Viscosity Test of Bituminous Material Experiment

Objective

To determine the viscosity of given bitumen sample by Tar Viscometer

IS Standards used:IS 1206 - 1978 (Part II)

Need and scope:Viscosity is defined as inverse of fluidity. Viscosity thus defines the fluid property of bituminous material. The degree of fluidity at the application temperature greatly influences the ability of bituminous material to spread, penetrate into the voids and also coat the aggregates and hence affects the strength characteristics of the resulting paving mixes.

Apparatus Required:

1. Tar Viscometer with 4mm and 10mm orifices- The apparatus consists of main parts like cup, valve, water bath, sleeves, stirrer, receiver, and thermometer etc.

Experimental procedure:

1. The tar cup is properly levelled and water in the bath is heated to the temperature specified for the test and is maintained throughout the test. Stirring is also continued.
2. The sample material is heated at the temperature 200C above the specified test temperature, and the material is allowed to cool. During this the material is continuously, stirred.
3. When material reaches slightly above test temperature, the same is poured in tar cup, until the levelling peg on the valve rod is just immersed. In the graduated receiver (cylinder), 25ml of mineral or one percent by weight solution of soft soap is poured. The receiver is placed under the orifice.
4. When the sample material reaches the specified testing temperature within +/- 0.1°C and is maintained for five minutes, the valve is opened.
5. The stopwatch is started, when cylinder records 25ml. The time is recorded for flow up to a mark of 75ml (i.e., 50ml of test sample to flow through the orifice).

Observations and Calculation:

The average viscosity value of the given sample of bitumen:

General remarks:

Viva Questions

1. What do you understand by viscosity?
2. How is strength of bituminous road affected by the viscosity of binder?