Old foreman showed me his cure time trick for high heat jobs in Phoenix

I was out on a driveway pour last July, temp was pushing 108, and I was about to hit the slab with the evaporation retarder. This old guy I was working with, been doing concrete for like 40 years, just shook his head and told me to wet the subgrade the night before instead of dumping water on top during the pour. Said it keeps the mix from drying out from underneath (which I never really thought about). So I tried it and the slab didnt spiderweb crack like the one I did the month before. Anyone else use that method or do you just stick with the spray-on stuff?

3 comments

3 Comments

seanjohnson1d ago

Started doing that a few years back after watching a slab suck moisture out of the ground so fast you could see it turning white before we even got the bull float on it. The trick is to really soak the subgrade good the night before, like standing water in spots, then hit it again early morning before the pour. Saved me a ton of headache with curling edges on hot days, plus you use way less retarder spray which adds up over a season.

david7391d ago

Man I felt that in my bones just reading it. Nothing humbles a guy faster than watching a fresh slab turn into a desert in five minutes flat lol. First time it happened to me I was so proud of the finish until it cracked like a freakin jigsaw puzzle an hour later. Now I feel like I'm watering the ground like a garden before a pour, neighbors probably think I'm trying to start a rice paddy. But yeah you're dead right about the curling edges, that's a nightmare I don't miss one bit.

diana_black221d ago

Last summer I tried this on a driveway pour and the mix stayed workable almost an hour longer than usual, which let us take our time with the broom finish. Made me wonder why more guys don't pre-wet when it's that simple, cause @seanjohnson is right about it knocking down the panic factor on hot pours. Now I keep a sprinkler on the subgrade overnight whenever the forecast hits 85.