Question

. In your own words , explain the predominant aging mechanisms in the short-term and the long-term aging in bituminous materials.?

Answer 1

Short term aging: This type of ageing is the earlier age hardening in the pavement. This occurs when hot mix asphalt is exposed to high temperature and air surrounding during the mixing process of aggregate. As short term ageing occurs earlier it is expected to start from the exposure of bitumen binder to plant burner and hot aggregates until transportation, placing and compaction of bitumen pavement. As of now, short term ageing is simulated by Rolling Thin Film Oven Test(RTFOT).

Long Term Ageing: Long term ageing is the slow ageing process and occurs after the hot mix asphalt pavement construction is completed and the pavement is exposed to environment throughout it's entire life cycle.The environmental conditions and the traffic loadings are the major factors that influence the long term ageing. Long term ageing process evolves with time where the asphalt is exposed to a relatively lower temperature and longer duration when compared to short term ageing. It is simulated by Pressure Ageing Vessel(PAV).