Steel corrosion induced by the penetration of aggressive agents (chlorides, carbon dioxide ...) from the environment is the main pathology that questions the durability of reinforced concrete structures. In order to prevent and/or limit the risk of corrosion by carbonation of some concrete structures, it is envisaged to use surface protection products to limit the exchange mechanisms between concrete and the environment. The protection products will act only by clogging the surface pores and/or micro-cracks of the concretes, thus preventing the penetration and the diffusion of external agents such as CO2 and O2 from the atmosphere into the cement matrix. The standard NF EN 1504-2 classifies these protection products in three families:

- Coating products that produce a continuous protective layer on the surface that acts as a physical barrier against the penetration of aggressive agents (i.e. epoxy, acrylic and polyurethane resins).

- Impregnation products that reduce porosity of the concrete skin. These products can be of two different natures, organic (epoxy, acrylic ...) or inorganic (sodium silicate, nano silica...).

- Hydrophobic impregnation products that create a water repellent surface; the pores are not filled but their inner surface is coated.

As part of this study one product from each family was selected: acrylic impregnation product, acrylic coating and silanes / siloxanes-based product (hydrophobic impregnation). This work has the objective to evaluate the efficiency and the durability of the selected surface protection products by investigating their impacts on concrete carbonation and transport properties (gas diffusion). With that in mind, different experimental devices (carbonation chamber, diffusion cells) are used.