Bitumen has excellent adhesive qualities provided the conditions are favourable. However in presence of water the adhesion does create some problems. Most of the aggregates used in road construction possess a weak negative charge on the surface. The bitumen aggregate bond is because of a weak dispersion force. Water is highly polar and hence it gets strongly attached to the aggregate displacing the bituminous coating.
The factors influencing aggregate bitumen adhesion are plenty and some of the factors influencing this property are as below:
External: Rainfall, Humidity, Water pH, Presence of salts, Temperature,
Temperature cycle, Traffic, Design, Workmanship, Drainage