A pour in Boise made me rethink my bull float timing

We were finishing a big warehouse slab out there last fall, and the sun was brutal. The concrete started setting up way faster than I expected, maybe 15 minutes after the screed. I went in with my magnesium bull float like normal, and it just started tearing the surface. My foreman, Dave, yelled over, 'You're late, get the darby on it now!' I switched tools immediately and saved it. Now I always check the air temp and mix design before I even pick up the float. Anyone else had a job where the weather completely threw off your timing?

4 comments

4 Comments

ray6432mo ago

Reading the slab is one thing, but a sudden temp swing can really mess with your head. That fifteen minute window turning into five is no joke. You really think just feeling the surface is enough when the mix itself is cooking faster than planned?

kevin_williams2mo ago

Tbh I read somewhere that feeling the surface can lie if the mix is heating up from the inside.

john5062mo ago

Honestly, checking the air temp sounds like overthinking it. A good finisher should just read the slab and feel when it's ready.

sandragrant29d ago

Oh man, I gotta push back a little here. The air temp isn't just some numbers on a gadget, it's literally the control knob for how fast that slab sets. You can have the best feel in the world, but if the air is 95 degrees and the sun is beating down, your "read" on the surface might be a wet sheen that's actually a crust forming over a hot, fast-setting core. I've been burned (literally, in a heat rash kind of way) by that exact trap. Feeling the slab is a huge part of it, sure, but ignoring the air is like driving with your eyes on the dash and thinking you know the road. It's a tool in the box, not a replacement for skill.