PENETRATION
AIM
To determine the penetration of bitumen as per IS: 1203 - 1978.
PRINCIPLE
The penetration of a bituminous material is the distance in tenths
of a mm, that a standard needle would penetrate vertically, into a
sample of the material under standard conditions of temperature,
load and time.
APPARATUS
PENETROMETER
i) Penetrometer
ii) Water bath
iii) Bath thermometer - Range 0 to 44 °C, Graduation 0.2 °C
SAMPLE
Bitumen should be just sufficient to fill the container to a depth
of at least 15 mm in excess of the expected penetration.
PROCEDURE
i) Soften the bitumen above the softening point (between 75
and 100oC). Stir it thoroughly to remove air bubbles and
water.
ii) Pour it into a container to a depth of at least 15 mm in
excess of the expected penetration.
iii) Cool it at an atmospheric temperature of 15 to 30 °C for
1 h 30 min. Then place it in a transfer dish in the water bath at
25.0 + 0.1 °C for 1 h 30 min
iv) Keep the container on the stand of the penetration
apparatus.
v) Adjust the needle to make contact with the surface of the
sample.
vi) Adjust the dial reading to zero.
vii) With the help of the timer, release the needle for exactly
5 seconds.
viii) Record the dial reading.
ix) Repeat the above procedure thrice.
REPORTING OF RESULTS
The value of penetration reported should be the mean of not less
than three determinations expressed in tenths of a mm.