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Clear rock, self compacting?

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JRremodelers

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Discussion starter · #1 ·
Geotechnical engineer is telling us we need to add clear rock throughout the bottom of basement excavation - not just the footings. Anyways, is compaction required? Excavation company contractor said it’s not necessary. But it seems in our case it may seem so.

We hit water down in the excavation and standing water causes that 1st inch to be soft.i would imagine just pouring clear rock on that and leaving it be wouldn’t be adequate. I do, however, feel that using the skid steer tracks as mean of compaction would be adequate in this case.




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#2 ·
never heard the term "clear rock" which i'm guessing to be wash rock.

anything i have ever seen put in as fill was put in in lifts and compacted.

only way around this is to use Controlled Density Fill (CDF) otherwise known as a slurry mix.
 
#3 ·
I'll read a little more into this.

The engineer said you need to quickly put rock in all over when you get the hole dug to stabilize the sand. He isn't even talking fill and compaction yet.

Does that fit?
 
#4 ·
The undercut project I referred to in the other thread we put down what we call here #2 stone. Which is crushed blue stone that is 2" to 3" pieces with no stone smaller than 2" and contains no fines. We put in 2 feet of that stone.

Then we topped that with what we call #57 stone which contains crushed blue stone that ranges in size from 3/4" up to 1-1/2" and contains no fines. we put in 1 foot of the #57 stone. We were not required to compact any of the stone as it was installed.

So the answer is yes the stone product is essentially self consolidating and does not need to be compacted, as long as you are using the correct product. I, like you, would still track it in with a machine just to make sure.
 
#5 ·
JRremodelers said:
I do, however, feel that using the skid steer tracks as mean of compaction would be adequate in this case.

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Just to be clear, if you don't have a pretty substantial lift of stone, tracking it in will just ruin the subgrade by pulling the mud up into the clean stone. Another reason we use filter fabric in the hole.
 
#6 ·
I think what's being referred to is what's commonly know as #57 clean, crushed stone. Here it's typically called 3/4 clean. It's crushed granite that pretty much compacts in free fall, but it's usually run over with a plate compactor.
 
#9 · (Edited)
River rock, aggregate that is mostly spherical that is near just one size never realy compacts....

crushed rocks will pack better then rock that has rolled down several hundreds of miles of creeks and river beds

Unless you built on an artesian well, anything over 4" thick of sub slab rock is waste in my opinion, wall footings with inside and outside tiles run to day light( Gravity NEVER fails) or a sump out side and back up system, indoor spring drainage, window well failures.

Don't forget the vapour barriers, I'd consider the newer spread footing liner/vapour barriers to reduce basement moisture issues.

At some point, use some geo grid between rock lifts to increase strength and reduce thickness of rock.

Raising the FFL Might be cheaper and provide some flash flood resistance..
 
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#10 ·
Never heard of clear rock, but washed pea gravel can be dumped into an excavation without compacting it. If you have a deep trench you don't want to enter and need to backfill it in a hurry, it's not a bad way to go.

I don't like it directly under concrete pours as it shifts around walking on it leaving hills & valleys. If it's going under a pour, I would cover it with a filter fabric, then top with a few inches of compacted crushed stone or bank run that would hold it's shape better.
 
#12 ·
In general, the harder to consolidate blends of aggregate have lower angles of repose( the pile is "flatter")

A bucket with compacting rock placed in it will "shrink" more when shaken/vibrated...... then fill that is sorted to just one or two sizes of rock.
 
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#14 ·
Fouthgeneration said:
In general, the harder to consolidate blends of aggregate have lower angles of repose( the pile is "flatter")
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I'd disagree that it's significant.

Big rock, various crushed and screened, tar, road mix for compaction, topsoil, it all turns out about the same angle of repose. It's one of the reasons code can use 45 degrees and not specify what the stuff is.
 
#15 ·
It is the difference between laying round glacial rocks vs prism shaped quarried stone, you can dry stack a 60 foot tall tower out stones with two faces parallel to each other, not so much with marbles....

Cracked concrete made with crushed aggregates has added strength then aggregates made up of water formed mostly rounded shapes, all other things being equal....

Crushed gravels spread loads at greater angles then rounded products, resulting in stronger road paving systems.
 
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#16 ·
Fouthgeneration said:
It is the difference between laying round glacial rocks vs prism shaped quarried stone, you can dry stack a 60 foot tall tower out stones with two faces parallel to each other, not so much with marbles....

Cracked concrete made with crushed aggregates has added strength then aggregates made up of water formed mostly rounded shapes, all other things being equal....

Crushed gravels spread loads at greater angles then rounded products, resulting in stronger road paving systems.
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Like I said, even topsoil.
 
#17 ·
dayexco said:
I would say yes, any material can have voids, shake them out of there

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That's how I feel.

Clean stone requires much less compaction, but it never hurts to run a tamper over it a few times.
 
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