How long does mortor have to be cured before it can be drilled and an
expanding bolt put in it. I am putting some decking along side a raised
pond. Sods law when drilling a hole to take a bolt it was too close to the
edge of concrete block and the edge broke away.
I repaired it but how long before I can safely drill it?

Kevin

Zen83237
wibbled on Monday 22 March 2010 17:25

How long does mortor have to be cured before it can be drilled and an
expanding bolt put in it. I am putting some decking along side a raised
pond. Sods law when drilling a hole to take a bolt it was too close to the
edge of concrete block and the edge broke away.
I repaired it but how long before I can safely drill it?

Kevin

Couple of weeks at least - preferably longer, for the mortar to get to any
sort of decent hardness. IME a strong mix will take plugs after a couple of
days, but no way for metal expanding bolts.

Given you've broken it once, now the repair is likely weaker, have you
considered using some chemical bolts (resin + stud) instead? There will be
no expansion forces so if you are confident of any pull or lateral forces
being OK on that bit, it will be a much stronger fixing and I think you
could safely proceed after a few days depending on how strong your mortar
mix was.

Expanding bolts near the edge of any substrate usually spells disaster

If you want to be cheap but still effective, Screwfix no-nonsense chemical
mortar/resin is OK (but needs the larger mastic gun, not the normal DIY
size). You might be able to get small volume tubs if you look around, or
even one shot capsules. A2 stainless rod from Toolstation or anywhere else
in 10 or 12mm would generally work out cheaper than a box of the "proper"
studs, and certainly much cheaper than the proper studs in stainless. A2 is
bendier than zinc passivated studs but in 10 or 12mm it is unlikely to be a
problem. I've used this technique to fix up bog cisterns and basins to
crappy thermalite block walls with much success.

All you need is to blow the hole out thoroughly and a bit of tube taped to a
car or bike pump which will work fine, or use your mouth if needs be on said
tube (it's only to blow the dust out from the back of the hole).

Half fill the hole with resin, ram stud in, clean up excess gunk (cut it off
with a screwdriver when it hits the plastic phase that lasts a few mins),
hold stud in place for 5 mins, leave for an hour or two then fit whatever to
it. Best to leave for a few hours before finally tightening everything up
fully (check the instructions).

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

On 22 Mar, 17:42, Tim Watts wrote:
Zen83237
wibbled on Monday 22 March 2010 17:25

How long does mortor have to be cured before it can be drilled and an
expanding bolt put in it. I am putting some decking along side a raised
pond. Sods law when drilling a hole to take a bolt it was too close to the
edge of concrete block and the edge broke away.
I repaired it but how long before I can safely drill it?

Kevin

Couple of weeks at least - preferably longer, for the mortar to get to any
sort of decent hardness. IME a strong mix will take plugs after a couple of
days, but no way for metal expanding bolts.

Given you've broken it once, now the repair is likely weaker, have you
considered using some chemical bolts (resin + stud) instead? There will be
no expansion forces so if you are confident of any pull or lateral forces
being OK on that bit, it will be a much stronger fixing and I think you
could safely proceed after a few days depending on how strong your mortar
mix was.

Expanding bolts near the edge of any substrate usually spells disaster

If you want to be cheap but still effective, Screwfix no-nonsense chemical
mortar/resin is OK (but needs the larger mastic gun, not the normal DIY
size). You might be able to get small volume tubs if you look around, or
even one shot capsules. A2 stainless rod from Toolstation or anywhere else
in 10 or 12mm would generally work out cheaper than a box of the "proper"
studs, and certainly much cheaper than the proper studs in stainless. A2 is
bendier than zinc passivated studs but in 10 or 12mm it is unlikely to be a
problem. I've used this technique to fix up bog cisterns and basins to
crappy thermalite block walls with much success.

All you need is to blow the hole out thoroughly and a bit of tube taped to a
car or bike pump which will work fine, or use your mouth if needs be on said
tube (it's only to blow the dust out from the back of the hole).

indeed, my fave (for more than the odd one) is a kids drink straw and
a vaccuum (sp) cleaner:-
insert straw to end of hole, hold vac nozzle as tightly around hole
with fingers to form as much seal as you can *leaving outer end of
straw open to air* , switch on - air sucked thru straw to deep end of
hole and then back out with all dust etc into vac - simples!

