I am lifting the roof on an old pig farrowing barn to accommodate a
furniture restorer.

The roof is heavy but can be moved in one piece. So far I have raised
one side on Acrows and intend to lay two courses of brick to gain the
height needed.

What is a reasonable time to wait before heavily loading fresh
brickwork? I am particularly nervous of any side thrust encountered as I
start to jack up the other side.

regards
--
Tim Lamb

On 29 Oct, 11:19, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate a
furniture restorer.

The roof is heavy but can be moved in one piece. So far I have raised
one side on Acrows and intend to lay two courses of brick to gain the
height needed.

What is a reasonable time to wait before heavily loading fresh
brickwork? I am particularly nervous of any side thrust encountered as I
start to jack up the other side.

regards
--
Tim Lamb

I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed load,
but as you point out there is side thrust, and bricks not particularly
strong in that direction.

use a good 3:1 mix and suitable bricks, deep frog frettons as a
minimum, laid frog up, and fully filled ... or engineering if you have
them.

I would leave it 48Hrs ...

That seems very, very short.

Watching my brickies recently take off a couple of courses where
they'd made a mistake on a chimney stack, 2 days after they'd gone on
- they had not the slightest difficulty in such green mortar - still
very easy to clean off.

ISTR - a long, long time ago when I worked for Costain - the cure time
for mass concrete (in the Summer) was 4 weeks after the shutters came
off. Certainly when I'm using concrete, I'm surprised how easy it is
to chip for the first week or two - compared to how hard it gets
eventually.

In the current cold weather I'd plan on doing some other job - before
putting, as you say, a significant sheer load on your new courses.

You might find useful manufacturers data here - certainly their advice
on concrete I found useful:

http://www.lafargecement.co.uk/site_...ge/default.asp

In message
,
Osprey writes
On 29 Oct, 11:19, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate a
furniture restorer.

The roof is heavy but can be moved in one piece. So far I have raised
one side on Acrows and intend to lay two courses of brick to gain the
height needed.

What is a reasonable time to wait before heavily loading fresh
brickwork? I am particularly nervous of any side thrust encountered as I
start to jack up the other side.

regards
--
Tim Lamb

I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed load,
but as you point out there is side thrust, and bricks not particularly
strong in that direction.

use a good 3:1 mix and suitable bricks, deep frog frettons as a
minimum, laid frog up, and fully filled ... or engineering if you have
them.

OK. The brickwork will be Flettons for the first course and
semi-engineering for the top. Basically because that is what I have
lying about the farm:-) I can easily wait 3 days as I also have to fit a
wider door and re-plumb the electrical conduit.

regards
--
Tim Lamb

In message
,
" writes

I would leave it 48Hrs ...

That seems very, very short.

Watching my brickies recently take off a couple of courses where
they'd made a mistake on a chimney stack, 2 days after they'd gone on
- they had not the slightest difficulty in such green mortar - still
very easy to clean off.

ISTR - a long, long time ago when I worked for Costain - the cure time
for mass concrete (in the Summer) was 4 weeks after the shutters came
off. Certainly when I'm using concrete, I'm surprised how easy it is
to chip for the first week or two - compared to how hard it gets
eventually.

In the current cold weather I'd plan on doing some other job - before
putting, as you say, a significant sheer load on your new courses.

You might find useful manufacturers data here - certainly their advice
on concrete I found useful:

http://www.lafargecement.co.uk/site_...ge/default.asp

Interesting site.

They give 2 days = 16-26 N/mm2

7 days= 27-37 N/mm2

28 days= 37-47 N/mm2

for compressive strength on CEM 1 product.

I should be able to wait 5 days and get roughly half final strength.

regards

--
Tim Lamb

"Tim Lamb" wrote in message
...
In message
,
Osprey writes
On 29 Oct, 11:19, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate
a
furniture restorer.

The roof is heavy but can be moved in one piece. So far I have
raised
one side on Acrows and intend to lay two courses of brick to gain
the
height needed.

What is a reasonable time to wait before heavily loading fresh
brickwork? I am particularly nervous of any side thrust
encountered as I
start to jack up the other side.

regards
--
Tim Lamb

I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed
load,
but as you point out there is side thrust, and bricks not
particularly
strong in that direction.

use a good 3:1 mix and suitable bricks, deep frog frettons as a
minimum, laid frog up, and fully filled ... or engineering if you
have
them.

