DYWI® Drill Hollow Bar System
DYWI® Drill Injection Anchors are used extensively in temporary works, as the anchor can be drilled into a range of difficult ground conditions or collapsing soils without the need for a casing. The bond stress of both rope thread and “T” thread bars is high and compares favourably with reinforcing bars of similar diameter (this has been proved by tests carried out by the Technical University of Munich).
The DYWI® Drill free length system incorporates a special de-bond sleeve and compression collar so that the selfdrilled anchors remain de-bonded in the free length for stressing.
The stressing operation and acceptance tests ensure that each anchor is fully tested and that additional extension will not occur during its service life.
Irrespective of threadform, hollow bar systems are only suitable as temporary anchors. The high impact energy during rotary percussive drilling prevents the use of an adequate corrosion protection system approved by the building authorities.
However, corrosion protection is mandatory for stressed (active) permanent anchors, in accordance with the design standards for permanent anchors (EN 1537).