Interaction between the original and the new concrete parts

One of the main problems encountered in strengthening is how to achieve compatibility and interaction between the existing structure and the strengthening elements. The force transfer across the joint between old and new concrete can be accomplished in different ways:

• simple friction between surfaces of the existing concrete and the prefabricated concrete member (dry joint)
• simple bond between the existing concrete surface and the concrete of the new part cast on site (wet joint)
• the efficiency of both joints can be considerably improved through increasing the force normal to the joint.

This may be easily achieved by post-tensioning. For this purpose DYWIDAG Tendons can be employed. In the case of very short tendons, the fine thread at the end of the smooth bar results in an anchorage with an extremely small slip. In the case of short tendons, where bond is required, bar tendons using DYWIDAG Bars (THREADBAR ^® ) may be used. For longer and curved tendons, strands offer a solution.