313323 HEN Practical No: 03 Conduct Softening point test on bitumen
Bitumen does not suddenly change from a solid to a liquid state, but as the temperature increases, it gradually becomes softer until it flows readily. All semi-solid state bitumen grades need sufficient fluidity before they are used for application with the aggregate mix. For this purpose, bitumen is sometimes cut back with solvent like kerosene. The common procedure however is to liquefy the bitumen by heating.
The softening point is the temperature at which the substance attains particular degree of softening under specified condition of test. Bitumen, it is usually determined by Ring and Ball Test. A brass ring containing the test sample of bitumen is suspended in liquid like water or glycerin at a given temperature. A steel ball is placed upon the bitumen and the liquid medium is then heated at a specified rate. The temperature at which the softened bitumen touches the metal plate placed at a specified distance below the ring is recorded as the softening point of a particular bitumen. The apparatus and test procedure is standardized by ISI. Harder-grade bitumen possesses a higher softening point than softer-grade bitumen.
Observation Table:
Practical Related Questions:
1. Give the significance of softening point of bitumen for road construction works.
Answer:
1. Road Construction: In road construction, the softening point is critical for selecting bitumen that can withstand local temperature ranges. A higher softening point is desirable in hot climates to prevent road surfaces from becoming too soft and rutting, while a lower softening point may be sufficient in cooler regions.
2. Roofing and Waterproofing: For roofing and waterproofing applications, bitumen with an appropriate softening point ensures durability and resistance to weather conditions. A higher softening point in bitumen prevents material flow under high temperatures, maintaining structural integrity.
3. Industrial Uses: In industrial settings, bitumen is used in applications such as adhesives, sealants, and coatings. The softening point helps determine the operational temperature range, ensuring that the bitumen remains effective in bonding and sealing.
2. State the media used for heating the bitumen sample in this experiment.
Answer:
distilled water, glycerin, or an oven
3. State the softening point of bitumen of various grades used in bituminous pavement construction.
Answer:
The softening point of various bitumen grades generally lies between 35°C to 70°C.
Softening point of bitumen to be used for road construction at a place where the maximum temperature is 40°C should be greater than the 40°C.
4. Compare the softening point for asphalt and tar.
Answer:
5. State the rate of heating the bitumen sample
Answer:
A steel ball is placed upon the bitumen sample and the liquid medium is heated at a rate of 5 C per minute. Temperature is noted when the softened bitumen touches the metal plate which is at a specified distance below.
Conclusion
We completed 313323 HEN Practical No: 03 and conducted a Softening point test on bitumen successfully.