Question
What is major importance of air void content in bituminous pavements?
Answer
Air void content of bituminous materials is important control parameter for quality of bitumen being laid and compacted. If air void content is also high, it let for intrusion of air and water. Furthermore, it also increases rate of hardening of binders which create premature embrittlement of pavements. In adding, too high a void satisfied will also lead to differential compaction question to traffic loads and result in creation of ruts and grooves along wheel track.
Though, a minimum amount of air void has to be maintained to avoid instability during compaction progression and to provide space for bitumen flow in long-term consolidation under interchange loads. A enough amount of air voids have to be designed to create room for expansion of binder in summer and compaction by road traffic as optional by National Association of Australian State Road Authorities in 1968, or else bleeding and loss of stability might occur and pavement will deform readily under severe loads.