DYWI Drill Hollow Bar Rock Bolt

Self-drilling system for loose soil, no casing required.

DYWI Drill Hollow Bar Rock Bolts are used for rock bolting and grouting into softer rocks where there is loose ground or sections prone to collapse. The speed of installation, combined with the ability to grout through the bore of the bar, make them a popular choice for rock bolting in remote locations and challenging drilling conditions.

Drilling options include grout or water flush, followed by grout injection. Alternatively, the simultaneous drill and grout technique can be used for softer ground.

  • Quicker installation as drilling and grouting are done simultaneously

  • Left-hand thread compatible with percussive drill tooling for complete installation flexibility

  • Bar diameters R25-R51 supplied with rope thread; T40 and T76 supplied with trapezoidal thread

  • Range of drill bits for rock, including tungsten carbide buttons and chisels to suit all applications

  • External thread enables the bars to be cut and coupled at any point, as well as terminated with a nut, for easy on-site length adjustments

Main standards for steel nuances

Europe/ Asia/ Latin America: EN 10083-1

UK: EN 10083-1

North America: Tendons with ultimate loads from 45 kips to 832 kips


  • Rotary injection adapters to connect between the hammer and the hollow bar, enable grout to be injected into a rotating bar

  • Drill bit adaptor sleeves offer the option of using larger diameter drill bits with smaller bars

  • Beveled washers for use on bearing plates on uneven ground support

  • Range of drill tooling including reducing couplers, box/pin adaptors and drill spanners

  • Corrosion protection options include grout cover, sacrificial corrosion allowance, hot-dip galvanizing, Duplex (hot-dip galvanizing and epoxy coating)

  • Bearing plates with angle compensation or shear tubes

  • Domed nuts, hex nuts, couplers and steel spacers