pea gravel/slab

How much are you filling?

I get a product called "man sand" from a limestone quarry. It's nothing more than course sand screened from the stone crushing process. It doesn't bridge when filling tall spaces, doesn' require much packing...works well. I don't recall the price per ton...but it was cheaper than "normal sand"

depends on how heavy the loads'll be that you're placing on the floor AND what the base material's like,,, my garage floor's 5" thick & has 8" graded aggregate base compacted in 2 4" lifts over ga clay,,, think some call gab crusher run, item 4, or even ' mansand ' :laughing:

if you're filling 8' between the ' concreate ' walls, be a good idea to go no more'n 8" lifts.

My vote would be for 1.5" to 2" fractured stone , if you can easily find it locally. It's a little more expensive than pea stone, but performs much better. 2" fractured stone also fills more area per ton, although it may cost slightly more. If I remember correctly, most larger fractured stone is something like 95% to 97% compacted dumped directly out of the truck. I cant say I've poured on sand backfill in a garage, especially 8' worth, since the 1980's, when it was more acceptable. When you figure the time & water needed to "flood" sand to completly settle it, it's a waste IMO.

Im filling in 8 feet with pea gravel so far unless there's something better.

Pea gravel drains well but is a poor base for concrete, it does not compact well. As suggested above, crushed stone(crusher run), compacted makes the best base.