Filling void under concrete from settling soil


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Old 05-11-16, 06:51 PM
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Question Filling void under concrete from settling soil

The soil around my house has settled about 2-3 inches. This has left voids under some of the concrete walkways. One of them cracked, but most are still in one piece. I am looking for a way to fill the voids under them to keep them intact. I would like to do this myself if possible.

I have been researching what to do, and it looks like spray-in polyurethane foam is the best way to go. Will any expanding PU foam do, or is there a particular type for this kind of use? Is there a better way?

Side note: this is not a drainage issue, it is from a soil compaction issue when the house was built 50 years ago.
 
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Old 05-11-16, 07:04 PM
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You will have to wait for the pros but I'd probably make up a stiff batch (low slump) of ready mix concrete and force it under. If the ground sinks more you can dig it out and redo.
 

Last edited by ray2047; 05-11-16 at 09:24 PM.
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Old 05-11-16, 07:55 PM
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I would buy a few bags of clean silica sand and fill it with that, using compressed air or water from a garden sprayer as needed to get it to flow back where you need it to. Then cover it with topsoil. No way would I use foam.
 
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Old 05-11-16, 09:29 PM
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To clarify my answer I would only put the concrete under the step. After it started to cure I'd fill in next to the step with dirt. To me that is easier then trying to compact the sand and keep it in place while you fill in the dirt. But that is just gut guessing not from experience.
 
 

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