CALDERYS DANMARK A/S

Bossong injected anchors with sock and Presstec grout with GBOS bars. Stainless steel bars fully threated. Stainless steel smooth bars. Couplers, turnbuckers, nuts, standard end and architectural end plates.

Over the last recent years a greater and greater attention to the existing building heritage and to the activities aimed to the preservation of both buildings with high architectural value and those belonging to the category of traditional buildings has been developed. Among the restoring interventions of existing buildings there are often strengthening works, in which one provides the embedment of metal anchors into masonry or wood stitching of cracks, bonding between reinforcement metal anchors and the existing structures, tierod or reinforcement ring put to contain the action of pushing elements such as arches and vaults, connection between floor slabs and outside masonry walls, embedding of anchorages inside the walls in order to increase their resistance and the global behaviour of structures also for seismic upgrading.

Bossong anchors are embedded into boreholes made in the masonry to be strengthened through drilling machines with diamond bits, that work only with rotation movement in order to avoid vibration and percussion effects on the masonry. Depending on the type of masonry and on the particular setting of the site drilling works can be done with water or air cooling or with techniques that help to avoid the spread of cooling liquids. The choice of the drilling technique is decisive when works are done in unique and precious settings where painting, ancient plasters and stuccoes are present and have to be saved and preserved. The borehole diameter is designed according to anchors size it is usually about three times the steel bar diameter; the length of the anchor is another parameter to be evaluated for the right choice of the borehole diameter.

The need to begin studies in the field of injection anchors is testified by the stronger and stronger request by the designers for instruments and guidelines for the design of anchors and their application in the strengthening of masonry structures. One of the main aims of research is just that of supplying design recommendations which may be of help for designers and technicians working in this field. Laboratory tests In collaboration with the Civil Engineering Department (DICATA) of the University of Brescia a set of laboratory tests were carried on masonry samples in order to check the capacity of the injection anchors with sock in terms of adherence and mechanical interlocking with the substrate. The execution, during the research activity, of a great number of tests has lead to the definition of parameters that are fundamental for the design of injected anchors with sock, as the bond strength at the steel barinjected grout interface an at the injected groutsubstrate interface.