Whether you are building an amazing pizza oven, a gorgeous and fully functioning fireplace to complete your backyard oasis, or even a forge/furnace, it is important to have a good recipe for making your own refractory cement right at home.
Whether you are completely unsure of how to begin this project or simply need a quick refresher course on refractory concrete, the following information is exactly what you are looking for.
In addition to looking at several simple recipes for refractory concrete that any D.I.Y’er can do, we will also examine several alternatives to refractory cement.
Thank you everyone!
Last time I posted a questionnaire asking "Why do you want to make refractory cement" and 189 amazing people responded with great information, a massive 80% of you wanted to make a Pizza Oven or Other outside Oven, Which is great! some other remarkable uses were for:
- Forge for blacksmithing
- Foundry for melting metal
- Rocket stove (very cool look them up if you haven't heard of them).
So I looked around the internet for plans and a great guide to link to on how to build an outdoor pizza oven and I couldn't find one that had all the information, some good videos but missing plans.
I'd love to make a guide on how to make a pizza oven from scratch with full plans in both metric and imperial and I realized it could be a great way to help support the site with hosting costs and my time and effort into putting it all together as one all-in-one guide.
I understand there is a lot of information on making pizza ovens online but it's never very comprehensive and you have to spend hours looking at multiple sources to get some idea of what to do and often the source information isn't fully something you can trust.
So the question is if I did, would you pay for it and how much? I've created another questionnaire here (click to answer):
Please note: this isn't a contact form and I can't reply to your queries/answers via it, sorry.
Refractory Cement Recipe #1
What You Will Need:
- Portland cement (You can purchase a 94 lb. bag at your local hardware store for less than $10.)
- Perlite (Can be purchased for $10 to $25.)
- Silica Sand (A 50 lb. bag costs less than $25.)
- Fire clay or Well drillers mud (A 50 lb. bag averages less than $10.)
1.5 parts Portland cement + 2 parts Perlite + 2 parts silica sand + 2 parts fire clay
What to Do:
Using the portions listed measurements listed above, mix the Portland cement, Perlite, and silica sand together thoroughly.
Combine the mixture with 2 parts fire clay.
Once the mix has the consistency of stiff cookie dough, pack it into the performed form. You may need to add a little bit of water to get the right consistency.
Allow it to dry for several days.
Refractory Cement Recipe #2
This recipe is an excellent option if you can find ready made furnace cement. (Many home improvement stores do sell it in ½ gallon buckets for $12 to $20.)
What You Will Need:
- Furnace cement
Formula1 part Furnace cement + 4 parts Perlite (This is by volume. For example, if you use ½ gallon of Furnace cement, you will need to purchase 2 gallons of Perlite.)
What to Do:
Mix the ingredients together thoroughly using the above measurements. Be sure to stick to the formula. If you use more than 4 parts Perlite for each part of Furnace cement, the results will be weak. However, if you use less than 4 parts Perlite for each part of Furnace cement, it will take forever for it to seal.
When the Furnace cement and Perlite are combined, you will get a consistency that is very sticky to say the least. If you add around 2 cups of water per gallon of cement, it will be much easier to work with because it will have a consistency comparable to thin plaster.
Form your preferred shape and allow to completely dry.
If your looking to make a furnace check out this video series: How to build your own D.I.Y Foundry for casting and refining.
Refractory Cement Recipe #3
Note: This recipe is for absolute bare-bones refractory cement.
What You Need:
- Pure Perlite Standard 2.0-5.0 mm
- Fire cement rated a minimum of 1400⁰F or higher. (Make sure it is at least 1800⁰F for brass.)
4 parts Perlite + 1 part fire cement
What to Do:
- Mix Perlite and Fire cement using the above measurements.
- Allow it to try for several days at room temperature. (68⁰F -72⁰F)
- Bake at 250⁰F for several hours until no steam or smoke is coming out of it. Allow it to cool completely.
- Repeat at a slightly higher temperature. Repeat this step until it is completely baked in.
Regardless of what recipe you use, be sure to follow it just right. If the slightest little thing is done wrong, you could end up with cement that completely crumbles when its fired up to its full temperature.
When purchasing Perlite, make certain to choose a pure form. Do not purchase Vermiculite or a blend of several ingredients meant for plants.
