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My foreman in Dallas bet me $50 that wetting the subgrade before a pour was a waste, and he paid up
I poured a 22x30 slab last Tuesday in Dallas and the subgrade was bone dry, so I hosed it down before we screeded, which is something a finisher named Ray showed me back in 2019. My foreman laughed and said it was a waste of water, but the mix stopped sucking moisture out of the paste, and we got way fewer plastic shrinkage cracks than the pour we did the week before on dry dirt. Anyone else notice a difference on dry vs damp subgrade, or is it just a north Texas clay thing?
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theas2821d ago
Damp subgrade also keeps the ground from pulling water up out of the concrete while it cures, which matters more than people give it credit for. On dry clay the suction is strong enough that the bottom of the slab sets faster than the top, and that uneven curing is what bites you later with curling and edge cracks. Your foreman probably only ever watched the surface, so he never saw what was happening underneath.
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