How to Insulate Refractory Concrete

Refractory concrete is made to release water from within its structure through curing and heating. This lack of water creates a material filled with air pockets that can help to absorb great levels of heat, allowing it to be used in high-heat applications, as with the body of a pizza oven, for example. Unfortunately, the heat also tends to pass through the material, heating the exterior of the concrete and reducing the efficiency in heat containment within. You can make your own insulative material using vermiculite, cement and lime for coverage of the concrete. Once applied, the concrete will have a layer of protection to prevent burns, and have a surface that prevents much of the heat from escaping through the concrete itself.

Rubber gloves
Safety goggles
Face mask
#3 grade vermiculite
Portland cement
Lime
Steel trowel

Instructions

- 1
  Put on a pair of rubber gloves, some safety goggles and a face mask before mixing the materials to make the insulation. This should help you avoid inhaling the materials, as well as prevent contact with skin or eyes.
- 2
  Mix by volume 13 parts vermiculite, 1 part Portland cement and 1 part lime in a large bucket to create your insulative coating. Add water to the mixture until it becomes slightly solid instead of a powder, but remains spreadable.
- 3
  Spread the mixture over the refractory concrete with a trowel, building up a 1-inch layer of the material. Allow the layer to set firm, then spread two more layers over the first, allowing each to set before applying the next.
- 4
  Mix a final batch of the insulative material using 2 parts cement instead of 1. Spread a new layer over the previous three, making this one only 1/2-inch thick.

Installation Instructions for Duro-Last Single-Ply Roofing

The Dimensions of Concrete Trench Blocks

Building Materials & Supplies