Mud or Dirt

Companies that use Mud or Dirt to raise the concrete are assuming you are ignorant.

NO reputable contractor grades out dirt and pours concrete over it. They ALWAYS use a Roadbase product or Gravel. The Aggregate is needed to hold the material in place.

When you just have dirt, the moment it gets wet it moves. Prove it to yourself. Drive out into a farmers field when it's wet and try not to get stuck. If you drive out on gravel road you won't have an issue but on dirt, you will.

So why would anyone put mud or dirt under a sunken concrete pad?

The "We Add Concrete to the Dirt" claim.

We have some competitors who claim they add "6 bag concrete" to their mud or dirt mix it somehow increases the strength.
Again, they are assuming you are ignorant.
Concrete does not Bond to Dirt or Mud. Jack Hammer out a piece and you will see.

The Facts

These companies use Mud or Dirt because it's cheaper. Also, they don't like pumping the Aggregate because it's harder on the machine, not to mention most don't have a machine capable of pumping a Gravel Slurry like Concrete.

Dirt is everywhere. It's readily available and cheap while it takes a special Roadbase to do the job properly, which costs a lot more.
I've actually seen a Mud D company run out of material on a job and pull into a farmers field to load up a bit more to finish.
There are "Mud Pumps" that only pump mud. They are specifically made to pump grout in certain commercial building projects and these are the machines these "Mud Jackers" use. In fact, these machines come with warnings, "Do not pump aggregate."
Our machine is a high pressure Concrete Pump capable of pumping the Roadbase mix we need at a pressure of up to 700 p.s.i. It's a mini version of the ones you see with the big telescoping boom when they pump concrete over a larger area.