Lime not needed?

[swarm1023]

Hey guys, I've been checking stuff out on FB for quite a while. Thinking and planning to build a WFO. I work at a ceramic tile manufacturing plant and was given some old fire brick from a kiln that was taken out of service, so now I'm all in in building my oven. I've been trying to check out mainly what people are saying about mortar mixtures, and I checked with a local brick company trying to find hydrated lime and the guy told me that they don't sell it and it isn't necessary. They sell firebrick and even pizza oven kits and only recommend portland cement, sand and fireclay. He said they have never had any problems with fireplaces or oven using this mixture. My search isn't completely exhausted, but I live in a small town and don't have many other options to find lime. Any thoughts?

I started working this past weekend on my oven, got the base dug out and surrounding walls started.

[DavidApp]

Hello Swarm 1023

I understand that the lime helps to make the mortar more plastic and easier to apply. It may also have some bearing on it's high temperature properties. I used HeatStop 50 because I could not find the "S" Type lime and did not want to follow the advice from the brick yard. I would rather follow the experience on this forum and use the complete home brew formula or a refractory mortar.

David

[Cubslover]

I believe the Lime is necessary.

The general consensus is a 3:1:1:1 mix and it serves everyone well. I found my lime at menards of all places. cheap stuff. I also increased the sand a bit in my mix. I had to travel an hour for the fireclay. I think you should probably expect to travel a bit for certain materials.

Where are you located?

[Tscarborough]

He is located in the past as this is an old thread. Also the consensus is not 3:1:1:1, it is (correctly stated) 1:1:1:5-6 portland/lime/fireclay/sand