1. Waterproofing and wearing course

Water penetration inside the deck (rainwater, washing water and, above all, water laden with anti-icing salts in the case of road bridges) entails serious risks of corrosion of steel reinforcement (passive and active) and must be avoided, whatever the material used. To this end, a waterproofing screed (representing 2 to 3% of the cost of the new structure) is generally applied to the concrete slab, or a waterproof complex to the steel decking (orthotropic decking).

If traffic is light, a 10 mm layer of a mixture of asphalt and bitumen can give good results. If traffic is heavy, more elaborate solutions are required: for example, a thick mastic asphalt screed, or a thin screed consisting of a film adhering to the substrate, or prefabricated bituminous sheets, etc.

Whatever the process used, very strict precautions...