Desirable Properties of Bitumen:
For performing as a good binder for road works, bitumen should have the following desirable properties:
(a) When heated to the mixing temperature, it should be liquid enough to coat the particles of the aggregates.
(b) When heated to a spraying temperature, it should be liquid enough to pass through the spraying nozzles and give a uniform coverage.
(c) It should not become soft when the outside temperature is high (as in summer) and lose its strength, nor should it become too hard and brittle at very low temperatures.
(d) It should have good affinity to the aggregates, and stripping should not take place in the presence of water.