What is the minimum amount of mass required for a field sample for method C in Standard/Modified Proctors?

The minimum amount of mass required for a field sample when using method C in Standard/Modified Proctors is indeed 45 Kg moist. This mass ensures that there is enough material to accurately determine the moisture-density relationship of the soil.

Using a sample that is too small can lead to inaccurate results, as it may not fully represent the characteristics of the material in place. Moist samples are preferred in this context because they provide a better indication of the soil's behavior under field conditions, taking into account the water content that affects compaction and overall soil stability.

In the context of Proctor tests, which assess the optimum moisture content for compaction, having a sufficient quantity of material allows for multiple tests to be undertaken, ensuring reliability in the results. The specified mass accounts for variations that may occur in the natural soil, hence supporting consistent and reproducible testing outcomes that reflect real-world scenarios.