The expansion is measured, and indicates if the slag is suitable for use as a roadbuilding material. Two chambers 250 mm diameter contain samples of steel slag. Water under the chambers is heated electrically and steam passes upward through the samples. Glass beads are placed over the samples which are held down by special weights, ensuring samples are held firmly in position. Expansion upwards is measured by linear transducers.
Water lost by evaporation is replenished by an automatic system.
The rate of evaporation can be controlled from 0.5 to 4.0 litres per hour. The machine operates continuously under computer control, and records time elapsed and expansion. Each chamber can be operated independently. Length of Test Depending on the type of slag, the test can run for 7 days. Automatic control removes the need for continuous supervision by an operator.