Loading…
6
Pouring a slab in the rain in Amarillo taught me more about mix water than 5 years of books
Back in March I was finishing a 30x40 shop slab outside Amarillo and the sky opened up about an hour after we screeded it. I panicked and wanted to tarp the whole thing, but the old timer running the pump told me to leave it and just watch the bleed water. He said rain on fresh concrete is bad mostly when you work it back in and change your water cement ratio at the surface. So we waited it out, let the sheen come back, and finished it with a magnesium float once it set up enough to hold a edge. That slab cured out harder than anything I poured all spring, no dusting, no scaling, nothing. I used to think any water on top was a death sentence, but the real killer is troweling too early and sealing that water in. Now I keep a cheap plastic sheet in the truck for downpours but I dont freak out over a little sprinkle. Any of you ever had a pour get rained on and come out better than expected?
1 comments
Log in to join the discussion
Log In1 Comment
derek6563d ago
Did you ever read that ACI report on hot weather and rain effects on fresh concrete? I remember reading somewhere that light rain during bleeding can actually help because it keeps the surface from drying out too fast, which is kinda the opposite of what most guys assume. The real problem is the timing, like you said, if you get after it with a trowel while that water is still sitting there you're just pushing a weak paste around on top. Sounds like that old timer knew exactly when to let it sit and when to work it. Most of the scaling and dusting jobs I've seen were guys fighting the weather instead of reading the slab.
9