We have a project spinning where we need to but base rock down for a building slab. I typically use a limestone base rock as 1.25" down to fines. It works and finishes pretty good. However, I have stumbled into some crushed shale product that is way closer to the site. Problem is I have never used shale and not sure how it may work. Anyone have experience with it?
I have mines both. In my opinion, the shale will be useless, a it will mash into dust under heavy load. Also, if you have an moisture from heavy morning dew, up to heavy rain, it will begin turning to mud. One good rain and you are done. I don't care how hard it looks now. It won't be hard after a little rain.
What kind of slab? Residential, commercial, industrial? Are there any specs? What does the building code allow?
All I know is if you just tap on a piece for the shale I'm familiar with it crumbles. Now the limestone at the quarry where I worked was pretty strong and you had to hit it good and hard to break it. But I also know that the stone here is nothing like the stone at a sister quarry the other side of the state. Here our crushers could go for a couple years with out changing liners but that other quarry had to do it maybe twice in one season!
Depends on the quarry. I can get limestone 40 miles away that turns to mush the second time you drive on it when wet. And 150 miles away I can get limestone that hasn't broken down in 5 years.
I was told many decades ago by an old council works supervisor, that if "road base comes out hard, it goes down hard. If it comes out soft, it stays soft". By that he meant that if the road base material was hard ripping to break up, it would compact hard, and stay hard, regardless of weather and heavy traffic use. But if the material could be dozed out without ripping, it might compact and look good, but it would start to break up, once the pressure came on it.
And the stone even in the same pit can have different characteristics. forget any details but know there was one area of the pit where I worked that they "saved" for certain uses. Guess it depended on what kind of sea creatures that died and got turned to stone over the centuries!
Locally we have calcium carbonate (limestone) quarries. State of VT projects, & even some private projects they won't allow its use, too soft. A local paver quarries stone, can't say what it is, it is harder than limestone. I'll agree with others here that shale is too soft to consider for any use where air space is needed. Maybe under a building it would be fine.
We had a huge plaza were the ground was all shale. They decided to use it as the base under the blacktop. It all turned to mush. That lot was a mess crumbling and full of potholes. It did make allot of money though patching it up.