blinding layer, wack or not wack

[gravelrash]

Builder has spent day putting down blinding layer for insulation before concrete.  He has not wackered the blinding (50mm) sand, although some tamping before scraping. Is this normal practice? There seems very little advice in blinding hardcore. How do mcb and other icf foundation companies do it?

[markc]

Blinding should be compacted or it will compress when loaded

[SuperJohnG]

I didnt compact mine. It was 50mm sand blinding also prior to putting down insulated foundations, you can't compact sand.

 

I'm sure I asked the same question at the time as I was doing it myself. As long as the sand is fully filled it'll be fine. 

[SuperJohnG]

6 minutes ago, markc said:

Blinding should be compacted or it will compress when loaded

How do you compact sand? 

[markc]

Wacker plate or walk around on it or use a thumper ( never known real name, heavy block with a long handle).

often surprising how far it will compact … you are really just knocking the air pockets out of it

[gravelrash]

whacking will compress the voids... as when they block pave

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