The drying apparatus used for dry preparation of a sample must not exceed which temperature?

The correct temperature limit for the drying apparatus during the dry preparation of a sample is 60°C. This threshold is established to prevent any potential alteration of the material's properties, particularly for aggregates that may be sensitive to temperature changes. Exceeding this temperature can lead to undesired effects, such as the loss of moisture that might be critical for maintaining the integrity of the particles, or even cause physical changes in the aggregate itself, such as a change in gradation or strength characteristics.

In aggregate testing procedures, maintaining appropriate drying conditions ensures that the sample remains representative of the material's conditions in the field. The chosen temperature of 60°C is low enough to mitigate these risks while still effectively removing moisture from the sample for accurate analysis.

By adhering to this temperature limit, technicians can ensure consistency and reliability in their testing results, which is paramount for quality control in construction projects.