Ever seen a concrete 'blister'? Here’s how to avoid that nightmare. 😱 #shorts

Added: 2026-05-18

[00:00:00]We don't steel trowel exterior concrete here in Maine cuz our concrete's all air-entrained, which means it has tiny little air bubbles in it. So, when water does get on it and soaks into it and freezes, those little air bubbles allow the water to the frozen water to expand inside it without popping the concrete and spalling it.

[00:00:19]So, if we steel trowel it right now instead of magging it, the steel trowel seals that surface off and it will seal some of the moisture or it could seal some of the air that escapes under the surface of the concrete and it'll cause a blister, and that's just trouble. So, we mag it. The magging it doesn't seal the surface off as much, and then obviously when you pull that broom over it, that helps open the surface back up, too. There's still There's a lot of moisture coming out of this even though you can't see it.

[00:00:49]You can't seal that moisture in there.

[00:00:52]You can see I'm just lightly pulling that broom back. That's a concrete finishing broom, leaves a nice light broom finish.