Softening Point Test

Softening Point Test
  • Author: Farhan Khan
  • Posted On: June 11, 2021
  • Updated On: June 11, 2021


Bitumen is defined as a binding material used in the pavement to bind the aggregates together and provide a certain strength to the road. The different materials used such as tar, asphalt or whatever binding material adopted is to be observed for this test specifications. Any object used for the building/ construction purposes should be clear enough to narrate its properties and its values against the external sources or aspects.

Related theory:

Softening point of anything is defined as:

The temperature at which any material is subjected to the softening or its consistency of solidifying starts to reduce is termed as the softening point of that sample under a specific set of conditions.

This test is performed to point out the minimum temperature for this action as the regions have different temperatures specifically based on the polar region. Some are subjected to lower temperatures so this property is to be keenly observed and studied in order to avoid any future hazards.

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Figure 1 Ring & Ball Apparatus

The roads are subjected towards direct atmospheric scenarios such as heat, sunlight, UV rays etc. there are two types of methods depending on the bitumen tendency of heat absorption such as below 80 or above 80.


IS: 1205-1978


  • The ball and ring apparatus.
  • A temperature measuring device: thermometer with a lower range of -2 to 80 and a graduation of 0.2 and a higher range of 30 to 200 and a graduation of 0.5.
  • Bitumen, coal, tar sample


  1. A softening point determination apparatus geometry is set.
  2. Take a certain amount of sample to fill the ring and scrape of the extra sample from its surface through knife.
  3. The material is now subjected to heat ranging from 75 to 100 along with stirring to remove the air bubbles if any and any water constituent lately filtered through an IS Sieve 30 if required.
  4. Now heat the ring of the apparatus with an application of glycerin on its internal surfaces.
  5. The ring is now filled with the sample and allowed to rest for a certain time of 30 minutes.
  6. The excess is scraped off using a knife or scrapper.

For materials softening below 80:

  1. The apparatus is set up with all its parts i.e. ring, thermometer, ball apparatus.
  2. A beaker is filled with water heated at a temperature of 5 0.5 /minute.
  3. The heat is subjected continuously now until the ball passes through the ring.
  4. This temperature is then recorded as its softening point. A minimum of 2 readings are adopted.

For materials softening above 80:

  1. The method adopted here is approximately same the only changes observed are the glycerin is replicated with water along with a starting temperature of 35.


Softening point of sample #1 = _______

Softening point of sample #2 = _______

Softening point =mean of the two values = _______


The consistency of the sample is determined along with the report is prepared based on its use on the site and considerable precautions adopted for it.


  1. The sample should be properly prepared.
  2. The ring should be greased properly.
  3. The temperature should be maintained accurately to have a proper value.
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Author: Farhan Khan

Farhan is a highly experienced civil engineer from the Southern side of Texas and has been associated with ConstructionHow since 2020. Over almost a decade, his wide span of expertise enabled him to bring forth his fair share of stories and experiences related to the most iconic engineering examples worldwide. He has also contributed to online and offline publications on requests. Engineering is his passion, which is why he chose to become part of our honorable team of industry experts looking to provide authentic and credible guidelines to the reader.