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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 or briquette 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 BIS.
Figure 0.1 shows ductility moulds to be filled with bitumen.
Figure 1:
Ductility Test
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