Originally Posted by BBQchef33
A pizza stone is a cheap alternative.
A lot of cheap pizza stones can't take the heat, either. They have been known so shatter or explode when used on a grill.
I read somewhere that the heat causes moisture in the concrete to expand and that is what causes the problem. The older the concrete the less moisture, but I still wouldn't take the chance. I did use my PBC on the front walk, but it was 18 degrees outside so it apparently didn't get hot enough to cause a problem.