Be aware that Portland cement is not a ready made mix. It is a pure cement that does not contain sand or rocks.
If you are building a forge, do not use a recipe that calls for Portland sand. It tends to turn to dust and crumble away quickly.
Be aware that it can take quite some time for the fire clay to bond to the silica sand when mixing the dry ingredients together. If you have a vibrating tumbler, cement mixer, or rolling tumbler available, you may want to use it in order to make this process faster and easier. However, you can no longer use these things once water has been added because the mix will be too gooey and thick.
When adding water, add as little as possible.
Under NO circumstances should you try to fire up your pizza oven/ fireplace/ furnace/ etc. to a high heat UNTIL you are absolutely certain it is COMPLETELY DRY. There is a possibility that it could explode.
It will take SEVERAL days to dry, especially if it is a bigger furnace or fireplace. Do not try to speed up the process. Be patient!
Alternatives to Refractory Cement
Old Red Clay Bricks with a solid middle: They are great heat deterrents. Stay away from new red clay bricks because they tend to be cheaply made, as well as any bricks that are burnt or have a black carbon color in the center. The best place to find old red clay bricks is in demolition yards. You may also be able to find someone selling them or even giving them away online or in an advertisement in the paper.
Fire brick (sometimes referred to as a refractory brick or a fire clay brick): They are heavy, last for extended periods of time even at extremely high temperatures, and work well in wood-fired ovens, fireplaces, fireboxes, and even large industrial furnaces. They are available in most home improvement stores. Do not confuse them with insulating lightweight firebricks.
Ankar sandstone (sometimes referred to as Angkor sandstone or Ankar firebrick: This is a type of sandstone that comes in a grayish-green color with a tone that is fine-grained. It is derived from volcanoes and is not that easy to find.
Soapstone: This is a metamorphic rock that absorbs the heat from a fire quickly.
Now that you have the information you need to make homemade refractory cement, it is time to run out to your local home improvement store and get everything you need to get started.
What project are you making with Refractory Cement? Let us know what and why!
Migrated from the old site's commenting system.
I want to use your recipe to make replacement firebrick for my wood burning stove (Vermont Castings). Should/can I add reinforcing metal rods or wire (something like hog wire) to strengthen it? Will the resulting brick be suitable for this application? They will be approximately 1" thick and 16" x 12".
What type of portland cement in formula 1 ?
Excellent formula No. 1 excellent explanation and excellent advice!!!
In the Helpful Tips section "Portland sand" must be a typo that really means Portland cement. As noted, that's not a mix, because straight Portland cement doesn't contain the sand that would be needed to make concrete (which isn't the goal here).
I could really use a refractory cement that can go up to 2500 degrees or so. I want to use it for a Wood-Fired Kiln to make ceramics. Any thoughts on what might be able to take me up to those higher temperatures? Thanks, this was very informative.
Hi there, I was thinking of using recipe #2 for my Microwave Kiln. Is it safe to microwave? Let me know if you can. Janet
Where do you get your perlite, or what is the best source, I could give a hoot less about the food value or for growing plants, I want to make good refractroy cement and I would like the best perlite available, amazon would be a plus since we are 100 miles from the first big city where they dont gouge on prices
alumina Hydrated .sodium silicate make furnace cement rice hush make silica carbon ceramic furnace insulating brick fired to cone 10 .firewood compressed air rice husk power fire clay is what ceramic motor are made of My glass furnace are made like this
Thank you so much for this information. Im building a rocket mass heater core soon and studying different (inexpensive) ways to make mix. In recipe 1 it says to use Portland cement. Ive read that Portland cement may crack under a lot of heat. Do you think this will be a problem?
Was anyone able to find all the products for any of the recipe? For #1 I cant find Fire Clay, for #2 I cant find Furnace Cement, and for 3 I cant find Fire Cement...
fire clay--- https://store.brickwoodovens.com/fire-clay furnace Cement---https://www.homedepot.com/p/Hercules-32-oz-High-Temperature-Furnace-Cement-045105/202262883 Fire cement----https://www.vitcas.com/prd/cty/fire-cement
For a baking oven, I want thermal mass so can the perlite be deleted or reduced from Recipe #1? Or is it crucial to the integrity of the finished structure? There will be a ceramic blanket over the inner oven layer, then another layer of castable, again without perlite.
