A foreman in Dayton told me to stop finishing concrete in the heat of the day and I thought he was full of it
Back in July we were pouring a 30 by 40 slab and I wanted to keep working through the afternoon like always. He said wait until 5pm or you'll get crazing and a weak top, and I figured he was just stalling. Sure enough, my morning pours that week came out clean and the one hot pour I rushed had spider cracks all over it by Friday. Anybody else schedule around temps or do you just deal with the finish however it lands?
30 by 40 is a big pour and yeah the sun will cook the top, but spider cracks by Friday sounds more like you got on it too late with the trowel than the heat itself. Guys have been pouring in Texas and Arizona summers forever and somehow the slabs hold up fine. Sounds to me like the foreman was right for the wrong reason, because waiting till 5 is about having enough hands to finish it before it sets, not some magic temperature rule. I still think a good finisher can handle a hot pour if he stays ahead of it.