Fiber-reinforced concrete structures have significant advantages in terms of mechanical properties compared to conventional concrete structures. Especially in the production of UHPC (Ultra-High Performance Concrete) components, the use of short micro-wire fibers is necessary to ensure ductile behavior. In the event of crack enlargement, the fibers act as crack brakes and should preferably be pulled out of the concrete matrix. However, the ductile behavior depends on the bond between the concrete matrix and the fiber surface. If the adhesion of the matrix or the coefficients of sliding friction are increased, for example by coating the fibers, a higher energy is absorbed when the fibers are pulled out due to the higher forces for the same fiber length. For this reason, a thermoplastic elastomer (TPE) is to be used as a fiber coating in the concrete in this research project to optimize the composite behavior and, in particular, the post-fracture behavior. The fibers are coated as wire via a pultrusion process, or strand drawing process. This is a standard process for the production of plastic coating systems, e.g. for wires and cables. Following the coating process, the wire is cut to the usual fiber lengths (e.g. 13 mm). One advantage is that coating also improves the performance of fibers that are not of high quality, or fibers that have low bonding behavior. The prerequisite is that the plastic coating forms a good bond with the fiber. Another positive aspect is the corrosion resistance of the fibers due to a full-surface TPE coating, which plays an overriding role especially in normal concrete or high-strength concrete.

The project is being carried out in cooperation with Professor Heim's plastics engineering department.