An original concept is presented for the durable rehabilitation of concrete bridge deck slabs. The main idea is to add a layer of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) with steel reinforcing bars over the concrete slab to create a composite section. The layer of UHPFRC is waterproof and protects the reinforced concrete against severe environmental influences. It also strengthens the structural element for high traffic loads. Experimental studies on composite beams in a cantilever setup were carried out to identify the different failure modes and the contribution of the UHPFRC layer to the resistance. Analytical models were then developed to calculate the resistance of composite beams. The concept has been validated by field applications demonstrating that the technology of UHPFRC is mature for cast in-situ.