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Old timer told me to wet the subgrade before pouring. I thought he was crazy.
Guy named Hank, been pouring since the 70s, told me to hose down the dirt before my slab pour on a hot day in Phoenix. I figured it would just turn into mud. Did it anyway because he was buying lunch. That slab didn't crack a week later while my other dry-pour jobs looked like a spiderweb. Has anyone else tried this trick, or am I just late to the party?
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vera_lewis5mo ago
Saw a study once that said @wesleyc75 was right, moisture control stops cracks.
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graym494mo ago
Wetting that subgrade stops the dry dirt from sucking all the moisture out of your concrete" - you're giving the dirt too much credit. If you oversaturate the subgrade, you're just swapping one problem for another. That moisture has to go somewhere once it's trapped under the slab, and it usually finds its way up through the cracks you're trying to prevent. I've seen more slab failures from over-wetting than from dry soils pulling moisture out. The real trick is getting a consistent moisture content, not just flooding it and calling it good. Study or not, there's a fine line between damp and swamp.
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wesleyc755mo ago
Ngl, Hank was right. Wetting that subgrade stops the dry dirt from sucking all the moisture out of your concrete.
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