That old finisher in Kansas City told me to wet burlap my slab and I thought he was nuts

I was sure the air was dry enough to just let it cure on its own, but after it spiderwebbed on me I guess the 90 degree heat proved him right. Anybody else ever get burned by ignoring advice from the greybeards on site?

3 comments

3 Comments

the_diana29d ago

Oh man, that's the thing about old timers. They've seen enough concrete fail in ways most of us haven't even imagined yet. The real angle nobody talks about is how air temperature and wind speed can trick you into thinking the surface is fine while the core is still cooking off. That burlap trick does two things people miss: it keeps the water from evaporating too fast and it maintains a more even temperature across the whole slab. I had a crew foreman once tell me that concrete curing is like making a souffle, you can't rush the middle or the whole thing falls apart. Your 90 degree heat was probably pulling moisture out before the chemical reaction even had a chance to finish. People think curing is just keeping it wet, but it's really about keeping the temperature gradient from getting too wild between the surface and the bottom.

piper_kim29d ago

Old timers have a way of being right about stuff that sounds crazy at first. Guy I used to work with always said to put a tarp over foundation walls after they're poured and leave it for a week. I thought he was just being lazy until the next job I skipped it on and the top inch crumbled like stale cornbread when I went to drill anchor holes. Never skipped the tarp again after that.

emmaclark29d agoOG Member

That souffle analogy hits hard. Never thought about the temperature gradient like that.