Does hot charcoal ruin concrete

Answer 1

Charcoal burns pretty hot, as things go. It might not be a good idea to leave it on concrete, at least not in a big pile. There is a problem with leaving a pile of burning charcoal on concrete. Concrete or any stone does not conduct heat really well. Sure, these materials get hot on hot days, and hold heat well. But if you heat concrete or stone or ceramic with a very hot source (charcoal burns at something on the order of 1100°C or 2000°F on contact, ball park), something called differential expansion breaks up the surface of the material being heated. Take a breath and read on. The intense heat from a source will cause localized expansion of material. And not enough heat will be conducted quickly into the underlying material to keep the difference in the expansion rates between the surface material and underlying material from breaking off tiny pieces at the surface of the material. Stone can actually be cut by "burning through" it with a hot source. The stone is not actually burned away, but differential thermal expansion nibbles it away, and a hot torch can cut stone (or concrete) in this way. If you spread burning charcoal out on concrete, you'll probably be okay. (Ash will insulate it a bit.) But it might not be a good idea to leave it in a pile.

Answer 2

Hot charcoal can potentially damage concrete through thermal shock, which occurs when a sudden extreme temperature change causes the material to expand and contract rapidly, leading to cracks or spalling. To prevent this, it's recommended to use insulating pads or trays underneath the charcoal when grilling on concrete surfaces to minimize direct contact and heat transfer.