Will dry dirt pack as good as waste lime/road rock?

I am getting ready to pour a concrete foundation for a grain bin. I had a dozer root out one good size and two small maple trees. Got all of the roots out and left a good size hole under half of where the concrete pad will go. The hole is probably up to 1.5 to 2 feet below grade in places. I said I was going to go to the quary and get fill which is waste lime/limestone and layer/pack it into the hole. I have used waste lime before to level up grain bin sites. The contractor/dozer operator said the dirt was so dry that it would pack as well the lime. We are in a flash drought in Eastern Iowa. Is that the case with dry dirt? Can I layer the dry dirt in and pack it with the skid loader or should I stay with the waste lime? I don't want any uneven settlement. Any opinions? Thank you.

i am not understanding how dry dirt can pack. you need a base. pretty sure you idea is better than his. and if your pouring a foundation you want to remove the dirt and build a good base. gravel and sand pack would be one idea. railroad tie's also work. is this for a hopper bin or flat bottom?

Soil does need a small amount of moisture to compact to its optimum. But typically soil only achieves 95% compaction anyway, so some settling will always happen.

Hard does not mean compacted. All dirt requires water to achieve compaction. Yes you can achieve compaction with your existing dirt as long it isn't full of organics that will decompose and leave voids. If you add water while you replace the dirt and compact in lifts you would be fine. Don't make mud but enough that it is moist. We usually do 8 to 12 lifts if using machines for compaction 4-6 using jumping jacks.

Any topsoil, typically 12 to 24 inches in Iowa is going to be comprised of a lot of organic material. As you know typically topsoil is stripped from a site and saved for respread after the project is completed. I would go with the material from the quarry, keep your lifts around 8 inches if you are just wheel rolling or using a vibratory plate compactor. just my opinion from doing the inspection on this kind of work for 20 years. gobble

Quarries in my area will give you all the red clay dirt you want to get rid of it,can't beat red clay sub soil to pack tight and stay hard.As said with any dirt need to add moisture as you pack.

I'd go with fill sand and or rock myself. Obviously with a layer of sand on top. I'd shy away from the dry dirt idea.

Pee stone is about 98 % compacted when poured in the hole then the rest will not take long.the down side is it can be washed out of the hole if you have the chute over the spot.it will not move a lot but some can be disturbed that way if the chute is to high or the mud is to soupy. Crushed lime or concrete would pack in there better than dust dry dirt. Then a sand cap or even some crushed material for a level top.

Disagree. Higher percentages are easily achievable.

I've had 2 pole barns built. After the poles were set, I got a good rain. The dirt around the posts settled after a good rain.

I don't think dry dirt will pack in for a foundation.
Flood the place with water to pack in the dirt.

My experience here in southern Ontario is to put 4-6 inches of gravel over top of the sub soil and then pack it down with a packer or turn the lawn sprinkler on it and let the water settle it down. When dry crib it up ,lay your mesh , and pour tour concrete. It all depends on the type of aggregate at your disposal.

Dry dirt will never compact.
The friction between the particles will not let the air out.

On the other hand flooded dirt or clay is hard to compact.
While it does not have air in the mix it has water.
But once the water drains compaction can happen.
Clay will compact better than dirt because of all the small particles to fill the tiny voids.
The problem with using dirt or clay under a slab is the organic matter in the mix.
This will cause it to settle as the organic matter rots away.
If you can get some clay dirt mix; most likely red driveway clay; from a pit that is digging well below any organic matter that would be best.

Nothing (in my mind) compacts better than crusher run; 1 inch rocks to dust; limestone.
A small dozer can not rip it up.

Sand never fully compacts.
Think of a beach.
But once you flood compact it that is it.
It will not settle more.
This and the fact it has little to no organic matter makes it a good cheap fill.

I would clean any disturbed soil out the hole and fill it with sand.
Flood it and let drain.
Flood it again and let drain.
Once you got the hole filled cover the dirt sand with a fabric and put down a layer of limestone.

Dry dirt as in dust does not compact it should be somewhat coheisive But you need to have your building pad uniform ,as in not hard dry cut dirt on one side and dust fill on the other is not good.

I like crushed gravel. In Minnesota where I lived most of my life, it's called Class 5. Where I live now in Wisconsin, they call it 3'4" base or 1 1/4" base. I have two pole sheds here and that's what I did and compacted in 8" lifts. It also rained on it a few times before the building went up. Turned out perfect.
DWF