When is the workability index for plastic refractories to be measured?

The workability index for plastic refractories is best measured immediately after mixing. This timing is crucial because the workability of the material is directly related to its fresh state and the immediate properties following the mixing phase. Measuring workability at this point allows for an accurate assessment of the consistency and ease of installation of the refractory material, which is critical for ensuring proper application and performance.

While some options mention timeframes after the mixing process, such as seven days after manufacture or during installation, these are not appropriate for measuring the workability index. The properties of the refractories may change significantly when they have been left for an extended period or once they begin to set, which can adversely affect the workability assessment. Thus, measuring workability at the right moment—immediately after mixing—ensures that the material’s manipulative characteristics are accurately evaluated, providing essential information for its practical application.