The thickness of cored specimens should be at least how many times the maximum aggregate size used in the HMA mixture?

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Multiple Choice

The thickness of cored specimens should be at least how many times the maximum aggregate size used in the HMA mixture?

Explanation:
The key idea is that a core must be thick enough relative to the largest aggregate in the mix so the test results truly reflect the in-place material, not distortions from the cut ends. Setting the minimum core thickness at 1.5 times the maximum aggregate size ensures there’s enough material around the faces for the test to average out the arrangement of aggregates and the air voids, and it reduces edge effects that can bias density and other properties. For example, if the largest aggregate used is 20 mm, the core should be at least 30 mm thick. That extra thickness helps guarantee a representative cross-section. Choosing a thinner thickness (1x) risks bias from the ends; thicker options like 2x or 2.5x aren’t required by standard practice, though they would still be usable. The specified minimum is 1.5x because it provides the right balance between practicality and getting a representative sample.

The key idea is that a core must be thick enough relative to the largest aggregate in the mix so the test results truly reflect the in-place material, not distortions from the cut ends. Setting the minimum core thickness at 1.5 times the maximum aggregate size ensures there’s enough material around the faces for the test to average out the arrangement of aggregates and the air voids, and it reduces edge effects that can bias density and other properties.

For example, if the largest aggregate used is 20 mm, the core should be at least 30 mm thick. That extra thickness helps guarantee a representative cross-section.

Choosing a thinner thickness (1x) risks bias from the ends; thicker options like 2x or 2.5x aren’t required by standard practice, though they would still be usable. The specified minimum is 1.5x because it provides the right balance between practicality and getting a representative sample.

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