Specific Gravity Test for Bitumen

Hello Friends, This is Mukesh from Learning Technology. I will tell you in today’s post, Specific Gravity Test for Bitumen in a very easy way.

Object of Experiment

To determine the specific gravity of given bituminous material.

Theory and Scope

The specific gravity of bitumen is defined as the ratio of the mass of a given volume of bitumen of known content to the mass of an equal volume of water at 27 degree Celsius. The specific gravity can be measured using either a pycnometer or preparing a cube specimen of bitumen in semi-solid or solid-state. The specific gravity of bitumen is greatly influenced by its chemical composition. It increases with the increase in aromatic type mineral impurities. Thus, the property of specific gravity is of importance in classifying or grading the binders.

In pavement construction works, the bitumen is measured by weight, but when used with aggregates bitumen content is converted to volume using its density.

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Equipment

Specific gravity bottles

Water bath

Bath thermometer with range 0 to 44 degree Celsius and least count 0.2 degree Celsius

Balance and distilled water

> Specific gravity bottle of 50 ml capacity. It may be either ordinary or Wide-mouthed capillary type as per IS: 1202 – 1978.

The method of using a specific gravity bottle is called a pycnometer method.

Procedure

1.  Weigh the clean, dried specific gravity bottle along with the stopper.

2.  Fill the specific gravity bottle with freshly boiled distilled water and insert the stopper firmly. Place the filled gravity bottle in the water bath having a temperature of 27 ± 0.1 degree Celsius for not less than 30 minutes.

3.  Remove the bottle from the water bath and clean it from outside. Weigh the specific gravity bottle containing distilled water.

4.  Empty and clean the specific gravity bottle.

5.  Heat the bituminous material to the pouring consistency and approximately half fill the empty cleaned specific gravity bottle, by taking care to prevent the entry of air bubbles.

6.  Weigh the specific gravity bottle with the material.

7. Fill the remaining space in a specific gravity bottle with distilled water at 27 degrees Celsius.

8.   Weigh the specific gravity bottle about half-filled with the material and the other half with distilled water.

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Observations and Calculations

Average Specific Gravity of given bituminous material is …………………..

Precautions

1.  Wear safety glasses and/or face shields, heat resistant gloves with close-fitting cuffs.

2.  There shall be no smoking or the presence of other ignition sources in close proximity of test set-up.

3.  Check the samples for the presence of water while the material is still cold. If water is present drain off as much water as possible and allows the sample to dry at room temperature or blow-dry with clean compressed air.

4.  Care should be taken to prevent the entry of air bubbles while pouring the bitumen in a specific gravity bottle.

5.  The specific gravity bottle should be held in a constant temperature water bath sufficiently long to ensure the same temperature before each weighing is made.

6.  Duplicate determination of specific gravity should agree within 0.01

Discussion

The test is based on the principle that specific gravity is the ratio of the mass of a given volume of bitumen to the mass of an equal volume of water, both taken at a specified temperature. This test can also be used to determine the specific gravity of road tars, creosote and anthracene oils as per IS: 1202 – 1978. The specific gravity of bitumen varies from 0.97 to 1.02. The specific gravity of any grade of bitumen to be used in payments should not be less than 0.99