Asphalt protects bridges.

In Europe most (if not all) steel and concrete bridges have an asphalt surfacing on top.

One of the main reasons for using asphalt on these bridges is to protect the steel and concrete structures from water and de-icing salts.

There are many requirements for surface layers on bridge decks. They need to have:
• good skid resistance, 
• a flat surface, 
• low sound levels, 
• sufficient resistance against deterioration, 
• resistance against oil, 
• water and minerals, 
• less susceptibility to weather conditions, 
• providing a waterproofing layer, 
• high stability, resistance against fatigue, 
• resistant to permanent deformation, 
• and the ability to spread the loads for a safe and comfortable drive. 

Surface layers made of asphalt can meet these requirements. Generally Dense Asphalt Concrete, Mastic Asphalt and SMA are used as asphalt mixture on the bridges.

Modern asphalt concrete combined with well-designed waterproofing solutions and with appropriate maintenance are great solutions to match the current expected 120 year design life of bridges. The innate waterproofing qualities of asphalt can be used to double as waterproofing layer through the use of Mastic Asphalt.

Although different application techniques and materials can be used on steel and concrete bridge decks, the general construction on a bridge deck starts by preparing (cleaning) of the deck, followed by sealing layer, a waterproofing layer, a protecting layer and the surface layer on top. The waterproofing layer + the protecting layer are often called “waterproofing system”. The surface and subsurface drainage system should be applied on both steel and concrete decks. The sealing layer can be made from various materials, including bituminous materials.

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More information can be found in:
“EAPA Paper - Asphalt pavements on Bridge Decks – 2013”