What is the drop height of the rammer used in the modified Proctor test?

In the modified Proctor test, the correct drop height of the rammer is 457 mm (or 18 inches). This specific height is critical for ensuring that the soil is compacted to a standard that simulates the conditions of heavy loading found in construction and civil engineering applications. The use of this drop height allows for the application of a consistent and high-energy impact on the soil sample, which is necessary to achieve a desired level of compaction.

Using a rammer at this height helps in assessing the moisture-density relationship of the soil, providing valuable information for projects involving earthwork, foundation stability, and pavement design. Adhering to the prescribed height is essential to maintain uniformity in testing and to ensure that the results are reliable and can be compared across different tests or materials.