Forum / poured oven floor vs fire brick

I have looked everywhere for info on poured oven floors and can only find fire brick answers. I found a company that says they have food grade refractory castable cement but they've never sold it for pizza ovens. What should I look out for? Is there a certain temperature that it has to hit in order for the ingredients to bond? Will I need to make a couple of surface cuts to allow for expansion? Why do I see many restaurant ovens use a poured floor and not fire brick and yet I can't find info on how to do it? Here is a sample of the floor I'm looking for

Best Pizza Ovens | Best Wood-Fired Ovens - King of the Coals