Concrete base problem in garage shop. Any construction folks?

So the crushed gravel is used for water drain under the concrete and help with leveling out of the concrete to maintain thickness. In New England we use crushed granite -3/4” washed and compact evenly every 2-3” thick until desired height is obtained. Typically a 4” pour (I prefer 6”) of 3500psi concrete (minimum 30day cure with cuts for stress cracks)with reinforcement like fiber mesh or #4/5 rebar is used per engineered plans. I’ve not worked with lime stone before but from what I was told it does not like more than a few inches and Does not pack well.