Retaining wall base


Old 06-24-18, 07:26 AM
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Join Date: Aug 2015
Posts: 13
Retaining wall base

Hey all, i recently started a project with a friend of mine and we are using 3/4 inch rock for the retaining wall base. This rock seems kind of squishy when walked on, and it has me concerned. For me, it seems to have the same "properties" as pea gravel, although its not nearly as bad. There is 6 inches of rock here, and the surface below it was compacted and is very solid. The wall will be a little under 4ft.

Please see the pictures and let me know if I should replace this base, or at least try to mix in some sand with it?
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Old 06-24-18, 01:12 PM
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Join Date: Mar 2003
Location: NC, USA
Posts: 18,729
That stone doesn't look as sharp and angular as my crushed stone but the varying sizes and angular shape should allow it to work well. I would NOT try to mix in sand or anything else to "firm" it up. Compaction should firm it up and if you're not compacting before setting the blocks then the weight of the wall will solidify it quite nicely.

I normally use #75 crushed stone. Even after running over it with a plate compactor you can still leave foot divots when walking on it. It doesn't firm up as hard as a stone blend like crusher run that has more particle sizes all the way down to dust. So, in spite of seeming "soft" it's great at supporting the weight of a load. And, the clean stone allows water to freely drain away which is a huge benefit.

As for setting the wall... make sure all the blocks in your first course are completely level and set at the same height. Get the first row perfect and you'll fly through setting all the blocks above. Minor problems at the bottom tend to magnify as you go up so you can't bury problems.
Old 06-24-18, 07:15 PM
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Join Date: Aug 2015
Posts: 13
Thanks for the info, it makes feel a ton better. I'm going to get some geogrid for this project for peace of mind.... seems it is required anyway due to my 45 degree angles, and the stone I'm using.

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