I’m putting in a monlithic slab for my garage and I excavated too much dirt.
So I’m thinking that I’ll order extra gravel and just fill the low areas–is there any problem with this technique?
Thanks for any advice or suggestions.
cje
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Replies
Not at all, so long as the gravel is compacted in layers of around 4 to 5 inches or so. It should not be dry when compacted, and you must use a jumping jack style compactor or a compaction roller. Plate compactors do not compact sufficiently for structural purposes.
To me "gravel" means rounded stones mixed with sand, which doesn't compact into a solid base. The proper material to use is crushed stone. The sharp shapes and range of sizes produced by crushing lock together superbly.
The dealer I get the gravel from calls it:
GravelGranite #573/4" - 1 1/4"(Base/Drain Use)
And it's like you mentioned sharp edges and such.
I'd never heard about making sure the gravel is wet--is a simple hose down enough or does it neeed to be sopping?
cje
Take what you want, leave the rest
Very simple hose down.Remember.... 5" at a time. Compact, then 5" more...
Are we there yet ?
Don't make it sopping wet. Just enough to get a good packed consistency, you should have a bit of excess liquid right around the tamper plate while it's running, but not much more than that. Get carried away with the water and you've got a new set of headaches. If you've got the fines in the material in question you should be fine ......If you aren't one of the one's I'm talking about,you shouldn't have any complaints....
Like the others said, a light spray is enough. The water acts as a lubricant which results in better compaction, and it doesn't take much, just the grains being wet. If it's sopping wet, the water fills in the spaces between the grains. Since water is incompressible, if the spaces are too full the material won't compact fully.
GravelGranite #573/4" - 1 1/4"(Base/Drain Use)
You can wet it as much as you want or not at all.
The only thing adding water to that sorted/graded gravel will do is make mud under it.
There are no fines in 3/4-1 1/4 gravel. The nomenclature means that the gravel has been graded so that there are no stones smaller than 3/4" and non larger than 1 1/4". There will be a very small percentage (=<1%) outside the range.
WAYNEL5; 61407.2, Ed Hilton; 61407.3, and a NY'er stuck in Oklahoma; 61407.6, are not talking about the same thing your dealer is.<!----> <!----> They are speaking of unsorted Crusher Run, or, of gravel that has only been sorted for the max allowed size.
Something like
GravelGranite1 1/4"-(Base)
The 1 1/4"- reads "inch and a quarter minus" and means everything from dust up to 1 1/4" in size.
Everybody is right about compacting <6" lifts.
I prefer a plate compactor with graded gravel, unlike "minus" grades when it is better to dampen and use a JJ or VR compactor.
SamT
we call them 57 stone and B base, its called B base because the highway book has it listed as a type "B" material.
You get the milkbones for that one Sam.
Good post, excellent advice.
Dave
Order some base material. Around here, it is a crushed limestone mix of small-ish rock ( maybe 3/4"?) liberally mixed with fines. Kind of a dirty tan color. Get it damp and pack well, and it's the devil to remove. Used for foundation and roadbed fill here.
I'm sorry, I thought you wanted it done the right way.
no problem - we have to remove humus and clay and recopact 18" of structural fill. For a shallow frost rpotected foundation, at least 18" of good draining gravel is needed.
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Everybody is saying gravel, which I will not dispute. But why not get a good sharpe sand and compact in lifts using water.
whole lot cheaper and just as effective.
But why not get a good sharpe sand and compact in lifts using water.
...because sand will wash out if there is any groundwater running under that slab. It takes a hell of a lot more water running a hell of a lot harder to wash out ¾-Net crushed stone.
We spec crushed rock with the two outside numbers. So what a lot of the boys are calling "¾-inch rock with fines" we will call ZERO/THREE-QUARTER meaning it's got stuff in it of any size between those two numbers.
Three-Quarter Net (or Washed) means just that; all chips are small enough to pass a 1" screen and too big to pass a ¾" screen. The 'fines' have all been washed out. This is the stone to use where you want flow-through conditions to deal with ground water.
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
I don't see anywhere in the original post groundwater being mentioned. If the mans got groundwater running under the slab , he will need a hell of alot more then crushed stone. Interior drain tiles, footing drains and a sump pump, would be more appropriate don't you think?
Um...he said this is a monolithic slab. On the surface. Not a basement. No footings. The slab is not going to be below grade.
Where exactly do you get the idea he's going to need interior drain tiles (interior to what??), footing drains (there are no footings), and a sump pump?
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.