SPECIFIC GRAVITY TEST ON BITUMEN

Objective :
To determine the Specific gravity of given Bituminous material by Pycnometer method.

Apparatus used :
Specific gravity Bottle, Balance and Distilled water.

Principle

The density of a bitumen binder is a fundamental property frequently used as an aid in

classifying the binders for use in paving jobs. In most applications, the bitumen is weighed,

but finally in use with aggregate system, the bitumen content is converted on volume basis.

Thus an accurate density value is required for conversion of weight to volume. The specific

gravity is greatly influenced by the chemical composition of binder. Increased amount of

aromatic type compounds cause an increase in the specific gravity.

The specific gravity is defined by ISI as the ratio of the mass of a given volume of the

bituminous material to the mass of an equal volume of water, the temperature of both being

specified at 27ºC±0.1ºC.

The code of practice used to determine the specific gravity is IS: 1202.

Procedure

➤ The clean, dried specific gravity bottle is weighed let that be W1 g.

➤ Then it is filled with fresh distilled water and then kept in water bath for at least half

an hour at temperature 27ºC±0.1ºC.

➤ The bottle is then removed and cleaned from outside. The specific gravity bottle

containing distilled water is now weighed. Let this be W2 g.

➤ Then the specific gravity bottle is emptied and cleaned. The bituminous material is

heated to a pouring temperature and the material is poured half the bottle, by taking

care to prevent entry of air bubbles. Then it is weighed. Let this be W3 g.

➤ The remaining space in specific gravity bottle is filled with distilled water at 27ºC and

is weighed. Let this be W4 g. Then specific gravity of bituminous material is given by

formula, specific gravity= (W3-W1)/(W2-W1)-(W4-W3)

After calculation

The specific gravity of given bituminous binder is (...........)