The aims of the preliminary study reported in this document were twofold. Firstly, within the context of the application of UHPFRC for the rehabilitation of reinforced concrete structures, to identify the phenomena that require further study with respect to the risk of delamination, transverse cracking and overall performance of the new layer and of the composite structural elements with UHPFRC. Secondly, on the basis of a state of the art, of experimental tests and numerical simulations, to select the UHPFRC materials that will be used in the main test series on the basis of their performance with respect to the processing (mixing, casting) as well as in the hardened state, for protection or reinforcement.