Cracks in concrete

[aaront]

Been rendering my bathroom for the last few weeks. Did a large thick section last weekend and as its dried its developed deep cracks.

Is this a sign of the wrong cement/sand mix? Too much/little water? Or have i laid it on too thick (3/4 of an inch in places)?

Thanks for any advice.

 

[cobweb]

It could be any of the above or movement in the wall in question.

Did you mix as specified?
Was the new render to replace previously cracked - in a similar place - render?

3/4 seems a little heavy to me...perhaps two skim layers would have been better? Not that helps you now! Sorry.

 

[masona]

Sand & Cement are not really any good at 3/4" thick in one go,you've been better off using bonding plaster for that thickness.