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Crushed concrete as aggregate under basement concrete slab

bongo30 | Posted in General Questions on

Can 3/4 crushed concrete be used under basement concrete slab? The only other option we have is 3/4 bluestone gravel and it’s twice the cost. Thank you.

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  1. Expert Member

    B30 B30,

    Sure, for the majority of the substrate, but because crushed concrete will take up water much as the slab itself would, you will still need to top dress with a thin layer of stone as a capillary break.

    1. bongo30 | | #3

      If that’s the case, it probably just makes sense to do all stone instead of crushed concrete. It’s only 4” of aggregate under the slab, doesn’t make any sense to mix both. Thank you!

  2. plumb_bob | | #2

    Ask your local inspector. The code I use (BC) requires a clean granular material with no fines, so if the material you are proposing conforms then it may be allowed. In principal I do not see a problem.

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