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Heyd
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# Posted: 19 Jan 2024 18:28 - Edited by: Heyd
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https://geohydro.com/aggregate-piers-filling-gap/
https://www.researchgate.net/figure/Rammed-aggregate-pier-construction-process_fig2_2 73748893
What do you think about this method for building piers?
Have you ever seen or constructed these before?
How do you think they would fare against frost heave?
I had the thought to build them surrounded by 6 inches of rammed gravel to protect against horizontal ice lensing grabbing on to them. Your thoughts?
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spencerin
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# Posted: 19 Jan 2024 22:35
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Are these basically pits filled by compacted gravel to grade?
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Heyd
Member
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# Posted: 19 Jan 2024 23:25
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^ yes or alternatively small cinderblock-sized boulders stacked on top of eachother
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Steve_S
Member
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# Posted: 20 Jan 2024 06:01
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Honestly, if you are going to do piers, I wouldn't make ANY compromise that will likely come back to bite you hard...
I would suggest you seriously consider using a Bigfoot base for piers. These are available all over North America and many Big Box building supply houses have them in stock.
https://www.bigfootsystems.com/index.htm
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Brettny
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# Posted: 20 Jan 2024 06:50
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In clay soil those would fill with water and be worse than blocks on the surface.
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spencerin
Member
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# Posted: 20 Jan 2024 12:33
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If one is going to do all that digging and filling in, might as well do sonotubes. And, I'm not even sure it'll be cheaper than sonotubes. Aggregate isn't cheap. Sonotubes will likely be more reliable in the long run, too.
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ICC
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# Posted: 20 Jan 2024 14:15 - Edited by: ICC
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A quote from the first link... "Although in many cases aggregate piers can be used successfully, there are instances when aggregate piers are simply not a good match for the site subsurface conditions. Forcing the use of aggregate piers on the wrong site can cause considerable construction schedule delays and cost overruns. Knowing when to deploy aggregate piers, and when not to, can make or break a project. "
Sounds like an engineer's evaluation is required. Once an engineer is involved I think a full perimeter concrete or concrete block foundation is likely better and you don't need an engineer for that as methods are prescribed in the codebook.
Quoting: Heyd I had the thought to build them surrounded by 6 inches of rammed gravel
So a rammed aggregate pier surrounded by 6 inches of rammed gravel. Aggregate is crushed stone with angular edges and gravel is natutrally rounded stone with smooth edges. Right? I fail to see the practical difference as described.
I have seen rammed aggregate piers used in sandy, silty soil in an earthquake zone. They made a large grid of multiple rammed aggregate piers. The aggregate spreadout as it was compacted. Then a monolithic concrete slab was poured over everything. The concrete and steel-framed building was constructed upon that.
How would you connect your cabin to the rammed aggregate piers to provide lateral and uplift resistance?
-izzy
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Heyd
Member
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# Posted: 21 Jan 2024 05:16
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Quoting: ICC So a rammed aggregate pier surrounded by 6 inches of rammed gravel. Aggregate is crushed stone with angular edges and gravel is natutrally rounded stone with smooth edges. Right? I fail to see the practical difference as described.
My apologies for not making myself more clear: my thought was to do this with roughly discoid-shaped boulders the size of a CPU, not aggregate.
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spencerin
Member
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# Posted: 21 Jan 2024 14:10
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Why are you wanting to use this method? What are the dimensions (L x W x H) of the structure you're wanting to build?
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Heyd
Member
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# Posted: 21 Jan 2024 17:35
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^ there's no concrete supply where I'm building and honestly I just find the idea of using so much concrete for a small cabin foundation to be absurd.
As for dimensions: cabin would be 10×12 or 12×12.
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spencerin
Member
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# Posted: 21 Jan 2024 19:51
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You don't need to do all that work for a 12 x 12. Do block piers on top of a properly graded gravel pad for each pier.
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gcrank1
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# Posted: 21 Jan 2024 19:57
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I have used 'silo block' as the ground pads for two cabins bigger (1st in '83-'84) than yours with NO issues.
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Brettny
Member
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# Posted: 21 Jan 2024 20:55
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Cmu block right on the dirt for a 12x12. Level useing more concrete blocks or Pat wood. Dont need to over think such a small building.
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Tim_Ohio
Member
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# Posted: 22 Jan 2024 08:35
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This, thumbs up.
Quoting: spencerin You don't need to do all that work for a 12 x 12. Do block piers on top of a properly graded gravel pad for each pier.
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