What is the maximum particle size allowed for soils used in Modified Proctor tests?

The correct response highlights the standardized procedures established for conducting Modified Proctor tests, which are critical in assessing the compaction characteristics of soils. In these tests, the specified maximum particle size is crucial to ensure that the test results accurately reflect the compaction behavior of the soil sample being analyzed.

For Modified Proctor tests, the maximum particle size permitted is ¾ inch. This limit is set to minimize the influence of larger particles on the compacted density measurements, allowing for a more uniform distribution of soil particles within the sample. If the particle size exceeded this limit, it could lead to inaccurate results due to the potential for larger aggregates to behave differently than the smaller particles during the compaction process.

The other options suggest maximum particle sizes that are too small or suggest no limit at all, which would not conform to established testing protocols that aim to ensure consistency and reliability in the results. By adhering to the ¾ inch maximum particle size, technicians can ensure their tests yield results that are relevant and applicable in practical engineering contexts, such as determining the optimal moisture content and maximum dry density of the soil.