Description
The DSI Double Corrosion Protected Bolt (DCP Bolt) is a pre-tensioned & post-grouted rock bolt. It allows for immediate ground support using an expansion shell and has a high density corrugated polyethylene (HDPE) sheath along the bar length that provides long term corrosion protection and load transfer. The system can also be provided with triple corrosion protection (TCP Bolt) using special anti-corrosion bars, galvanizing or epoxy-coating.

Components
The DCP Bolt comprises a ⁷/₈" diameter steel bar pre-assembled with an expansion shell, corrugated polyethylene (HDPE) sheath attached to a grouting bell and domed hex nut (36mm A/F). The nut is slotted for post-grouting. The required dome plates are supplied separately and are generally ASTM F432 grade 2 or 3 material.

Bolt Handling
DCP bolts must be kept clean at all times. Care must be taken not to damage the HDPE sheath, grout bells and expansion shells during shipping and handling.

Drilling
Depending on the size of the expansion shell, drill either 45mm or 50mm (1-³/₄" or 2") holes the total length of the bolt plus 50mm (2"). Thoroughly flush the hole with water after drilling. Ensure that the bearing surface for the dome plate is within ± 15 degrees from being perpendicular to the bolt

Installation
Slide a plate over the top of the bolt and insert the pre-assembled DCP bolt into the hole until the domed plate bears against the strata. Do not rotate the bolt while inserting. Important: ensure that the HDPE sheath does not scrape against the collar of the hole.

Pre-loading
Once the plate is hard against the rock face, apply left-hand rotation to engage the expansion shell. Pre-load the DCP bolt to the required torque. Use a torque wrench with a 36mm (1-³/₈") deep socket.
Note: percussion must not be used for tightening the nut.

Load testing (if required)
A minimum of 30mm (1.2") of bolt thread must protrude behind the nut. Install the testing equipment and perform loading tests - however, do not overstress the bar. Warning: never stand behind the jack during testing and read DSI's Safety and Operating Instruction prior to testing.

Post-grouting
The cement grout mixture must be thick enough to adhere to an overturned hand (mayonnaise consistency). The optimal water:cement ratio is 0.30:1 by weight for Type I-II cement. This is equivalent to 0.3 lbs of water per 1 lb of cement or 3.4 gallons of water per 94 lb sack of cement. A typical 2 or 3 stage progressive cavity pump can pump a 0.30:1 water:cement ratio grout through a ³/₄" hose for 15m (45-ft) and 6m (10-ft) of bolt.

If the grout is thinner than 0.3:1 it may run out of the hole. If thin grout is kept in the hole the water will bleed away from the grout thus failing to fully encapsulate the bolt.

The normal post-grouting steps are:

• Prepare grout with proper amounts of water and cement.
• Pump some grout to the end of the hose, check consistency and stop pumping. [Install a ball valve in the hose near the Chicago fitting to control grout flow.]
• Attach Chicago fitting to DCP bolt grouting adapter.
• Connect the DCP bolt grouting adapter onto the bayonet mount of the grouting bell, rotating to the right and tightening with the handle on the adapter.

• Open ball valve and restart pumping at a slow to medium rate until grout appears around the plate.
• Stop pumping and disconnect the adaptor.
  Important: if grout drains from the nut and/or the plate, the bolt must be grouted again with a thicker grout mix.
• Move to a new bolt & repeat above steps.
• Clean the grout adaptor thoroughly after use.
• Warning: when grouting, the operator should wear the prescribed protective equipment in addition to gloves and safety glassed. Consult the applicable MSDS.