What should the overall length of the tamping rod not exceed?

The correct answer is that the overall length of the tamping rod should not exceed 600 mm. This specification is critical in ensuring that the tamping rod is of a manageable size for proper handling and use during testing. A tamping rod that is too long could lead to difficulties in achieving the necessary compaction of materials, such as concrete or soil samples, which could ultimately affect the accuracy of test results.

In standard practices, the dimensions of testing tools and equipment are specified to ensure consistency and reliability in testing methods. The limitation on the length helps users maintain control over the tool while using it and allows for the proper application of force during the tamping process. This results in uniform compaction and ensures reliable test outcomes.