How to make Refractory Cement 3+ Recipes

Ben -

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!

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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:

  1. Forge for blacksmithing
  2. Foundry for melting metal
  3. 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):

Would you pay for a guide on how to make a pizza oven with plans.

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.)

The Formula

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.

Download refractory cement recipe one

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
  • Perlite
  • Water

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.

Download refractory cement recipe two

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.)

Formula

4 parts Perlite + 1 part fire cement

What to Do:

  1. Mix Perlite and Fire cement using the above measurements.
  2. Allow it to try for several days at room temperature. (68⁰F -72⁰F)
  3. Bake at 250⁰F for several hours until no steam or smoke is coming out of it. Allow it to cool completely.
  4. Repeat at a slightly higher temperature. Repeat this step until it is completely baked in.

Helpful Tips

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.

Download refractory cement recipe three

Safety Information

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!