According to AASHTO T180 and ASTM standards, how many blows are required for compaction in a 4-inch mold?

The correct answer is rooted in the specific requirements set by both AASHTO T180 and ASTM standards for the compaction of soil and aggregate materials in a laboratory setting. According to these standards, when using a 4-inch diameter mold, the procedure specifies that 25 blows using a standard compaction hammer should be applied to achieve proper compaction.

This number is derived from comprehensive testing protocols designed to ensure that the material reaches a uniform density, allowing for accurate assessment of its properties. The approach ensures consistency in test results, providing engineers and technicians with reliable data for evaluating the materials' suitability for use in construction applications.

The other options do not meet the established standard requirements for this particular mold size, leading to discrepancies in compaction and potentially affecting the overall integrity of the testing process. Adhering to the specified number of blows is essential for maintaining standardization across different tests and materials.