Cheers
JimK

Tim Watts wrote:
Zen83237
wibbled on Monday 22 March 2010 17:25

How long does mortor have to be cured before it can be drilled and
an expanding bolt put in it. I am putting some decking along side a
raised pond. Sods law when drilling a hole to take a bolt it was too
close to the edge of concrete block and the edge broke away.
I repaired it but how long before I can safely drill it?

Kevin

Couple of weeks at least - preferably longer, for the mortar to get
to any sort of decent hardness. IME a strong mix will take plugs
after a couple of days, but no way for metal expanding bolts.

Given you've broken it once, now the repair is likely weaker, have you
considered using some chemical bolts (resin + stud) instead? There
will be no expansion forces so if you are confident of any pull or
lateral forces being OK on that bit, it will be a much stronger
fixing and I think you could safely proceed after a few days
depending on how strong your mortar mix was.

Expanding bolts near the edge of any substrate usually spells
disaster

An alternative is the multi monti/thunderbolt type fixing, my weapon of
choice for attatching joists to walls when decking.
http://www.screwfix.com/prods/98732/...0MONTI-_-98732
Various sizes available of course. Some hire shops & BM's sell them loose
if you only want a few.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

Tim Watts
wibbled on Monday 22 March 2010 17:42


If you want to be cheap but still effective, Screwfix no-nonsense chemical
mortar/resin is OK (but needs the larger mastic gun, not the normal DIY
size). You might be able to get small volume tubs if you look around, or
even one shot capsules. A2 stainless rod from Toolstation or anywhere else
^^^^

Threaded stud

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

In article ,
Tim Watts writes:
Zen83237
wibbled on Monday 22 March 2010 17:25

How long does mortor have to be cured before it can be drilled and an
expanding bolt put in it. I am putting some decking along side a raised
pond. Sods law when drilling a hole to take a bolt it was too close to the
edge of concrete block and the edge broke away.
I repaired it but how long before I can safely drill it?

Kevin

Couple of weeks at least - preferably longer, for the mortar to get to any

Around 6 weeks to get almost full strength, but varies with temp,
water, additives, etc. For most purposes, full strength isn't
required, but an expanding bolt is probably a case where it is.
To be honest, an expanding bolt in mortar is probably not a good
idea in any case.

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

On Mar 22, 7:39*pm, (Andrew Gabriel)
wrote:
To be honest, an expanding bolt in mortar is probably not a good
idea in any case.

Indeed, even if it holds unless the bolt is stainless over time it
will corrode and fracture the mortar layer. Even without this,
expanding bolts are not particularly strong fixings compared to
alternatives.

Resin joint, Multi-monti, Fischer SX8/SX10 extra length.

"Andrew Gabriel" wrote in message
...
In article ,
Tim Watts writes:
Zen83237
wibbled on Monday 22 March 2010 17:25

How long does mortor have to be cured before it can be drilled and an
expanding bolt put in it. I am putting some decking along side a raised
pond. Sods law when drilling a hole to take a bolt it was too close to
the
edge of concrete block and the edge broke away.
I repaired it but how long before I can safely drill it?

Kevin

Couple of weeks at least - preferably longer, for the mortar to get to
any

Around 6 weeks to get almost full strength, but varies with temp,
water, additives, etc. For most purposes, full strength isn't
required, but an expanding bolt is probably a case where it is.
To be honest, an expanding bolt in mortar is probably not a good
idea in any case.

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

This one hole is only one of 5 on the piece of wood that I am bolting to the
side of the pond. I could just as easily redrill the timber then put the
bolt a couple of inches to the left or right but then to a pefectionist like
me I would have one fixing not equally spaced even though you wont see it as
it will be underneath the decking.

It is a 12 mm bolt and not taking a huge load so I think it will suffice in
this instance.

Zen83237 wrote:
How long does mortor have to be cured before it can be drilled and an
expanding bolt put in it. I am putting some decking along side a raised
pond. Sods law when drilling a hole to take a bolt it was too close to the
edge of concrete block and the edge broke away.
I repaired it but how long before I can safely drill it?

Kevin


this time of year, two to three days AT LEAST.