OK. The brickwork will be Flettons for the first course and
semi-engineering for the top. Basically because that is what I have
lying about the farm:-) I can easily wait 3 days as I also have to
fit a
wider door and re-plumb the electrical conduit.

regards
--
Tim Lamb

Tim,

Very temperature dependant: I've just laid 8 cu m of RC40 concrete and
it took two days in the current cold snap to 'not' take a finger
impression. Earlier in the year I laid a batch of the very same stuff
on a blazing hot day and we couldn't finish tamping before it set
solid (perhaps 1.5 hours from delivery)

Cement re-hydradtion (ie setting) is a chemical reaction and thus very
dependent on the temp. When it starts to go off though it is
exothermic - ie gives off heat.

AWEM

In message , Andrew Mawson
writes
Tim,

Very temperature dependant: I've just laid 8 cu m of RC40 concrete and
it took two days in the current cold snap to 'not' take a finger
impression. Earlier in the year I laid a batch of the very same stuff
on a blazing hot day and we couldn't finish tamping before it set
solid (perhaps 1.5 hours from delivery)

Cement re-hydradtion (ie setting) is a chemical reaction and thus very
dependent on the temp. When it starts to go off though it is
exothermic - ie gives off heat.

Hmm.. only a few degrees above freezing for the next few days:-(

I suppose I could make a temporary timber frame to support side 1 while
I move the acrows to side 2. Lots of extra work though.

I think I will avoid bricks with a high moisture content (stored
outside) and try poking the mortar after a few days. The wall plate will
be strapped down anyway. Temporary buttresses could be screwed to
various bits of concrete if it still looks dodgy.

Thanks all.

regards

--
Tim Lamb

In message , writes
On 30 Oct,
Tim Lamb wrote:

I think I will avoid bricks with a high moisture content (stored
outside) and try poking the mortar after a few days. The wall plate will
be strapped down anyway. Temporary buttresses could be screwed to
various bits of concrete if it still looks dodgy.

If the cement dries out too quickly it won't set to full strength. Ensure it
remains damp for a few days. Covering with polythene may do it.

This is a *damp* agricultural wall. No roof gutters, doubtful damp
course and probably impregnated with years of pig excrement. Drying too
quickly is unlikely to be an issue:-)

regards


--
Tim Lamb

On Oct 29, 10:54 pm, "Andrew Mawson"
wrote:
"Tim Lamb" wrote in message

...



In message
,
Osprey writes
On 29 Oct, 11:19, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate
a
furniture restorer.

The roof is heavy but can be moved in one piece. So far I have
raised
one side on Acrows and intend to lay two courses of brick to gain
the
height needed.

What is a reasonable time to wait before heavily loading fresh
brickwork? I am particularly nervous of any side thrust
encountered as I
start to jack up the other side.

regards
--
Tim Lamb

I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed
load,
but as you point out there is side thrust, and bricks not
particularly
strong in that direction.

use a good 3:1 mix and suitable bricks, deep frog frettons as a
minimum, laid frog up, and fully filled ... or engineering if you
have
them.

OK. The brickwork will be Flettons for the first course and
semi-engineering for the top. Basically because that is what I have
lying about the farm:-) I can easily wait 3 days as I also have to
fit a
wider door and re-plumb the electrical conduit.

regards
--
Tim Lamb

Tim,

Very temperature dependant: I've just laid 8 cu m of RC40 concrete and
it took two days in the current cold snap to 'not' take a finger
impression. Earlier in the year I laid a batch of the very same stuff
on a blazing hot day and we couldn't finish tamping before it set
solid (perhaps 1.5 hours from delivery)

Cement re-hydradtion (ie setting) is a chemical reaction and thus very
dependent on the temp. When it starts to go off though it is
exothermic - ie gives off heat.

The heat given off can be an issue with bulk concrete (they
incorporated cooling pipes in the Hoover Dam), but it's extremely
likely to be detectable for mortar joints between bricks - there just
isn't enough of it!

(But the point about temperature dependance is /very/ relevant.)

Martin Bonner wrote:
On Oct 29, 10:54 pm, "Andrew Mawson"
wrote:
"Tim Lamb" wrote in message

...



In message
,
Osprey writes
On 29 Oct, 11:19, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate
a
furniture restorer.
The roof is heavy but can be moved in one piece. So far I have
raised
one side on Acrows and intend to lay two courses of brick to gain
the
height needed.
What is a reasonable time to wait before heavily loading fresh
brickwork? I am particularly nervous of any side thrust
encountered as I
start to jack up the other side.
regards
--
Tim Lamb
I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed
load,
but as you point out there is side thrust, and bricks not
particularly
strong in that direction.
use a good 3:1 mix and suitable bricks, deep frog frettons as a
minimum, laid frog up, and fully filled ... or engineering if you
have
them.
OK. The brickwork will be Flettons for the first course and
semi-engineering for the top. Basically because that is what I have
lying about the farm:-) I can easily wait 3 days as I also have to
fit a
wider door and re-plumb the electrical conduit.
regards
--
Tim Lamb
Tim,

Very temperature dependant: I've just laid 8 cu m of RC40 concrete and
it took two days in the current cold snap to 'not' take a finger
impression. Earlier in the year I laid a batch of the very same stuff
on a blazing hot day and we couldn't finish tamping before it set
solid (perhaps 1.5 hours from delivery)

Cement re-hydradtion (ie setting) is a chemical reaction and thus very
dependent on the temp. When it starts to go off though it is
exothermic - ie gives off heat.

