concrete for hearth slab

Posted by ken

Hi Rado,
I have three questions.

1. What's the concrete mixture for the hearth slab? Is it 4:1:1 - 4 parts concrete blend : one part Portland cement : and one part lime? What's the lime for?

2. I understand that concrete becomes weaker when it is heated. I this a problem for the hearth slab?

3. Are you familiar with Quikrete? Quikrete - Basically, it's a "just add water" type of mixture. I am using it for the oven slab. I was thinking about using it for the hearth slab but I would add lime as well as water. Basically I am trying to avoid having to buy both sand and gravel.

Thanks for all your help! I am pouring the oven slab this weekend. I can hardly wait!
ken