Break up clays for proctors

If there's no gravel or coarse sand in it, a commercial grade cheese grater would be my choice. It should still be moist. Then air dry the gratings, shake them in a bucket, and pass them through the screen.

You can break it into chunks, air dry it in front of a fan overnight, and then tumble it in a concrete mixer for a bit. I like to cover the mixer opening by strapping plastic or a piece of tarp over it during the tumble.

This link is for a soil processor that is moderately effective I've used one, but it has pluses and minuses.

Do a Charpy test on it.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

Previous life but we used to used put the soil is large metal trays/pans to dry overnight in a large soil drying cabinet or use fans if there were too many samples to fit in the oven. Then break up the soil by placing the pan on the ground and using a soil tamper or sledge hammer (like a soil tamper). Once the sample pieces are relatively small you can rely on the water from the proctor to help break it up more. Just mix the sample after you have added water and let it sit then remix.