Penetration Value of Bitumen | Determination for Road Construction
Method of penetration test of bitumen for determination grade of bitumen. Penetration value of bitumen is the vertical penetrated measure of the standard needle into the bituminous material under specific weight and temperature.
This distance is measured in one-tenths of a millimeter. Penetration test of bitumen is used for evaluating the consistency of bitumen.
Test Standard : IS 1203:1978
Test Apparatus :
- Container : A flat bottom cylindrical container made of glass or metal with diameter of 55mm & 35mm deep for determining the penetrations below 225 and diameter of 70mm & 45mm deep for determining the penetrations above 225.
- Needle: A straight, highly polished, cylindrical, stainless steel rod, The needle is provided WIth a shank approximately 3 mm in diameter into which it
is immovably fixed.
- Thermostatically controlled water bath
- Transfer dish
- Penetration apparatus.
- Thermometer of range 0 to 44 °C
- Stop watch or Time device
- Soften the bitumen to the pouring consistency at a temperature not more than 90°C and stir it thoroughly until it is homogeneous and is free from air bubbles and water.
- Pour the bitumen into the container 10 mm excess of the expected penetration.
- Allow it cool to a temperature between 15 to 30°C for 1.5 to 2 hours and keep also room temperature 25.0 +/- 0.1°C.
- Place it in a tray and keep it in water bath at 25.0 +/- 0.1°C for 1.5 to 2 hours.
- Fill the transfer dish with water from the water bath to a depth sufficient to cover the container completely. Place the sample in the tray and place it upon the stand of the penetration apparatus.
- Clean the needle with benzene, dry and load to make contact with the surface of the sample.
- Load the needle with the weight required making a total moving weight ( that is, the sum of the weights of the needle, carrier and superimposed weights) of 100+/-0.25 gm.
- Bring the dial on the pointer to zero. On the stopwatch and release the needle simultaneously and record the reading of the dial of the penetration apparatus when a time of 5+/-0.1 seconds elapsed.
- Make at least 3 determinations on the surface at 10 mm apart but not less than 10 mm from the sides of container.
- After every determination returns the tray with container into water bath and clean the needle with benzene and dry.
- Express the depth of penetration in the tenths of a millimetre.
The value of penetration reported is the mean of not less than three determinations whose value do not differ by more than the following:
|0 to 49||2|
|50 to 149||4|
|150 to 249||6|
|250 and above||8|
The duplicate results should not differ by more than the following:
|Below 50||1 Unit||4 Units|
|Above 50||3 percent of their mean||8 percent of their mean|
- If the sample contains extraneous matter, it should be sieved through IS Sieve 30.
- Avoid overheating bitumen.
- While the needle is penetrating into the sample, if there is any movement of the container, that determination shall be discarded.
- Take care of the temperature as per standard.
Read more : Method of Softening point test of bitumen
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