Refractories - Crushed Firebricks and Portland Cement

No. At much over 400F to 500F it will probably blow apart.

Make up a small batch and test it, wear safety glasses.

if i have crushed firebricks then, what could i use to this mixture to line a furnace?

There's nothing you can use crushed firebrick for, except perhaps a hearth lining.

A better option is to go with a blanket type insulation. Overall, less expensive that brick, with greater insulating properties.

http://materials.globalspec.com/datasheets/4194/LITIndustries/16E15BDA-64E0-42DE-9D96-D317463AC538

Sodium silicate, chopped fiberglass or rock wool, and your crushed firebrick. You'll have to experiment with the quantities of each and the mix of particle size on the crushed firebrick. Chopped fiberglass is used to reinforce concrete shapes when extreme structural strength is not needed such as in flower pots, benches, garden decorations, etc., even burial vaults. Stay away from Portland cement in the mix. It tends to spall at elevated temperatures. Anyway, I would not use this mixture for temperatures much greater than 500F without a lot of testing.

You might also talk with some pottery people about using thick slip as the binder for your crushed firebrick.

For furnace lining, there are quite a few castable refractories available from industrial suppliers.

Mixing the crushed firebrick would be a bad idea. It would be a self defeating action.

I would love to hear if you have a lot of the crushed refractory.

You can use the crushed brick as filler with several binders and have excellent firebrick or sprayable liner.

Below are several binders that would be good choices

MgPo4

MgChl2

Alkalai activated alumino-silicate

Sodium silicate based binders.

There are more but I would rally need to know more about what the parameters are you are trying to meet.

well,i have a large bag full of the stuff.

i was hoping to use it in a mixture to line a homemade furnace with minimal cost/ expendature involved...

but by the sound of things, its not such a good idea afterall :(

How big is your furnace and at what temp.? There may be other ways for very little or no money.

Crushed fire brick can be used as aggregate in aluminite concrete. 309 or 310 stainless steel needles can be used as re-enforcement.

I have read that when firebricks are made they use crushed fire-clay and crushed reject firebricks...called grog. That is then mixed with fire-clay and fired again making the firebricks.

Could you mix your bag of grog with fire-clay and then fire the furnace slowly to fire the fire-clay mixture?

well, i have the drum ready together with a wooden former for the inside of the furnace, but all i need is a mixture that would withstand plus minus 1500*C. i was hoping that by combining portland cement and crushed firebricks i could make this mixture... what do you guys reckon?

1500C! That is VERY hot! What fuel do you plan to use to acquire such temperatures?

Why not check with local scrap dealers for a source of used firebrick.

Indeed...I glossed over that thinking 1500 F...

Here's a neat site that might give you some ideas on refractories.

http://www.backyardmetalcasting.com/

By the way, if you are making a foundry, I'm really jealous! I have wanted to make a foundry for a while, but more essential projects always seem to get in the way...roofing the house, tiling the bathroom...

Check your local brick yard for fire-clay mixes.

Mix your grog with refractory cement and use this to fill in and cover your fire brick lining.

Test your system first and take precautions.

Harbison-Walker NO 36 REFRACTORY CEMENT is good to 3200F.

But the help of some one who builds high heat furnaces is recommended.

Brad

thanks for everyones input. i know now

for certain plain portland cement in the mix

definately wont work.

thanks again.