How to Properly Mix Castable Refractory with Stainless Steel Fibers


#1

WHEN YOU MIX YOUR CASTABLE REFRACTORY WITH STAINLESS STEEL FIBERS AND CLEAN WATER, IT IS CRUCIAL THAT YOU MIX ALL THE INGREDIENTS EXACTLY AS DESCRIBED! FAILURE TO DO SO MAY RESULT IN A WEAK AND/OR BRITTLE HEARTH SLAB!

  1. Only use clean drinkable water when mixing castable refractory. In COLD weather, warm / tepid water can be used to bring the blended refractory mix to 60° - 75°. In HOT weather, cool water can be used to keep the mix under 80°. Keep in mind – warm water accelerates the refractory setting time (it will begin curing quickly). And cold water can delay the setting time (it will cure slowly – giving you more working / mixing time). If you are working / mixing the steps that involve the mixing of castable refractory by yourself – use cold water. Avoid using excessive water when mixing castable – too much water dilutes the binder and weakens the refractory.

  2. Only mix castable refractory in a wheelbarrow or mixing tub. DO NOT use a cement mixer as the mixing process will generate heat through friction - which will accelerate the curing process.

  3. When adding (1) of the 1lb bags of Stainless Steel Fibers per (1) 50lb-55lb of castable refractory, make sure you SPRINKLE the fibers over the dry castable refractory before you add water. If you just dump the bag of fibers on top of the castable refractory, you will not get a good blend as the fibers are jagged and prone to interlock to each other.

  4. Never cast castable refractory or cure / dry during freezing temperatures (32°F / 0°C).

  5. On the final day of curing / drying (Day 6 of 7), uncover the slab and allow to air-dry for the final 24 hours.

FUN FACT: Each 1lb bag of 1.5” Stainless Steel Fibers contain around 5000 of those SHARP jagged little fibers. When you multiply that by 7 bags, that’s around 35,000 fibers functioning like miniature rebar in your hearth slab!


#9

I used a 3.5CY Cement mixer and it worked like a charm. Midday temp was about 88F, so I used ice water. I bought 2 20lb. bags of ice and put it into a 5 gal bucket of water with a mesh bag. I got the water pretty frigid. As refractory was packed into the mold, it remained fairly cool to the touch and quite workable, which allowed us to slow down and pace ourselves over aprox. 3 hours. The heat from curing didn’t start to several hours later. We did try to mix the last bag in a tub, but it is EXTREMELY difficult especially with the fibers in it. So we finished it in the mixer.