Mastic asphalt is a specialised bituminous mixture whose void-free structure forms an impermeable surfacing. That property makes it, above all on bridge and viaduct decks, a waterproofing layer that protects the deck concrete from water and chloride attack.
The mixture is prepared at high temperature in dedicated cookers and transported to site in a flowable state. Because it self-levels without compaction, it is straightforward to place in narrow and heavily reinforced areas.
Before laying, the deck surface is prepared by shot blasting or milling and a bond coat is applied. After surfacing, anti-skid aggregate is spread to bring the friction value to the required level.
