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Why does nobody dampen the substrate before pouring?
I watched a crew pour a 40x60 slab last week and they didn't wet the ground AT ALL before dumping the concrete. The dirt sucked all the moisture out and we got crusty edges within 20 minutes. Has anyone else had to deal with fixing slabs where the finisher skipped this step?
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averymartin6d ago
Oh man, I've been there. Dampening the subgrade makes a huge difference, especially in hot weather. If you're stuck with a slab that's already crusting up, hitting those edges with a mist and a trowel as soon as possible is about all you can do.
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oscar7436d ago
Wait, aren't you supposed to dampen the subgrade before you pour, not after? Once that crust starts forming, misting it can actually mess with the surface and cause dusting or scaling if you're not careful. I've seen guys make it worse by adding water too late, so timing is everything with that trick.
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chen.adam3d ago
...and my buddy learned this one the hard way last summer. He was helping a crew pour a small garage slab and they just dumped it right on dry dirt. Within ten minutes the edges were already setting up rough. He tried hitting it with a light mist from a hand sprayer but that just made the surface go kind of crumbly in spots. The finisher ended up having to kill an hour troweling the whole thing twice just to smooth out those crunchy areas. I mean maybe it's just me but I'd rather spend the five minutes soaking the ground first than deal with that mess.
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