Ductility is the property of bitumen that permits it to undergo great deformation or elongation.
Ductility is defined as “The distance in cm, to which a standard sample of the material will be elongated without breaking”.
Dimension of the briquette thus formed is exactly 1 cm square. The bitumen sample is heated and poured in the mould assembly placed on a plate. These samples with moulds are cooled in the air and then in water bath at 27 °C temperature.
The excess bitumen is cut and the surface is leveled using a hot knife.
Then the mould with assembly containing sample is kept in water bath of the ductility machine for about 90 minutes.
The sides of the moulds are removed, the clips are hooked on the machine and the machine is operated.
The distance up to the point of breaking of thread is the ductility value which is reported in cm.
The ductility value gets affected by factors such as pouring temperature, test temperature, rate of pulling etc. A minimum ductility value of 75 cm has been specified by the IS