How bad are cement bricks?

[zeek]

I've had the dream of making a brick bbq grill and pizza oven combo for a long time and have been gathering pieces to make this a reality. I've now got a large collection of bricks, an extremely heavy steel/cast iron fireplace insert, and what appear to be a couple pieces of flue tile. I'm about to start excavating for the pad and have been surfing looking for inspiration which is how I found the FB site.

I seem to have picked up a large number of portland cement based bricks, which I was planning on using on the inside (firebox, oven), and I was going to put the red clay bricks on the outside, since I think the red bricks look a lot better. Reading around the FB site suggests that portland cement bricks are not up to the task for a firebox or oven.

How likely are the cement bricks to spall or crack? Do cement bricks hold heat well or are they good insulating bricks? I don't really have any spare funds to buy fire bricks right now so I'm not really sure what to do if the cement bricks are not up to the task.

What are good uses for cement bricks -- structure?

[brickie in oz]

Originally Posted by zeek

How likely are the cement bricks to spall or crack?

Very, they will fail at the lowest of temperature and you will be eating concrete, do you like concrete pizzas?

[dmun]

Yep, portland cement decays rapidly in direct exposure to heat. If it's a zero budget project, put your clay bricks on the inside, and your concrete bricks on the outside. And no matter how low your budget is, don't skimp on insulation.

My advice? Keep looking. Scan craigslist and freecycle. Talk to masons. You'll find someone with a pile of firebricks, at least for your floor. With any luck you'll find finish bricks for your exterior that you don't have to chip mortar off of: You're likely to be sore and discouraged before you lay a single brick.

[Ken524]

For really inexpensive new bricks, visit a local brickyard and see if they have any piles of partial pallets. Our local yard has seconds and leftovers for 50 cents each (USD). There are plenty of matching bricks for small projects.

[roofcoatings]

If you are going to make a cement brick, i suggest you to not use it because it will not work for a long time, i suggest you to use some coatings to make the fireplace strong or consult some service provider but make sure before consulting him he should have his license, because the only license holder take the responsibility till the warranted time.
Best of luck

[DimTex]

Another place to look for inexpensive firebrick is to visit homebuilding sites and ask around. Many times they have leftovers from building the fireplace. Craigslist and Freecycle are also good alternatives

[Willox Perez]

Roofcoating is right!! You should not go for cement bricks because it will not last long.it w'd be better idea to do coating for strong fireplace.