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Gravel vs. stone

Porsche998's picture

I am in the process of leveling a to pour footings in rock that has been blasted,  I need to bring the height up about 1-2 feet.  The contractor has said the I need to use stone at $200 a load rather than gravel at $140 a load (both 1 1/2 inches).  It would seem that either would do and the stone should be fine.  Any thoughts?


 


Thanks

(post #55878, reply #1 of 10)

if you can get perfect compaction.. either would do... but you will probably have better success with the stone...

Mike Smith Rhode Island : Design / Build / Repair / Restore

              www.mfsmithbuilder.com

(post #55878, reply #2 of 10)

Everytime the subject of rock or stone comes up here, I'm always amazed at how the terminology does vary from region to region.


So I'm going to just assume here that when you say "stone" you are referring to crushed rock and when you say "gravel" you are referring to unbroken pebbles or river stone screened to a certain size.  Not knowing your location, I can't speak to the cost difference or your terminology so bear with me:


If my assumption is correct, then crushed rock is definitely preferable for fill and compaction because, unless it is purely screened to size, it will consist of broken rock from sand/grit size to 1 1/2" and all sizes in between (and probably a small percentage of dirt, a good thing, actually) with jagged uneven edges.  Such a material bonds together really well, with most voids being filled during compaction, the friction between the broken edges and faces limiting the movement of individual pieces and the fines and dirt serving to kind of "cement" it together.


Stone, or what I think you're calling gravel, on the other hand, will be mostly of one size and will remain somewhat loose with a lot of voids even with compaction.


For the record, here in the Pacific Northwest, if I was to order "gravel" for the purpose you describe, I would specify the largest size (in your case inch and a half) with the term "minus" to indicate I wanted the mix of fines that result from crushing to be included.


If I wanted "stones" I would specify "inch and a half open."


If I wanted drain rock, or river pebbles I would spec the rock size and expect it to be consistent to the size ordered.  (Pea gravel: pea sized.  Inch and a half drain rock: river stone of mostly inch and a half size.  Cobbles: large riverstone, usually used for stone masonry or decorative work. Pit run: boulders created during blasting in a quarry that have not been processed, used for heavy service, like dikes, revetments, jetties, major fills, etc,)


If you get more responses here, you'll probably see different terminology for what I've basically described, plus there are probably other factors due the the diverse geology of North America. 


(And I've given just a sampling of the range of rock specifications).


 


 



Jules Quaver for President   2004


Edited 2/5/2003 11:40:42 PM ET by Notchman

 

(post #55878, reply #3 of 10)

here, gravel is just that ... with "bank-run " being the most common..


 any thing that modifies "bank-run " makes it "processed gravel" which means it may have been screened to take the bones out, or a binder may have been added and mixed ..


a good digger knows which yards are selling  which kind of bank-run for specific jobs..


 stone is stone... either crushed and screened or just screened...


3/4 " stone will pass a 3/4 screen but not a 1/2" screen..


1 1/2" stone will pass a 1.5" screen but not a 1" screen.


 if the poster doesn't have the knowledge or the equipment to compact the gravel, he'd get more uniform bearing with the stone  than with uncompacted gravel


but hey, whadda i no ?

Mike Smith Rhode Island : Design / Build / Repair / Restore

              www.mfsmithbuilder.com

(post #55878, reply #4 of 10)

Yeah, that's what bothered me about even responding to that post.  I've seen threads here in the past and was unfamiliar with all the regional terms and specs that showed up.


I worked for a sand/gravel/concrete outfit for about a year and mostly running heavy equip and the crusher.  We were crushing mostly for US Forest Service and BLM logging roads so the specs were for crushed rock of different sizes, depending on the "lift" or layer they were putting on the roads at a given time.


But the terminologies used in that application are the same we use in general out here whether the end use is a road bed, road topping, compacted base for concrete footings or slabs, etc. etc. 


Rock for ready mix concrete also has various specs than can be requested although standard mixes in my area use screened and washed 3/4" river stone proportioned with 1/8" river sand.


Most of the rock here is basalt. 



Jules Quaver for President   2004


Edited 2/6/2003 12:09:25 AM ET by Notchman

 

(post #55878, reply #10 of 10)

In the Denver area, 25 years ago when I worked for the lawn sprinkler company, crushed rock was crushed rock that would fit through one screen and not the next smaller screen. Round rock or river rock was the same way. The stuff that had all different sizes from sand on up was called road base. I never heard anybody order mixed sizes of crushed rock or round rock without fines, so I don't know how they specified that. The concrete guys may have had a different vocabulary than the sprinkler and landscaping guys. I don't think I ever heard anyone refer to gravel of any size or composition as stone.

(post #55878, reply #5 of 10)

I don't know if the contractor you refer to is an excavation/dirt work guy or the building contractor.

Assuming that he is a real 'contractor', that means he has a vested interest in doing it right, ie. who is responsible for cracks in the foundation?

He didn't just tell you what to use to make more money. The difference is probably in the yard cost and he makes the same money for hauling twelve yardss of either so don't be suspicious of him. It sounds like he's on your side.

.

Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #55878, reply #6 of 10)

As stated in previous posts terminolgy varies in regions. That stated if I'am going to pour footings and I have a overdig or have to raise grade before railing footings, I want something that is compactable, (100%crushed stone, crushed concrete) these materials will have a certain amount of crusher dust and fines that give material some binding. and when compacted with a vibaratoral plate, get hard like ####. If you compact it you will probably average approx. 95% compaction. You won't get that with round stone, it doesn't compact.   

(post #55878, reply #7 of 10)

dan... it does compact if it is confined... the poster's description s"sounds" like it is trenches , so whatever material he uses could be installed and compacted in lifts..


the average dude will not compact to 95%.. so the stone would give a more uniform bearing, uniformity being alsmost as desireable as full compaction

Mike Smith Rhode Island : Design / Build / Repair / Restore

              www.mfsmithbuilder.com

(post #55878, reply #8 of 10)

Thanks for all your input-


To answer a couple of questions - the work is in the Northeast and the contractor is the excavator.  I had costed out the job at 10 loads @ $1400 through contacting the local gravel company.  When the excavator called to start the work he stated that the cost of the fill would be $200 a load or $2000, I questioned the difference and he said the difference was that his $200 cost was for stone and the $140 was for gravel. 


Thanks for you help.


 

(post #55878, reply #9 of 10)

I spent the better part of my youth excavating in CT, and we'd call gravel a mix of small round stone and sand, of random proportions, and generally dug as-is from mother earth.  Stone was just that, no sand or fines, unless you asked for it, and could be crushed or round.  These terms were the commn vernacular, and I'm assuming that's how he's using them. 


If you're pouring footings on blasted ledge, your contractor may be anticipating ground water over or through the existing ledge, and the rock would provide better drainage and stability than gravel, without any fines to wash away or move.  It seemed that every other job I worked on in southern CT required some blasting, hammering, or redesign to avoid it, and water could show up anywhere, and often did in basements.  If there's a large hill or ridge above the site, expect ground water running along the ledge, and where it will show up is anyone's guess (and your footing trenches would be a good guess).


I'm not a soils and foundation engineer, so don't take the above as expert advice.  It's just the common wisdom from the companies and people I worked for, and the fact that I grew up where you couldn't put a shovel into the ground more than 6 inches without hitting something hard.  Ask you contractor why he wants stone instead of gravel.  If he's a decent guy, he'll give you a decent explanation.  But everything is sitting on this base, so think carefully before you insist on the lower cost fill.


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