Objective

For determination of softening point of a given bitumen. 

Reference Standards

IS : 1205-1978-Indian standard methods for testing tar and bituminious materials (Determination of softening point)

Equipment & Apparatus 

•  Ring and Ball apparatus,
•  Steel balls
•  Brass rings
•  Ball guide  
•  Support
•  Thermometer
•  Bath with stirrer 

Procedure

1. Sample material is heated to a temperature between 75° and 100°C above the approximate softening point until it is completely fluid and is poured in heated rings placed on the metal plate.
2. To avoid sticking of the bitumen to metal plate, coating is done to this with a solution of glycerin and dextrin.
3. After cooling the rings in air for 30 minutes, the excess bitumen is trimmed and rings are placed in the support.
4. At this time the temperature of distilled water is kept at 5°C. This temperature IS maintained for 15 minutes after which the balls are placed in position.
5. Then the temperature of water is raised at uniform rate of 5°C per minute with a controlled heating unit, until the bitumen softens and touches the bottom plate by sinking of balls. At least two observations are made. For material whose softening point is above 80°C, glycerin is used for heating medium and the starting temperature is 35°C instead of 5°C. 

Record /Reports

The temperature at the instant when each of the ball and sample touches the bottom plate of support is recorded as softening point value.An average value of two tests is reported as softening point value.

Safety & Precautions

• Use hand gloves, apron while removing containers from hot plate after switching off the hotplate.
• Use glycerin for remove of bitumen from the container.
• Use distilled water in test for accuracy result.
• Use safety shoes & Apron at the time of test.
• Equipment should be cleaned thoroughly before testing & after testing.