Concrete set up in 20 minutes flat thanks to a surprise rainstorm

I was finishing a porch slab in Boise last Friday when the sky opened up and dumped on us before I could get the tarp on. Spent the next hour scrambling to cut control joints through concrete that was already harder than a rock (which is not fun with a standard jointer, let me tell you). Has anyone else had to deal with a sudden weather change mid-pour or am I the only unlucky one?

3 comments

3 Comments

ivanross24d ago

Actually rain slows down concrete setting not speeds it up, extra water makes it weaker not faster.

janarivera24d ago

That rainstorm SAVED you time honestly concrete sets slower without that extra moisture.

leodavis20d ago

Wait, did you actually get to cut joints or was it already too far gone? Man, that's the worst. Next time you get caught like that, grab a broom and push some water off the edges if you can, but don't mess with the surface too much. That extra water from rain actually can make the top layer weaker, so if you can tarp it fast enough or even just use plastic sheeting next time, you'll save yourself a headache. For joints on concrete that's already setting up like that, I've had good luck with a diamond blade on a grinder instead of fighting with a jointer. Just take it slow and let the blade do the work.