Expansion shell bolts are easy to handle, while they are implemented fast. In the case of expanding anchors the anchor foot is braced against the borehole wall with wedge-shaped spreading elements. Resins or mortars are not required to secure the anchor.
Upon insertion of the expansion anchor into the borehole, the plastic ring holding the wedges at their minimum diameter is scraped at the borehole edge. Immediately after this, the liberated wedges assume the geometry of the borehole under the spring effect. Any return movement is now excluded and each load transferred from the anchor rod to the expanding head causes further spreading of the wedges.