BOND STRENGTH OF INJECTION ANCHORS

Supplementary injection anchors are used as a repairing-system inside historic masonry. They basically consist of a tensile element usually steel inserted into the slightly larger borehole and the annulus is grouted with cement. Assuming successful grouting, considerable tensile forces can be transferred at short bond lengths. More then 500 pull-out tests in laboratory and in-situ have been performed to obtain the loadbearing characteristics of such anchors. As a result, design recommendations have been developed. The paper summarises the state of the design recommodations from the point of structural failure and reects on the interaction between fresh grout and surrounding masonry. Latest results about the inuence of restraint to free transverse deformations are provided.