Chasing a slab crack for 2 days, turned out to be one dumb pour detail

Ran a residential job out in Fresno last Friday, 12 yard pad for a patio. Customer points out this hairline crack running corner to corner, looks like a cold joint but I know we poured it continuous. I spent all Saturday grinding it out, patching it, trying to match the color, cussing at my finisher for not keeping the crew moving faster. Then the old guy down the street walks over and asks if we wet the subgrade before we poured. I did NOT. Bone dry dirt sucked the moisture out of the bottom of the slab before it set, that's the whole story. Two days of work and it was a 5 minute fix on the next pour, just hose the ground down. Anyone else ever fought a mystery crack that was just bad prep under the slab?

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betty_palmer14d ago

That bone dry dirt got me too once, water is cheap compared to grinding and patching.