The main characteristics determining the properties of bitumen are penetration, softening point, extensibility and viscosity. They are measured according to GOST standards. The method for determining the extensibility of bitumen is prescribed in GOST 11505-75. A special device, ductilometer, is used for measurements. The extensibility is determined at a temperature of 25 ° C in centimeters.
Determination of the extensibility of bitumen according to GOST
The extensibility of bitumen (ductility) is the ability to stretch into a thin thread when exposed to a tensile force. This characteristic is measured in centimeters. The material is heated to a liquid state (but not more than 160-180 ° C), and then poured into brass molds-eights in a ductilometer. The device has two plates. The first one is fixed at the end wall, the second one moves along the long side of the ductilometer. The speed of movement is 5 centimeters per minute. There is a measuring ruler on one of the walls of the box. A pointer attached to a movable plate slides along it.
For testing, water is poured into the ductilometer at a temperature of 25 ° C. It should cover the bitumen molds by at least 2.5 cm. In this way, the material is cooled to the temperature required for testing. It is required to control the temperature of the water in the bathroom, if necessary, adding boiling water or lowering ice. The material is kept in the bathroom for 1 hour, after which the next stage begins.
To calculate the extensibility of bitumen, the molds are fixed in a ductilometer, their side parts are removed. Next, the motor turns on, and the movable plate moves along the wall of the box, stretching the bitumen. The material is pulled into a thread, and then a rupture occurs. The length of the thread at the moment when it broke is taken as the value of the extensibility of bitumen.
There are several important aspects to measuring:
What does the extensibility of bitumen affect?
The amount of bitumen stretching directly depends on its composition. The more resins are added, the higher the score. Due to its high extensibility, bitumen becomes more elastic. This is important for road and roofing brands, as well as for the manufacture of bitumen-based paint coatings. If bitumen contains a lot of solid paraffin, asphaltenes or suspended particles, then its extensibility will be low, and, accordingly, its elasticity will decrease. When stretched in a ductilometer, the thread will break almost immediately.
Characteristics according to GOST
The extensibility of bitumen according to GOST 22245-90 for road grades is as follows:
Determination of the extensibility of bitumen according to GOST
The extensibility of bitumen (ductility) is the ability to stretch into a thin thread when exposed to a tensile force. This characteristic is measured in centimeters. The material is heated to a liquid state (but not more than 160-180 ° C), and then poured into brass molds-eights in a ductilometer. The device has two plates. The first one is fixed at the end wall, the second one moves along the long side of the ductilometer. The speed of movement is 5 centimeters per minute. There is a measuring ruler on one of the walls of the box. A pointer attached to a movable plate slides along it.
For testing, water is poured into the ductilometer at a temperature of 25 ° C. It should cover the bitumen molds by at least 2.5 cm. In this way, the material is cooled to the temperature required for testing. It is required to control the temperature of the water in the bathroom, if necessary, adding boiling water or lowering ice. The material is kept in the bathroom for 1 hour, after which the next stage begins.
To calculate the extensibility of bitumen, the molds are fixed in a ductilometer, their side parts are removed. Next, the motor turns on, and the movable plate moves along the wall of the box, stretching the bitumen. The material is pulled into a thread, and then a rupture occurs. The length of the thread at the moment when it broke is taken as the value of the extensibility of bitumen.
There are several important aspects to measuring:
- The extensibility of bitumen is calculated three times and the arithmetic mean is output.
- The standard is considered to be testing at 25 ° C, but the characteristic can also be set at a temperature of 0 ° C.
- For the purity of the tests, bitumen is dehydrated in advance, heated, getting rid of air bubbles, and filtered through a metal sieve.
- The molds into which the material is poured are treated with talc or dextrin mixed with glycerin.
- The extensibility at zero degrees and the softening temperature after heating according to GOST 22245-90 are recommended to be determined at least once every 10 days.
What does the extensibility of bitumen affect?
The amount of bitumen stretching directly depends on its composition. The more resins are added, the higher the score. Due to its high extensibility, bitumen becomes more elastic. This is important for road and roofing brands, as well as for the manufacture of bitumen-based paint coatings. If bitumen contains a lot of solid paraffin, asphaltenes or suspended particles, then its extensibility will be low, and, accordingly, its elasticity will decrease. When stretched in a ductilometer, the thread will break almost immediately.
Characteristics according to GOST
The extensibility of bitumen according to GOST 22245-90 for road grades is as follows:
