I have recently broke up my old concrete shed base which was 100mm thick, I also have quite a lot of gravel. The broke up shed base is quite large chunks of concrete so could I use that a long with the gravel as a sub base for the new concrete base I am about to lay? The chunks are a range of sizes from 20mm to about 90mm. Would it be ok for me to whack it down? Or should I just buy some proper stuff. The new base is for our new summerhouse.

Thanks for looking.


  • This is the way road work is done... the old (concrete) road is broken up with a sheeps foot road roller and new concrete is poured on top. – Ben Welborn Jul 28 '16 at 13:02

Crushed concrete is a very good substrate for a slab. The key is to not have chunks so large that air pockets are created. Maybe bring in a layer of sand to fill the voids and level things a bit. A water rinse will help bring air out and compact the material.

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