In article ,
YAPH writes:
Is there such a thing? The boiler I have to replace on Monday will have
one of its fixing holes in the hole which I'll have to block up from the
large un-fanned flue of the boiler I'm replacing.

There are various ways I could work around the problem but the ideal would
be a mortar that sets in, say, 30 mins - 1 hour.

Cements/mortars take weeks to reach full strength, and this is a case
where you need full strength, not just set. Plaster doesn't have the
same strength.

I would look for something which reaches full strength much faster,
such as one of the resin suggestions, possibly mixed with some fibres.

If you can get a brick well mortared in the hole, such that the fixing
goes into the brick and not the mortar, then a fast setting cement
might just be acceptable, if you can drill the hole without vibrating
the mortar to bits (or if you're really clever, before you mortar the
brick in;-).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]