building with breeze blocks

[Jsmithy]

Hi everyone,

I wanted to know if i can build on top of concrete blocks with breeze blocks(the furnace ash type) medium weight.
i had to use sold concrete as halfway t first floor was retaining wall filled with c35 concrete, i need to get more blocks to finish first floor to wall plate, and wondered if i could go for breeze instead than the heavier concrete,
thanks for input

 

[^woody^]

Yes

 

[Jsmithy]

thanks woody,
a mate said they could expand at different rates and might crack? is there any truth in this?
the wall is 6.3m long
thanks

 

[^woody^]

Your mate is not that clued up

Blocks don't expand.

Wall contraction (ie initial shrinkage) will depend on the mortar not the blocks

You'll be OK for what you are using them for