt by the polyethylene sleeve

• Unique choice of the corrosion protection level
• Protection of the load-bearing components of the CT-Bolt ^TM according to given levels of corrosive environments
• Bolts are available black, hot dip galvanised, or with a special Combi Coat® (combination of hot-dip galvanizing, zinc phosphate, and powder coating)
• Indicated lifetimes for load-bearing components of the fully-grouted CT-Bolt ^TM by accelerated corrosion tests performed by Vik Ørsta AS from 50 (black type) to 150 (Combi Coat ^® type) years

• Rock bolt testing equipment
• Rock bolt testing provides a quality control of the rock bolt system behaviour in combination with given ground conditions
• Bolt load indicators and custom-specific pull test kits are provided upon request

Specifications and Prime Advantages of the CT-Bolt ^TM

¹⁾ After grouting
²⁾ Expansion shells for larger borehole diameters available on request
³⁾ Delivery lengths up to 8.0 m are available on request

Prime Advantages

• Combination rock bolt
• Efficient, practically proven, and reliable rock reinforcement system
• Combination of an immediate point anchorage and a fully grouted rock bolt
• Immediate load-bearing capacity after installation by the mechanical anchor
• Fast installation and flexible post-grouting behind the working face
• Double corrosion protection by the polyethylene sleeve and grout coverage
• Easy adjustment of the corrosion protection level to costumer demands
• Fully automated or manual installation procedure