Chemical grout on organics 3

[pelelo]

Experts,

I am working on a remediation plan (sinkhole) of a property in which the shallow soils (4 to 6 ft) are composed of organics.

As part of the remediation plan, I was going compact grouting and in the top 10 feet chemical grout. Since chemical grout doesn't work in soils with high amount of fines (organics), do you think that by only underpinning the whole property it could be enough?, or do you know if there is any alternative to this?

Please let me know,

Thanks

 

[dik]

They often use cementitious grouts for pressure grouting soils when constructing large dam projects to help ensure that no water will leak through the base material.

I don't know what sort of volume you are looking at and there is the possibility that some of the grout will work its way through the organic material.

Dik

 

[oldestguy]

If you have the bucks go ahead with Portland cement grout. Only don't put a quantity limit on the contractor because pressure injected grouts sometimes take crazy routes and quantities may be much more than first estimated. Be prepared for sewers nearby to get plugged or house basement nearby filled.

 

[pelelo]

Gents,

Thanks for your comments.

The problem is that at this time, the organics are between 8 and 10 feet deep. when we grout (compaction grouting), we grout up to 10 feet below ground surface to avoid heaving.

So pretty much, the organic issue remains.

Chemical grout doesn't work in high fine contents.

 

[Okiryu]

pelelo, can you start injecting below the organic layer? If not, you may underpin and then use chemical grouting for repair the sinkhole. If chemical grouting does not work for the organic soils, it does not matter because you will underpin. Is the floor slab, a slab-on-grade or structural slab? Also, check with the grouting company if there are any additives for Portland cement that can be used for dealing with organic soils. Anyways, appears to be an expensive repair.

 

[pelelo]

Okiryu.

1 - Yes, I can start injecting (grouting) below the organic layer, that is not a problem.

2 - Yes, the plan is to do both Underpining + compaction grouting. I understand your comment when you say "If chemical grouting does not work for the organic soils, it does not matter because you will underpin". Based, on your comments, then what is the point of chem grout then?. Most of sinkhole solutions around my area use Underpin, compaction grouting and chemical grout.

I know that compaction grouting is usually done up to 10 ft below ground level, in order to avoid heave. That means that there are 10 ft of soils "unimproved", but again, yes, if underpins are being placed, then i don't see the point of improving the top 10 ft as the structure will be supported by the underpins.

In case, the improvement is only compaction grout, and no underpins, that's a different situation. In that case, I do understand that Chem grout will play a critical role as the top 10 ft will need to be improved.

3 - It is a structural slab.

Thanks

 

[Okiryu]

I think that your grouting is not providing any structural support, the grouting is there to just "fill the voids". Structural support is provided by underpinning of the foundations. For lateral loading, grouting to fill the voids may provide some lateral support for the underpinning elements or friction under the foundations. For the floor slab, it is good that you have a structural slab.

 

[dik]

He could use a lean mix CLSM type of material... maybe mix designed for economy.

Dik