The heat given off can be an issue with bulk concrete (they
incorporated cooling pipes in the Hoover Dam), but it's extremely
likely to be detectable for mortar joints between bricks - there just
isn't enough of it!

(But the point about temperature dependance is /very/ relevant.)

Indeed. 2 hours to 2 days to just go 'crunchy' is the variation I have
noted. Over 0C-30C temp range.

"Tim Lamb" wrote in message
...
In message
,
Osprey writes
On 29 Oct, 11:19, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate a
furniture restorer.

The roof is heavy but can be moved in one piece. So far I have raised
one side on Acrows and intend to lay two courses of brick to gain the
height needed.

What is a reasonable time to wait before heavily loading fresh
brickwork? I am particularly nervous of any side thrust encountered as I
start to jack up the other side.

regards
--
Tim Lamb

I would leave it 48Hrs ... 24 Hrs is no problem if a simple daed load,
but as you point out there is side thrust, and bricks not particularly
strong in that direction.

use a good 3:1 mix and suitable bricks, deep frog frettons as a
minimum, laid frog up, and fully filled ... or engineering if you have
them.

OK. The brickwork will be Flettons for the first course and
semi-engineering for the top. Basically because that is what I have lying
about the farm:-) I can easily wait 3 days as I also have to fit a wider
door and re-plumb the electrical conduit.

regards
--
Tim Lamb


Tim .... my comment about 48 Hrs is a practical one, if you are using an OPC
& sand mix .... it would have enough partial strength after 48 Hrs.
If you have any doubt use rapid set cement ... or an accelerator additive.

If you can leave it longer then all the better.

Some of the other comments about exothernmic reactions, and time to
compressive strength are valid for bulk concrete, but not that relevant for
coursed brickwork.

Obviously the longer you leave it the more strength it has, but courses and
lintols (=dead load) are built up next working day on site.

On Oct 29, 11:19*am, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate a
furniture restorer.

The roof is heavy but can be moved in one piece. So far I have raised
one side on Acrows and intend to lay two courses of brick to gain the
height needed.

What is a reasonable time to wait before heavily loading fresh
brickwork? I am particularly nervous of any side thrust encountered as I
start to jack up the other side.

regards


would it be practical to add temporary wooden legs to the roof
structure so it sits on the original brickwork, then the fill-in
brickwork doesn't support the load. At a later date the legs could be
cut away and brickwork finished. Or perhaps timber legs, if they ever
deteriorate the roof will already be sitting on the newer fully cured
brickwork by then.


NT

In message
,
writes
On Oct 29, 11:19*am, Tim Lamb wrote:
I am lifting the roof on an old pig farrowing barn to accommodate a
furniture restorer.

The roof is heavy but can be moved in one piece. So far I have raised
one side on Acrows and intend to lay two courses of brick to gain the
height needed.

What is a reasonable time to wait before heavily loading fresh
brickwork? I am particularly nervous of any side thrust encountered as I
start to jack up the other side.

regards


would it be practical to add temporary wooden legs to the roof
structure so it sits on the original brickwork, then the fill-in
brickwork doesn't support the load. At a later date the legs could be
cut away and brickwork finished. Or perhaps timber legs, if they ever
deteriorate the roof will already be sitting on the newer fully cured
brickwork by then.

Certainly practical. Is it necessary?

Work is rarely scheduled on farms so there is always something waiting
to be done. Even in the current *overnight frost* weather it looks as
though half compressive strength will be reached after 5 days. My plan
is to get the brickwork done today (snow was melting off the roof
yesterday and dripping down my neck!) and get on with other things.

I see the danger point as when I start to jack up the other side to
match. The only thing preventing the whole roof sliding sideways will be
the new brickwork and wall straps. Elsewhere I have secured some strong
angle iron to the concrete floor and a wall and then used an acrow to
straighten the wall which was *leaning* from the damp course. I suppose
something similar could be done with a couple of timber
braces/buttresses to provide reassurance:-)

The mortar from a superficial pier I finished yesterday evening is
*biscuity* this morning.

regards

--
Tim Lamb