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My old boss told me to stop floating edges so wet, and now my slabs show way fewer hairline cracks
I was finishing a 30 by 40 slab in Fresno last spring and running the magnesium float over edges while the mix was still shiny wet. The guy who trained me, 22 years pouring flatwork, walked up on the pour and asked me why I was working the edge that early. He said the bleed water comes back up and the paste goes soupy, then the edge dries weak and cracks along the forms. I started waiting until the sheen was gone, usually 20 to 30 minutes depending on the mix and the wind, before touching the edges at all. Did a 24 by 24 pad last week with that same crew and not one hairline crack along the perimeter. Anyone else get pushed to float edges sooner and fight cracks later?
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skyler_white11d ago
That line about the paste going soupy is the real deal, and I love how the fix is basically doing nothing for half an hour. Bosses hate it because you look lazy standing there staring at wet concrete, but the slab does the work for you if you just leave the edges alone. Meanwhile the guy who trained me wanted me on the edge the second the screed came off, then acted shocked when every pour looked like a spider web by the next morning. Funny how 22 years of experience beats whatever hurry the schedule is in. Tell your old boss he can float his own cracks.
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