Mastic Asphalt is mixture of bitumen, fine aggregates and filler in suitable proportions which yields a void less and impermeable mass. It is a very durable and completely impervious material. It can be withstand only very slight distortion. 
It can absorbs vibrations and hence, it is also used as surface dressing on bridge deck slabs, where bridge deck subjected to vibrations due to dynamic loading of vehicles. 
It has the property of self-healing of cracks without bleeding. 
It should be spread at around 200°C temperature to a thickness of 25 to 50 mm. 
Bituminous felt is a form of waterproof sheeting that is used to cover flat roofs. It is made from bitumen that has been either mixed with sand or crushed limestone. 
Bituminous felt is also used for water proofing or damp proofing; however, it is less impervious as compared to Mastic asphalt, so Mastic asphalt is preferred for damp proofing.