Sorry to ask, are there any alternative for the pearlite?
Any recommendations on where to get fireclay from?
try pottery supply store, eg CCG in Auckland
Ben, In recipe 1 do you mix the dry fire clay with water then add to mix or just mix all ingredients other then fire clay then add the dry fire clay, followed by water?
I really liked his teachings, I have a question if this mass is only for the fire zone, on the walls and floor of the barbecue where the charcoal is placed for burning, or oven, and for the other parts the ducts to the chimney?
I recomend using microsilica (Silica Fume) from Poland from comapny Mikrosilika Trade. Its very good product (best quality) for refractory cement and concrete.
I want to cast aluminium discs and plates to be used on a lathe and this foundry plan looks easy to make. A question I have is: Does the refactory material (sand and plaster of paris) last? I'm seeing other internet posts where they say it cracks and breaks up - better to use perlite formulas etc. How have you users found your foundries lasting?
Has anyone experimented with aircrete? Seems would have great possibilities, only need a refractory binder, sans perlite.
Hi, Ben! Thank you for this post, it's very informative! I have a question about your recipes: are the measurements by volume or weight? I'm assuming volume since perlite is so light, but I wanted to double check. This is an old post so I'm really hoping you still check in from time to time. Thanks!
Hey Christina, as luck would have it, I did check and thanks for pointing that out! I wish I'd added comments to my site years ago and we could have saved so many people asking themselves the same question! The Answer: #2 does say it volume but both #1 and #3 fail to mention anything, as memory serves all 3 are by volume not by weight. Thanks for your question and please remember to be safe! Never use high heat on your refractory until it's completely dry or it could explode! (see "Safety Information" for more details). Have a great day!
Thanks for the reply!! One more question: can any of these recipes be used for the cooking surface? Or do I need something else? Excellent article, super helpful!
I'm looking to make a pizza stone as a replacement for a broken ones from this oven "ultimate-pizza-oven-bundle" from blackstoneproducts.com (since I can't find a substitute locally). My preferred choice would be recipe 2. Would this perlite be ok? "egmont-perlite-rootmix-5-litre-white" from bunnings.co.nz
Hello Andrea, If it's pure and doesn't contain anything else then It should be okay BUT that one does say "Egmont's Perlite is a light weight sterile potting media" and googling "sterile potting media" comes up with this rough definition: "Sterile soil is garden or potting soil that has undergone heat or chemical processing to kill any pathogens and seeds that are in it" so I'd personally be worried about this "chemical processing" was and if it's harmful to humans? I don't really know enough to recommend it, so to be safe I'd advise against using it unless you can find some reliable information, confirming it's safe and If you do, it would be great if you'd share your findings here! Remember I am not a professional anything just some guy who owns a website.
I run a fire service training center, and we have a Class A concrete burn building. Having issues with the walls that are directly exposed to high heat, and then water at approximately 95 GPM with 100PSI. Any suggestions for making repairs or rebuilding the wall? The walls are not supportive.
Hello Marc, Honestly no idea, high temperatures don't mix well with water/moisture if you have to constantly repair this wall I'd be very careful of the fact, that if refractory that is NOT 100% COMPLETELY DRY is exposed to high temperatures it can explode. I assume the wall is made out of fire bricks? maybe take a trip to your local fireplace maker/installer and see what they have to say.
Which recipe would be most suitable for a forge? I haven't seen maximum temperature ranges for these sort of mixes anywhere.
#3 does specify a temperature, depending how you make your forge most the heat goes in a upwards direction so sometimes the temperature your forge can reach doesn't have to be the same as the temperature it can withstand. Some people even make them out of car rims and sometimes lawn mower bodies (Not plastic or aluminum ones obviously) for example.
Forges made from wood lined with Red Georgia Clay have been used for blacksmithing. Like Ben says the hear goes up.
Hi! For recipe #1, are the parts by weight or volume? Formula 2 specifies volume, although weight would probably be more standard, so it's not clear. Thanks!
Hello, sorry about that! from memory, all are by volume
hi !! thank you very much about those informations. cana i use this formula for refractory kiln wagons production? i tried to produce Refractory Kiln Wagon Bricks for Red Clay Brick manufacturing but no good results till now.