What is the standard referred to for drying of the sample?

The standard referred to for drying of the sample is ITP 255. This standard provides guidelines for the proper procedures to ensure that aggregate samples are dried effectively before testing. Effective drying is crucial as it helps to remove moisture from the aggregates, which can otherwise lead to inaccuracies in determining the aggregate's weight and other properties.

By following ITP 255, technicians can achieve consistent results when preparing samples for further testing, such as size analysis or specific gravity determinations. This standard outlines the necessary steps and precautions needed to ensure that moisture content does not affect the test results, leading to reliable data for ensuring quality in aggregate materials used in construction.

The other standards listed pertain to different testing methods or aspects of construction materials. ASTM C136 and AASHTO T 27 are primarily concerned with the sieve analysis of fine and coarse aggregates, discussing how to determine particle size distributions. ISO 679 pertains to the testing of cement and not directly to the drying of aggregate samples. Thus, while these standards are relevant in the broader context of material testing, ITP 255 specifically targets the drying process critical for accurate testing of aggregates.