Harry Bloomfield wrote:
explained on 13/03/2005 :

Lobster wrote:

I've got an old brick shed with a concrete slab roof; watertight at the
mo, but in one corner (external) the surface of the concrete has broken
up under the influence of weather; probably an inch deep? in a 4-5 inch
slab.

3:1 is the strongest non-shrinking mix, and just a little pva makes it
adhere better.

Thanks guys. Are we definitely 100% sure about the PVA thing? :-) I
always thought it was a complete no-no outdoors. and wouldn't want to
cock this up...

Then once properly dry, consider adding a waterproof membrane to prevent
water getting into and freezing in the concrete again.

How do you mean, paint-on bitumen type stuff? Aquaseal? Or felt of some
sort? Wouldn't just adding waterproofer to the cement mix do the job
(or would that interact with PVA?)

Thanks
David