Softening point

The softening point ring and ball ( short EP BCT ) is a measure for the classification of bitumen.

When determining this value, a steel ball is placed onto a mounted in a ring bitumen layer. In the course of the experiment, the material is heated uniformly. If the sample has been bent by 25.4 ± 0.2 millimeters down, the corresponding temperature is held. This test is carried out twice.

In this case, the steel ball has a diameter of about 9.8 millimeters and a weight of 3.5 grams. The weight must differ by 0.05 grams up and down. The ring has an outer diameter of the top 23 and has an inner diameter of 19.9 mm, an outer bottom diameter of 19 and an inner diameter of 15.9 millimeters. From these values, deviations of 0.2 mm are allowed.

Implementation

In general, two samples are prepared and tested simultaneously. The rings are heated for filling with bitumen to 120 ° C, for filling with oxidation bitumen and bitumen high vacuum at 180 ° C. Then they are placed on a plate such that the larger diameter faces upwards. Then you fill the interior of the rings completely and slightly convex on the surface to be tested with the liquefied bitumen. After 30 minutes cooling, the edge projecting beyond the bitumen is cut off so that the surface becomes smooth and even. It is important to ensure that the circumcision of the sample is carried out at a room temperature of 18-28 ° C. Bitumen, which soften even below 30 ° C, is allowed to a temperature of about 8 ° C above the expected softening point to cool.

The rings are then clamped in a holder, which ball is inserted into a first receptacle located thereon in a waiting position adjacent to the above sample. Below the ring, a plate is fixed at a distance of 25.4 ± 0.2 mm. Then everything is put together in a beaker and decanting of liquid. The liquid has to be 100 ± 3 mm high in the cup, the ring must be 50 ± 3 mm submerged. Subsequently, a thermometer is inserted so that it is at the height of the ring, but does not touch it. The nature of the liquid and of the thermometer is determined by the expected softening point.

At the beginning the apparatus is maintained at the initial temperature for 15 minutes. Then, the ball is rolled onto the sample. Then the liquid is heated so that the temperature rises in one minute by 5 ° C. The first three minutes are yet to adjust the temperature rise. After the rise in temperature may be made only within 60 ± 5 seconds. If this is not complied with, the specimen must be rejected. When the sample reaches the plate by means of bent, the temperature is read. This test is carried out twice. When the temperatures more than 1 ° C apart, the test is not valid and must be repeated.