I have installed a wood/coal burning cast iron insert and mantlepiece and have filled the space behind the insert with hardcore. I have been told, in the interest of safety, to skim the top of the hardcore with fireproof cement. All I can find is 2kg tubs of fire cement from Wickes which I have used to do some repointing inside the fireplace. Although relatively inexpensive, I would need quite a few tubs to put a screed over the hardcore. Is there a fireproof cement that can be bought in larger quantities or is there something I can add to normal cement? If not can I render with a sharp sand/cement mix then skim over with the Wickes fire cement? I have visited most of the builders merchants and fireplace suppliers in Bedford but have been greeted with blank expressions.
Any advice would be greatly appreciated.

Chris Learmouth wrote:
I have installed a wood/coal burning cast iron insert and mantlepiece
and have filled the space behind the insert with hardcore. I have been
told, in the interest of safety, to skim the top of the hardcore with
fireproof cement. All I can find is 2kg tubs of fire cement from
Wickes which I have used to do some repointing inside the fireplace.
Although relatively inexpensive, I would need quite a few tubs to put
a screed over the hardcore. Is there a fireproof cement that can be
bought in larger quantities or is there something I can add to normal
cement? If not can I render with a sharp sand/cement mix then skim
over with the Wickes fire cement? I have visited most of the builders
merchants and fireplace suppliers in Bedford but have been greeted
with blank expressions.
Any advice would be greatly appreciated.

You only need it around the inside edge of the fireplace,hence why they
only sell it in small 2Kg tubs
--
Sir Benjamin Middlethwaite

Chris Learmouth wrote:
I have installed a wood/coal burning cast iron insert and mantlepiece
and have filled the space behind the insert with hardcore. I have been
told, in the interest of safety, to skim the top of the hardcore with
fireproof cement.

I wonder what the exact reason is supposed to be. I'm not sure about
this technique at all. Do they really mean fire cement?


All I can find is 2kg tubs of fire cement from
Wickes which I have used to do some repointing inside the fireplace.

I have used Wickes fire cement. It's not as good as Purimachos
products IMO (but not bad enough to scrape out and replace).


Although relatively inexpensive, I would need quite a few tubs to put a
screed over the hardcore. Is there a fireproof cement that can be
bought in larger quantities or is there something I can add to normal
cement? If not can I render with a sharp sand/cement mix

Don't use strong sand/cement, it will crack up in very short order.
This is one place where a bag of sharp sand and lime (Castle, from
Jewson's or B&Q whorehouse) is the thing. You could use very weak
sand and cement (about 1:7 cement:sand) I suppose, but I'd use lime
at 1:3ish.


then skim over
with the Wickes fire cement?

I think that would be pointless...


I have visited most of the builders
merchants and fireplace suppliers in Bedford but have been greeted with
blank expressions.
Any advice would be greatly appreciated.

Talk to a solid fuel (fireplaces) place, they're usually quite
chatty.

On Wed, 14 Jun 2006 16:59:18 +0100, Chris Learmouth
wrote:

Is there a fireproof cement that can be bought in larger quantities

Talk to Purimachos in Bristol. Helpful and cheap, if you're avoiding the
retail layer.

Usually the face is a solid slab that you buy ready-made, the infill is
vermiculite and you only need a small tub of fire cement to fill the
gaps. There are also DIY recipes (concrete, but with vermiculite as
aggregate) if you need to cast something monstrous.

Chris Bacon wrote:

Don't use strong sand/cement, it will crack up in very short order.

the two I've done have remained uncracked for 8 and 4 years respectively.

Andy Dingley wrote:
Chris Learmouth wrote:

Is there a fireproof cement that can be bought in larger quantities

Usually the face is a solid slab that you buy ready-made, the infill is
vermiculite and you only need a small tub of fire cement to fill the
gaps.

It sounds as though he's got a cast-iron insert with no fireback,
rubble-filled behind in the normal way.

.. wrote:
Chris Bacon wrote:
Don't use strong sand/cement, it will crack up in very short order.

the two I've done have remained uncracked for 8 and 4 years respectively.

You must be lucky, then, it's cartainly not recommended. What
mix did you use?

Chris Bacon wrote:
. wrote:
Chris Bacon wrote:
Don't use strong sand/cement, it will crack up in very short order.

the two I've done have remained uncracked for 8 and 4 years
respectively.

You must be lucky, then, it's cartainly not recommended. What
mix did you use?

can't remember. 2:1 ? 3:1 OPC & building sand. there may be microcracks
in the flaunching but it all gets sooted up quite quickly. I also used a slurry
of vermiculite & cement to backfill the firebacks.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Chris Learmouth
saying something like:


I have installed a wood/coal burning cast iron insert and mantlepiece
and have filled the space behind the insert with hardcore. I have been
told, in the interest of safety, to skim the top of the hardcore with
fireproof cement. All I can find is 2kg tubs of fire cement from
Wickes which I have used to do some repointing inside the fireplace.
Although relatively inexpensive, I would need quite a few tubs to put a
screed over the hardcore. Is there a fireproof cement that can be
bought in larger quantities or is there something I can add to normal
cement? If not can I render with a sharp sand/cement mix then skim over
with the Wickes fire cement? I have visited most of the builders
merchants and fireplace suppliers in Bedford but have been greeted with
blank expressions.
Any advice would be greatly appreciated.

From another place.
How to make fire cement...

A good heat insulation material can be made either from mica or
pearlite.

Expanded mica granuls are sold as a soil adiditve to keep the soil free
drained, as isulation as is pearlite which is white beads of mineral.
Expanded mica is a better insilator whilst pearlite probably has the
advantage of highte compressive strength and may incandess better than
mica.

You can make any shape you with from either material by mixing enough
water
with the matereial to make it damp but NOT WET. You can then dust the
damp
mix with 'high alumina' cement, then when throroughly coated pack into
moulds of the correct shape. You must not use ordinary cement as it
will
not stand the heat.

Alternativly you can use sodium silicate, or commonly it used to be
called
'water glass'. You mix the sodium silicate with water and then use it
to
mix in with your agregate (the insulation). It sets to a glass like
material to bind the insulation together. The one problem is with it is
that it takes time to set, the two advantages are that it does not alter
the
reflective qualities of the agregate by coating it with a grey or black
cement, instead it is galss clear so the mica chips or the white
pearlite
still reflect heat and the gloss surface adds to this. At very high
temperatures the glass softens so becomes a little plastic. The great
advantage is that the 'stock' of sodium silicate not used will last for
donkey's years where the cement will go off and probably have to be
purchased in 20kg bags.

Sodium silicate sets by absorbing carbon dioxide either from the air as
it
dries or by blowing carbon dioxide through the material. Placing the
moulded material after sufficient drying to get it to hold up, in a
carbon
dioxide rich poly bag etc will speed up the curing.

Using methods like this you can make and re-make refractory and
insulation
materials from broken fire bricks. fired expanded clay pebbles and all
sorts
to suit your needs.

--

Dave