In most cases, the restoration of historic concrete structures imposes the conservation of the aspect of the construction material (raw concrete, washed concrete ...). These requirements tend to limit the choice of the repair techniques and can constitute a challenge for the architects and the contractors involved in the restoration projects. In this study, protective treatments based on transparent coatings and water-repellents were compared. These systems could represent new solutions allowing at the same time to provide a protection again corrosion induced by carbonation and to meet the requirements linked to the conservation of the aspect. To evaluate the potential and the limits of these solutions several products were tested on concrete cubes and instrumented concrete slabs. The effect of the treatments on water absorption of concrete and on corrosion of the reinforcing bars was evaluated by several techniques.