Ductility Test of Bitumen (Ref - IS: 1208)
OBJECTIVE:
To measure the ductility value of bitumen.
To determine the suitability of bitumen for its use in road construction.
THEORY:
Ductility is a measure of elasticity of adhesiveness of bitumen. It is expressed as the distance in centimeters to which a standard briquette of bitumen can be stretched before the thread breaks. As per I.S. 1208-1958, the test should be conducted at 27±0.5° C and the pull should be applied at the rate of 50±2.5 mm per minute. The minimum width of cross-section should be 10×10 mm.
APPARATUS /EQUIPMENTS REQUIRED:
The apparatus for the standard ductility test as per IS: 1208-1978 consists of the following;
1. Briquette mould of following dimensions
Total length = 75.0±0.5 mm
Distance between clips=30±0.3 mm
Width at mouth of clip = 20±0.2 mm
Width at min cross section = 10±0.1 mm
Thickness throughout = 10±0.1 mm
2. Pulling device with distance measuring dial.
3. Water bath arrangement.
4. Knife.
5. Heater.
6. Thermometer.
7. Glycerin.
PROCEDURE:
OBJECTIVE:
To measure the ductility value of bitumen.
To determine the suitability of bitumen for its use in road construction.
THEORY:
Ductility is a measure of elasticity of adhesiveness of bitumen. It is expressed as the distance in centimeters to which a standard briquette of bitumen can be stretched before the thread breaks. As per I.S. 1208-1958, the test should be conducted at 27±0.5° C and the pull should be applied at the rate of 50±2.5 mm per minute. The minimum width of cross-section should be 10×10 mm.
APPARATUS /EQUIPMENTS REQUIRED:
The apparatus for the standard ductility test as per IS: 1208-1978 consists of the following;
1. Briquette mould of following dimensions
Total length = 75.0±0.5 mm
Distance between clips=30±0.3 mm
Width at mouth of clip = 20±0.2 mm
Width at min cross section = 10±0.1 mm
Thickness throughout = 10±0.1 mm
2. Pulling device with distance measuring dial.
3. Water bath arrangement.
4. Knife.
5. Heater.
6. Thermometer.
7. Glycerin.
PROCEDURE:
- The bitumen sample is heated at the temperature between 75 to 100 deg C to bring it in fluid state.
- In order to prevent the material under test from sticking, coat the surface of the plate and interior surface of the sides of the mould with a mixture of glycerin and dextrin.
- Pour the heated bitumen in the briquette assembly and placed on a brass plate.
- The whole assembly including bitumen briquette along with brass plate is allowed to cool in air for about 30 to 40 minutes.
- The excess bitumen is cut and surface is leveled with the help of a hot knife.
- The whole assembly now is kept in a water bath maintained at 27±0.5°C for about 85 to 95 minutes.
- The side of the mould removed, the clips hooked on the machine and the pointer adjusted to zero value or initial reading noted.
- Now the clips are pulled apart horizontally at the rate of 50.0 ± 2.5 mm per min. and the distance up to the point of breaking of thread is noted. This distance in centimeter gives the value of ductility of bitumen.
- The ductility of bitumen may vary from 5 to 100 for different bitumen grades, but for satisfactory performance it should not be less than 50.
