What sieve is used in Method C of a Standard/Modified Proctor?

In Method C of the Standard/Modified Proctor test, a ¾" sieve is utilized to separate the coarse particles from the sample being tested. This method is crucial for determining the maximum density and optimum moisture content of soils, particularly for larger aggregate sizes.

The ¾" sieve allows for effective screening of materials that could significantly affect the compaction process, ensuring that the test is relevant for the types of soil and aggregate commonly encountered in construction applications. By retaining larger particles, this method helps to focus the evaluation on the smaller particles that influence the soil's compaction properties more directly.

Using a different sieve size would alter the size distribution of the material being tested, potentially leading to misleading results regarding the soil's compaction characteristics. For example, a No. 4 sieve would retain different particle sizes and therefore not align with the procedures defined for Method C.

Overall, the utilization of a ¾" sieve is essential for maintaining consistency and accuracy in the testing process, enabling engineers and technicians to derive valuable information pertaining to soil behavior under load during construction.